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 beforepoll_fn udp_beforepoll;
29 static afterpoll_fn udp_afterpoll;
30 static comm_sendmsg_fn udp_sendmsg;
32 #define UDP_MAX_SOCKETS 3 /* 2 ought to do really */
42 struct udpsock socks[UDP_MAX_SOCKETS];
49 * Re comm_addr.ix: This field allows us to note in the comm_addr
50 * which socket an incoming packet was received on. This is required
51 * for conveniently logging the actual source of a packet. But the ix
52 * does not formally form part of the address: it is not used when
53 * sending, nor when comparing two comm_addrs.
55 * The special value -1 means that the comm_addr was constructed by
56 * another module in secnet (eg the resolver), rather than being a
57 * description of the source of an incoming packet.
60 static const char *udp_addr_to_string(void *commst, const struct comm_addr *ca)
62 struct udp *st=commst;
63 struct udp *socks=st; /* for now */
64 static char sbuf[100];
65 int ix=ca->ix>=0 ? ca->ix : 0;
67 assert(ix>=0 && ix<socks->n_socks);
68 snprintf(sbuf, sizeof(sbuf), "udp:%s%s-%s",
69 iaddr_to_string(&socks->socks[ix].addr),
71 iaddr_to_string(&ca->ia));
75 static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
80 struct udp *socks=st; /* for now */
81 BEFOREPOLL_WANT_FDS(socks->n_socks);
82 for (i=0; i<socks->n_socks; i++) {
83 fds[i].fd=socks->socks[i].fd;
89 static void udp_afterpoll(void *state, struct pollfd *fds, int nfds)
92 struct commcommon *cc=&st->cc;
93 struct udp *socks=st; /* for now */
94 struct udp *uc=st; /* for now */
101 for (i=0; i<st->n_socks; i++) {
102 if (i>=nfds) continue;
103 if (!(fds[i].revents & POLLIN)) continue;
104 assert(fds[i].fd == socks->socks[i].fd);
105 int fd=socks->socks[i].fd;
107 fromlen=sizeof(from);
108 BUF_ASSERT_FREE(cc->rbuf);
109 BUF_ALLOC(cc->rbuf,"udp_afterpoll");
110 buffer_init(cc->rbuf,calculate_max_start_pad());
111 rv=recvfrom(fd, cc->rbuf->start,
112 buf_remaining_space(cc->rbuf),
113 0, &from.sa, &fromlen);
117 /* Check that the packet came from our poxy server;
118 we shouldn't be contacted directly by anybody else
119 (since they can trivially forge source addresses) */
120 if (!iaddr_equal(&from,&uc->proxy)) {
121 Message(M_INFO,"udp: received packet that's not "
126 /* proxy protocol supports ipv4 transport only */
127 from.sa.sa_family=AF_INET;
128 BUF_GET_BYTES(unprepend,cc->rbuf,&from.sin.sin_addr,4);
129 buf_unprepend(cc->rbuf,2);
130 BUF_GET_BYTES(unprepend,cc->rbuf,&from.sin.sin_port,2);
136 done=comm_notify(&cc->notify, cc->rbuf, &ca);
139 if (cc->rbuf->size>12 /* prevents traffic amplification */
140 && ((msgtype=get_uint32(cc->rbuf->start+8))
142 uint32_t source,dest;
143 /* Manufacture and send NAK packet */
144 source=get_uint32(cc->rbuf->start); /* Us */
145 dest=get_uint32(cc->rbuf->start+4); /* Them */
146 send_nak(&ca,source,dest,msgtype,cc->rbuf,"unwanted");
150 BUF_ASSERT_FREE(cc->rbuf);
158 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
159 const struct comm_addr *dest)
161 struct udp *st=commst;
162 struct udp *uc=st; /* for now */
163 struct udp *socks=st; /* for now */
167 sa=buf_prepend(buf,8);
168 if (dest->ia.sa.sa_family != AF_INET) {
170 "udp: proxy means dropping outgoing non-IPv4 packet to %s\n",
171 iaddr_to_string(&dest->ia));
174 memcpy(sa,&dest->ia.sin.sin_addr,4);
176 memcpy(sa+6,&dest->ia.sin.sin_port,2);
177 sendto(socks->socks[0].fd,sa,buf->size+8,0,&uc->proxy.sa,
178 iaddr_socklen(&uc->proxy));
179 buf_unprepend(buf,8);
182 bool_t allunsupported=True;
183 for (i=0; i<socks->n_socks; i++) {
184 if (dest->ia.sa.sa_family != socks->socks[i].addr.sa.sa_family)
185 /* no point even trying */
187 r=sendto(socks->socks[i].fd, buf->start, buf->size, 0,
188 &dest->ia.sa, iaddr_socklen(&dest->ia));
189 if (r>=0) return True;
190 if (!(errno==EAFNOSUPPORT || errno==ENETUNREACH))
191 /* who knows what that error means? */
192 allunsupported=False;
194 return !allunsupported; /* see doc for comm_sendmsg_fn in secnet.h */
200 static void udp_make_socket(struct udp *st, struct udpsock *us)
202 const union iaddr *addr=&us->addr;
203 struct commcommon *cc=&st->cc; /* for now */
204 struct udp *uc=st; /* for now */
205 us->fd=socket(addr->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
207 fatal_perror("udp (%s:%d): socket",cc->loc.file,cc->loc.line);
209 if (fcntl(us->fd, F_SETFL, fcntl(us->fd, F_GETFL)|O_NONBLOCK)==-1) {
210 fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
211 cc->loc.file,cc->loc.line);
215 if (addr->sa.sa_family==AF_INET6) {
218 socklen_t optlen=sizeof(optval);
219 r=setsockopt(us->fd,IPPROTO_IPV6,IPV6_V6ONLY,&optval,optlen);
220 if (r) fatal_perror("udp (%s:%d): setsockopt(,IPV6_V6ONLY,&1,)",
221 cc->loc.file,cc->loc.line);
229 /* XXX this fork() and waitpid() business needs to be hidden
230 in some system-specific library functions. */
233 fatal_perror("udp_phase_hook: fork() for authbind");
236 char *argv[5], addrstr[33], portstr[5];
239 switch (addr->sa.sa_family) {
241 sprintf(addrstr,"%08lX",(long)addr->sin.sin_addr.s_addr);
242 port=addr->sin.sin_port;
249 sprintf(addrstr+i*2,"%02X",addr->sin6.sin6_addr.s6_addr[i]);
250 port=addr->sin6.sin6_port;
254 #endif /*CONFIG_IPV6*/
256 fatal("udp (%s:%d): unsupported address family for authbind",
257 cc->loc.file,cc->loc.line);
259 sprintf(portstr,"%04X",port);
260 argv[0]=uc->authbind;
263 argv[3]=(char*)addrfam;
266 execvp(uc->authbind,argv);
269 while (waitpid(c,&status,0)==-1) {
270 if (errno==EINTR) continue;
271 fatal_perror("udp (%s:%d): authbind",cc->loc.file,cc->loc.line);
273 if (WIFSIGNALED(status)) {
274 fatal("udp (%s:%d): authbind died on signal %d",cc->loc.file,
275 cc->loc.line, WTERMSIG(status));
277 if (WIFEXITED(status) && WEXITSTATUS(status)!=0) {
278 fatal("udp (%s:%d): authbind died with status %d",cc->loc.file,
279 cc->loc.line, WEXITSTATUS(status));
282 if (bind(us->fd, &addr->sa, iaddr_socklen(addr))!=0) {
283 fatal_perror("udp (%s:%d): bind",cc->loc.file,cc->loc.line);
288 static void udp_phase_hook(void *sst, uint32_t new_phase)
291 struct udp *socks=st; /* for now */
293 for (i=0; i<socks->n_socks; i++)
294 udp_make_socket(st,&socks->socks[i]);
296 register_for_poll(st,udp_beforepoll,udp_afterpoll,"udp");
299 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
308 COMM_APPLY(st,&st->cc,udp_,"udp",loc);
309 struct commcommon *cc=&st->cc; /* for now */
310 struct udp *uc=st; /* for now */
311 struct udp *socks=st; /* for now */
315 COMM_APPLY_STANDARD(st,&st->cc,"udp",args);
317 int port=dict_read_number(d,"port",True,"udp",cc->loc,0);
319 union iaddr defaultaddrs[] = {
321 { .sin6 = { .sin6_family=AF_INET6,
322 .sin6_port=htons(port),
323 .sin6_addr=IN6ADDR_ANY_INIT } },
325 { .sin = { .sin_family=AF_INET,
326 .sin_port=htons(port),
327 .sin_addr= { .s_addr=INADDR_ANY } } }
330 caddrl=dict_lookup(d,"address");
331 socks->n_socks=caddrl ? list_length(caddrl) : (int)ARRAY_SIZE(defaultaddrs);
332 if (socks->n_socks<=0 || socks->n_socks>UDP_MAX_SOCKETS)
333 cfgfatal(cc->loc,"udp","`address' must be 1..%d addresses",
336 for (i=0; i<socks->n_socks; i++) {
337 struct udpsock *us=&socks->socks[i];
338 if (!list_length(caddrl)) {
339 us->addr=defaultaddrs[i];
341 string_item_to_iaddr(list_elem(caddrl,i),port,&us->addr,"udp");
346 uc->authbind=dict_read_string(d,"authbind",False,"udp",cc->loc);
347 l=dict_lookup(d,"proxy");
350 uc->proxy.sa.sa_family=AF_INET;
352 if (!item || item->type!=t_string) {
353 cfgfatal(cc->loc,"udp","proxy must supply ""addr"",port\n");
355 a=string_item_to_ipaddr(item,"proxy");
356 uc->proxy.sin.sin_addr.s_addr=htonl(a);
358 if (!item || item->type!=t_number) {
359 cfgfatal(cc->loc,"udp","proxy must supply ""addr"",port\n");
361 uc->proxy.sin.sin_port=htons(item->data.number);
364 update_max_start_pad(&comm_max_start_pad, uc->use_proxy ? 8 : 0);
366 add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
368 return new_closure(&cc->cl);
371 void udp_module(dict_t *dict)
373 add_closure(dict,"udp",udp_apply);