-/* $Id: evdns.c,v 1.14 2007-11-05 16:45:43 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