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>
20 #include "unaligned.h"
23 static beforepoll_fn udp_beforepoll;
24 static afterpoll_fn udp_afterpoll;
25 static comm_request_notify_fn request_notify;
26 static comm_release_notify_fn release_notify;
27 static comm_sendmsg_fn udp_sendmsg;
32 struct notify_list *next;
42 struct buffer_if *rbuf;
43 struct notify_list *notify;
45 struct sockaddr_in proxy;
48 static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
49 int *timeout_io, const struct timeval *tv,
63 static void udp_afterpoll(void *state, struct pollfd *fds, int nfds,
64 const struct timeval *tv, uint64_t *now)
67 struct sockaddr_in from;
69 struct notify_list *n;
73 if (nfds && (fds->revents & POLLIN)) {
76 BUF_ASSERT_FREE(st->rbuf);
77 BUF_ALLOC(st->rbuf,"udp_afterpoll");
78 rv=recvfrom(st->fd, st->rbuf->start, st->rbuf->len, 0,
79 (struct sockaddr *)&from, &fromlen);
83 /* Check that the packet came from our poxy server;
84 we shouldn't be contacted directly by anybody else
85 (since they can trivially forge source addresses) */
86 if (memcmp(&from.sin_addr,&st->proxy.sin_addr,4)!=0 ||
87 memcmp(&from.sin_port,&st->proxy.sin_port,2)!=0) {
88 Message(M_INFO,"udp: received packet that's not "
93 memcpy(&from.sin_addr,buf_unprepend(st->rbuf,4),4);
94 buf_unprepend(st->rbuf,2);
95 memcpy(&from.sin_port,buf_unprepend(st->rbuf,2),2);
98 for (n=st->notify; n; n=n->next) {
99 if (n->fn(n->state, st->rbuf, &from)) {
105 uint32_t source,dest;
106 /* Manufacture and send NAK packet */
107 source=get_uint32(st->rbuf->start); /* Us */
108 dest=get_uint32(st->rbuf->start+4); /* Them */
109 Message(M_INFO,"udp (port %d): sending NAK\n",st->port);
110 buffer_init(st->rbuf,0);
111 buf_append_uint32(st->rbuf,dest);
112 buf_append_uint32(st->rbuf,source);
113 buf_append_uint32(st->rbuf,0); /* NAK is msg type 0 */
114 sendto(st->fd, st->rbuf->start, st->rbuf->size, 0,
115 (struct sockaddr *)&from, sizeof(from));
118 BUF_ASSERT_FREE(st->rbuf);
126 static void request_notify(void *commst, void *nst, comm_notify_fn *fn)
128 struct udp *st=commst;
129 struct notify_list *n;
131 n=safe_malloc(sizeof(*n),"request_notify");
138 static void release_notify(void *commst, void *nst, comm_notify_fn *fn)
140 struct udp *st=commst;
141 struct notify_list *n, **p, *t;
145 for (n=st->notify; n; )
147 if (n->state==nst && n->fn==fn) {
159 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
160 struct sockaddr_in *dest)
162 struct udp *st=commst;
167 memcpy(sa,&dest->sin_addr,4);
169 memcpy(sa+6,&dest->sin_port,2);
170 sendto(st->fd,sa,buf->size+8,0,(struct sockaddr *)&st->proxy,
173 sendto(st->fd, buf->start, buf->size, 0,
174 (struct sockaddr *)dest, sizeof(*dest));
180 static void udp_phase_hook(void *sst, uint32_t new_phase)
183 struct sockaddr_in addr;
185 st->fd=socket(AF_INET, SOCK_DGRAM, 0);
187 fatal_perror("udp (%s:%d): socket",st->loc.file,st->loc.line);
189 if (fcntl(st->fd, F_SETFL, fcntl(st->fd, F_GETFL)|O_NONBLOCK)==-1) {
190 fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
191 st->loc.file,st->loc.line);
193 if (fcntl(st->fd, F_SETFD, FD_CLOEXEC)==-1) {
194 fatal_perror("udp (%s:%d): fcntl(set FD_CLOEXEC)",
195 st->loc.file,st->loc.line);
198 memset(&addr, 0, sizeof(addr));
199 addr.sin_family=AF_INET;
200 addr.sin_port=htons(st->port);
205 /* XXX this fork() and waitpid() business needs to be hidden
206 in some system-specific library functions. */
209 fatal_perror("udp_phase_hook: fork() for authbind");
213 argv[0]=st->authbind;
214 argv[1]=strdup("00000000");
215 if (!argv[1]) exit(ENOMEM);
217 if (!argv[2]) exit(ENOMEM);
218 sprintf(argv[2],"%04X",htons(st->port));
221 execvp(st->authbind,argv);
224 waitpid(c,&status,0);
225 if (WEXITSTATUS(status)!=0) {
226 errno=WEXITSTATUS(status);
227 fatal_perror("udp (%s:%d): authbind",st->loc.file,st->loc.line);
230 if (bind(st->fd, (struct sockaddr *)&addr, sizeof(addr))!=0) {
231 fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
235 register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp");
238 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
247 st=safe_malloc(sizeof(*st),"udp_apply(st)");
249 st->cl.description="udp";
252 st->cl.interface=&st->ops;
254 st->ops.min_start_pad=0;
255 st->ops.min_end_pad=0;
256 st->ops.request_notify=request_notify;
257 st->ops.release_notify=release_notify;
258 st->ops.sendmsg=udp_sendmsg;
263 if (!i || i->type!=t_dict) {
264 cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
268 st->port=dict_read_number(d,"port",True,"udp",st->loc,0);
269 st->rbuf=find_cl_if(d,"buffer",CL_BUFFER,True,"udp",st->loc);
270 st->authbind=dict_read_string(d,"authbind",False,"udp",st->loc);
271 l=dict_lookup(d,"proxy");
274 memset(&st->proxy,0,sizeof(st->proxy));
275 st->proxy.sin_family=AF_INET;
277 if (!i || i->type!=t_string) {
278 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
280 a=string_item_to_ipaddr(i,"proxy");
281 st->proxy.sin_addr.s_addr=htonl(a);
283 if (!i || i->type!=t_number) {
284 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
286 st->proxy.sin_port=htons(i->data.number);
287 st->ops.min_start_pad=8;
290 add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
292 return new_closure(&st->cl);
295 init_module udp_module;
296 void udp_module(dict_t *dict)
298 add_closure(dict,"udp",udp_apply);