Participate in UTP.

This adds code to participate in the UTP protocol, but without doing anything
useful yet -- we just shut down immediately any incoming connexion request.

libtransmission/Makefile.am

@@ -56,6 +56,7 @@ libtransmission_a_SOURCES = \
     tr-dht.c \
     tr-lpd.c \
     tr-udp.c \
+    tr-utp.c \
     tr-getopt.c \
     trevent.c \
     upnp.c \
@@ -108,6 +109,7 @@ noinst_HEADERS = \
     transmission.h \
     tr-dht.h \
     tr-udp.h \
+    tr-utp.h \
     tr-lpd.h \
     trevent.h \
     upnp.h \

libtransmission/tr-udp.c

@@ -30,6 +30,7 @@ THE SOFTWARE.
 #include "net.h"
 #include "session.h"
 #include "tr-dht.h"
+#include "tr-utp.h"
 #include "tr-udp.h"
 
 /* BEP-32 has a rather nice explanation of why we need to bind to one
@@ -139,8 +140,9 @@ event_callback(int s, short type UNUSED, void *sv)
         buf[rc] = '\0';
         tr_dhtCallback(buf, rc, (struct sockaddr*)&from, fromlen, sv);
     } else {
-        /* Probably a UTP packet. */
-        /* Nothing yet. */
+        rc = tr_utpPacket(buf, rc, (struct sockaddr*)&from, fromlen, ss);
+        if(!rc)
+            tr_ndbg("UDP", "Unexpected UDP packet");
     }
 
     free(buf);

libtransmission/tr-utp.c

@@ -0,0 +1,79 @@
+/*
+Copyright (c) 2010 by Juliusz Chroboczek
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+*/
+
+#include <unistd.h>
+
+#include <event.h>
+#include "utp.h"
+
+#include "transmission.h"
+#include "net.h"
+#include "session.h"
+#include "crypto.h"
+#include "tr-utp.h"
+
+static struct event *utp_timer = NULL;
+
+static void
+incoming(void *closure UNUSED, struct UTPSocket *s)
+{
+    UTP_Close(s);
+}
+
+static void
+send_to(void *closure, const unsigned char *buf, size_t buflen,
+        const struct sockaddr *to, socklen_t tolen)
+{
+    tr_session *ss = (tr_session*)closure;
+
+    if(to->sa_family == AF_INET && ss->udp_socket)
+        sendto(ss->udp_socket, buf, buflen, 0, to, tolen);
+    else if(to->sa_family == AF_INET6 && ss->udp_socket)
+        sendto(ss->udp6_socket, buf, buflen, 0, to, tolen);
+}
+
+static void
+timer_callback(int s UNUSED, short type UNUSED, void *closure UNUSED)
+{
+    UTP_CheckTimeouts();
+    tr_timerAdd(utp_timer, 0, tr_cryptoWeakRandInt(2000000));
+}
+
+int
+tr_utpPacket(const unsigned char *buf, size_t buflen,
+             const struct sockaddr *from, socklen_t fromlen,
+             tr_session *ss)
+{
+    if(utp_timer == NULL) {
+        utp_timer = tr_new0(struct event, 1);
+        if(utp_timer == NULL)
+            return -1;
+        evtimer_set(utp_timer, timer_callback, NULL);
+        tr_timerAdd(utp_timer, 0, tr_cryptoWeakRandInt(2000000));
+    }
+
+    return UTP_IsIncomingUTP(incoming, send_to, ss,
+                             buf, buflen, from, fromlen);
+}
+
+    

libtransmission/tr-utp.h

@@ -0,0 +1,26 @@
+/*
+Copyright (c) 2010 by Juliusz Chroboczek
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+*/
+
+int tr_utpPacket(const unsigned char *buf, size_t buflen,
+                 const struct sockaddr *from, socklen_t fromlen,
+                 tr_session *ss);