source: trunk/libtransmission/tr-udp.c @ 12378

Last change on this file since 12378 was 12378, checked in by jch, 11 years ago

Optimise UDP dispatch (fixes #4209).

Make quick inline tests for the DHT and UDP tracker protocols, which
avoids calling tau_handle_message for each µTP packet.

File size: 9.3 KB
Line 
1/*
2Copyright (c) 2010 by Juliusz Chroboczek
3
4Permission is hereby granted, free of charge, to any person obtaining a copy
5of this software and associated documentation files (the "Software"), to deal
6in the Software without restriction, including without limitation the rights
7to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8copies of the Software, and to permit persons to whom the Software is
9furnished to do so, subject to the following conditions:
10
11The above copyright notice and this permission notice shall be included in
12all copies or substantial portions of the Software.
13
14THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
17AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20THE SOFTWARE.
21
22*/
23
24#include <assert.h>
25#include <string.h> /* memcmp(), memcpy(), memset() */
26#include <stdlib.h> /* malloc(), free() */
27
28#include <unistd.h> /* close() */
29
30#include <event2/event.h>
31
32#include "transmission.h"
33#include "net.h"
34#include "session.h"
35#include "tr-dht.h"
36#include "tr-utp.h"
37#include "tr-udp.h"
38
39/* Since we use a single UDP socket in order to implement multiple
40   uTP sockets, try to set up huge buffers. */
41
42#define RECV_BUFFER_SIZE (4 * 1024 * 1024)
43#define SEND_BUFFER_SIZE (1 * 1024 * 1024)
44#define SMALL_BUFFER_SIZE (32 * 1024)
45
46static void
47set_socket_buffers(int fd, int large)
48{
49    int size, rbuf, sbuf, rc;
50    socklen_t rbuf_len = sizeof(rbuf), sbuf_len = sizeof(sbuf);
51
52    size = large ? RECV_BUFFER_SIZE : SMALL_BUFFER_SIZE;
53    rc = setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &size, sizeof(size));
54    if(rc < 0)
55        tr_nerr("UDP", "Failed to set receive buffer: %s",
56                tr_strerror(errno));
57
58    size = large ? SEND_BUFFER_SIZE : SMALL_BUFFER_SIZE;
59    rc = setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &size, sizeof(size));
60    if(rc < 0)
61        tr_nerr("UDP", "Failed to set send buffer: %s",
62                tr_strerror(errno));
63
64    if(large) {
65        rc = getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &rbuf, &rbuf_len);
66        if(rc < 0)
67            rbuf = 0;
68
69        rc = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &sbuf, &sbuf_len);
70        if(rc < 0)
71            sbuf = 0;
72
73        if(rbuf < RECV_BUFFER_SIZE) {
74            tr_nerr("UDP", "Failed to set receive buffer: requested %d, got %d",
75                    RECV_BUFFER_SIZE, rbuf);
76#ifdef __linux__
77            tr_ninf("UDP",
78                    "Please add the line "
79                    "\"net.core.rmem_max = %d\" to /etc/sysctl.conf",
80                    RECV_BUFFER_SIZE);
81#endif
82        }
83
84        if(sbuf < SEND_BUFFER_SIZE) {
85            tr_nerr("UDP", "Failed to set send buffer: requested %d, got %d",
86                    SEND_BUFFER_SIZE, sbuf);
87#ifdef __linux__
88            tr_ninf("UDP",
89                    "Please add the line "
90                    "\"net.core.wmem_max = %d\" to /etc/sysctl.conf",
91                    SEND_BUFFER_SIZE);
92#endif
93        }
94    }
95}
96
97void
98tr_udpSetSocketBuffers(tr_session *session)
99{
100    bool utp = tr_sessionIsUTPEnabled(session);
101    if(session->udp_socket >= 0)
102        set_socket_buffers(session->udp_socket, utp);
103    if(session->udp6_socket >= 0)
104        set_socket_buffers(session->udp6_socket, utp);
105}
106
107
108
109
110/* BEP-32 has a rather nice explanation of why we need to bind to one
111   IPv6 address, if I may say so myself. */
112
113static void
114rebind_ipv6(tr_session *ss, bool force)
115{
116    bool is_default;
117    const struct tr_address * public_addr;
118    struct sockaddr_in6 sin6;
119    const unsigned char *ipv6 = tr_globalIPv6();
120    int s = -1, rc;
121    int one = 1;
122
123    /* We currently have no way to enable or disable IPv6 after initialisation.
124       No way to fix that without some surgery to the DHT code itself. */
125    if(ipv6 == NULL || (!force && ss->udp6_socket < 0)) {
126        if(ss->udp6_bound) {
127            free(ss->udp6_bound);
128            ss->udp6_bound = NULL;
129        }
130        return;
131    }
132
133    if(ss->udp6_bound != NULL && memcmp(ipv6, ss->udp6_bound, 16) == 0)
134        return;
135
136    s = socket(PF_INET6, SOCK_DGRAM, 0);
137    if(s < 0)
138        goto fail;
139
140#ifdef IPV6_V6ONLY
141        /* Since we always open an IPv4 socket on the same port, this
142           shouldn't matter.  But I'm superstitious. */
143        setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
144#endif
145
146    memset(&sin6, 0, sizeof(sin6));
147    sin6.sin6_family = AF_INET6;
148    if(ipv6)
149        memcpy(&sin6.sin6_addr, ipv6, 16);
150    sin6.sin6_port = htons(ss->udp_port);
151    public_addr = tr_sessionGetPublicAddress(ss, TR_AF_INET6, &is_default);
152    if(public_addr && !is_default)
153        sin6.sin6_addr = public_addr->addr.addr6;
154
155    rc = bind(s, (struct sockaddr*)&sin6, sizeof(sin6));
156    if(rc < 0)
157        goto fail;
158
159    if(ss->udp6_socket < 0) {
160        ss->udp6_socket = s;
161    } else {
162        rc = dup2(s, ss->udp6_socket);
163        if(rc < 0)
164            goto fail;
165        close(s);
166    }
167
168    if(ss->udp6_bound == NULL)
169        ss->udp6_bound = malloc(16);
170    if(ss->udp6_bound)
171        memcpy(ss->udp6_bound, ipv6, 16);
172
173    return;
174
175 fail:
176    /* Something went wrong.  It's difficult to recover, so let's simply
177       set things up so that we try again next time. */
178    tr_nerr("UDP", "Couldn't rebind IPv6 socket");
179    if(s >= 0)
180        close(s);
181    if(ss->udp6_bound) {
182        free(ss->udp6_bound);
183        ss->udp6_bound = NULL;
184    }
185}
186
187static void
188event_callback(int s, short type UNUSED, void *sv)
189{
190    tr_session *ss = sv;
191    unsigned char *buf;
192    struct sockaddr_storage from;
193    socklen_t fromlen;
194    int rc;
195
196    assert(tr_isSession(sv));
197    assert(type == EV_READ);
198
199    buf = malloc(4096);
200    if(buf == NULL) {
201        tr_nerr("UDP", "Couldn't allocate buffer");
202        return;
203    }
204
205    fromlen = sizeof(from);
206    rc = recvfrom(s, buf, 4096 - 1, 0,
207                  (struct sockaddr*)&from, &fromlen);
208
209    /* Since most packets we receive here are µTP, make quick inline
210       checks for the other protocols.  The logic is as follows:
211       - all DHT packets start with 'd';
212       - all UDP tracker packets start with a 32-bit (!) "action", which
213         is between 0 and 3;
214       - the above cannot be µTP packets, since these start with a 4-bit
215         version number (1). */
216    if(rc > 0) {
217        if( buf[0] == 'd' ) {
218            buf[rc] = '\0';     /* required by the DHT code */
219            tr_dhtCallback(buf, rc, (struct sockaddr*)&from, fromlen, sv);
220        } else if( rc >= 8 &&
221                   buf[0] == 0 && buf[1] == 0 && buf[2] == 0 && buf[3] <= 3 ) {
222            rc = tau_handle_message( ss, buf, rc );
223            if( !rc )
224                tr_ndbg("UDP", "Couldn't parse UDP tracker packet.");
225        } else {
226            rc = tr_utpPacket(buf, rc, (struct sockaddr*)&from, fromlen, ss);
227            if( !rc )
228                tr_ndbg("UDP", "Unexpected UDP packet");
229        }
230    }
231
232    free(buf);
233}
234
235void
236tr_udpInit(tr_session *ss)
237{
238    bool is_default;
239    const struct tr_address * public_addr;
240    struct sockaddr_in sin;
241    int rc;
242
243    assert(ss->udp_socket < 0);
244    assert(ss->udp6_socket < 0);
245
246    ss->udp_port = tr_sessionGetPeerPort(ss);
247    if(ss->udp_port <= 0)
248        return;
249
250    ss->udp_socket = socket(PF_INET, SOCK_DGRAM, 0);
251    if(ss->udp_socket < 0) {
252        tr_nerr("UDP", "Couldn't create IPv4 socket");
253        goto ipv6;
254    }
255
256    memset(&sin, 0, sizeof(sin));
257    sin.sin_family = AF_INET;
258    public_addr = tr_sessionGetPublicAddress(ss, TR_AF_INET, &is_default);
259    if(public_addr && !is_default)
260        memcpy(&sin.sin_addr, &public_addr->addr.addr4, sizeof (struct in_addr));
261    sin.sin_port = htons(ss->udp_port);
262    rc = bind(ss->udp_socket, (struct sockaddr*)&sin, sizeof(sin));
263    if(rc < 0) {
264        tr_nerr("UDP", "Couldn't bind IPv4 socket");
265        close(ss->udp_socket);
266        ss->udp_socket = -1;
267        goto ipv6;
268    }
269    ss->udp_event =
270        event_new(ss->event_base, ss->udp_socket, EV_READ | EV_PERSIST,
271                  event_callback, ss);
272    if( ss->udp_event == NULL )
273        tr_nerr("UDP", "Couldn't allocate IPv4 event");
274
275 ipv6:
276    if(tr_globalIPv6())
277        rebind_ipv6(ss, true);
278    if(ss->udp6_socket >= 0) {
279        ss->udp6_event =
280            event_new(ss->event_base, ss->udp6_socket, EV_READ | EV_PERSIST,
281                      event_callback, ss);
282        if(ss->udp6_event == NULL)
283            tr_nerr("UDP", "Couldn't allocate IPv6 event");
284    }
285
286    tr_udpSetSocketBuffers(ss);
287
288    if(ss->isDHTEnabled)
289        tr_dhtInit(ss);
290
291    if(ss->udp_event)
292        event_add(ss->udp_event, NULL);
293    if(ss->udp6_event)
294        event_add(ss->udp6_event, NULL);
295}
296
297void
298tr_udpUninit(tr_session *ss)
299{
300    if(ss->udp_socket >= 0) {
301        tr_netCloseSocket( ss->udp_socket );
302        ss->udp_socket = -1;
303    }
304
305    if(ss->udp_event) {
306        event_free(ss->udp_event);
307        ss->udp_event = NULL;
308    }
309
310    if(ss->udp6_socket >= 0) {
311        tr_netCloseSocket( ss->udp6_socket );
312        ss->udp6_socket = -1;
313    }
314
315    if(ss->udp6_event) {
316        event_free(ss->udp6_event);
317        ss->udp6_event = NULL;
318    }
319
320    if(ss->udp6_bound) {
321        free(ss->udp6_bound);
322        ss->udp6_bound = NULL;
323    }
324}
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