Se agrega opción para recibir paquetes de un host específico y se mejora el

[z.facultad/75.74/practicos.git] / practicas / pipi / src / ipout.cpp

diff --git a/practicas/pipi/src/ipout.cpp b/practicas/pipi/src/ipout.cpp
index 48cbc30ac34b61a4f43f8e0b71c0b90beb7e8e4a..84a3733f7b32e330dc1d9a74283e950c8007c465 100644 (file)
--- a/practicas/pipi/src/ipout.cpp
+++ b/practicas/pipi/src/ipout.cpp
@@ -1,43 +1,116 @@
 
 #include "ipout.h"
 #include "ipheader.h"
+#include <ctime>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/ipc.h>
+#include <sys/msg.h>
+#ifdef DEBUG
+#include <iostream>
+#endif
 
 /// Constructor
-IPOut::IPOut(const IPAddr& ip, Dev& dev, std::ostream& log):
-    ip(ip), dev(dev), log(log)
-{}
+IPOut::IPOut(const IPAddr& ip, RouteTable& rtable, Dev& forward_que, std::ostream& log):
+    ip(ip), rtable(rtable), forward_que(forward_que), log(log)
+{
+}
 
 void IPOut::drop(const std::string& msg, const std::string& buf)
 {
-    log << "IPOut::drop: " << msg << "\n\tBuffer: " << buf << "\n";
+    log << "IPOut::drop (" << ip << "): " << msg << "\n\tBuffer: " << buf
+            << "\n";
 }
 
 void IPOut::drop(const std::string& msg, const IPHeader& iph)
 {
-    log << "IPOut::drop: " << msg << "\n\tIPHeader: " << iph << "\n";
+    log << "IPOut::drop (" << ip << "): " << msg << "\n\tIPHeader: " << iph
+            << "\n";
 }
 
 /// Envía un paquete IP
-bool IPOut::send(const std::string& data, IPAddr& src, IPAddr& dst,
-        uint8_t proto, bool df, uint8_t ttl, uint16_t id)
+bool IPOut::send(const std::string& data, uint8_t proto, IPAddr dst, IPAddr src,
+        bool df, uint8_t ttl, uint16_t id)
     throw (std::runtime_error)
 {
-    // TODO fragmentar
-    if (IPHeader::header_len() + data.size() > dev.mtu)
+    // Armamos cabecera
+    if (!src)
+        src = ip;
+    if (!id)
+        id = get_id();
+    IPHeader iph(4, IPHeader::header_len() + data.size(), id, df, 0, 0,
+            ttl, proto, src, dst);
+    // Enviamos
+    return send(iph, data);
+}
+
+/// Envía un paquete IP
+bool IPOut::send(IPHeader iph, std::string data) throw (std::runtime_error)
+{
+    // Buscamos ruta
+    RouteTable::Route* r = rtable.get(iph.dst);
+    if (!r)
     {
-        drop("Tamaño de paquete más grande que MTU", data);
+        // ICMP
+        drop("No existe una ruta para el destino -> ICMP", iph);
         return false;
     }
-    IPHeader iph(4, IPHeader::header_len() + data.size(), id, df, 0, 0,
-            ttl, proto, src, dst);
-    std::string buf((char*) &iph, sizeof(IPHeader));
-    buf += data;
+    // No quieren fragmentar
+    if (iph.df && (IPHeader::header_len() + data.size() > r->mtu))
+    {
+        // Silencioso
+        drop("Tamaño de paquete más grande que MTU y DF=1", iph);
+        return false;
+    }
+    // Fragmenta (de ser necesario)
+    int max_payload = r->mtu - IPHeader::header_len();
+    int cant_frag = data.size() / max_payload;
+    if (data.size() % max_payload)
+        ++cant_frag;
+    for (int i = 0; i < cant_frag; ++i)
+    {
+        IPHeader iph2 = iph;
+        if (i != (cant_frag - 1))
+            iph2.mf = 1;
+        iph2.offset += i * max_payload;
+        iph2.total_len -= i * max_payload;
+        iph2.do_checksum();
+        std::string buf((char*) &iph2, sizeof(IPHeader));
+        buf += data.substr(i * max_payload, max_payload);
 #ifdef DEBUG
-    log << "IPOut::send: IPHeader: " << iph << "\n";
-    log << "IPOut::send: buf = " << buf << "\n";
+        std::cout << "IPOut::send (" << ip << "): Fragmento " << i
+                << " => IPHeader: " << iph2 << "\n";
+        std::string tmp = data.substr(i * max_payload, max_payload);
+        std::cout << "\tdata (" << tmp.size() << ") = " << tmp << "\n";
 #endif
-    dev.transmit(buf, dst /*TODO rutear */);
+        r->iface->transmit(buf, r->gateway ? r->gateway : IPAddr(iph.dst));
+    }
     return true;
 }
 
+/// Realiza el forwarding de paquetes (en un loop infinito)
+void IPOut::forward_loop()
+    throw (std::runtime_error)
+{
+    while (true)
+    {
+        std::string buf = forward_que.receive();
+        IPHeader iph(buf);
+#ifdef DEBUG
+        std::cout << "IPOut::forward_loop (" << ip << "): A forwardear (id "
+                << iph.id << ", offset " << iph.offset << ")\n";
+#endif
+        send(iph, buf.substr(iph.header_len()));
+    }
+}
+
+/// Obtiene un identificador para el paquete
+uint16_t IPOut::get_id() const
+{
+    static uint16_t st = time(NULL);
+    uint16_t tt = time(NULL);
+    return (tt == st) ? ++st : tt;
+}
+
 // vim: set et sw=4 sts=4 :