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"
27 static beforepoll_fn udp_beforepoll;
28 static afterpoll_fn udp_afterpoll;
29 static comm_request_notify_fn request_notify;
30 static comm_release_notify_fn release_notify;
31 static comm_sendmsg_fn udp_sendmsg;
33 struct comm_notify_entry {
36 LIST_ENTRY(comm_notify_entry) entry;
38 LIST_HEAD(comm_notify_list, comm_notify_entry) notify;
40 #define MAX_SOCKETS 3 /* 2 ought to do really */
52 struct udpsock socks[MAX_SOCKETS];
54 struct buffer_if *rbuf;
55 struct comm_notify_list notify;
61 * Re comm_addr.ix: This field allows us to note in the comm_addr
62 * which socket an incoming packet was received on. This is required
63 * for conveniently logging the actual source of a packet. But the ix
64 * does not formally form part of the address: it is not used when
65 * sending, nor when comparing two comm_addrs.
67 * The special value -1 means that the comm_addr was constructed by
68 * another module in secnet (eg the resolver), rather than being a
69 * description of the source of an incoming packet.
72 static const char *addr_to_string(void *commst, const struct comm_addr *ca) {
73 struct udp *st=commst;
74 static char sbuf[100];
75 int ix=ca->ix>=0 ? ca->ix : 0;
77 assert(ix>=0 && ix<st->n_socks);
78 snprintf(sbuf, sizeof(sbuf), "udp:%s%s-%s",
79 iaddr_to_string(&st->socks[ix].addr),
81 iaddr_to_string(&ca->ia));
85 static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
90 if (*nfds_io<st->n_socks) {
95 for (i=0; i<st->n_socks; i++) {
96 fds[i].fd=st->socks[i].fd;
102 static void udp_afterpoll(void *state, struct pollfd *fds, int nfds)
104 struct udp *st=state;
107 struct comm_notify_entry *n;
112 for (i=0; i<st->n_socks; i++) {
113 if (i>=nfds) continue;
114 if (!(fds[i].revents & POLLIN)) continue;
115 assert(fds[i].fd == st->socks[i].fd);
116 int fd=st->socks[i].fd;
118 fromlen=sizeof(from);
119 BUF_ASSERT_FREE(st->rbuf);
120 BUF_ALLOC(st->rbuf,"udp_afterpoll");
121 buffer_init(st->rbuf,calculate_max_start_pad());
122 rv=recvfrom(fd, st->rbuf->start,
123 buf_remaining_space(st->rbuf),
124 0, &from.sa, &fromlen);
128 /* Check that the packet came from our poxy server;
129 we shouldn't be contacted directly by anybody else
130 (since they can trivially forge source addresses) */
131 if (!iaddr_equal(&from,&st->proxy)) {
132 Message(M_INFO,"udp: received packet that's not "
137 /* proxy protocol supports ipv4 transport only */
138 from.sa.sa_family=AF_INET;
139 memcpy(&from.sin.sin_addr,buf_unprepend(st->rbuf,4),4);
140 buf_unprepend(st->rbuf,2);
141 memcpy(&from.sin.sin_port,buf_unprepend(st->rbuf,2),2);
148 LIST_FOREACH(n, &st->notify, entry) {
149 if (n->fn(n->state, st->rbuf, &ca)) {
156 if (st->rbuf->size>12 /* prevents traffic amplification */
157 && ((msgtype=get_uint32(st->rbuf->start+8))
159 uint32_t source,dest;
160 /* Manufacture and send NAK packet */
161 source=get_uint32(st->rbuf->start); /* Us */
162 dest=get_uint32(st->rbuf->start+4); /* Them */
163 send_nak(&ca,source,dest,msgtype,st->rbuf,"unwanted");
167 BUF_ASSERT_FREE(st->rbuf);
175 static void request_notify(void *commst, void *nst, comm_notify_fn *fn)
177 struct udp *st=commst;
178 struct comm_notify_entry *n;
180 n=safe_malloc(sizeof(*n),"request_notify");
183 LIST_INSERT_HEAD(&st->notify, n, entry);
186 static void release_notify(void *commst, void *nst, comm_notify_fn *fn)
188 struct udp *st=commst;
189 struct comm_notify_entry *n, *t;
192 LIST_FOREACH_SAFE(n, &st->notify, entry, t) {
193 if (n->state==nst && n->fn==fn) {
194 LIST_REMOVE(n, entry);
200 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
201 const struct comm_addr *dest)
203 struct udp *st=commst;
207 sa=buf_prepend(buf,8);
208 if (dest->ia.sa.sa_family != AF_INET) {
210 "udp: proxy means dropping outgoing non-IPv4 packet to %s\n",
211 iaddr_to_string(&dest->ia));
214 memcpy(sa,&dest->ia.sin.sin_addr,4);
216 memcpy(sa+6,&dest->ia.sin.sin_port,2);
217 sendto(st->socks[0].fd,sa,buf->size+8,0,&st->proxy.sa,
218 iaddr_socklen(&st->proxy));
219 buf_unprepend(buf,8);
222 bool_t allunsupported=True;
223 for (i=0; i<st->n_socks; i++) {
224 if (dest->ia.sa.sa_family != st->socks[i].addr.sa.sa_family)
225 /* no point even trying */
227 r=sendto(st->socks[i].fd, buf->start, buf->size, 0,
228 &dest->ia.sa, iaddr_socklen(&dest->ia));
229 if (r>=0) return True;
230 if (!(errno==EAFNOSUPPORT || errno==ENETUNREACH))
231 /* who knows what that error means? */
232 allunsupported=False;
234 return !allunsupported; /* see doc for comm_sendmsg_fn in secnet.h */
240 static void udp_make_socket(struct udp *st, struct udpsock *us)
242 const union iaddr *addr=&us->addr;
243 us->fd=socket(addr->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
245 fatal_perror("udp (%s:%d): socket",st->loc.file,st->loc.line);
247 if (fcntl(us->fd, F_SETFL, fcntl(us->fd, F_GETFL)|O_NONBLOCK)==-1) {
248 fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
249 st->loc.file,st->loc.line);
253 if (addr->sa.sa_family==AF_INET6) {
256 socklen_t optlen=sizeof(optval);
257 r=setsockopt(us->fd,IPPROTO_IPV6,IPV6_V6ONLY,&optval,optlen);
258 if (r) fatal_perror("udp (%s:%d): setsockopt(,IPV6_V6ONLY,&1,)",
259 st->loc.file,st->loc.line);
267 /* XXX this fork() and waitpid() business needs to be hidden
268 in some system-specific library functions. */
271 fatal_perror("udp_phase_hook: fork() for authbind");
274 char *argv[5], addrstr[33], portstr[5];
277 switch (addr->sa.sa_family) {
279 sprintf(addrstr,"%08lX",(long)addr->sin.sin_addr.s_addr);
280 port=addr->sin.sin_port;
287 sprintf(addrstr+i*2,"%02X",addr->sin6.sin6_addr.s6_addr[i]);
288 port=addr->sin6.sin6_port;
292 #endif /*CONFIG_IPV6*/
294 fatal("udp (%s:%d): unsupported address family for authbind",
295 st->loc.file,st->loc.line);
297 sprintf(portstr,"%04X",port);
298 argv[0]=st->authbind;
301 argv[3]=(char*)addrfam;
304 execvp(st->authbind,argv);
307 while (waitpid(c,&status,0)==-1) {
308 if (errno==EINTR) continue;
309 fatal_perror("udp (%s:%d): authbind",st->loc.file,st->loc.line);
311 if (WIFSIGNALED(status)) {
312 fatal("udp (%s:%d): authbind died on signal %d",st->loc.file,
313 st->loc.line, WTERMSIG(status));
315 if (WIFEXITED(status) && WEXITSTATUS(status)!=0) {
316 fatal("udp (%s:%d): authbind died with status %d",st->loc.file,
317 st->loc.line, WEXITSTATUS(status));
320 if (bind(us->fd, &addr->sa, iaddr_socklen(addr))!=0) {
321 fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
326 static void udp_phase_hook(void *sst, uint32_t new_phase)
330 for (i=0; i<st->n_socks; i++)
331 udp_make_socket(st,&st->socks[i]);
333 register_for_poll(st,udp_beforepoll,udp_afterpoll,MAX_SOCKETS,"udp");
336 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
347 st=safe_malloc(sizeof(*st),"udp_apply(st)");
349 st->cl.description="udp";
352 st->cl.interface=&st->ops;
354 st->ops.request_notify=request_notify;
355 st->ops.release_notify=release_notify;
356 st->ops.sendmsg=udp_sendmsg;
357 st->ops.addr_to_string=addr_to_string;
359 LIST_INIT(&st->notify);
361 item=list_elem(args,0);
362 if (!item || item->type!=t_dict) {
363 cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
367 int port=dict_read_number(d,"port",True,"udp",st->loc,0);
369 union iaddr defaultaddrs[] = {
371 { .sin6 = { .sin6_family=AF_INET6,
372 .sin6_port=htons(port),
373 .sin6_addr=IN6ADDR_ANY_INIT } },
375 { .sin = { .sin_family=AF_INET,
376 .sin_port=htons(port),
377 .sin_addr= { .s_addr=INADDR_ANY } } }
380 caddrl=dict_lookup(d,"address");
381 st->n_socks=caddrl ? list_length(caddrl) : (int)ARRAY_SIZE(defaultaddrs);
382 if (st->n_socks<=0 || st->n_socks>MAX_SOCKETS)
383 cfgfatal(st->loc,"udp","`address' must be 1..%d addresses",
386 for (i=0; i<st->n_socks; i++) {
387 struct udpsock *us=&st->socks[i];
388 if (!list_length(caddrl)) {
389 us->addr=defaultaddrs[i];
391 string_item_to_iaddr(list_elem(caddrl,i),port,&us->addr,"udp");
396 st->rbuf=find_cl_if(d,"buffer",CL_BUFFER,True,"udp",st->loc);
397 st->authbind=dict_read_string(d,"authbind",False,"udp",st->loc);
398 l=dict_lookup(d,"proxy");
401 st->proxy.sa.sa_family=AF_INET;
403 if (!item || item->type!=t_string) {
404 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
406 a=string_item_to_ipaddr(item,"proxy");
407 st->proxy.sin.sin_addr.s_addr=htonl(a);
409 if (!item || item->type!=t_number) {
410 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
412 st->proxy.sin.sin_port=htons(item->data.number);
415 update_max_start_pad(&comm_max_start_pad, st->use_proxy ? 8 : 0);
417 add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
419 return new_closure(&st->cl);
422 void udp_module(dict_t *dict)
424 add_closure(dict,"udp",udp_apply);