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>
22 #include "unaligned.h"
26 static beforepoll_fn udp_beforepoll;
27 static afterpoll_fn udp_afterpoll;
28 static comm_request_notify_fn request_notify;
29 static comm_release_notify_fn release_notify;
30 static comm_sendmsg_fn udp_sendmsg;
35 struct notify_list *next;
46 struct buffer_if *rbuf;
47 struct notify_list *notify;
49 struct sockaddr_in proxy;
52 static const char *saddr_to_string(const struct sockaddr_in *sin) {
53 static char bufs[2][100];
57 snprintf(bufs[b], sizeof(bufs[b]), "[%s]:%d",
58 inet_ntoa(sin->sin_addr),
59 ntohs(sin->sin_port));
63 static const char *addr_to_string(void *commst, const struct comm_addr *ca) {
64 struct udp *st=commst;
65 static char sbuf[100];
67 struct sockaddr_in la;
68 la.sin_addr.s_addr=htonl(st->addr);
69 la.sin_port=htons(st->port);
71 snprintf(sbuf, sizeof(sbuf), "udp:%s-%s",
72 saddr_to_string(&la), saddr_to_string(&ca->sin));
76 static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
90 static void udp_afterpoll(void *state, struct pollfd *fds, int nfds)
93 struct sockaddr_in from;
95 struct notify_list *n;
99 if (nfds && (fds->revents & POLLIN)) {
102 fromlen=sizeof(from);
103 BUF_ASSERT_FREE(st->rbuf);
104 BUF_ALLOC(st->rbuf,"udp_afterpoll");
105 rv=recvfrom(st->fd, st->rbuf->start, st->rbuf->len, 0,
106 (struct sockaddr *)&from, &fromlen);
110 /* Check that the packet came from our poxy server;
111 we shouldn't be contacted directly by anybody else
112 (since they can trivially forge source addresses) */
113 if (memcmp(&from.sin_addr,&st->proxy.sin_addr,4)!=0 ||
114 memcmp(&from.sin_port,&st->proxy.sin_port,2)!=0) {
115 Message(M_INFO,"udp: received packet that's not "
120 memcpy(&from.sin_addr,buf_unprepend(st->rbuf,4),4);
121 buf_unprepend(st->rbuf,2);
122 memcpy(&from.sin_port,buf_unprepend(st->rbuf,2),2);
125 for (n=st->notify; n; n=n->next) {
130 if (n->fn(n->state, st->rbuf, &ca)) {
137 if (st->rbuf->size>12 /* prevents traffic amplification */
138 && ((msgtype=get_uint32(st->rbuf->start+8))
140 uint32_t source,dest;
141 /* Manufacture and send NAK packet */
142 source=get_uint32(st->rbuf->start); /* Us */
143 dest=get_uint32(st->rbuf->start+4); /* Them */
144 Message(M_INFO,"udp (port %d, peer %s):"
145 " %08"PRIx32"<-%08"PRIx32": %08"PRIx32":"
146 " unwanted/incorrect, sending NAK\n",
147 st->port, saddr_to_string(&from),
148 dest, source, msgtype);
149 buffer_init(st->rbuf,0);
150 buf_append_uint32(st->rbuf,dest);
151 buf_append_uint32(st->rbuf,source);
152 buf_append_uint32(st->rbuf,LABEL_NAK);
153 sendto(st->fd, st->rbuf->start, st->rbuf->size, 0,
154 (struct sockaddr *)&from, sizeof(from));
158 BUF_ASSERT_FREE(st->rbuf);
166 static void request_notify(void *commst, void *nst, comm_notify_fn *fn)
168 struct udp *st=commst;
169 struct notify_list *n;
171 n=safe_malloc(sizeof(*n),"request_notify");
178 static void release_notify(void *commst, void *nst, comm_notify_fn *fn)
180 struct udp *st=commst;
181 struct notify_list *n, **p, *t;
185 for (n=st->notify; n; )
187 if (n->state==nst && n->fn==fn) {
199 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
200 const struct comm_addr *dest)
202 struct udp *st=commst;
207 memcpy(sa,&dest->sin.sin_addr,4);
209 memcpy(sa+6,&dest->sin.sin_port,2);
210 sendto(st->fd,sa,buf->size+8,0,(struct sockaddr *)&st->proxy,
213 sendto(st->fd, buf->start, buf->size, 0,
214 (struct sockaddr *)&dest->sin, sizeof(dest->sin));
220 static void udp_phase_hook(void *sst, uint32_t new_phase)
223 struct sockaddr_in addr;
225 st->fd=socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
227 fatal_perror("udp (%s:%d): socket",st->loc.file,st->loc.line);
229 if (fcntl(st->fd, F_SETFL, fcntl(st->fd, F_GETFL)|O_NONBLOCK)==-1) {
230 fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
231 st->loc.file,st->loc.line);
233 if (fcntl(st->fd, F_SETFD, FD_CLOEXEC)==-1) {
234 fatal_perror("udp (%s:%d): fcntl(set FD_CLOEXEC)",
235 st->loc.file,st->loc.line);
239 addr.sin_family=AF_INET;
240 addr.sin_addr.s_addr=htonl(st->addr);
241 addr.sin_port=htons(st->port);
246 /* XXX this fork() and waitpid() business needs to be hidden
247 in some system-specific library functions. */
250 fatal_perror("udp_phase_hook: fork() for authbind");
253 char *argv[4], addrstr[9], portstr[5];
254 sprintf(addrstr,"%08lX",(long)addr.sin_addr.s_addr);
255 sprintf(portstr,"%04X",addr.sin_port);
256 argv[0]=st->authbind;
261 execvp(st->authbind,argv);
264 while (waitpid(c,&status,0)==-1) {
265 if (errno==EINTR) continue;
266 fatal_perror("udp (%s:%d): authbind",st->loc.file,st->loc.line);
268 if (WIFSIGNALED(status)) {
269 fatal("udp (%s:%d): authbind died on signal %d",st->loc.file,
270 st->loc.line, WTERMSIG(status));
272 if (WIFEXITED(status) && WEXITSTATUS(status)!=0) {
273 fatal("udp (%s:%d): authbind died with status %d",st->loc.file,
274 st->loc.line, WEXITSTATUS(status));
277 if (bind(st->fd, (struct sockaddr *)&addr, sizeof(addr))!=0) {
278 fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
282 register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp");
285 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
294 st=safe_malloc(sizeof(*st),"udp_apply(st)");
296 st->cl.description="udp";
299 st->cl.interface=&st->ops;
301 st->ops.min_start_pad=0;
302 st->ops.min_end_pad=0;
303 st->ops.request_notify=request_notify;
304 st->ops.release_notify=release_notify;
305 st->ops.sendmsg=udp_sendmsg;
306 st->ops.addr_to_string=addr_to_string;
311 if (!i || i->type!=t_dict) {
312 cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
316 j=dict_find_item(d,"address",False,"udp",st->loc);
317 st->addr=j?string_item_to_ipaddr(j, "udp"):INADDR_ANY;
318 st->port=dict_read_number(d,"port",True,"udp",st->loc,0);
319 st->rbuf=find_cl_if(d,"buffer",CL_BUFFER,True,"udp",st->loc);
320 st->authbind=dict_read_string(d,"authbind",False,"udp",st->loc);
321 l=dict_lookup(d,"proxy");
325 st->proxy.sin_family=AF_INET;
327 if (!i || i->type!=t_string) {
328 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
330 a=string_item_to_ipaddr(i,"proxy");
331 st->proxy.sin_addr.s_addr=htonl(a);
333 if (!i || i->type!=t_number) {
334 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
336 st->proxy.sin_port=htons(i->data.number);
337 st->ops.min_start_pad=8;
340 add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
342 return new_closure(&st->cl);
345 void udp_module(dict_t *dict)
347 add_closure(dict,"udp",udp_apply);