+/* $Id: evdns.c,v 1.21 2007-11-08 18:38:52 root Exp $ */
+
+/* The original version of this module was written by Adam Langley; for
+ * a history of modifications, check out the subversion logs.
+ *
+ * When editing this module, try to keep it re-mergeable by Adam. Don't
+ * reformat the whitespace, add Tor dependencies, or so on.
+ *
+ * TODO:
+ * - Support IPv6 and PTR records.
+ * - Replace all externally visible magic numbers with #defined constants.
+ * - Write doccumentation for APIs of all external functions.
+ */
+
+/* Async DNS Library
+ * Adam Langley <agl@imperialviolet.org>
+ * http://www.imperialviolet.org/eventdns.html
+ * Public Domain code
+ *
+ * This software is Public Domain. To view a copy of the public domain dedication,
+ * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to
+ * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.
+ *
+ * I ask and expect, but do not require, that all derivative works contain an
+ * attribution similar to:
+ * Parts developed by Adam Langley <agl@imperialviolet.org>
+ *
+ * You may wish to replace the word "Parts" with something else depending on
+ * the amount of original code.
+ *
+ * (Derivative works does not include programs which link against, run or include
+ * the source verbatim in their source distributions)
+ *
+ * Version: 0.1b
+ */
+
+#include <sys/types.h>
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#ifdef WIN32
+#ifndef EV_STANDALONE
+#include "misc.h"
+#endif
+#endif
+
+/* #define NDEBUG */
+
+#ifndef DNS_USE_CPU_CLOCK_FOR_ID
+#ifndef DNS_USE_GETTIMEOFDAY_FOR_ID
+#ifndef DNS_USE_OPENSSL_FOR_ID
+#error Must configure at least one id generation method.
+#error Please see the documentation.
+#endif
+#endif
+#endif
+
+/* #define _POSIX_C_SOURCE 200507 */
+#define _GNU_SOURCE
+
+#ifdef DNS_USE_CPU_CLOCK_FOR_ID
+#ifdef DNS_USE_OPENSSL_FOR_ID
+#error Multiple id options selected
+#endif
+#ifdef DNS_USE_GETTIMEOFDAY_FOR_ID
+#error Multiple id options selected
+#endif
+#include <time.h>
+#endif
+
+#ifdef DNS_USE_OPENSSL_FOR_ID
+#ifdef DNS_USE_GETTIMEOFDAY_FOR_ID
+#error Multiple id options selected
+#endif
+#include <openssl/rand.h>
+#endif
+
+#define _FORTIFY_SOURCE 3
+
+#include <string.h>
+#include <fcntl.h>
+#include <sys/time.h>
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#endif
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+#include <unistd.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <ctype.h>
+#include <stdio.h>
+#include <stdarg.h>
+
+#include "evdns.h"
+#ifdef WIN32
+#include <windows.h>
+#include <winsock2.h>
+#include <iphlpapi.h>
+#else
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#endif
+
+#ifdef HAVE_NETINET_IN6_H
+#include <netinet/in6.h>
+#endif
+
+#ifdef WIN32
+typedef int socklen_t;
+#endif
+
+#define EVDNS_LOG_DEBUG 0
+#define EVDNS_LOG_WARN 1
+
+#ifndef HOST_NAME_MAX
+#define HOST_NAME_MAX 255
+#endif
+
+#ifndef NDEBUG
+#include <stdio.h>
+#endif
+
+#undef MIN
+#define MIN(a,b) ((a)<(b)?(a):(b))
+
+#ifdef __USE_ISOC99B
+/* libevent doesn't work without this */
+typedef uint8_t u_char;
+typedef unsigned int uint;
+#endif
+#include <event.h>
+
+#define u64 uint64_t
+#define u32 uint32_t
+#define u16 uint16_t
+#define u8 uint8_t
+
+#define MAX_ADDRS 4 /* maximum number of addresses from a single packet */
+/* which we bother recording */
+
+#define TYPE_A EVDNS_TYPE_A
+#define TYPE_CNAME 5
+#define TYPE_PTR EVDNS_TYPE_PTR
+#define TYPE_AAAA EVDNS_TYPE_AAAA
+
+#define CLASS_INET EVDNS_CLASS_INET
+
+struct request {
+ u8 *request; /* the dns packet data */
+ unsigned int request_len;
+ int reissue_count;
+ int tx_count; /* the number of times that this packet has been sent */
+ unsigned int request_type; /* TYPE_PTR or TYPE_A */
+ void *user_pointer; /* the pointer given to us for this request */
+ evdns_callback_type user_callback;
+ struct nameserver *ns; /* the server which we last sent it */
+
+ /* elements used by the searching code */
+ int search_index;
+ struct search_state *search_state;
+ char *search_origname; /* needs to be free()ed */
+ int search_flags;
+
+ /* these objects are kept in a circular list */
+ struct request *next, *prev;
+
+ struct event timeout_event;
+
+ u16 trans_id; /* the transaction id */
+ char request_appended; /* true if the request pointer is data which follows this struct */
+ char transmit_me; /* needs to be transmitted */
+};
+
+#ifndef HAVE_STRUCT_IN6_ADDR
+struct in6_addr {
+ u8 s6_addr[16];
+};
+#endif
+
+struct reply {
+ unsigned int type;
+ unsigned int have_answer;
+ union {
+ struct {
+ u32 addrcount;
+ u32 addresses[MAX_ADDRS];
+ } a;
+ struct {
+ u32 addrcount;
+ struct in6_addr addresses[MAX_ADDRS];
+ } aaaa;
+ struct {
+ char name[HOST_NAME_MAX];
+ } ptr;
+ } data;
+};
+
+struct nameserver {
+ int socket; /* a connected UDP socket */
+ u32 address;
+ int failed_times; /* number of times which we have given this server a chance */
+ int timedout; /* number of times in a row a request has timed out */
+ struct event event;
+ /* these objects are kept in a circular list */
+ struct nameserver *next, *prev;
+ struct event timeout_event; /* used to keep the timeout for */
+ /* when we next probe this server. */
+ /* Valid if state == 0 */
+ char state; /* zero if we think that this server is down */
+ char choked; /* true if we have an EAGAIN from this server's socket */
+ char write_waiting; /* true if we are waiting for EV_WRITE events */
+};
+
+static struct request *req_head = NULL, *req_waiting_head = NULL;
+static struct nameserver *server_head = NULL;
+
+/* Represents a local port where we're listening for DNS requests. Right now, */
+/* only UDP is supported. */
+struct evdns_server_port {
+ int socket; /* socket we use to read queries and write replies. */
+ int refcnt; /* reference count. */
+ char choked; /* Are we currently blocked from writing? */
+ char closing; /* Are we trying to close this port, pending writes? */
+ evdns_request_callback_fn_type user_callback; /* Fn to handle requests */
+ void *user_data; /* Opaque pointer passed to user_callback */
+ struct event event; /* Read/write event */
+ /* circular list of replies that we want to write. */
+ struct server_request *pending_replies;
+};
+
+/* Represents part of a reply being built. (That is, a single RR.) */
+struct server_reply_item {
+ struct server_reply_item *next; /* next item in sequence. */
+ char *name; /* name part of the RR */
+ u16 type : 16; /* The RR type */
+ u16 class : 16; /* The RR class (usually CLASS_INET) */
+ u32 ttl; /* The RR TTL */
+ char is_name; /* True iff data is a label */
+ u16 datalen; /* Length of data; -1 if data is a label */
+ void *data; /* The contents of the RR */
+};
+
+/* Represents a request that we've received as a DNS server, and holds */
+/* the components of the reply as we're constructing it. */
+struct server_request {
+ /* Pointers to the next and previous entries on the list of replies */
+ /* that we're waiting to write. Only set if we have tried to respond */
+ /* and gotten EAGAIN. */
+ struct server_request *next_pending;
+ struct server_request *prev_pending;
+
+ u16 trans_id; /* Transaction id. */
+ struct evdns_server_port *port; /* Which port received this request on? */
+ struct sockaddr_storage addr; /* Where to send the response */
+ socklen_t addrlen; /* length of addr */
+
+ int n_answer; /* how many answer RRs have been set? */
+ int n_authority; /* how many authority RRs have been set? */
+ int n_additional; /* how many additional RRs have been set? */
+
+ struct server_reply_item *answer; /* linked list of answer RRs */
+ struct server_reply_item *authority; /* linked list of authority RRs */
+ struct server_reply_item *additional; /* linked list of additional RRs */
+
+ /* Constructed response. Only set once we're ready to send a reply. */
+ /* Once this is set, the RR fields are cleared, and no more should be set. */
+ char *response;
+ size_t response_len;
+
+ /* Caller-visible fields: flags, questions. */
+ struct evdns_server_request base;
+};
+
+/* helper macro */
+#define OFFSET_OF(st, member) ((off_t) (((char*)&((st*)0)->member)-(char*)0))
+
+/* Given a pointer to an evdns_server_request, get the corresponding */
+/* server_request. */
+#define TO_SERVER_REQUEST(base_ptr) \
+ ((struct server_request*) \
+ (((char*)(base_ptr) - OFFSET_OF(struct server_request, base))))
+
+/* The number of good nameservers that we have */
+static int global_good_nameservers = 0;
+
+/* inflight requests are contained in the req_head list */
+/* and are actually going out across the network */
+static int global_requests_inflight = 0;
+/* requests which aren't inflight are in the waiting list */
+/* and are counted here */
+static int global_requests_waiting = 0;
+
+static int global_max_requests_inflight = 64;
+
+static struct timeval global_timeout = {5, 0}; /* 5 seconds */
+static int global_max_reissues = 1; /* a reissue occurs when we get some errors from the server */
+static int global_max_retransmits = 3; /* number of times we'll retransmit a request which timed out */
+/* number of timeouts in a row before we consider this server to be down */
+static int global_max_nameserver_timeout = 3;
+
+/* These are the timeout values for nameservers. If we find a nameserver is down */
+/* we try to probe it at intervals as given below. Values are in seconds. */
+static const struct timeval global_nameserver_timeouts[] = {{10, 0}, {60, 0}, {300, 0}, {900, 0}, {3600, 0}};
+static const int global_nameserver_timeouts_length = sizeof(global_nameserver_timeouts)/sizeof(struct timeval);
+
+static struct nameserver *nameserver_pick(void);
+static void evdns_request_insert(struct request *req, struct request **head);
+static void nameserver_ready_callback(int fd, short events, void *arg);
+static int evdns_transmit(void);
+static int evdns_request_transmit(struct request *req);
+static void nameserver_send_probe(struct nameserver *const ns);
+static void search_request_finished(struct request *const);
+static int search_try_next(struct request *const req);
+static int search_request_new(int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg);
+static void evdns_requests_pump_waiting_queue(void);
+static u16 transaction_id_pick(void);
+static struct request *request_new(int type, const char *name, int flags, evdns_callback_type callback, void *ptr);
+static void request_submit(struct request *req);
+
+static int server_request_free(struct server_request *req);
+static void server_request_free_answers(struct server_request *req);
+static void server_port_free(struct evdns_server_port *port);
+static void server_port_ready_callback(int fd, short events, void *arg);
+
+static int strtoint(const char *const str);
+
+#ifdef WIN32
+static int
+last_error(int sock)
+{
+ int optval, optvallen=sizeof(optval);
+ int err = WSAGetLastError();
+ if (err == WSAEWOULDBLOCK && sock >= 0) {
+ if (getsockopt(sock, SOL_SOCKET, SO_ERROR, (void*)&optval,
+ &optvallen))
+ return err;
+ if (optval)
+ return optval;
+ }
+ return err;
+
+}
+static int
+error_is_eagain(int err)
+{
+ return err == EAGAIN || err == WSAEWOULDBLOCK;
+}
+static int
+inet_aton(const char *c, struct in_addr *addr)
+{
+ uint32_t r;
+ if (strcmp(c, "255.255.255.255") == 0) {
+ addr->s_addr = 0xffffffffu;
+ } else {
+ r = inet_addr(c);
+ if (r == INADDR_NONE)
+ return 0;
+ addr->s_addr = r;
+ }
+ return 1;
+}
+#define CLOSE_SOCKET(x) closesocket(x)
+#else
+#define last_error(sock) (errno)
+#define error_is_eagain(err) ((err) == EAGAIN)
+#define CLOSE_SOCKET(x) close(x)
+#endif
+
+#define ISSPACE(c) isspace((int)(unsigned char)(c))
+#define ISDIGIT(c) isdigit((int)(unsigned char)(c))
+
+#ifndef NDEBUG
+static const char *
+debug_ntoa(u32 address)
+{
+ static char buf[32];
+ u32 a = ntohl(address);
+ snprintf(buf, sizeof(buf), "%d.%d.%d.%d",
+ (int)(u8)((a>>24)&0xff),
+ (int)(u8)((a>>16)&0xff),
+ (int)(u8)((a>>8 )&0xff),
+ (int)(u8)((a )&0xff));
+ return buf;
+}
+#endif
+
+static evdns_debug_log_fn_type evdns_log_fn = NULL;
+
+void
+evdns_set_log_fn(evdns_debug_log_fn_type fn)
+{
+ evdns_log_fn = fn;
+}
+
+#ifdef __GNUC__
+#define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3)))
+#else
+#define EVDNS_LOG_CHECK
+#endif
+
+static void _evdns_log(int warn, const char *fmt, ...) EVDNS_LOG_CHECK;
+static void
+_evdns_log(int warn, const char *fmt, ...)
+{
+ va_list args;
+ static char buf[512];
+ if (!evdns_log_fn)
+ return;
+ va_start(args,fmt);
+#ifdef WIN32
+ _vsnprintf(buf, sizeof(buf), fmt, args);
+#else
+ vsnprintf(buf, sizeof(buf), fmt, args);
+#endif
+ buf[sizeof(buf)-1] = '\0';
+ evdns_log_fn(warn, buf);
+ va_end(args);
+}
+
+#define log _evdns_log
+
+/* This walks the list of inflight requests to find the */
+/* one with a matching transaction id. Returns NULL on */
+/* failure */
+static struct request *
+request_find_from_trans_id(u16 trans_id) {
+ struct request *req = req_head, *const started_at = req_head;
+
+ if (req) {
+ do {
+ if (req->trans_id == trans_id) return req;
+ req = req->next;
+ } while (req != started_at);
+ }
+
+ return NULL;
+}
+
+/* a libevent callback function which is called when a nameserver */
+/* has gone down and we want to test if it has came back to life yet */
+static void
+nameserver_prod_callback(int fd, short events, void *arg) {
+ struct nameserver *const ns = (struct nameserver *) arg;
+ (void)fd;
+ (void)events;
+
+ nameserver_send_probe(ns);
+}
+
+/* a libevent callback which is called when a nameserver probe (to see if */
+/* it has come back to life) times out. We increment the count of failed_times */
+/* and wait longer to send the next probe packet. */
+static void
+nameserver_probe_failed(struct nameserver *const ns) {
+ const struct timeval * timeout;
+ (void) evtimer_del(&ns->timeout_event);
+ if (ns->state == 1) {
+ /* This can happen if the nameserver acts in a way which makes us mark */
+ /* it as bad and then starts sending good replies. */
+ return;
+ }
+
+ timeout =
+ &global_nameserver_timeouts[MIN(ns->failed_times,
+ global_nameserver_timeouts_length - 1)];
+ ns->failed_times++;
+
+ evtimer_set(&ns->timeout_event, nameserver_prod_callback, ns);
+ if (evtimer_add(&ns->timeout_event, (struct timeval *) timeout) < 0) {
+ log(EVDNS_LOG_WARN,
+ "Error from libevent when adding timer event for %s",
+ debug_ntoa(ns->address));
+ /* ???? Do more? */
+ }
+}
+
+/* called when a nameserver has been deemed to have failed. For example, too */
+/* many packets have timed out etc */
+static void
+nameserver_failed(struct nameserver *const ns, const char *msg) {
+ struct request *req, *started_at;
+ /* if this nameserver has already been marked as failed */
+ /* then don't do anything */
+ if (!ns->state) return;
+
+ log(EVDNS_LOG_WARN, "Nameserver %s has failed: %s",
+ debug_ntoa(ns->address), msg);
+ global_good_nameservers--;
+ assert(global_good_nameservers >= 0);
+ if (global_good_nameservers == 0) {
+ log(EVDNS_LOG_WARN, "All nameservers have failed");
+ }
+
+ ns->state = 0;
+ ns->failed_times = 1;
+
+ evtimer_set(&ns->timeout_event, nameserver_prod_callback, ns);
+ if (evtimer_add(&ns->timeout_event, (struct timeval *) &global_nameserver_timeouts[0]) < 0) {
+ log(EVDNS_LOG_WARN,
+ "Error from libevent when adding timer event for %s",
+ debug_ntoa(ns->address));
+ /* ???? Do more? */
+ }
+
+ /* walk the list of inflight requests to see if any can be reassigned to */
+ /* a different server. Requests in the waiting queue don't have a */
+ /* nameserver assigned yet */
+
+ /* if we don't have *any* good nameservers then there's no point */
+ /* trying to reassign requests to one */
+ if (!global_good_nameservers) return;
+
+ req = req_head;
+ started_at = req_head;
+ if (req) {
+ do {
+ if (req->tx_count == 0 && req->ns == ns) {
+ /* still waiting to go out, can be moved */
+ /* to another server */
+ req->ns = nameserver_pick();
+ }
+ req = req->next;
+ } while (req != started_at);
+ }
+}
+
+static void
+nameserver_up(struct nameserver *const ns) {
+ if (ns->state) return;
+ log(EVDNS_LOG_WARN, "Nameserver %s is back up",
+ debug_ntoa(ns->address));
+ evtimer_del(&ns->timeout_event);
+ ns->state = 1;
+ ns->failed_times = 0;
+ ns->timedout = 0;
+ global_good_nameservers++;
+}
+
+static void
+request_trans_id_set(struct request *const req, const u16 trans_id) {
+ req->trans_id = trans_id;
+ *((u16 *) req->request) = htons(trans_id);
+}
+
+/* Called to remove a request from a list and dealloc it. */
+/* head is a pointer to the head of the list it should be */
+/* removed from or NULL if the request isn't in a list. */
+static void
+request_finished(struct request *const req, struct request **head) {
+ if (head) {
+ if (req->next == req) {
+ /* only item in the list */
+ *head = NULL;
+ } else {
+ req->next->prev = req->prev;
+ req->prev->next = req->next;
+ if (*head == req) *head = req->next;
+ }
+ }
+
+ log(EVDNS_LOG_DEBUG, "Removing timeout for request %lx",
+ (unsigned long) req);
+ evtimer_del(&req->timeout_event);
+
+ search_request_finished(req);
+ global_requests_inflight--;
+
+ if (!req->request_appended) {
+ /* need to free the request data on it's own */
+ free(req->request);
+ } else {
+ /* the request data is appended onto the header */
+ /* so everything gets free()ed when we: */
+ }
+
+ free(req);
+
+ evdns_requests_pump_waiting_queue();
+}
+
+/* This is called when a server returns a funny error code. */
+/* We try the request again with another server. */
+/* */
+/* return: */
+/* 0 ok */
+/* 1 failed/reissue is pointless */
+static int
+request_reissue(struct request *req) {
+ const struct nameserver *const last_ns = req->ns;
+ /* the last nameserver should have been marked as failing */
+ /* by the caller of this function, therefore pick will try */
+ /* not to return it */
+ req->ns = nameserver_pick();
+ if (req->ns == last_ns) {
+ /* ... but pick did return it */
+ /* not a lot of point in trying again with the */
+ /* same server */
+ return 1;
+ }
+
+ req->reissue_count++;
+ req->tx_count = 0;
+ req->transmit_me = 1;
+
+ return 0;
+}
+
+/* this function looks for space on the inflight queue and promotes */
+/* requests from the waiting queue if it can. */
+static void
+evdns_requests_pump_waiting_queue(void) {
+ while (global_requests_inflight < global_max_requests_inflight &&
+ global_requests_waiting) {
+ struct request *req;
+ /* move a request from the waiting queue to the inflight queue */
+ assert(req_waiting_head);
+ if (req_waiting_head->next == req_waiting_head) {
+ /* only one item in the queue */
+ req = req_waiting_head;
+ req_waiting_head = NULL;
+ } else {
+ req = req_waiting_head;
+ req->next->prev = req->prev;
+ req->prev->next = req->next;
+ req_waiting_head = req->next;
+ }
+
+ global_requests_waiting--;
+ global_requests_inflight++;
+
+ req->ns = nameserver_pick();
+ request_trans_id_set(req, transaction_id_pick());
+
+ evdns_request_insert(req, &req_head);
+ evdns_request_transmit(req);
+ evdns_transmit();
+ }
+}
+
+static void
+reply_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply) {
+ switch (req->request_type) {
+ case TYPE_A:
+ if (reply)
+ req->user_callback(DNS_ERR_NONE, DNS_IPv4_A,
+ reply->data.a.addrcount, ttl,
+ reply->data.a.addresses,
+ req->user_pointer);
+ else
+ req->user_callback(err, 0, 0, 0, NULL, req->user_pointer);
+ return;
+ case TYPE_PTR:
+ if (reply) {
+ char *name = reply->data.ptr.name;
+ req->user_callback(DNS_ERR_NONE, DNS_PTR, 1, ttl,
+ &name, req->user_pointer);
+ } else {
+ req->user_callback(err, 0, 0, 0, NULL,
+ req->user_pointer);
+ }
+ return;
+ case TYPE_AAAA:
+ if (reply)
+ req->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA,
+ reply->data.aaaa.addrcount, ttl,
+ reply->data.aaaa.addresses,
+ req->user_pointer);
+ else
+ req->user_callback(err, 0, 0, 0, NULL, req->user_pointer);
+ return;
+ }
+ assert(0);
+}
+
+/* this processes a parsed reply packet */
+static void
+reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) {
+ int error;
+ static const int error_codes[] = {DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST, DNS_ERR_NOTIMPL, DNS_ERR_REFUSED};
+
+ if (flags & 0x020f || !reply || !reply->have_answer) {
+ /* there was an error */
+ if (flags & 0x0200) {
+ error = DNS_ERR_TRUNCATED;
+ } else {
+ u16 error_code = (flags & 0x000f) - 1;
+ if (error_code > 4) {
+ error = DNS_ERR_UNKNOWN;
+ } else {
+ error = error_codes[error_code];
+ }
+ }
+
+ switch(error) {
+ case DNS_ERR_NOTIMPL:
+ case DNS_ERR_REFUSED:
+ /* we regard these errors as marking a bad nameserver */
+ if (req->reissue_count < global_max_reissues) {
+ char msg[64];
+ snprintf(msg, sizeof(msg), "Bad response %d (%s)",
+ error, evdns_err_to_string(error));
+ nameserver_failed(req->ns, msg);
+ if (!request_reissue(req)) return;
+ }
+ break;
+ case DNS_ERR_SERVERFAILED:
+ /* rcode 2 (servfailed) sometimes means "we are broken" and
+ * sometimes (with some binds) means "that request was very
+ * confusing." Treat this as a timeout, not a failure.
+ */
+ log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver %s; "
+ "will allow the request to time out.",
+ debug_ntoa(req->ns->address));
+ break;
+ default:
+ /* we got a good reply from the nameserver */
+ nameserver_up(req->ns);
+ }
+
+ if (req->search_state && req->request_type != TYPE_PTR) {
+ /* if we have a list of domains to search in, try the next one */
+ if (!search_try_next(req)) {
+ /* a new request was issued so this request is finished and */
+ /* the user callback will be made when that request (or a */
+ /* child of it) finishes. */
+ request_finished(req, &req_head);
+ return;
+ }
+ }
+
+ /* all else failed. Pass the failure up */
+ reply_callback(req, 0, error, NULL);
+ request_finished(req, &req_head);
+ } else {
+ /* all ok, tell the user */
+ reply_callback(req, ttl, 0, reply);
+ nameserver_up(req->ns);
+ request_finished(req, &req_head);
+ }
+}
+
+static int
+name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) {
+ int name_end = -1;
+ int j = *idx;
+ int ptr_count = 0;
+#define GET32(x) do { if (j + 4 > length) goto err; memcpy(&_t32, packet + j, 4); j += 4; x = ntohl(_t32); } while(0)
+#define GET16(x) do { if (j + 2 > length) goto err; memcpy(&_t, packet + j, 2); j += 2; x = ntohs(_t); } while(0)
+#define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while(0)
+
+ char *cp = name_out;
+ const char *const end = name_out + name_out_len;
+
+ /* Normally, names are a series of length prefixed strings terminated */
+ /* with a length of 0 (the lengths are u8's < 63). */
+ /* However, the length can start with a pair of 1 bits and that */
+ /* means that the next 14 bits are a pointer within the current */
+ /* packet. */
+
+ for(;;) {
+ u8 label_len;
+ if (j >= length) return -1;
+ GET8(label_len);
+ if (!label_len) break;
+ if (label_len & 0xc0) {
+ u8 ptr_low;
+ GET8(ptr_low);
+ if (name_end < 0) name_end = j;
+ j = (((int)label_len & 0x3f) << 8) + ptr_low;
+ /* Make sure that the target offset is in-bounds. */
+ if (j < 0 || j >= length) return -1;
+ /* If we've jumped more times than there are characters in the
+ * message, we must have a loop. */
+ if (++ptr_count > length) return -1;
+ continue;
+ }
+ if (label_len > 63) return -1;
+ if (cp != name_out) {
+ if (cp + 1 >= end) return -1;
+ *cp++ = '.';
+ }
+ if (cp + label_len >= end) return -1;
+ memcpy(cp, packet + j, label_len);
+ cp += label_len;
+ j += label_len;
+ }
+ if (cp >= end) return -1;
+ *cp = '\0';
+ if (name_end < 0)
+ *idx = j;
+ else
+ *idx = name_end;
+ return 0;
+ err:
+ return -1;
+}
+
+/* parses a raw request from a nameserver */
+static int
+reply_parse(u8 *packet, int length) {
+ int j = 0; /* index into packet */
+ u16 _t; /* used by the macros */
+ u32 _t32; /* used by the macros */
+ char tmp_name[256]; /* used by the macros */
+
+ u16 trans_id, questions, answers, authority, additional, datalength;
+ u16 flags = 0;
+ u32 ttl, ttl_r = 0xffffffff;
+ struct reply reply;
+ struct request *req = NULL;
+ unsigned int i;
+
+ GET16(trans_id);
+ GET16(flags);
+ GET16(questions);
+ GET16(answers);
+ GET16(authority);
+ GET16(additional);
+ (void) authority; /* suppress "unused variable" warnings. */
+ (void) additional; /* suppress "unused variable" warnings. */
+
+ req = request_find_from_trans_id(trans_id);
+ if (!req) return -1;
+
+ memset(&reply, 0, sizeof(reply));
+
+ /* If it's not an answer, it doesn't correspond to any request. */
+ if (!(flags & 0x8000)) return -1; /* must be an answer */
+ if (flags & 0x020f) {
+ /* there was an error */
+ goto err;
+ }
+ /* if (!answers) return; */ /* must have an answer of some form */
+
+ /* This macro skips a name in the DNS reply. */
+#define SKIP_NAME \
+ do { tmp_name[0] = '\0'; \
+ if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0) \
+ goto err; \
+ } while(0);
+
+ reply.type = req->request_type;
+
+ /* skip over each question in the reply */
+ for (i = 0; i < questions; ++i) {
+ /* the question looks like
+ * <label:name><u16:type><u16:class>
+ */
+ SKIP_NAME;
+ j += 4;
+ if (j >= length) goto err;
+ }
+
+ /* now we have the answer section which looks like
+ * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...>
+ */
+
+ for (i = 0; i < answers; ++i) {
+ u16 type, class;
+
+ SKIP_NAME;
+ GET16(type);
+ GET16(class);
+ GET32(ttl);
+ GET16(datalength);
+
+ if (type == TYPE_A && class == CLASS_INET) {
+ int addrcount, addrtocopy;
+ if (req->request_type != TYPE_A) {
+ j += datalength; continue;
+ }
+ if ((datalength & 3) != 0) /* not an even number of As. */
+ goto err;
+ addrcount = datalength >> 2;
+ addrtocopy = MIN(MAX_ADDRS - reply.data.a.addrcount, (unsigned)addrcount);
+
+ ttl_r = MIN(ttl_r, ttl);
+ /* we only bother with the first four addresses. */
+ if (j + 4*addrtocopy > length) goto err;
+ memcpy(&reply.data.a.addresses[reply.data.a.addrcount],
+ packet + j, 4*addrtocopy);
+ j += 4*addrtocopy;
+ reply.data.a.addrcount += addrtocopy;
+ reply.have_answer = 1;
+ if (reply.data.a.addrcount == MAX_ADDRS) break;
+ } else if (type == TYPE_PTR && class == CLASS_INET) {
+ if (req->request_type != TYPE_PTR) {
+ j += datalength; continue;
+ }
+ if (name_parse(packet, length, &j, reply.data.ptr.name,
+ sizeof(reply.data.ptr.name))<0)
+ goto err;
+ ttl_r = MIN(ttl_r, ttl);
+ reply.have_answer = 1;
+ break;
+ } else if (type == TYPE_AAAA && class == CLASS_INET) {
+ int addrcount, addrtocopy;
+ if (req->request_type != TYPE_AAAA) {
+ j += datalength; continue;
+ }
+ if ((datalength & 15) != 0) /* not an even number of AAAAs. */
+ goto err;
+ addrcount = datalength >> 4; /* each address is 16 bytes long */
+ addrtocopy = MIN(MAX_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount);
+ ttl_r = MIN(ttl_r, ttl);
+
+ /* we only bother with the first four addresses. */
+ if (j + 16*addrtocopy > length) goto err;
+ memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount],
+ packet + j, 16*addrtocopy);
+ reply.data.aaaa.addrcount += addrtocopy;
+ j += 16*addrtocopy;
+ reply.have_answer = 1;
+ if (reply.data.aaaa.addrcount == MAX_ADDRS) break;
+ } else {
+ /* skip over any other type of resource */
+ j += datalength;
+ }
+ }
+
+ reply_handle(req, flags, ttl_r, &reply);
+ return 0;
+ err:
+ if (req)
+ reply_handle(req, flags, 0, NULL);
+ return -1;
+}
+
+/* Parse a raw request (packet,length) sent to a nameserver port (port) from */
+/* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */
+/* callback. */
+static int
+request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, socklen_t addrlen)
+{
+ int j = 0; /* index into packet */
+ u16 _t; /* used by the macros */
+ char tmp_name[256]; /* used by the macros */
+
+ int i;
+ u16 trans_id, flags, questions, answers, authority, additional;
+ struct server_request *server_req = NULL;
+
+ /* Get the header fields */
+ GET16(trans_id);
+ GET16(flags);
+ GET16(questions);
+ GET16(answers);
+ GET16(authority);
+ GET16(additional);
+
+ if (flags & 0x8000) return -1; /* Must not be an answer. */
+ if (flags & 0x7800) return -1; /* only standard queries are supported */
+ flags &= 0x0300; /* Only TC and RD get preserved. */
+
+ server_req = malloc(sizeof(struct server_request));
+ if (server_req == NULL) return -1;
+ memset(server_req, 0, sizeof(struct server_request));
+
+ server_req->trans_id = trans_id;
+ memcpy(&server_req->addr, addr, addrlen);
+ server_req->addrlen = addrlen;
+
+ server_req->base.flags = flags;
+ server_req->base.nquestions = 0;
+ server_req->base.questions = malloc(sizeof(struct evdns_server_question *) * questions);
+ if (server_req->base.questions == NULL)
+ goto err;
+
+ for (i = 0; i < questions; ++i) {
+ u16 type, class;
+ struct evdns_server_question *q;
+ int namelen;
+ if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)
+ goto err;
+ GET16(type);
+ GET16(class);
+ namelen = strlen(tmp_name);
+ q = malloc(sizeof(struct evdns_server_question) + namelen);
+ if (!q)
+ goto err;
+ q->type = type;
+ q->class = class;
+ memcpy(q->name, tmp_name, namelen+1);
+ server_req->base.questions[server_req->base.nquestions++] = q;
+ }
+
+ /* Ignore answers, authority, and additional. */
+
+ server_req->port = port;
+ port->refcnt++;
+ port->user_callback(&(server_req->base), port->user_data);
+
+ return 0;
+err:
+ if (server_req) {
+ if (server_req->base.questions) {
+ for (i = 0; i < server_req->base.nquestions; ++i)
+ free(server_req->base.questions[i]);
+ free(server_req->base.questions);
+ }
+ free(server_req);
+ }
+ return -1;
+
+#undef SKIP_NAME
+#undef GET32
+#undef GET16
+#undef GET8
+}
+
+/* Try to choose a strong transaction id which isn't already in flight */
+static u16
+transaction_id_pick(void) {
+ for (;;) {
+ const struct request *req = req_head, *started_at;
+#ifdef DNS_USE_CPU_CLOCK_FOR_ID
+ struct timespec ts;
+ u16 trans_id;
+#ifdef CLOCK_MONOTONIC
+ if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1)
+#else
+ if (clock_gettime(CLOCK_REALTIME, &ts) == -1)
+#endif
+ event_err(1, "clock_gettime");
+ trans_id = ts.tv_nsec & 0xffff;
+#endif
+
+#ifdef DNS_USE_GETTIMEOFDAY_FOR_ID
+ struct timeval tv;
+ u16 trans_id;
+ gettimeofday(&tv, NULL);
+ trans_id = tv.tv_usec & 0xffff;
+#endif
+
+#ifdef DNS_USE_OPENSSL_FOR_ID
+ u16 trans_id;
+ if (RAND_pseudo_bytes((u8 *) &trans_id, 2) == -1) {
+ /* in the case that the RAND call fails we back */
+ /* down to using gettimeofday. */
+ struct timeval tv;
+ gettimeofday(&tv, NULL);
+ trans_id = tv.tv_usec & 0xffff; */
+ abort();
+ }
+#endif
+
+ if (trans_id == 0xffff) continue;
+ /* now check to see if that id is already inflight */
+ req = started_at = req_head;
+ if (req) {
+ do {
+ if (req->trans_id == trans_id) break;
+ req = req->next;
+ } while (req != started_at);
+ }
+ /* we didn't find it, so this is a good id */
+ if (req == started_at) return trans_id;
+ }
+}
+
+/* choose a namesever to use. This function will try to ignore */
+/* nameservers which we think are down and load balance across the rest */
+/* by updating the server_head global each time. */
+static struct nameserver *
+nameserver_pick(void) {
+ struct nameserver *started_at = server_head, *picked;
+ if (!server_head) return NULL;
+
+ /* if we don't have any good nameservers then there's no */
+ /* point in trying to find one. */
+ if (!global_good_nameservers) {
+ server_head = server_head->next;
+ return server_head;
+ }
+
+ /* remember that nameservers are in a circular list */
+ for (;;) {
+ if (server_head->state) {
+ /* we think this server is currently good */
+ picked = server_head;
+ server_head = server_head->next;
+ return picked;
+ }
+
+ server_head = server_head->next;
+ if (server_head == started_at) {
+ /* all the nameservers seem to be down */
+ /* so we just return this one and hope for the */
+ /* best */
+ assert(global_good_nameservers == 0);
+ picked = server_head;
+ server_head = server_head->next;
+ return picked;
+ }
+ }
+}
+
+/* this is called when a namesever socket is ready for reading */
+static void
+nameserver_read(struct nameserver *ns) {
+ u8 packet[1500];
+
+ for (;;) {
+ const int r = recv(ns->socket, packet, sizeof(packet), 0);
+ if (r < 0) {
+ int err = last_error(ns->socket);
+ if (error_is_eagain(err)) return;
+ nameserver_failed(ns, strerror(err));
+ return;
+ }
+ ns->timedout = 0;
+ reply_parse(packet, r);
+ }
+}
+
+/* Read a packet from a DNS client on a server port s, parse it, and */
+/* act accordingly. */
+static void
+server_port_read(struct evdns_server_port *s) {
+ u8 packet[1500];
+ struct sockaddr_storage addr;
+ socklen_t addrlen;
+ int r;
+
+ for (;;) {
+ addrlen = sizeof(struct sockaddr_storage);
+ r = recvfrom(s->socket, packet, sizeof(packet), 0,
+ (struct sockaddr*) &addr, &addrlen);
+ if (r < 0) {
+ int err = last_error(s->socket);
+ if (error_is_eagain(err)) return;
+ log(EVDNS_LOG_WARN, "Error %s (%d) while reading request.",
+ strerror(err), err);
+ return;
+ }
+ request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen);
+ }
+}
+
+/* Try to write all pending replies on a given DNS server port. */
+static void
+server_port_flush(struct evdns_server_port *port)
+{
+ while (port->pending_replies) {
+ struct server_request *req = port->pending_replies;
+ int r = sendto(port->socket, req->response, req->response_len, 0,
+ (struct sockaddr*) &req->addr, req->addrlen);
+ if (r < 0) {
+ int err = last_error(port->socket);
+ if (error_is_eagain(err))
+ return;
+ log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", strerror(err), err);
+ }
+ if (server_request_free(req)) {
+ /* we released the last reference to req->port. */
+ return;
+ }
+ }
+
+ /* We have no more pending requests; stop listening for 'writeable' events. */
+ (void) event_del(&port->event);
+ event_set(&port->event, port->socket, EV_READ | EV_PERSIST,
+ server_port_ready_callback, port);
+ if (event_add(&port->event, NULL) < 0) {
+ log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server.");
+ /* ???? Do more? */
+ }
+}
+
+/* set if we are waiting for the ability to write to this server. */
+/* if waiting is true then we ask libevent for EV_WRITE events, otherwise */
+/* we stop these events. */
+static void
+nameserver_write_waiting(struct nameserver *ns, char waiting) {
+ if (ns->write_waiting == waiting) return;
+
+ ns->write_waiting = waiting;
+ (void) event_del(&ns->event);
+ event_set(&ns->event, ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST,
+ nameserver_ready_callback, ns);
+ if (event_add(&ns->event, NULL) < 0) {
+ log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s",
+ debug_ntoa(ns->address));
+ /* ???? Do more? */
+ }
+}
+
+/* a callback function. Called by libevent when the kernel says that */
+/* a nameserver socket is ready for writing or reading */
+static void
+nameserver_ready_callback(int fd, short events, void *arg) {
+ struct nameserver *ns = (struct nameserver *) arg;
+ (void)fd;
+
+ if (events & EV_WRITE) {
+ ns->choked = 0;
+ if (!evdns_transmit()) {
+ nameserver_write_waiting(ns, 0);
+ }
+ }
+ if (events & EV_READ) {
+ nameserver_read(ns);
+ }
+}
+
+/* a callback function. Called by libevent when the kernel says that */
+/* a server socket is ready for writing or reading. */
+static void
+server_port_ready_callback(int fd, short events, void *arg) {
+ struct evdns_server_port *port = (struct evdns_server_port *) arg;
+ (void) fd;
+
+ if (events & EV_WRITE) {
+ port->choked = 0;
+ server_port_flush(port);
+ }
+ if (events & EV_READ) {
+ server_port_read(port);
+ }
+}
+
+/* This is an inefficient representation; only use it via the dnslabel_table_*
+ * functions, so that is can be safely replaced with something smarter later. */
+#define MAX_LABELS 128
+/* Structures used to implement name compression */
+struct dnslabel_entry { char *v; off_t pos; };
+struct dnslabel_table {
+ int n_labels; /* number of current entries */
+ /* map from name to position in message */
+ struct dnslabel_entry labels[MAX_LABELS];
+};
+
+/* Initialize dnslabel_table. */
+static void
+dnslabel_table_init(struct dnslabel_table *table)
+{
+ table->n_labels = 0;
+}
+
+/* Free all storage held by table, but not the table itself. */
+static void
+dnslabel_clear(struct dnslabel_table *table)
+{
+ int i;
+ for (i = 0; i < table->n_labels; ++i)
+ free(table->labels[i].v);
+ table->n_labels = 0;
+}
+
+/* return the position of the label in the current message, or -1 if the label */
+/* hasn't been used yet. */
+static int
+dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label)
+{
+ int i;
+ for (i = 0; i < table->n_labels; ++i) {
+ if (!strcmp(label, table->labels[i].v))
+ return table->labels[i].pos;
+ }
+ return -1;
+}
+
+/* remember that we've used the label at position pos */
+static int
+dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos)
+{
+ char *v;
+ int p;
+ if (table->n_labels == MAX_LABELS)
+ return (-1);
+ v = strdup(label);
+ if (v == NULL)
+ return (-1);
+ p = table->n_labels++;
+ table->labels[p].v = v;
+ table->labels[p].pos = pos;
+
+ return (0);
+}
+
+/* Converts a string to a length-prefixed set of DNS labels, starting */
+/* at buf[j]. name and buf must not overlap. name_len should be the length */
+/* of name. table is optional, and is used for compression. */
+/* */
+/* Input: abc.def */
+/* Output: <3>abc<3>def<0> */
+/* */
+/* Returns the first index after the encoded name, or negative on error. */
+/* -1 label was > 63 bytes */
+/* -2 name too long to fit in buffer. */
+/* */
+static off_t
+dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j,
+ const char *name, const int name_len,
+ struct dnslabel_table *table) {
+ const char *end = name + name_len;
+ int ref = 0;
+ u16 _t;
+
+#define APPEND16(x) do { \
+ if (j + 2 > (off_t)buf_len) \
+ goto overflow; \
+ _t = htons(x); \
+ memcpy(buf + j, &_t, 2); \
+ j += 2; \
+ } while (0)
+#define APPEND32(x) do { \
+ if (j + 4 > (off_t)buf_len) \
+ goto overflow; \
+ _t32 = htonl(x); \
+ memcpy(buf + j, &_t32, 4); \
+ j += 4; \
+ } while (0)
+
+ if (name_len > 255) return -2;
+
+ for (;;) {
+ const char *const start = name;
+ if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) {
+ APPEND16(ref | 0xc000);
+ return j;
+ }
+ name = strchr(name, '.');
+ if (!name) {
+ const unsigned int label_len = end - start;
+ if (label_len > 63) return -1;
+ if ((size_t)(j+label_len+1) > buf_len) return -2;
+ if (table) dnslabel_table_add(table, start, j);
+ buf[j++] = label_len;
+
+ memcpy(buf + j, start, end - start);
+ j += end - start;
+ break;
+ } else {
+ /* append length of the label. */
+ const unsigned int label_len = name - start;
+ if (label_len > 63) return -1;
+ if ((size_t)(j+label_len+1) > buf_len) return -2;
+ if (table) dnslabel_table_add(table, start, j);
+ buf[j++] = label_len;
+
+ memcpy(buf + j, start, name - start);
+ j += name - start;
+ /* hop over the '.' */
+ name++;
+ }
+ }
+
+ /* the labels must be terminated by a 0. */
+ /* It's possible that the name ended in a . */
+ /* in which case the zero is already there */
+ if (!j || buf[j-1]) buf[j++] = 0;
+ return j;
+ overflow:
+ return (-2);
+}
+
+/* Finds the length of a dns request for a DNS name of the given */
+/* length. The actual request may be smaller than the value returned */
+/* here */
+static int
+evdns_request_len(const int name_len) {
+ return 96 + /* length of the DNS standard header */
+ name_len + 2 +
+ 4; /* space for the resource type */
+}
+
+/* build a dns request packet into buf. buf should be at least as long */
+/* as evdns_request_len told you it should be. */
+/* */
+/* Returns the amount of space used. Negative on error. */
+static int
+evdns_request_data_build(const char *const name, const int name_len,
+ const u16 trans_id, const u16 type, const u16 class,
+ u8 *const buf, size_t buf_len) {
+ off_t j = 0; /* current offset into buf */
+ u16 _t; /* used by the macros */
+
+ APPEND16(trans_id);
+ APPEND16(0x0100); /* standard query, recusion needed */
+ APPEND16(1); /* one question */
+ APPEND16(0); /* no answers */
+ APPEND16(0); /* no authority */
+ APPEND16(0); /* no additional */
+
+ j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL);
+ if (j < 0) {
+ return (int)j;
+ }
+
+ APPEND16(type);
+ APPEND16(class);
+
+ return (int)j;
+ overflow:
+ return (-1);
+}
+
+/* exported function */
+struct evdns_server_port *
+evdns_add_server_port(int socket, int is_tcp, evdns_request_callback_fn_type cb, void *user_data)
+{
+ struct evdns_server_port *port;
+ if (!(port = malloc(sizeof(struct evdns_server_port))))
+ return NULL;
+ memset(port, 0, sizeof(struct evdns_server_port));
+
+ assert(!is_tcp); /* TCP sockets not yet implemented */
+ port->socket = socket;
+ port->refcnt = 1;
+ port->choked = 0;
+ port->closing = 0;
+ port->user_callback = cb;
+ port->user_data = user_data;
+ port->pending_replies = NULL;
+
+ event_set(&port->event, port->socket, EV_READ | EV_PERSIST,
+ server_port_ready_callback, port);
+ event_add(&port->event, NULL); /* check return. */
+ return port;
+}
+
+/* exported function */
+void
+evdns_close_server_port(struct evdns_server_port *port)
+{
+ if (--port->refcnt == 0)
+ server_port_free(port);
+ port->closing = 1;
+}
+
+/* exported function */
+int
+evdns_server_request_add_reply(struct evdns_server_request *_req, int section, const char *name, int type, int class, int ttl, int datalen, int is_name, const char *data)
+{
+ struct server_request *req = TO_SERVER_REQUEST(_req);
+ struct server_reply_item **itemp, *item;
+ int *countp;
+
+ if (req->response) /* have we already answered? */
+ return (-1);
+
+ switch (section) {
+ case EVDNS_ANSWER_SECTION:
+ itemp = &req->answer;
+ countp = &req->n_answer;
+ break;
+ case EVDNS_AUTHORITY_SECTION:
+ itemp = &req->authority;
+ countp = &req->n_authority;
+ break;
+ case EVDNS_ADDITIONAL_SECTION:
+ itemp = &req->additional;
+ countp = &req->n_additional;
+ break;
+ default:
+ return (-1);
+ }
+ while (*itemp) {
+ itemp = &((*itemp)->next);
+ }
+ item = malloc(sizeof(struct server_reply_item));
+ if (!item)
+ return -1;
+ item->next = NULL;
+ if (!(item->name = strdup(name))) {
+ free(item);
+ return -1;
+ }
+ item->type = type;
+ item->class = class;
+ item->ttl = ttl;
+ item->is_name = is_name != 0;
+ item->datalen = 0;
+ item->data = NULL;
+ if (data) {
+ if (item->is_name) {
+ if (!(item->data = strdup(data))) {
+ free(item->name);
+ free(item);
+ return -1;
+ }
+ item->datalen = (u16)-1;
+ } else {
+ if (!(item->data = malloc(datalen))) {
+ free(item->name);
+ free(item);
+ return -1;
+ }
+ item->datalen = datalen;
+ memcpy(item->data, data, datalen);
+ }
+ }
+
+ *itemp = item;
+ ++(*countp);
+ return 0;
+}
+
+/* exported function */
+int
+evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl)
+{
+ return evdns_server_request_add_reply(
+ req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
+ ttl, n*4, 0, addrs);
+}
+
+/* exported function */
+int
+evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl)
+{
+ return evdns_server_request_add_reply(
+ req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET,
+ ttl, n*16, 0, addrs);
+}
+
+/* exported function */
+int
+evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl)
+{
+ u32 a;
+ char buf[32];
+ assert(in || inaddr_name);
+ assert(!(in && inaddr_name));
+ if (in) {
+ a = ntohl(in->s_addr);
+ snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
+ (int)(u8)((a )&0xff),
+ (int)(u8)((a>>8 )&0xff),
+ (int)(u8)((a>>16)&0xff),
+ (int)(u8)((a>>24)&0xff));
+ inaddr_name = buf;
+ }
+ return evdns_server_request_add_reply(
+ req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET,
+ ttl, -1, 1, hostname);
+}
+
+/* exported function */
+int
+evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl)
+{
+ return evdns_server_request_add_reply(
+ req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
+ ttl, -1, 1, cname);
+}
+
+
+static int
+evdns_server_request_format_response(struct server_request *req, int err)
+{
+ unsigned char buf[1500];
+ size_t buf_len = sizeof(buf);
+ off_t j = 0, r;
+ u16 _t;
+ u32 _t32;
+ int i;
+ u16 flags;
+ struct dnslabel_table table;
+
+ if (err < 0 || err > 15) return -1;
+
+ /* Set response bit and error code; copy OPCODE and RD fields from
+ * question; copy RA and AA if set by caller. */
+ flags = req->base.flags;
+ flags |= (0x8000 | err);
+
+ dnslabel_table_init(&table);
+ APPEND16(req->trans_id);
+ APPEND16(flags);
+ APPEND16(req->base.nquestions);
+ APPEND16(req->n_answer);
+ APPEND16(req->n_authority);
+ APPEND16(req->n_additional);
+
+ /* Add questions. */
+ for (i=0; i < req->base.nquestions; ++i) {
+ const char *s = req->base.questions[i]->name;
+ j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table);
+ if (j < 0) {
+ dnslabel_clear(&table);
+ return (int) j;
+ }
+ APPEND16(req->base.questions[i]->type);
+ APPEND16(req->base.questions[i]->class);
+ }
+
+ /* Add answer, authority, and additional sections. */
+ for (i=0; i<3; ++i) {
+ struct server_reply_item *item;
+ if (i==0)
+ item = req->answer;
+ else if (i==1)
+ item = req->authority;
+ else
+ item = req->additional;
+ while (item) {
+ r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table);
+ if (r < 0)
+ goto overflow;
+ j = r;
+
+ APPEND16(item->type);
+ APPEND16(item->class);
+ APPEND32(item->ttl);
+ if (item->is_name) {
+ off_t len_idx = j, name_start;
+ j += 2;
+ name_start = j;
+ r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table);
+ if (r < 0)
+ goto overflow;
+ j = r;
+ _t = htons( (j-name_start) );
+ memcpy(buf+len_idx, &_t, 2);
+ } else {
+ APPEND16(item->datalen);
+ if (j+item->datalen > (off_t)buf_len)
+ goto overflow;
+ memcpy(buf+j, item->data, item->datalen);
+ j += item->datalen;
+ }
+ item = item->next;
+ }
+ }
+
+ if (j > 512) {
+overflow:
+ j = 512;
+ buf[3] |= 0x02; /* set the truncated bit. */
+ }
+
+ req->response_len = j;
+
+ if (!(req->response = malloc(req->response_len))) {
+ server_request_free_answers(req);
+ dnslabel_clear(&table);
+ return (-1);
+ }
+ memcpy(req->response, buf, req->response_len);
+ server_request_free_answers(req);
+ dnslabel_clear(&table);
+ return (0);
+}
+
+/* exported function */
+int
+evdns_server_request_respond(struct evdns_server_request *_req, int err)
+{
+ struct server_request *req = TO_SERVER_REQUEST(_req);
+ struct evdns_server_port *port = req->port;
+ int r;
+ if (!req->response) {
+ if ((r = evdns_server_request_format_response(req, err))<0)
+ return r;
+ }
+
+ r = sendto(port->socket, req->response, req->response_len, 0,
+ (struct sockaddr*) &req->addr, req->addrlen);
+ if (r<0) {
+ int err = last_error(port->socket);
+ if (! error_is_eagain(err))
+ return -1;
+
+ if (port->pending_replies) {
+ req->prev_pending = port->pending_replies->prev_pending;
+ req->next_pending = port->pending_replies;
+ req->prev_pending->next_pending =
+ req->next_pending->prev_pending = req;
+ } else {
+ req->prev_pending = req->next_pending = req;
+ port->pending_replies = req;
+ port->choked = 1;
+
+ (void) event_del(&port->event);
+ event_set(&port->event, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port);
+
+ if (event_add(&port->event, NULL) < 0) {
+ log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server");
+ }
+
+ }
+
+ return 1;
+ }
+ if (server_request_free(req))
+ return 0;
+
+ if (port->pending_replies)
+ server_port_flush(port);
+
+ return 0;
+}
+
+/* Free all storage held by RRs in req. */
+static void
+server_request_free_answers(struct server_request *req)
+{
+ struct server_reply_item *victim, *next, **list;
+ int i;
+ for (i = 0; i < 3; ++i) {
+ if (i==0)
+ list = &req->answer;
+ else if (i==1)
+ list = &req->authority;
+ else
+ list = &req->additional;
+
+ victim = *list;
+ while (victim) {
+ next = victim->next;
+ free(victim->name);
+ if (victim->data)
+ free(victim->data);
+ free(victim);
+ victim = next;
+ }
+ *list = NULL;
+ }
+}
+
+/* Free all storage held by req, and remove links to it. */
+/* return true iff we just wound up freeing the server_port. */
+static int
+server_request_free(struct server_request *req)
+{
+ int i, rc=1;
+ if (req->base.questions) {
+ for (i = 0; i < req->base.nquestions; ++i)
+ free(req->base.questions[i]);
+ free(req->base.questions);
+ }
+
+ if (req->port) {
+ if (req->port->pending_replies == req) {
+ if (req->next_pending)
+ req->port->pending_replies = req->next_pending;
+ else
+ req->port->pending_replies = NULL;
+ }
+ rc = --req->port->refcnt;
+ }
+
+ if (req->response) {
+ free(req->response);
+ }
+
+ server_request_free_answers(req);
+
+ if (req->next_pending && req->next_pending != req) {
+ req->next_pending->prev_pending = req->prev_pending;
+ req->prev_pending->next_pending = req->next_pending;
+ }
+
+ if (rc == 0) {
+ server_port_free(req->port);
+ free(req);
+ return (1);
+ }
+ free(req);
+ return (0);
+}
+
+/* Free all storage held by an evdns_server_port. Only called when */
+static void
+server_port_free(struct evdns_server_port *port)
+{
+ assert(port);
+ assert(!port->refcnt);
+ assert(!port->pending_replies);
+ if (port->socket > 0) {
+ CLOSE_SOCKET(port->socket);
+ port->socket = -1;
+ }
+ (void) event_del(&port->event);
+ /* XXXX actually free the port? -NM */
+}
+
+/* exported function */
+int
+evdns_server_request_drop(struct evdns_server_request *_req)
+{
+ struct server_request *req = TO_SERVER_REQUEST(_req);
+ server_request_free(req);
+ return 0;
+}
+
+/* exported function */
+int
+evdns_server_request_get_requesting_addr(struct evdns_server_request *_req, struct sockaddr *sa, int addr_len)
+{
+ struct server_request *req = TO_SERVER_REQUEST(_req);
+ if (addr_len < (int)req->addrlen)
+ return -1;
+ memcpy(sa, &(req->addr), req->addrlen);
+ return req->addrlen;
+}
+
+#undef APPEND16
+#undef APPEND32
+
+/* this is a libevent callback function which is called when a request */
+/* has timed out. */
+static void
+evdns_request_timeout_callback(int fd, short events, void *arg) {
+ struct request *const req = (struct request *) arg;
+ (void) fd;
+ (void) events;
+
+ log(EVDNS_LOG_DEBUG, "Request %lx timed out", (unsigned long) arg);
+
+ req->ns->timedout++;
+ if (req->ns->timedout > global_max_nameserver_timeout) {
+ req->ns->timedout = 0;
+ nameserver_failed(req->ns, "request timed out.");
+ }
+
+ (void) evtimer_del(&req->timeout_event);
+ if (req->tx_count >= global_max_retransmits) {
+ /* this request has failed */
+ reply_callback(req, 0, DNS_ERR_TIMEOUT, NULL);
+ request_finished(req, &req_head);
+ } else {
+ /* retransmit it */
+ evdns_request_transmit(req);
+ }
+}
+
+/* try to send a request to a given server. */
+/* */
+/* return: */
+/* 0 ok */
+/* 1 temporary failure */
+/* 2 other failure */
+static int
+evdns_request_transmit_to(struct request *req, struct nameserver *server) {
+ const int r = send(server->socket, req->request, req->request_len, 0);
+ if (r < 0) {
+ int err = last_error(server->socket);
+ if (error_is_eagain(err)) return 1;
+ nameserver_failed(req->ns, strerror(err));
+ return 2;
+ } else if (r != (int)req->request_len) {
+ return 1; /* short write */
+ } else {
+ return 0;
+ }
+}
+
+/* try to send a request, updating the fields of the request */
+/* as needed */
+/* */
+/* return: */
+/* 0 ok */
+/* 1 failed */
+static int
+evdns_request_transmit(struct request *req) {
+ int retcode = 0, r;
+
+ /* if we fail to send this packet then this flag marks it */
+ /* for evdns_transmit */
+ req->transmit_me = 1;
+ if (req->trans_id == 0xffff) abort();
+
+ if (req->ns->choked) {
+ /* don't bother trying to write to a socket */
+ /* which we have had EAGAIN from */
+ return 1;
+ }
+
+ r = evdns_request_transmit_to(req, req->ns);
+ switch (r) {
+ case 1:
+ /* temp failure */
+ req->ns->choked = 1;
+ nameserver_write_waiting(req->ns, 1);
+ return 1;
+ case 2:
+ /* failed in some other way */
+ retcode = 1;
+ /* fall through */
+ default:
+ /* all ok */
+ log(EVDNS_LOG_DEBUG,
+ "Setting timeout for request %lx", (unsigned long) req);
+ evtimer_set(&req->timeout_event, evdns_request_timeout_callback, req);
+ if (evtimer_add(&req->timeout_event, &global_timeout) < 0) {
+ log(EVDNS_LOG_WARN,
+ "Error from libevent when adding timer for request %lx",
+ (unsigned long) req);
+ /* ???? Do more? */
+ }
+ req->tx_count++;
+ req->transmit_me = 0;
+ return retcode;
+ }
+}
+
+static void
+nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) {
+ struct nameserver *const ns = (struct nameserver *) arg;
+ (void) type;
+ (void) count;
+ (void) ttl;
+ (void) addresses;
+
+ if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) {
+ /* this is a good reply */
+ nameserver_up(ns);
+ } else nameserver_probe_failed(ns);
+}
+
+static void
+nameserver_send_probe(struct nameserver *const ns) {
+ struct request *req;
+ /* here we need to send a probe to a given nameserver */
+ /* in the hope that it is up now. */
+
+ log(EVDNS_LOG_DEBUG, "Sending probe to %s", debug_ntoa(ns->address));
+
+ req = request_new(TYPE_A, "www.google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns);
+ if (!req) return;
+ /* we force this into the inflight queue no matter what */
+ request_trans_id_set(req, transaction_id_pick());
+ req->ns = ns;
+ request_submit(req);
+}
+
+/* returns: */
+/* 0 didn't try to transmit anything */
+/* 1 tried to transmit something */
+static int
+evdns_transmit(void) {
+ char did_try_to_transmit = 0;
+
+ if (req_head) {
+ struct request *const started_at = req_head, *req = req_head;
+ /* first transmit all the requests which are currently waiting */
+ do {
+ if (req->transmit_me) {
+ did_try_to_transmit = 1;
+ evdns_request_transmit(req);
+ }
+
+ req = req->next;
+ } while (req != started_at);
+ }
+
+ return did_try_to_transmit;
+}
+
+/* exported function */
+int
+evdns_count_nameservers(void)
+{
+ const struct nameserver *server = server_head;
+ int n = 0;
+ if (!server)
+ return 0;
+ do {
+ ++n;
+ server = server->next;
+ } while (server != server_head);
+ return n;
+}
+
+/* exported function */
+int
+evdns_clear_nameservers_and_suspend(void)
+{
+ struct nameserver *server = server_head, *started_at = server_head;
+ struct request *req = req_head, *req_started_at = req_head;
+
+ if (!server)
+ return 0;
+ while (1) {
+ struct nameserver *next = server->next;
+ (void) event_del(&server->event);
+ (void) evtimer_del(&server->timeout_event);
+ if (server->socket >= 0)
+ CLOSE_SOCKET(server->socket);
+ free(server);
+ if (next == started_at)
+ break;
+ server = next;
+ }
+ server_head = NULL;
+ global_good_nameservers = 0;
+
+ while (req) {
+ struct request *next = req->next;
+ req->tx_count = req->reissue_count = 0;
+ req->ns = NULL;
+ /* ???? What to do about searches? */
+ (void) evtimer_del(&req->timeout_event);
+ req->trans_id = 0;
+ req->transmit_me = 0;
+
+ global_requests_waiting++;
+ evdns_request_insert(req, &req_waiting_head);
+ /* We want to insert these suspended elements at the front of
+ * the waiting queue, since they were pending before any of
+ * the waiting entries were added. This is a circular list,
+ * so we can just shift the start back by one.*/
+ req_waiting_head = req_waiting_head->prev;
+
+ if (next == req_started_at)
+ break;
+ req = next;
+ }
+ req_head = NULL;
+ global_requests_inflight = 0;
+
+ return 0;
+}
+
+
+/* exported function */
+int
+evdns_resume(void)
+{
+ evdns_requests_pump_waiting_queue();
+ return 0;
+}
+
+static int
+_evdns_nameserver_add_impl(unsigned long int address, int port) {
+ /* first check to see if we already have this nameserver */
+
+ const struct nameserver *server = server_head, *const started_at = server_head;
+ struct nameserver *ns;
+ struct sockaddr_in sin;
+ int err = 0;
+ if (server) {
+ do {
+ if (server->address == address) return 3;
+ server = server->next;
+ } while (server != started_at);
+ }
+
+ ns = (struct nameserver *) malloc(sizeof(struct nameserver));
+ if (!ns) return -1;
+
+ memset(ns, 0, sizeof(struct nameserver));
+
+ ns->socket = socket(PF_INET, SOCK_DGRAM, 0);
+ if (ns->socket < 0) { err = 1; goto out1; }
+#ifdef WIN32
+ {
+ u_long nonblocking = 1;
+ ioctlsocket(ns->socket, FIONBIO, &nonblocking);
+ }
+#else
+ fcntl(ns->socket, F_SETFL, O_NONBLOCK);
+#endif
+ sin.sin_addr.s_addr = address;
+ sin.sin_port = htons(port);
+ sin.sin_family = AF_INET;
+ if (connect(ns->socket, (struct sockaddr *) &sin, sizeof(sin)) != 0) {
+ err = 2;
+ goto out2;
+ }
+
+ ns->address = address;
+ ns->state = 1;
+ event_set(&ns->event, ns->socket, EV_READ | EV_PERSIST, nameserver_ready_callback, ns);
+ if (event_add(&ns->event, NULL) < 0) {
+ err = 2;
+ goto out2;
+ }
+
+ log(EVDNS_LOG_DEBUG, "Added nameserver %s", debug_ntoa(address));
+
+ /* insert this nameserver into the list of them */
+ if (!server_head) {
+ ns->next = ns->prev = ns;
+ server_head = ns;
+ } else {
+ ns->next = server_head->next;
+ ns->prev = server_head;
+ server_head->next = ns;
+ if (server_head->prev == server_head) {
+ server_head->prev = ns;
+ }
+ }
+
+ global_good_nameservers++;
+
+ return 0;
+
+out2:
+ CLOSE_SOCKET(ns->socket);
+out1:
+ free(ns);
+ log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d", debug_ntoa(address), err);
+ return err;
+}
+
+/* exported function */
+int
+evdns_nameserver_add(unsigned long int address) {
+ return _evdns_nameserver_add_impl(address, 53);
+}
+
+/* exported function */
+int
+evdns_nameserver_ip_add(const char *ip_as_string) {
+ struct in_addr ina;
+ int port;
+ char buf[20];
+ const char *cp;
+ cp = strchr(ip_as_string, ':');
+ if (! cp) {
+ cp = ip_as_string;
+ port = 53;
+ } else {
+ port = strtoint(cp+1);
+ if (port < 0 || port > 65535) {
+ return 4;
+ }
+ if ((cp-ip_as_string) >= (int)sizeof(buf)) {
+ return 4;
+ }
+ memcpy(buf, ip_as_string, cp-ip_as_string);
+ buf[cp-ip_as_string] = '\0';
+ cp = buf;
+ }
+ if (!inet_aton(cp, &ina)) {
+ return 4;
+ }
+ return _evdns_nameserver_add_impl(ina.s_addr, port);
+}
+
+/* insert into the tail of the queue */
+static void
+evdns_request_insert(struct request *req, struct request **head) {
+ if (!*head) {
+ *head = req;
+ req->next = req->prev = req;
+ return;
+ }
+
+ req->prev = (*head)->prev;
+ req->prev->next = req;
+ req->next = *head;
+ (*head)->prev = req;
+}
+
+static int
+string_num_dots(const char *s) {
+ int count = 0;
+ while ((s = strchr(s, '.'))) {
+ s++;
+ count++;
+ }
+ return count;
+}
+
+static struct request *
+request_new(int type, const char *name, int flags,
+ evdns_callback_type callback, void *user_ptr) {
+ const char issuing_now =
+ (global_requests_inflight < global_max_requests_inflight) ? 1 : 0;
+
+ const int name_len = strlen(name);
+ const int request_max_len = evdns_request_len(name_len);
+ const u16 trans_id = issuing_now ? transaction_id_pick() : 0xffff;
+ /* the request data is alloced in a single block with the header */
+ struct request *const req =
+ (struct request *) malloc(sizeof(struct request) + request_max_len);
+ int rlen;
+ (void) flags;
+
+ if (!req) return NULL;
+ memset(req, 0, sizeof(struct request));
+
+ /* request data lives just after the header */
+ req->request = ((u8 *) req) + sizeof(struct request);
+ /* denotes that the request data shouldn't be free()ed */
+ req->request_appended = 1;
+ rlen = evdns_request_data_build(name, name_len, trans_id,
+ type, CLASS_INET, req->request, request_max_len);
+ if (rlen < 0)
+ goto err1;
+ req->request_len = rlen;
+ req->trans_id = trans_id;
+ req->tx_count = 0;
+ req->request_type = type;
+ req->user_pointer = user_ptr;
+ req->user_callback = callback;
+ req->ns = issuing_now ? nameserver_pick() : NULL;
+ req->next = req->prev = NULL;
+
+ return req;
+err1:
+ free(req);
+ return NULL;
+}
+
+static void
+request_submit(struct request *const req) {
+ if (req->ns) {
+ /* if it has a nameserver assigned then this is going */
+ /* straight into the inflight queue */
+ evdns_request_insert(req, &req_head);
+ global_requests_inflight++;
+ evdns_request_transmit(req);
+ } else {
+ evdns_request_insert(req, &req_waiting_head);
+ global_requests_waiting++;
+ }
+}
+
+/* exported function */
+int evdns_resolve_ipv4(const char *name, int flags,
+ evdns_callback_type callback, void *ptr) {
+ log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
+ if (flags & DNS_QUERY_NO_SEARCH) {
+ struct request *const req =
+ request_new(TYPE_A, name, flags, callback, ptr);
+ if (req == NULL)
+ return (1);
+ request_submit(req);
+ return (0);
+ } else {
+ return (search_request_new(TYPE_A, name, flags, callback, ptr));
+ }
+}
+
+/* exported function */
+int evdns_resolve_ipv6(const char *name, int flags,
+ evdns_callback_type callback, void *ptr) {
+ log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
+ if (flags & DNS_QUERY_NO_SEARCH) {
+ struct request *const req =
+ request_new(TYPE_AAAA, name, flags, callback, ptr);
+ if (req == NULL)
+ return (1);
+ request_submit(req);
+ return (0);
+ } else {
+ return (search_request_new(TYPE_AAAA, name, flags, callback, ptr));
+ }
+}
+
+int evdns_resolve_reverse(struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
+ char buf[32];
+ struct request *req;
+ u32 a;
+ assert(in);
+ a = ntohl(in->s_addr);
+ snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
+ (int)(u8)((a )&0xff),
+ (int)(u8)((a>>8 )&0xff),
+ (int)(u8)((a>>16)&0xff),
+ (int)(u8)((a>>24)&0xff));
+ log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
+ req = request_new(TYPE_PTR, buf, flags, callback, ptr);
+ if (!req) return 1;
+ request_submit(req);
+ return 0;
+}
+
+int evdns_resolve_reverse_ipv6(struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
+ char buf[96];
+ char *cp;
+ struct request *req;
+ int i;
+ assert(in);
+ cp = buf;
+ for (i=15; i >= 0; --i) {
+ u8 byte = in->s6_addr[i];
+ *cp++ = "0123456789abcdef"[byte & 0x0f];
+ *cp++ = '.';
+ *cp++ = "0123456789abcdef"[byte >> 4];
+ *cp++ = '.';
+ }
+ assert(cp + strlen(".ip6.arpa") < buf+sizeof(buf));
+ memcpy(cp, ".ip6.arpa", strlen(".ip6.arpa")+1);
+ log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
+ req = request_new(TYPE_PTR, buf, flags, callback, ptr);
+ if (!req) return 1;
+ request_submit(req);
+ return 0;
+}
+
+/*/////////////////////////////////////////////////////////////////// */
+/* Search support */
+/* */
+/* the libc resolver has support for searching a number of domains */
+/* to find a name. If nothing else then it takes the single domain */
+/* from the gethostname() call. */
+/* */
+/* It can also be configured via the domain and search options in a */
+/* resolv.conf. */
+/* */
+/* The ndots option controls how many dots it takes for the resolver */
+/* to decide that a name is non-local and so try a raw lookup first. */
+
+struct search_domain {
+ int len;
+ struct search_domain *next;
+ /* the text string is appended to this structure */
+};
+
+struct search_state {
+ int refcount;
+ int ndots;
+ int num_domains;
+ struct search_domain *head;
+};
+
+static struct search_state *global_search_state = NULL;
+
+static void
+search_state_decref(struct search_state *const state) {
+ if (!state) return;
+ state->refcount--;
+ if (!state->refcount) {
+ struct search_domain *next, *dom;
+ for (dom = state->head; dom; dom = next) {
+ next = dom->next;
+ free(dom);
+ }
+ free(state);
+ }
+}
+
+static struct search_state *
+search_state_new(void) {
+ struct search_state *state = (struct search_state *) malloc(sizeof(struct search_state));
+ if (!state) return NULL;
+ memset(state, 0, sizeof(struct search_state));
+ state->refcount = 1;
+ state->ndots = 1;
+
+ return state;
+}
+
+static void
+search_postfix_clear(void) {
+ search_state_decref(global_search_state);
+
+ global_search_state = search_state_new();
+}
+
+/* exported function */
+void
+evdns_search_clear(void) {
+ search_postfix_clear();
+}
+
+static void
+search_postfix_add(const char *domain) {
+ int domain_len;
+ struct search_domain *sdomain;
+ while (domain[0] == '.') domain++;
+ domain_len = strlen(domain);
+
+ if (!global_search_state) global_search_state = search_state_new();
+ if (!global_search_state) return;
+ global_search_state->num_domains++;
+
+ sdomain = (struct search_domain *) malloc(sizeof(struct search_domain) + domain_len);
+ if (!sdomain) return;
+ memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len);
+ sdomain->next = global_search_state->head;
+ sdomain->len = domain_len;
+
+ global_search_state->head = sdomain;
+}
+
+/* reverse the order of members in the postfix list. This is needed because, */
+/* when parsing resolv.conf we push elements in the wrong order */
+static void
+search_reverse(void) {
+ struct search_domain *cur, *prev = NULL, *next;
+ cur = global_search_state->head;
+ while (cur) {
+ next = cur->next;
+ cur->next = prev;
+ prev = cur;
+ cur = next;
+ }
+
+ global_search_state->head = prev;
+}
+
+/* exported function */
+void
+evdns_search_add(const char *domain) {
+ search_postfix_add(domain);
+}
+
+/* exported function */
+void
+evdns_search_ndots_set(const int ndots) {
+ if (!global_search_state) global_search_state = search_state_new();
+ if (!global_search_state) return;
+ global_search_state->ndots = ndots;
+}
+
+static void
+search_set_from_hostname(void) {
+ char hostname[HOST_NAME_MAX + 1], *domainname;
+
+ search_postfix_clear();
+ if (gethostname(hostname, sizeof(hostname))) return;
+ domainname = strchr(hostname, '.');
+ if (!domainname) return;
+ search_postfix_add(domainname);
+}
+
+/* warning: returns malloced string */
+static char *
+search_make_new(const struct search_state *const state, int n, const char *const base_name) {
+ const int base_len = strlen(base_name);
+ const char need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1;
+ struct search_domain *dom;
+
+ for (dom = state->head; dom; dom = dom->next) {
+ if (!n--) {
+ /* this is the postfix we want */
+ /* the actual postfix string is kept at the end of the structure */
+ const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain);
+ const int postfix_len = dom->len;
+ char *const newname = (char *) malloc(base_len + need_to_append_dot + postfix_len + 1);
+ if (!newname) return NULL;
+ memcpy(newname, base_name, base_len);
+ if (need_to_append_dot) newname[base_len] = '.';
+ memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len);
+ newname[base_len + need_to_append_dot + postfix_len] = 0;
+ return newname;
+ }
+ }
+
+ /* we ran off the end of the list and still didn't find the requested string */
+ abort();
+ return NULL; /* unreachable; stops warnings in some compilers. */
+}
+
+static int
+search_request_new(int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg) {
+ assert(type == TYPE_A || type == TYPE_AAAA);
+ if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) &&
+ global_search_state &&
+ global_search_state->num_domains) {
+ /* we have some domains to search */
+ struct request *req;
+ if (string_num_dots(name) >= global_search_state->ndots) {
+ req = request_new(type, name, flags, user_callback, user_arg);
+ if (!req) return 1;
+ req->search_index = -1;
+ } else {
+ char *const new_name = search_make_new(global_search_state, 0, name);
+ if (!new_name) return 1;
+ req = request_new(type, new_name, flags, user_callback, user_arg);
+ free(new_name);
+ if (!req) return 1;
+ req->search_index = 0;
+ }
+ req->search_origname = strdup(name);
+ req->search_state = global_search_state;
+ req->search_flags = flags;
+ global_search_state->refcount++;
+ request_submit(req);
+ return 0;
+ } else {
+ struct request *const req = request_new(type, name, flags, user_callback, user_arg);
+ if (!req) return 1;
+ request_submit(req);
+ return 0;
+ }
+}
+
+/* this is called when a request has failed to find a name. We need to check */
+/* if it is part of a search and, if so, try the next name in the list */
+/* returns: */
+/* 0 another request has been submitted */
+/* 1 no more requests needed */
+static int
+search_try_next(struct request *const req) {
+ if (req->search_state) {
+ /* it is part of a search */
+ char *new_name;
+ struct request *newreq;
+ req->search_index++;
+ if (req->search_index >= req->search_state->num_domains) {
+ /* no more postfixes to try, however we may need to try */
+ /* this name without a postfix */
+ if (string_num_dots(req->search_origname) < req->search_state->ndots) {
+ /* yep, we need to try it raw */
+ struct request *const newreq = request_new(req->request_type, req->search_origname, req->search_flags, req->user_callback, req->user_pointer);
+ log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", req->search_origname);
+ if (newreq) {
+ request_submit(newreq);
+ return 0;
+ }
+ }
+ return 1;
+ }
+
+ new_name = search_make_new(req->search_state, req->search_index, req->search_origname);
+ if (!new_name) return 1;
+ log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, req->search_index);
+ newreq = request_new(req->request_type, new_name, req->search_flags, req->user_callback, req->user_pointer);
+ free(new_name);
+ if (!newreq) return 1;
+ newreq->search_origname = req->search_origname;
+ req->search_origname = NULL;
+ newreq->search_state = req->search_state;
+ newreq->search_flags = req->search_flags;
+ newreq->search_index = req->search_index;
+ newreq->search_state->refcount++;
+ request_submit(newreq);
+ return 0;
+ }
+ return 1;
+}
+
+static void
+search_request_finished(struct request *const req) {
+ if (req->search_state) {
+ search_state_decref(req->search_state);
+ req->search_state = NULL;
+ }
+ if (req->search_origname) {
+ free(req->search_origname);
+ req->search_origname = NULL;
+ }
+}
+
+/*/////////////////////////////////////////////////////////////////// */
+/* Parsing resolv.conf files */
+
+static void
+evdns_resolv_set_defaults(int flags) {
+ /* if the file isn't found then we assume a local resolver */
+ if (flags & DNS_OPTION_SEARCH) search_set_from_hostname();
+ if (flags & DNS_OPTION_NAMESERVERS) evdns_nameserver_ip_add("127.0.0.1");
+}
+
+#ifndef HAVE_STRTOK_R
+static char *
+strtok_r(char *s, const char *delim, char **state) {
+ return strtok(s, delim);
+}
+#endif
+
+/* helper version of atoi which returns -1 on error */
+static int
+strtoint(const char *const str) {
+ char *endptr;
+ const int r = strtol(str, &endptr, 10);
+ if (*endptr) return -1;
+ return r;
+}
+
+/* helper version of atoi that returns -1 on error and clips to bounds. */
+static int
+strtoint_clipped(const char *const str, int min, int max)
+{
+ int r = strtoint(str);
+ if (r == -1)
+ return r;
+ else if (r<min)
+ return min;
+ else if (r>max)
+ return max;
+ else
+ return r;
+}
+
+/* exported function */
+int
+evdns_set_option(const char *option, const char *val, int flags)
+{
+ if (!strncmp(option, "ndots:", 6)) {
+ const int ndots = strtoint(val);
+ if (ndots == -1) return -1;
+ if (!(flags & DNS_OPTION_SEARCH)) return 0;
+ log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots);
+ if (!global_search_state) global_search_state = search_state_new();
+ if (!global_search_state) return -1;
+ global_search_state->ndots = ndots;
+ } else if (!strncmp(option, "timeout:", 8)) {
+ const int timeout = strtoint(val);
+ if (timeout == -1) return -1;
+ if (!(flags & DNS_OPTION_MISC)) return 0;
+ log(EVDNS_LOG_DEBUG, "Setting timeout to %d", timeout);
+ global_timeout.tv_sec = timeout;
+ } else if (!strncmp(option, "max-timeouts:", 12)) {
+ const int maxtimeout = strtoint_clipped(val, 1, 255);
+ if (maxtimeout == -1) return -1;
+ if (!(flags & DNS_OPTION_MISC)) return 0;
+ log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d",
+ maxtimeout);
+ global_max_nameserver_timeout = maxtimeout;
+ } else if (!strncmp(option, "max-inflight:", 13)) {
+ const int maxinflight = strtoint_clipped(val, 1, 65000);
+ if (maxinflight == -1) return -1;
+ if (!(flags & DNS_OPTION_MISC)) return 0;
+ log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d",
+ maxinflight);
+ global_max_requests_inflight = maxinflight;
+ } else if (!strncmp(option, "attempts:", 9)) {
+ int retries = strtoint(val);
+ if (retries == -1) return -1;
+ if (retries > 255) retries = 255;
+ if (!(flags & DNS_OPTION_MISC)) return 0;
+ log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries);
+ global_max_retransmits = retries;
+ }
+ return 0;
+}
+
+static void
+resolv_conf_parse_line(char *const start, int flags) {
+ char *strtok_state;
+ static const char *const delims = " \t";
+#define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
+
+ char *const first_token = strtok_r(start, delims, &strtok_state);
+ if (!first_token) return;
+
+ if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) {
+ const char *const nameserver = NEXT_TOKEN;
+ struct in_addr ina;
+
+ if (inet_aton(nameserver, &ina)) {
+ /* address is valid */
+ evdns_nameserver_add(ina.s_addr);
+ }
+ } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) {
+ const char *const domain = NEXT_TOKEN;
+ if (domain) {
+ search_postfix_clear();
+ search_postfix_add(domain);
+ }
+ } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) {
+ const char *domain;
+ search_postfix_clear();
+
+ while ((domain = NEXT_TOKEN)) {
+ search_postfix_add(domain);
+ }
+ search_reverse();
+ } else if (!strcmp(first_token, "options")) {
+ const char *option;
+ while ((option = NEXT_TOKEN)) {
+ const char *val = strchr(option, ':');
+ evdns_set_option(option, val ? val+1 : "", flags);
+ }
+ }
+#undef NEXT_TOKEN
+}
+
+/* exported function */
+/* returns: */
+/* 0 no errors */
+/* 1 failed to open file */
+/* 2 failed to stat file */
+/* 3 file too large */
+/* 4 out of memory */
+/* 5 short read from file */
+int
+evdns_resolv_conf_parse(int flags, const char *const filename) {
+ struct stat st;
+ int fd, n, r;
+ u8 *resolv;
+ char *start;
+ int err = 0;
+
+ log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename);
+
+ fd = open(filename, O_RDONLY);
+ if (fd < 0) {
+ evdns_resolv_set_defaults(flags);
+ return 1;
+ }
+
+ if (fstat(fd, &st)) { err = 2; goto out1; }
+ if (!st.st_size) {
+ evdns_resolv_set_defaults(flags);
+ err = (flags & DNS_OPTION_NAMESERVERS) ? 6 : 0;
+ goto out1;
+ }
+ if (st.st_size > 65535) { err = 3; goto out1; } /* no resolv.conf should be any bigger */
+
+ resolv = (u8 *) malloc((size_t)st.st_size + 1);
+ if (!resolv) { err = 4; goto out1; }
+
+ n = 0;
+ while ((r = read(fd, resolv+n, (size_t)st.st_size-n)) > 0) {
+ n += r;
+ if (n == st.st_size)
+ break;
+ assert(n < st.st_size);
+ }
+ if (r < 0) { err = 5; goto out2; }
+ resolv[n] = 0; /* we malloced an extra byte; this should be fine. */
+
+ start = (char *) resolv;
+ for (;;) {
+ char *const newline = strchr(start, '\n');
+ if (!newline) {
+ resolv_conf_parse_line(start, flags);
+ break;
+ } else {
+ *newline = 0;
+ resolv_conf_parse_line(start, flags);
+ start = newline + 1;
+ }
+ }
+
+ if (!server_head && (flags & DNS_OPTION_NAMESERVERS)) {
+ /* no nameservers were configured. */
+ evdns_nameserver_ip_add("127.0.0.1");
+ err = 6;
+ }
+ if (flags & DNS_OPTION_SEARCH && (!global_search_state || global_search_state->num_domains == 0)) {
+ search_set_from_hostname();
+ }
+
+out2:
+ free(resolv);
+out1:
+ close(fd);
+ return err;
+}
+
+#ifdef WIN32
+/* Add multiple nameservers from a space-or-comma-separated list. */
+static int
+evdns_nameserver_ip_add_line(const char *ips) {
+ const char *addr;
+ char *buf;
+ int r;
+ while (*ips) {
+ while (ISSPACE(*ips) || *ips == ',' || *ips == '\t')
+ ++ips;
+ addr = ips;
+ while (ISDIGIT(*ips) || *ips == '.' || *ips == ':')
+ ++ips;
+ buf = malloc(ips-addr+1);
+ if (!buf) return 4;
+ memcpy(buf, addr, ips-addr);
+ buf[ips-addr] = '\0';
+ r = evdns_nameserver_ip_add(buf);
+ free(buf);
+ if (r) return r;
+ }
+ return 0;
+}
+
+typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*);
+
+/* Use the windows GetNetworkParams interface in iphlpapi.dll to */
+/* figure out what our nameservers are. */
+static int
+load_nameservers_with_getnetworkparams(void)
+{
+ /* Based on MSDN examples and inspection of c-ares code. */
+ FIXED_INFO *fixed;
+ HMODULE handle = 0;
+ ULONG size = sizeof(FIXED_INFO);
+ void *buf = NULL;
+ int status = 0, r, added_any;
+ IP_ADDR_STRING *ns;
+ GetNetworkParams_fn_t fn;
+
+ if (!(handle = LoadLibrary("iphlpapi.dll"))) {
+ log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll");
+ status = -1;
+ goto done;
+ }
+ if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) {
+ log(EVDNS_LOG_WARN, "Could not get address of function.");
+ status = -1;
+ goto done;
+ }
+
+ buf = malloc(size);
+ if (!buf) { status = 4; goto done; }
+ fixed = buf;
+ r = fn(fixed, &size);
+ if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) {
+ status = -1;
+ goto done;
+ }
+ if (r != ERROR_SUCCESS) {
+ free(buf);
+ buf = malloc(size);
+ if (!buf) { status = 4; goto done; }
+ fixed = buf;
+ r = fn(fixed, &size);
+ if (r != ERROR_SUCCESS) {
+ log(EVDNS_LOG_DEBUG, "fn() failed.");
+ status = -1;
+ goto done;
+ }
+ }
+
+ assert(fixed);
+ added_any = 0;
+ ns = &(fixed->DnsServerList);
+ while (ns) {
+ r = evdns_nameserver_ip_add_line(ns->IpAddress.String);
+ if (r) {
+ log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d",
+ (ns->IpAddress.String),(int)GetLastError());
+ status = r;
+ goto done;
+ } else {
+ log(EVDNS_LOG_DEBUG,"Succesfully added %s as nameserver",ns->IpAddress.String);
+ }
+
+ added_any++;
+ ns = ns->Next;
+ }
+
+ if (!added_any) {
+ log(EVDNS_LOG_DEBUG, "No nameservers added.");
+ status = -1;
+ }
+
+ done:
+ if (buf)
+ free(buf);
+ if (handle)
+ FreeLibrary(handle);
+ return status;
+}
+
+static int
+config_nameserver_from_reg_key(HKEY key, const char *subkey)
+{
+ char *buf;
+ DWORD bufsz = 0, type = 0;
+ int status = 0;
+
+ if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz)
+ != ERROR_MORE_DATA)
+ return -1;
+ if (!(buf = malloc(bufsz)))
+ return -1;
+
+ if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz)
+ == ERROR_SUCCESS && bufsz > 1) {
+ status = evdns_nameserver_ip_add_line(buf);
+ }
+
+ free(buf);
+ return status;
+}
+
+#define SERVICES_KEY "System\\CurrentControlSet\\Services\\"
+#define WIN_NS_9X_KEY SERVICES_KEY "VxD\\MSTCP"
+#define WIN_NS_NT_KEY SERVICES_KEY "Tcpip\\Parameters"
+
+static int
+load_nameservers_from_registry(void)
+{
+ int found = 0;
+ int r;
+#define TRY(k, name) \
+ if (!found && config_nameserver_from_reg_key(k,name) == 0) { \
+ log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \
+ found = 1; \
+ } else if (!found) { \
+ log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \
+ #k,#name); \
+ }
+
+ if (((int)GetVersion()) > 0) { /* NT */
+ HKEY nt_key = 0, interfaces_key = 0;
+
+ if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0,
+ KEY_READ, &nt_key) != ERROR_SUCCESS) {
+ log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError());
+ return -1;
+ }
+ r = RegOpenKeyEx(nt_key, "Interfaces", 0,
+ KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS,
+ &interfaces_key);
+ if (r != ERROR_SUCCESS) {
+ log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError());
+ return -1;
+ }
+ TRY(nt_key, "NameServer");
+ TRY(nt_key, "DhcpNameServer");
+ TRY(interfaces_key, "NameServer");
+ TRY(interfaces_key, "DhcpNameServer");
+ RegCloseKey(interfaces_key);
+ RegCloseKey(nt_key);
+ } else {
+ HKEY win_key = 0;
+ if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0,
+ KEY_READ, &win_key) != ERROR_SUCCESS) {
+ log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError());
+ return -1;
+ }
+ TRY(win_key, "NameServer");
+ RegCloseKey(win_key);
+ }
+
+ if (found == 0) {
+ log(EVDNS_LOG_WARN,"Didn't find any nameservers.");
+ }
+
+ return found ? 0 : -1;
+#undef TRY
+}
+
+int
+evdns_config_windows_nameservers(void)
+{
+ if (load_nameservers_with_getnetworkparams() == 0)
+ return 0;
+ return load_nameservers_from_registry();
+}
+#endif
+
+int
+evdns_init(void)
+{
+ int res = 0;
+#ifdef WIN32
+ evdns_config_windows_nameservers();
+#else
+ res = evdns_resolv_conf_parse(DNS_OPTIONS_ALL, "/etc/resolv.conf");
+#endif
+
+ return (res);
+}
+
+const char *
+evdns_err_to_string(int err)
+{
+ switch (err) {
+ case DNS_ERR_NONE: return "no error";
+ case DNS_ERR_FORMAT: return "misformatted query";
+ case DNS_ERR_SERVERFAILED: return "server failed";
+ case DNS_ERR_NOTEXIST: return "name does not exist";
+ case DNS_ERR_NOTIMPL: return "query not implemented";
+ case DNS_ERR_REFUSED: return "refused";
+
+ case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed";
+ case DNS_ERR_UNKNOWN: return "unknown";
+ case DNS_ERR_TIMEOUT: return "request timed out";
+ case DNS_ERR_SHUTDOWN: return "dns subsystem shut down";
+ default: return "[Unknown error code]";
+ }
+}
+
+void
+evdns_shutdown(int fail_requests)
+{
+ struct nameserver *server, *server_next;
+ struct search_domain *dom, *dom_next;
+
+ while (req_head) {
+ if (fail_requests)
+ reply_callback(req_head, 0, DNS_ERR_SHUTDOWN, NULL);
+ request_finished(req_head, &req_head);
+ }
+ while (req_waiting_head) {
+ if (fail_requests)
+ reply_callback(req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL);
+ request_finished(req_waiting_head, &req_waiting_head);
+ }
+ global_requests_inflight = global_requests_waiting = 0;
+
+ for (server = server_head; server; server = server_next) {
+ server_next = server->next;
+ if (server->socket >= 0)
+ CLOSE_SOCKET(server->socket);
+ (void) event_del(&server->event);
+ if (server->state == 0)
+ (void) event_del(&server->timeout_event);
+ free(server);
+ if (server_next == server_head)
+ break;
+ }
+ server_head = NULL;
+ global_good_nameservers = 0;
+
+ if (global_search_state) {
+ for (dom = global_search_state->head; dom; dom = dom_next) {
+ dom_next = dom->next;
+ free(dom);
+ }
+ free(global_search_state);
+ global_search_state = NULL;
+ }
+ evdns_log_fn = NULL;
+}
+
+#ifdef EVDNS_MAIN
+void
+main_callback(int result, char type, int count, int ttl,
+ void *addrs, void *orig) {
+ char *n = (char*)orig;
+ int i;
+ for (i = 0; i < count; ++i) {
+ if (type == DNS_IPv4_A) {
+ printf("%s: %s\n", n, debug_ntoa(((u32*)addrs)[i]));
+ } else if (type == DNS_PTR) {
+ printf("%s: %s\n", n, ((char**)addrs)[i]);
+ }
+ }
+ if (!count) {
+ printf("%s: No answer (%d)\n", n, result);
+ }
+ fflush(stdout);
+}
+void
+evdns_server_callback(struct evdns_server_request *req, void *data)
+{
+ int i, r;
+ (void)data;
+ /* dummy; give 192.168.11.11 as an answer for all A questions,
+ * give foo.bar.example.com as an answer for all PTR questions. */
+ for (i = 0; i < req->nquestions; ++i) {
+ u32 ans = htonl(0xc0a80b0bUL);
+ if (req->questions[i]->type == EVDNS_TYPE_A &&
+ req->questions[i]->class == EVDNS_CLASS_INET) {
+ printf(" -- replying for %s (A)\n", req->questions[i]->name);
+ r = evdns_server_request_add_a_reply(req, req->questions[i]->name,
+ 1, &ans, 10);
+ if (r<0)
+ printf("eeep, didn't work.\n");
+ } else if (req->questions[i]->type == EVDNS_TYPE_PTR &&
+ req->questions[i]->class == EVDNS_CLASS_INET) {
+ printf(" -- replying for %s (PTR)\n", req->questions[i]->name);
+ r = evdns_server_request_add_ptr_reply(req, NULL, req->questions[i]->name,
+ "foo.bar.example.com", 10);
+ } else {
+ printf(" -- skipping %s [%d %d]\n", req->questions[i]->name,
+ req->questions[i]->type, req->questions[i]->class);
+ }
+ }
+
+ r = evdns_request_respond(req, 0);
+ if (r<0)
+ printf("eeek, couldn't send reply.\n");
+}
+
+void
+logfn(int is_warn, const char *msg) {
+ (void) is_warn;
+ fprintf(stderr, "%s\n", msg);
+}
+int
+main(int c, char **v) {
+ int idx;
+ int reverse = 0, verbose = 1, servertest = 0;
+ if (c<2) {
+ fprintf(stderr, "syntax: %s [-x] [-v] hostname\n", v[0]);
+ fprintf(stderr, "syntax: %s [-servertest]\n", v[0]);
+ return 1;
+ }
+ idx = 1;
+ while (idx < c && v[idx][0] == '-') {
+ if (!strcmp(v[idx], "-x"))
+ reverse = 1;
+ else if (!strcmp(v[idx], "-v"))
+ verbose = 1;
+ else if (!strcmp(v[idx], "-servertest"))
+ servertest = 1;
+ else
+ fprintf(stderr, "Unknown option %s\n", v[idx]);
+ ++idx;
+ }
+ event_init();
+ if (verbose)
+ evdns_set_log_fn(logfn);
+ evdns_resolv_conf_parse(DNS_OPTION_NAMESERVERS, "/etc/resolv.conf");
+ if (servertest) {
+ int sock;
+ struct sockaddr_in my_addr;
+ sock = socket(PF_INET, SOCK_DGRAM, 0);
+ fcntl(sock, F_SETFL, O_NONBLOCK);
+ my_addr.sin_family = AF_INET;
+ my_addr.sin_port = htons(10053);
+ my_addr.sin_addr.s_addr = INADDR_ANY;
+ if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) {
+ perror("bind");
+ exit(1);
+ }
+ evdns_add_server_port(sock, 0, evdns_server_callback, NULL);
+ }
+ for (; idx < c; ++idx) {
+ if (reverse) {
+ struct in_addr addr;
+ if (!inet_aton(v[idx], &addr)) {
+ fprintf(stderr, "Skipping non-IP %s\n", v[idx]);
+ continue;
+ }
+ fprintf(stderr, "resolving %s...\n",v[idx]);
+ evdns_resolve_reverse(&addr, 0, main_callback, v[idx]);
+ } else {
+ fprintf(stderr, "resolving (fwd) %s...\n",v[idx]);
+ evdns_resolve_ipv4(v[idx], 0, main_callback, v[idx]);
+ }
+ }
+ fflush(stdout);
+ event_dispatch();
+ return 0;
+}
+#endif
projects / software / libev.git / blobdiff