comm, site: pass a new "struct comm_addr" rather than sockaddr_in
[secnet] / udp.c
1 /* UDP send/receive module for secnet */
2
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
6 * yet).
7 *
8 * Packets are offered to registered receivers in turn. Once one
9 * accepts it, it isn't offered to any more. */
10
11 #include "secnet.h"
12 #include <stdio.h>
13 #include <unistd.h>
14 #include <fcntl.h>
15 #include <string.h>
16 #include <errno.h>
17 #include <sys/socket.h>
18 #include <sys/wait.h>
19 #include "util.h"
20 #include "unaligned.h"
21 #include "ipaddr.h"
22
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;
28
29 struct notify_list {
30 comm_notify_fn *fn;
31 void *state;
32 struct notify_list *next;
33 };
34
35 struct udp {
36 closure_t cl;
37 struct comm_if ops;
38 struct cloc loc;
39 uint32_t addr;
40 uint16_t port;
41 int fd;
42 string_t authbind;
43 struct buffer_if *rbuf;
44 struct notify_list *notify;
45 bool_t use_proxy;
46 struct sockaddr_in proxy;
47 };
48
49 static int udp_beforepoll(void *state, struct pollfd *fds, int *nfds_io,
50 int *timeout_io)
51 {
52 struct udp *st=state;
53 if (*nfds_io<1) {
54 *nfds_io=1;
55 return ERANGE;
56 }
57 *nfds_io=1;
58 fds->fd=st->fd;
59 fds->events=POLLIN;
60 return 0;
61 }
62
63 static void udp_afterpoll(void *state, struct pollfd *fds, int nfds)
64 {
65 struct udp *st=state;
66 struct sockaddr_in from;
67 socklen_t fromlen;
68 struct notify_list *n;
69 bool_t done;
70 int rv;
71
72 if (nfds && (fds->revents & POLLIN)) {
73 do {
74 FILLZERO(from);
75 fromlen=sizeof(from);
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);
80 if (rv>0) {
81 st->rbuf->size=rv;
82 if (st->use_proxy) {
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 "
89 "from the proxy\n");
90 BUF_FREE(st->rbuf);
91 continue;
92 }
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);
96 }
97 done=False;
98 for (n=st->notify; n; n=n->next) {
99 struct comm_addr ca;
100 FILLZERO(ca);
101 ca.comm=&st->ops;
102 ca.sin=from;
103 if (n->fn(n->state, st->rbuf, &ca)) {
104 done=True;
105 break;
106 }
107 }
108 if (!done) {
109 uint32_t source,dest;
110 /* Manufacture and send NAK packet */
111 source=get_uint32(st->rbuf->start); /* Us */
112 dest=get_uint32(st->rbuf->start+4); /* Them */
113 Message(M_INFO,"udp (port %d): sending NAK\n",st->port);
114 buffer_init(st->rbuf,0);
115 buf_append_uint32(st->rbuf,dest);
116 buf_append_uint32(st->rbuf,source);
117 buf_append_uint32(st->rbuf,0); /* NAK is msg type 0 */
118 sendto(st->fd, st->rbuf->start, st->rbuf->size, 0,
119 (struct sockaddr *)&from, sizeof(from));
120 BUF_FREE(st->rbuf);
121 }
122 BUF_ASSERT_FREE(st->rbuf);
123 } else {
124 BUF_FREE(st->rbuf);
125 }
126 } while (rv>=0);
127 }
128 }
129
130 static void request_notify(void *commst, void *nst, comm_notify_fn *fn)
131 {
132 struct udp *st=commst;
133 struct notify_list *n;
134
135 n=safe_malloc(sizeof(*n),"request_notify");
136 n->fn=fn;
137 n->state=nst;
138 n->next=st->notify;
139 st->notify=n;
140 }
141
142 static void release_notify(void *commst, void *nst, comm_notify_fn *fn)
143 {
144 struct udp *st=commst;
145 struct notify_list *n, **p, *t;
146
147 /* XXX untested */
148 p=&st->notify;
149 for (n=st->notify; n; )
150 {
151 if (n->state==nst && n->fn==fn) {
152 t=n;
153 *p=n->next;
154 n=n->next;
155 free(t);
156 } else {
157 p=&n->next;
158 n=n->next;
159 }
160 }
161 }
162
163 static bool_t udp_sendmsg(void *commst, struct buffer_if *buf,
164 const struct comm_addr *dest)
165 {
166 struct udp *st=commst;
167 uint8_t *sa;
168
169 if (st->use_proxy) {
170 sa=buf->start-8;
171 memcpy(sa,&dest->sin.sin_addr,4);
172 memset(sa+4,0,4);
173 memcpy(sa+6,&dest->sin.sin_port,2);
174 sendto(st->fd,sa,buf->size+8,0,(struct sockaddr *)&st->proxy,
175 sizeof(st->proxy));
176 } else {
177 sendto(st->fd, buf->start, buf->size, 0,
178 (struct sockaddr *)&dest->sin, sizeof(dest->sin));
179 }
180
181 return True;
182 }
183
184 static void udp_phase_hook(void *sst, uint32_t new_phase)
185 {
186 struct udp *st=sst;
187 struct sockaddr_in addr;
188
189 st->fd=socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
190 if (st->fd<0) {
191 fatal_perror("udp (%s:%d): socket",st->loc.file,st->loc.line);
192 }
193 if (fcntl(st->fd, F_SETFL, fcntl(st->fd, F_GETFL)|O_NONBLOCK)==-1) {
194 fatal_perror("udp (%s:%d): fcntl(set O_NONBLOCK)",
195 st->loc.file,st->loc.line);
196 }
197 if (fcntl(st->fd, F_SETFD, FD_CLOEXEC)==-1) {
198 fatal_perror("udp (%s:%d): fcntl(set FD_CLOEXEC)",
199 st->loc.file,st->loc.line);
200 }
201
202 FILLZERO(addr);
203 addr.sin_family=AF_INET;
204 addr.sin_addr.s_addr=htonl(st->addr);
205 addr.sin_port=htons(st->port);
206 if (st->authbind) {
207 pid_t c;
208 int status;
209
210 /* XXX this fork() and waitpid() business needs to be hidden
211 in some system-specific library functions. */
212 c=fork();
213 if (c==-1) {
214 fatal_perror("udp_phase_hook: fork() for authbind");
215 }
216 if (c==0) {
217 char *argv[4], addrstr[9], portstr[5];
218 sprintf(addrstr,"%08lX",(long)st->addr);
219 sprintf(portstr,"%04X",st->port);
220 argv[0]=st->authbind;
221 argv[1]=addrstr;
222 argv[2]=portstr;
223 argv[3]=NULL;
224 dup2(st->fd,0);
225 execvp(st->authbind,argv);
226 _exit(255);
227 }
228 while (waitpid(c,&status,0)==-1) {
229 if (errno==EINTR) continue;
230 fatal_perror("udp (%s:%d): authbind",st->loc.file,st->loc.line);
231 }
232 if (WIFSIGNALED(status)) {
233 fatal("udp (%s:%d): authbind died on signal %d",st->loc.file,
234 st->loc.line, WTERMSIG(status));
235 }
236 if (WIFEXITED(status) && WEXITSTATUS(status)!=0) {
237 fatal("udp (%s:%d): authbind died with status %d",st->loc.file,
238 st->loc.line, WEXITSTATUS(status));
239 }
240 } else {
241 if (bind(st->fd, (struct sockaddr *)&addr, sizeof(addr))!=0) {
242 fatal_perror("udp (%s:%d): bind",st->loc.file,st->loc.line);
243 }
244 }
245
246 register_for_poll(st,udp_beforepoll,udp_afterpoll,1,"udp");
247 }
248
249 static list_t *udp_apply(closure_t *self, struct cloc loc, dict_t *context,
250 list_t *args)
251 {
252 struct udp *st;
253 item_t *i,*j;
254 dict_t *d;
255 list_t *l;
256 uint32_t a;
257
258 st=safe_malloc(sizeof(*st),"udp_apply(st)");
259 st->loc=loc;
260 st->cl.description="udp";
261 st->cl.type=CL_COMM;
262 st->cl.apply=NULL;
263 st->cl.interface=&st->ops;
264 st->ops.st=st;
265 st->ops.min_start_pad=0;
266 st->ops.min_end_pad=0;
267 st->ops.request_notify=request_notify;
268 st->ops.release_notify=release_notify;
269 st->ops.sendmsg=udp_sendmsg;
270 st->port=0;
271 st->use_proxy=False;
272
273 i=list_elem(args,0);
274 if (!i || i->type!=t_dict) {
275 cfgfatal(st->loc,"udp","first argument must be a dictionary\n");
276 }
277 d=i->data.dict;
278
279 j=dict_find_item(d,"address",False,"udp",st->loc);
280 st->addr=j?string_item_to_ipaddr(j, "udp"):INADDR_ANY;
281 st->port=dict_read_number(d,"port",True,"udp",st->loc,0);
282 st->rbuf=find_cl_if(d,"buffer",CL_BUFFER,True,"udp",st->loc);
283 st->authbind=dict_read_string(d,"authbind",False,"udp",st->loc);
284 l=dict_lookup(d,"proxy");
285 if (l) {
286 st->use_proxy=True;
287 FILLZERO(st->proxy);
288 st->proxy.sin_family=AF_INET;
289 i=list_elem(l,0);
290 if (!i || i->type!=t_string) {
291 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
292 }
293 a=string_item_to_ipaddr(i,"proxy");
294 st->proxy.sin_addr.s_addr=htonl(a);
295 i=list_elem(l,1);
296 if (!i || i->type!=t_number) {
297 cfgfatal(st->loc,"udp","proxy must supply ""addr"",port\n");
298 }
299 st->proxy.sin_port=htons(i->data.number);
300 st->ops.min_start_pad=8;
301 }
302
303 add_hook(PHASE_GETRESOURCES,udp_phase_hook,st);
304
305 return new_closure(&st->cl);
306 }
307
308 void udp_module(dict_t *dict)
309 {
310 add_closure(dict,"udp",udp_apply);
311 }