1 /* UDP send/receive module for secnet */
3 /* This module enables sites to communicate by sending UDP
4 * packets. When an instance of the module is created we can
5 * optionally bind to a particular local IP address (not implemented
8 * Packets are offered to registered receivers in turn. Once one
9 * accepts it, it isn't offered to any more. */
17 #include <sys/socket.h>
19 #include <netinet/in.h>
20 #include <arpa/inet.h>
23 #include "unaligned.h"
26 #include "comm-common.h"
28 static comm_sendmsg_fn udp_sendmsg;
32 struct udpsocks socks;
36 * Re comm_addr.ix: This field allows us to note in the comm_addr
37 * which socket an incoming packet was received on. This is required
38 * for conveniently logging the actual source of a packet. But the ix
39 * does not formally form part of the address: it is not used when
40 * sending, nor when comparing two comm_addrs.
42 * The special value -1 means that the comm_addr was constructed by
43 * another module in secnet (eg the resolver), rather than being a
44 * description of the source of an incoming packet.
47 static const char *udp_addr_to_string(void *commst, const struct comm_addr *ca)
49 struct udp *st=commst;
50 struct udpsocks *socks=&st->socks;
51 static char sbuf[100];
52 int ix=ca->ix>=0 ? ca->ix : 0;
54 assert(ix>=0 && ix<socks->n_socks);
55 snprintf(sbuf, sizeof(sbuf), "udp:%s%s-%s",
56 iaddr_to_string(&socks->socks[ix].addr),
58 iaddr_to_string(&ca->ia));
62 static int udp_socks_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
65 struct udpsocks *socks=state;
67 BEFOREPOLL_WANT_FDS(socks->n_socks);
68 for (i=0; i<socks->n_socks; i++) {
69 fds[i].fd=socks->socks[i].fd;
75 static void udp_socks_afterpoll(void *state, struct pollfd *fds, int nfds)
77 struct udpsocks *socks=state;
78 struct udpcommon *uc=socks->uc;
85 struct commcommon *cc=&uc->cc;
87 for (i=0; i<socks->n_socks; i++) {
88 if (i>=nfds) continue;
89 if (!(fds[i].revents & POLLIN)) continue;
90 assert(fds[i].fd == socks->socks[i].fd);
91 int fd=socks->socks[i].fd;
94 BUF_ASSERT_FREE(cc->rbuf);
95 BUF_ALLOC(cc->rbuf,"udp_afterpoll");
96 buffer_init(cc->rbuf,calculate_max_start_pad());
97 rv=recvfrom(fd, cc->rbuf->start,
98 buf_remaining_space(cc->rbuf),
99 0, &from.sa, &fromlen);
103 /* Check that the packet came from our poxy server;
104 we shouldn't be contacted directly by anybody else
105 (since they can trivially forge source addresses) */
106 if (!iaddr_equal(&from,&uc->proxy)) {
107 Message(M_INFO,"udp: received packet that's not "
112 /* proxy protocol supports ipv4 transport only */
113 from.sa.sa_family=AF_INET;
114 BUF_GET_BYTES(unprepend,cc->rbuf,&from.sin.sin_addr,4);
115 buf_unprepend(cc->rbuf,2);
116 BUF_GET_BYTES(unprepend,cc->rbuf,&from.sin.sin_port,2);
122 done=comm_notify(&cc->notify, cc->rbuf, &ca);
125 if (cc->rbuf->size>12 /* prevents traffic amplification */
126 && ((msgtype=get_uint32(cc->rbuf->start+8))
128 uint32_t source,dest;
129 /* Manufacture and send NAK packet */
130 source=get_uint32(cc->rbuf->start); /* Us */
131 dest=get_uint32(cc->rbuf->start+4); /* Them */
132 send_nak(&ca,source,dest,msgtype,cc->rbuf,"unwanted");
136 BUF_ASSERT_FREE(cc->rbuf);
144 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
145 const struct comm_addr *dest)
147 struct udp *st=commst;
148 struct udpcommon *uc=&st->uc;
149 struct udpsocks *socks=&st->socks;
153 sa=buf_prepend(buf,8);
154 if (dest->ia.sa.sa_family != AF_INET) {
156 "udp: proxy means dropping outgoing non-IPv4 packet to %s\n",
157 iaddr_to_string(&dest->ia));
160 memcpy(sa,&dest->ia.sin.sin_addr,4);
162 memcpy(sa+6,&dest->ia.sin.sin_port,2);
163 sendto(socks->socks[0].fd,sa,buf->size+8,0,&uc->proxy.sa,
164 iaddr_socklen(&uc->proxy));
165 buf_unprepend(buf,8);
168 bool_t allunsupported=True;
169 for (i=0; i<socks->n_socks; i++) {
170 if (dest->ia.sa.sa_family != socks->socks[i].addr.sa.sa_family)
171 /* no point even trying */
173 r=sendto(socks->socks[i].fd, buf->start, buf->size, 0,
174 &dest->ia.sa, iaddr_socklen(&dest->ia));
175 if (r>=0) return True;
176 if (!(errno==EAFNOSUPPORT || errno==ENETUNREACH))
177 /* who knows what that error means? */
178 allunsupported=False;
180 return !allunsupported; /* see doc for comm_sendmsg_fn in secnet.h */
186 void udp_destroy_socket(struct udpcommon *uc, struct udpsock *us)
194 bool_t udp_make_socket(struct udpcommon *uc, struct udpsock *us,
197 const union iaddr *addr=&us->addr;
198 struct commcommon *cc=&uc->cc;
201 #define FAIL_LG 0, cc->cl.description, &cc->loc, failmsgclass
202 #define FAIL(...) do{ \
203 lg_perror(FAIL_LG,errno,__VA_ARGS__); \
207 us->fd=socket(addr->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
208 if (us->fd<0) FAIL("socket");
209 if (fcntl(us->fd, F_SETFL, fcntl(us->fd, F_GETFL)|O_NONBLOCK)==-1)
210 FAIL("fcntl(set O_NONBLOCK)");
213 if (addr->sa.sa_family==AF_INET6) {
216 socklen_t optlen=sizeof(optval);
217 r=setsockopt(us->fd,IPPROTO_IPV6,IPV6_V6ONLY,&optval,optlen);
218 if (r) FAIL("setsockopt(,IPV6_V6ONLY,&1,)");
226 /* XXX this fork() and waitpid() business needs to be hidden
227 in some system-specific library functions. */
230 FAIL("fork() for authbind");
232 char *argv[5], addrstr[33], portstr[5];
235 switch (addr->sa.sa_family) {
237 sprintf(addrstr,"%08lX",(long)addr->sin.sin_addr.s_addr);
238 port=addr->sin.sin_port;
245 sprintf(addrstr+i*2,"%02X",addr->sin6.sin6_addr.s6_addr[i]);
246 port=addr->sin6.sin6_port;
250 #endif /*CONFIG_IPV6*/
252 fatal("udp (%s:%d): unsupported address family for authbind",
253 cc->loc.file,cc->loc.line);
255 sprintf(portstr,"%04X",port);
256 argv[0]=uc->authbind;
259 argv[3]=(char*)addrfam;
262 execvp(uc->authbind,argv);
265 while (waitpid(c,&status,0)==-1) {
266 if (errno==EINTR) continue;
267 FAIL("waitpid for authbind");
270 if (WIFEXITED(status) && WEXITSTATUS(status)<127) {
271 int es=WEXITSTATUS(status);
272 lg_perror(FAIL_LG,es,
273 "authbind exited with error exit status %d;"
274 " indicates error",es);
276 lg_exitstatus(FAIL_LG,status,"authbind");
281 if (bind(us->fd, &addr->sa, iaddr_socklen(addr))!=0)
282 FAIL("bind (%s)",iaddr_to_string(addr));
287 udp_destroy_socket(uc,us);
293 void udp_socks_register(struct udpcommon *uc, struct udpsocks *socks)
297 register_for_poll(socks,udp_socks_beforepoll,udp_socks_afterpoll,"udp");
300 void udp_socks_deregister(struct udpcommon *uc, struct udpsocks *socks)
303 deregister_for_poll(socks->interest);
306 static void udp_phase_hook(void *sst, uint32_t new_phase)
309 struct udpsocks *socks=&st->socks;
310 struct udpcommon *uc=&st->uc;
312 for (i=0; i<socks->n_socks; i++)
313 udp_make_socket(uc,&socks->socks[i],M_FATAL);
315 udp_socks_register(uc,socks);
318 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
327 COMM_APPLY(st,&st->uc.cc,udp_,"udp",loc);
328 COMM_APPLY_STANDARD(st,&st->uc.cc,"udp",args);
329 UDP_APPLY_STANDARD(st,&st->uc,"udp");
331 struct udpcommon *uc=&st->uc;
332 struct udpsocks *socks=&st->socks;
333 struct commcommon *cc=&uc->cc;
335 union iaddr defaultaddrs[] = {
337 { .sin6 = { .sin6_family=AF_INET6,
338 .sin6_port=htons(uc->port),
339 .sin6_addr=IN6ADDR_ANY_INIT } },
341 { .sin = { .sin_family=AF_INET,
342 .sin_port=htons(uc->port),
343 .sin_addr= { .s_addr=INADDR_ANY } } }
346 caddrl=dict_lookup(d,"address");
347 socks->n_socks=caddrl ? list_length(caddrl) : (int)ARRAY_SIZE(defaultaddrs);
348 if (socks->n_socks<=0 || socks->n_socks>UDP_MAX_SOCKETS)
349 cfgfatal(cc->loc,"udp","`address' must be 1..%d addresses",
352 for (i=0; i<socks->n_socks; i++) {
353 struct udpsock *us=&socks->socks[i];
354 if (!list_length(caddrl)) {
355 us->addr=defaultaddrs[i];
357 string_item_to_iaddr(list_elem(caddrl,i),uc->port,&us->addr,"udp");
362 l=dict_lookup(d,"proxy");
365 uc->proxy.sa.sa_family=AF_INET;
367 if (!item || item->type!=t_string) {
368 cfgfatal(cc->loc,"udp","proxy must supply ""addr"",port\n");
370 a=string_item_to_ipaddr(item,"proxy");
371 uc->proxy.sin.sin_addr.s_addr=htonl(a);
373 if (!item || item->type!=t_number) {
374 cfgfatal(cc->loc,"udp","proxy must supply ""addr"",port\n");
376 uc->proxy.sin.sin_port=htons(item->data.number);
379 update_max_start_pad(&comm_max_start_pad, uc->use_proxy ? 8 : 0);
381 add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
383 return new_closure(&cc->cl);
386 void udp_module(dict_t *dict)
388 add_closure(dict,"udp",udp_apply);