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 BEFOREPOLL_WANT_FDS(st->n_socks);
91 for (i=0; i<st->n_socks; i++) {
92 fds[i].fd=st->socks[i].fd;
98 static void udp_afterpoll(void *state, struct pollfd *fds, int nfds)
100 struct udp *st=state;
103 struct comm_notify_entry *n;
108 for (i=0; i<st->n_socks; i++) {
109 if (i>=nfds) continue;
110 if (!(fds[i].revents & POLLIN)) continue;
111 assert(fds[i].fd == st->socks[i].fd);
112 int fd=st->socks[i].fd;
114 fromlen=sizeof(from);
115 BUF_ASSERT_FREE(st->rbuf);
116 BUF_ALLOC(st->rbuf,"udp_afterpoll");
117 buffer_init(st->rbuf,calculate_max_start_pad());
118 rv=recvfrom(fd, st->rbuf->start,
119 buf_remaining_space(st->rbuf),
120 0, &from.sa, &fromlen);
124 /* Check that the packet came from our poxy server;
125 we shouldn't be contacted directly by anybody else
126 (since they can trivially forge source addresses) */
127 if (!iaddr_equal(&from,&st->proxy)) {
128 Message(M_INFO,"udp: received packet that's not "
133 /* proxy protocol supports ipv4 transport only */
134 from.sa.sa_family=AF_INET;
135 memcpy(&from.sin.sin_addr,buf_unprepend(st->rbuf,4),4);
136 buf_unprepend(st->rbuf,2);
137 memcpy(&from.sin.sin_port,buf_unprepend(st->rbuf,2),2);
144 LIST_FOREACH(n, &st->notify, entry) {
145 if (n->fn(n->state, st->rbuf, &ca)) {
152 if (st->rbuf->size>12 /* prevents traffic amplification */
153 && ((msgtype=get_uint32(st->rbuf->start+8))
155 uint32_t source,dest;
156 /* Manufacture and send NAK packet */
157 source=get_uint32(st->rbuf->start); /* Us */
158 dest=get_uint32(st->rbuf->start+4); /* Them */
159 send_nak(&ca,source,dest,msgtype,st->rbuf,"unwanted");
163 BUF_ASSERT_FREE(st->rbuf);
171 static void request_notify(void *commst, void *nst, comm_notify_fn *fn)
173 struct udp *st=commst;
174 struct comm_notify_entry *n;
176 n=safe_malloc(sizeof(*n),"request_notify");
179 LIST_INSERT_HEAD(&st->notify, n, entry);
182 static void release_notify(void *commst, void *nst, comm_notify_fn *fn)
184 struct udp *st=commst;
185 struct comm_notify_entry *n, *t;
188 LIST_FOREACH_SAFE(n, &st->notify, entry, t) {
189 if (n->state==nst && n->fn==fn) {
190 LIST_REMOVE(n, entry);
196 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
197 const struct comm_addr *dest)
199 struct udp *st=commst;
203 sa=buf_prepend(buf,8);
204 if (dest->ia.sa.sa_family != AF_INET) {
206 "udp: proxy means dropping outgoing non-IPv4 packet to %s\n",
207 iaddr_to_string(&dest->ia));
210 memcpy(sa,&dest->ia.sin.sin_addr,4);
212 memcpy(sa+6,&dest->ia.sin.sin_port,2);
213 sendto(st->socks[0].fd,sa,buf->size+8,0,&st->proxy.sa,
214 iaddr_socklen(&st->proxy));
215 buf_unprepend(buf,8);
218 bool_t allunsupported=True;
219 for (i=0; i<st->n_socks; i++) {
220 if (dest->ia.sa.sa_family != st->socks[i].addr.sa.sa_family)
221 /* no point even trying */
223 r=sendto(st->socks[i].fd, buf->start, buf->size, 0,
224 &dest->ia.sa, iaddr_socklen(&dest->ia));
225 if (r>=0) return True;
226 if (!(errno==EAFNOSUPPORT || errno==ENETUNREACH))
227 /* who knows what that error means? */
228 allunsupported=False;
230 return !allunsupported; /* see doc for comm_sendmsg_fn in secnet.h */
236 static void udp_make_socket(struct udp *st, struct udpsock *us)
238 const union iaddr *addr=&us->addr;
239 us->fd=socket(addr->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
241 fatal_perror("udp (%s:%d): socket",st->loc.file,st->loc.line);
243 if (fcntl(us->fd, F_SETFL, fcntl(us->fd, F_GETFL)|O_NONBLOCK)==-1) {
244 fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
245 st->loc.file,st->loc.line);
249 if (addr->sa.sa_family==AF_INET6) {
252 socklen_t optlen=sizeof(optval);
253 r=setsockopt(us->fd,IPPROTO_IPV6,IPV6_V6ONLY,&optval,optlen);
254 if (r) fatal_perror("udp (%s:%d): setsockopt(,IPV6_V6ONLY,&1,)",
255 st->loc.file,st->loc.line);
263 /* XXX this fork() and waitpid() business needs to be hidden
264 in some system-specific library functions. */
267 fatal_perror("udp_phase_hook: fork() for authbind");
270 char *argv[5], addrstr[33], portstr[5];
273 switch (addr->sa.sa_family) {
275 sprintf(addrstr,"%08lX",(long)addr->sin.sin_addr.s_addr);
276 port=addr->sin.sin_port;
283 sprintf(addrstr+i*2,"%02X",addr->sin6.sin6_addr.s6_addr[i]);
284 port=addr->sin6.sin6_port;
288 #endif /*CONFIG_IPV6*/
290 fatal("udp (%s:%d): unsupported address family for authbind",
291 st->loc.file,st->loc.line);
293 sprintf(portstr,"%04X",port);
294 argv[0]=st->authbind;
297 argv[3]=(char*)addrfam;
300 execvp(st->authbind,argv);
303 while (waitpid(c,&status,0)==-1) {
304 if (errno==EINTR) continue;
305 fatal_perror("udp (%s:%d): authbind",st->loc.file,st->loc.line);
307 if (WIFSIGNALED(status)) {
308 fatal("udp (%s:%d): authbind died on signal %d",st->loc.file,
309 st->loc.line, WTERMSIG(status));
311 if (WIFEXITED(status) && WEXITSTATUS(status)!=0) {
312 fatal("udp (%s:%d): authbind died with status %d",st->loc.file,
313 st->loc.line, WEXITSTATUS(status));
316 if (bind(us->fd, &addr->sa, iaddr_socklen(addr))!=0) {
317 fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
322 static void udp_phase_hook(void *sst, uint32_t new_phase)
326 for (i=0; i<st->n_socks; i++)
327 udp_make_socket(st,&st->socks[i]);
329 register_for_poll(st,udp_beforepoll,udp_afterpoll,MAX_SOCKETS,"udp");
332 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
343 st=safe_malloc(sizeof(*st),"udp_apply(st)");
345 st->cl.description="udp";
348 st->cl.interface=&st->ops;
350 st->ops.request_notify=request_notify;
351 st->ops.release_notify=release_notify;
352 st->ops.sendmsg=udp_sendmsg;
353 st->ops.addr_to_string=addr_to_string;
355 LIST_INIT(&st->notify);
357 item=list_elem(args,0);
358 if (!item || item->type!=t_dict) {
359 cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
363 int port=dict_read_number(d,"port",True,"udp",st->loc,0);
365 union iaddr defaultaddrs[] = {
367 { .sin6 = { .sin6_family=AF_INET6,
368 .sin6_port=htons(port),
369 .sin6_addr=IN6ADDR_ANY_INIT } },
371 { .sin = { .sin_family=AF_INET,
372 .sin_port=htons(port),
373 .sin_addr= { .s_addr=INADDR_ANY } } }
376 caddrl=dict_lookup(d,"address");
377 st->n_socks=caddrl ? list_length(caddrl) : (int)ARRAY_SIZE(defaultaddrs);
378 if (st->n_socks<=0 || st->n_socks>MAX_SOCKETS)
379 cfgfatal(st->loc,"udp","`address' must be 1..%d addresses",
382 for (i=0; i<st->n_socks; i++) {
383 struct udpsock *us=&st->socks[i];
384 if (!list_length(caddrl)) {
385 us->addr=defaultaddrs[i];
387 string_item_to_iaddr(list_elem(caddrl,i),port,&us->addr,"udp");
392 st->rbuf=find_cl_if(d,"buffer",CL_BUFFER,True,"udp",st->loc);
393 st->authbind=dict_read_string(d,"authbind",False,"udp",st->loc);
394 l=dict_lookup(d,"proxy");
397 st->proxy.sa.sa_family=AF_INET;
399 if (!item || item->type!=t_string) {
400 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
402 a=string_item_to_ipaddr(item,"proxy");
403 st->proxy.sin.sin_addr.s_addr=htonl(a);
405 if (!item || item->type!=t_number) {
406 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
408 st->proxy.sin.sin_port=htons(item->data.number);
411 update_max_start_pad(&comm_max_start_pad, st->use_proxy ? 8 : 0);
413 add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
415 return new_closure(&st->cl);
418 void udp_module(dict_t *dict)
420 add_closure(dict,"udp",udp_apply);