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;
36 struct notify_list *next;
46 struct buffer_if *rbuf;
47 struct notify_list *notify;
52 static const char *addr_to_string(void *commst, const struct comm_addr *ca) {
53 struct udp *st=commst;
54 static char sbuf[100];
56 snprintf(sbuf, sizeof(sbuf), "udp:%s-%s",
57 iaddr_to_string(&st->addr), iaddr_to_string(&ca->ia));
61 static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
75 static void udp_afterpoll(void *state, struct pollfd *fds, int nfds)
80 struct notify_list *n;
84 if (nfds && (fds->revents & POLLIN)) {
88 BUF_ASSERT_FREE(st->rbuf);
89 BUF_ALLOC(st->rbuf,"udp_afterpoll");
90 buffer_init(st->rbuf,calculate_max_start_pad());
91 rv=recvfrom(st->fd, st->rbuf->start,
92 buf_remaining_space(st->rbuf),
93 0, (struct sockaddr *)&from, &fromlen);
97 /* Check that the packet came from our poxy server;
98 we shouldn't be contacted directly by anybody else
99 (since they can trivially forge source addresses) */
100 if (!iaddr_equal(&from,&st->proxy)) {
101 Message(M_INFO,"udp: received packet that's not "
106 /* proxy protocol supports ipv4 transport only */
108 from.sa.sa_family=AF_INET;
109 memcpy(&from.sin.sin_addr,buf_unprepend(st->rbuf,4),4);
110 buf_unprepend(st->rbuf,2);
111 memcpy(&from.sin.sin_port,buf_unprepend(st->rbuf,2),2);
118 for (n=st->notify; n; n=n->next) {
119 if (n->fn(n->state, st->rbuf, &ca)) {
126 if (st->rbuf->size>12 /* prevents traffic amplification */
127 && ((msgtype=get_uint32(st->rbuf->start+8))
129 uint32_t source,dest;
130 /* Manufacture and send NAK packet */
131 source=get_uint32(st->rbuf->start); /* Us */
132 dest=get_uint32(st->rbuf->start+4); /* Them */
133 send_nak(&ca,source,dest,msgtype,st->rbuf,"unwanted");
137 BUF_ASSERT_FREE(st->rbuf);
145 static void request_notify(void *commst, void *nst, comm_notify_fn *fn)
147 struct udp *st=commst;
148 struct notify_list *n;
150 n=safe_malloc(sizeof(*n),"request_notify");
157 static void release_notify(void *commst, void *nst, comm_notify_fn *fn)
159 struct udp *st=commst;
160 struct notify_list *n, **p, *t;
164 for (n=st->notify; n; )
166 if (n->state==nst && n->fn==fn) {
178 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
179 const struct comm_addr *dest)
181 struct udp *st=commst;
185 sa=buf_prepend(buf,8);
186 if (dest->ia.sa.sa_family != AF_INET) {
188 "udp: proxy means dropping outgoing non-IPv4 packet to %s\n",
189 iaddr_to_string(&dest->ia));
192 memcpy(sa,&dest->ia.sin.sin_addr,4);
194 memcpy(sa+6,&dest->ia.sin.sin_port,2);
195 sendto(st->fd,sa,buf->size+8,0,(struct sockaddr *)&st->proxy,
197 buf_unprepend(buf,8);
199 sendto(st->fd, buf->start, buf->size, 0,
200 &dest->ia.sa, iaddr_socklen(&dest->ia));
206 static void udp_make_socket(struct udp *st, struct udp *us)
208 const union iaddr *addr=&us->addr;
209 us->fd=socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
211 fatal_perror("udp (%s:%d): socket",st->loc.file,st->loc.line);
213 if (fcntl(us->fd, F_SETFL, fcntl(us->fd, F_GETFL)|O_NONBLOCK)==-1) {
214 fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
215 st->loc.file,st->loc.line);
223 /* XXX this fork() and waitpid() business needs to be hidden
224 in some system-specific library functions. */
227 fatal_perror("udp_phase_hook: fork() for authbind");
230 char *argv[4], addrstr[9], portstr[5];
231 switch (addr->sa.sa_family) {
233 sprintf(addrstr,"%08lX",(long)addr->sin.sin_addr.s_addr);
234 sprintf(portstr,"%04X",addr->sin.sin_port);
237 fatal("udp (%s:%d): unsupported address family for authbind",
238 st->loc.file,st->loc.line);
240 argv[0]=st->authbind;
245 execvp(st->authbind,argv);
248 while (waitpid(c,&status,0)==-1) {
249 if (errno==EINTR) continue;
250 fatal_perror("udp (%s:%d): authbind",st->loc.file,st->loc.line);
252 if (WIFSIGNALED(status)) {
253 fatal("udp (%s:%d): authbind died on signal %d",st->loc.file,
254 st->loc.line, WTERMSIG(status));
256 if (WIFEXITED(status) && WEXITSTATUS(status)!=0) {
257 fatal("udp (%s:%d): authbind died with status %d",st->loc.file,
258 st->loc.line, WEXITSTATUS(status));
261 if (bind(us->fd, &addr->sa, iaddr_socklen(addr))!=0) {
262 fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
267 static void udp_phase_hook(void *sst, uint32_t new_phase)
270 udp_make_socket(st,st);
271 register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp");
274 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
283 st=safe_malloc(sizeof(*st),"udp_apply(st)");
285 st->cl.description="udp";
288 st->cl.interface=&st->ops;
290 st->ops.request_notify=request_notify;
291 st->ops.release_notify=release_notify;
292 st->ops.sendmsg=udp_sendmsg;
293 st->ops.addr_to_string=addr_to_string;
298 if (!i || i->type!=t_dict) {
299 cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
303 st->addr.sa.sa_family=AF_INET;
304 j=dict_find_item(d,"address",False,"udp",st->loc);
305 st->addr.sin.sin_addr.s_addr=j?string_item_to_ipaddr(j, "udp"):INADDR_ANY;
306 st->addr.sin.sin_port=dict_read_number(d,"port",True,"udp",st->loc,0);
307 st->rbuf=find_cl_if(d,"buffer",CL_BUFFER,True,"udp",st->loc);
308 st->authbind=dict_read_string(d,"authbind",False,"udp",st->loc);
309 l=dict_lookup(d,"proxy");
313 st->proxy.sa.sa_family=AF_INET;
315 if (!i || i->type!=t_string) {
316 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
318 a=string_item_to_ipaddr(i,"proxy");
319 st->proxy.sin.sin_addr.s_addr=htonl(a);
321 if (!i || i->type!=t_number) {
322 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
324 st->proxy.sin.sin_port=htons(i->data.number);
327 update_max_start_pad(&comm_max_start_pad, st->use_proxy ? 8 : 0);
329 add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
331 return new_closure(&st->cl);
334 void udp_module(dict_t *dict)
336 add_closure(dict,"udp",udp_apply);