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)) {
87 BUF_ASSERT_FREE(st->rbuf);
88 BUF_ALLOC(st->rbuf,"udp_afterpoll");
89 buffer_init(st->rbuf,calculate_max_start_pad());
90 rv=recvfrom(st->fd, st->rbuf->start,
91 buf_remaining_space(st->rbuf),
92 0, &from.sa, &fromlen);
96 /* Check that the packet came from our poxy server;
97 we shouldn't be contacted directly by anybody else
98 (since they can trivially forge source addresses) */
99 if (!iaddr_equal(&from,&st->proxy)) {
100 Message(M_INFO,"udp: received packet that's not "
105 /* proxy protocol supports ipv4 transport only */
106 from.sa.sa_family=AF_INET;
107 memcpy(&from.sin.sin_addr,buf_unprepend(st->rbuf,4),4);
108 buf_unprepend(st->rbuf,2);
109 memcpy(&from.sin.sin_port,buf_unprepend(st->rbuf,2),2);
115 for (n=st->notify; n; n=n->next) {
116 if (n->fn(n->state, st->rbuf, &ca)) {
123 if (st->rbuf->size>12 /* prevents traffic amplification */
124 && ((msgtype=get_uint32(st->rbuf->start+8))
126 uint32_t source,dest;
127 /* Manufacture and send NAK packet */
128 source=get_uint32(st->rbuf->start); /* Us */
129 dest=get_uint32(st->rbuf->start+4); /* Them */
130 send_nak(&ca,source,dest,msgtype,st->rbuf,"unwanted");
134 BUF_ASSERT_FREE(st->rbuf);
142 static void request_notify(void *commst, void *nst, comm_notify_fn *fn)
144 struct udp *st=commst;
145 struct notify_list *n;
147 n=safe_malloc(sizeof(*n),"request_notify");
154 static void release_notify(void *commst, void *nst, comm_notify_fn *fn)
156 struct udp *st=commst;
157 struct notify_list *n, **p, *t;
161 for (n=st->notify; n; )
163 if (n->state==nst && n->fn==fn) {
175 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
176 const struct comm_addr *dest)
178 struct udp *st=commst;
182 sa=buf_prepend(buf,8);
183 if (dest->ia.sa.sa_family != AF_INET) {
185 "udp: proxy means dropping outgoing non-IPv4 packet to %s\n",
186 iaddr_to_string(&dest->ia));
189 memcpy(sa,&dest->ia.sin.sin_addr,4);
191 memcpy(sa+6,&dest->ia.sin.sin_port,2);
192 sendto(st->fd,sa,buf->size+8,0,&st->proxy.sa,
193 iaddr_socklen(&st->proxy));
194 buf_unprepend(buf,8);
196 sendto(st->fd, buf->start, buf->size, 0,
197 &dest->ia.sa, iaddr_socklen(&dest->ia));
203 static void udp_make_socket(struct udp *st, struct udp *us)
205 const union iaddr *addr=&us->addr;
206 us->fd=socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
208 fatal_perror("udp (%s:%d): socket",st->loc.file,st->loc.line);
210 if (fcntl(us->fd, F_SETFL, fcntl(us->fd, F_GETFL)|O_NONBLOCK)==-1) {
211 fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
212 st->loc.file,st->loc.line);
220 /* XXX this fork() and waitpid() business needs to be hidden
221 in some system-specific library functions. */
224 fatal_perror("udp_phase_hook: fork() for authbind");
227 char *argv[4], addrstr[9], portstr[5];
228 switch (addr->sa.sa_family) {
230 sprintf(addrstr,"%08lX",(long)addr->sin.sin_addr.s_addr);
231 sprintf(portstr,"%04X",addr->sin.sin_port);
234 fatal("udp (%s:%d): unsupported address family for authbind",
235 st->loc.file,st->loc.line);
237 argv[0]=st->authbind;
242 execvp(st->authbind,argv);
245 while (waitpid(c,&status,0)==-1) {
246 if (errno==EINTR) continue;
247 fatal_perror("udp (%s:%d): authbind",st->loc.file,st->loc.line);
249 if (WIFSIGNALED(status)) {
250 fatal("udp (%s:%d): authbind died on signal %d",st->loc.file,
251 st->loc.line, WTERMSIG(status));
253 if (WIFEXITED(status) && WEXITSTATUS(status)!=0) {
254 fatal("udp (%s:%d): authbind died with status %d",st->loc.file,
255 st->loc.line, WEXITSTATUS(status));
258 if (bind(st->fd, &addr->sa, iaddr_socklen(addr))!=0) {
259 fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
264 static void udp_phase_hook(void *sst, uint32_t new_phase)
267 udp_make_socket(st,st);
268 register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp");
271 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
280 st=safe_malloc(sizeof(*st),"udp_apply(st)");
282 st->cl.description="udp";
285 st->cl.interface=&st->ops;
287 st->ops.request_notify=request_notify;
288 st->ops.release_notify=release_notify;
289 st->ops.sendmsg=udp_sendmsg;
290 st->ops.addr_to_string=addr_to_string;
294 if (!i || i->type!=t_dict) {
295 cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
299 st->addr.sa.sa_family=AF_INET;
300 j=dict_find_item(d,"address",False,"udp",st->loc);
301 st->addr.sin.sin_addr.s_addr=j?string_item_to_ipaddr(j, "udp"):INADDR_ANY;
302 st->addr.sin.sin_port=dict_read_number(d,"port",True,"udp",st->loc,0);
303 st->rbuf=find_cl_if(d,"buffer",CL_BUFFER,True,"udp",st->loc);
304 st->authbind=dict_read_string(d,"authbind",False,"udp",st->loc);
305 l=dict_lookup(d,"proxy");
308 st->proxy.sa.sa_family=AF_INET;
310 if (!i || i->type!=t_string) {
311 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
313 a=string_item_to_ipaddr(i,"proxy");
314 st->proxy.sin.sin_addr.s_addr=htonl(a);
316 if (!i || i->type!=t_number) {
317 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
319 st->proxy.sin.sin_port=htons(i->data.number);
322 update_max_start_pad(&comm_max_start_pad, st->use_proxy ? 8 : 0);
324 add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
326 return new_closure(&st->cl);
329 void udp_module(dict_t *dict)
331 add_closure(dict,"udp",udp_apply);