2 * Encrypting tunnel for userv-ipif tunnels, actual implementation
5 * udptunnel-forwarder <public-local-fd> <private-in-fd> <private-out-fd>
6 * <mtu> <keepalive> <timeout>
7 * <public-remote-addr> [<public-remote-port>]
8 * <encdec-keys-fd> <encdec-keys-write>
9 * <mech1> [<mech1-params> ...]
10 * <mech2> [<mech2-params> ...]
13 * Remote addr may '' to mean wait to receive a packet and reply to
14 * whereever we get a good packet from first, in which case port
15 * should not be specified.
17 * <enc-keys-write> is '' to mean read, anything else to mean write.
19 * Every must be numeric. There is very little argument checking.
23 * 0 terminated due to outbound packet stream EOF
30 #include <sys/socket.h>
31 #include <netinet/in.h>
32 #include <arpa/inet.h>
33 #include <sys/utsname.h>
47 #define PROGRAM "udptunnel-forwarder"
48 char programid
[SYS_NMLN
+sizeof(PROGRAM
)+3];
50 static const char *const *argv
;
51 static size_t buffer_size
;
53 static int public_local_fd
, private_in_fd
, private_out_fd
;
54 static int mtu2
, keepalive
, timeout
;
55 static int public_remote_specd
;
56 static struct sockaddr_in public_remote
;
57 static int encdec_keys_fd
, encdec_keys_write
;
59 static const struct mechanism
*mechs
[MAXMECHS
];
61 static struct mechdata
*md_in
[MAXMECHS
], *md_out
[MAXMECHS
];
62 static size_t maxprefix
, maxsuffix
;
64 static struct buffer buf_in
, buf_out
;
65 static unsigned char *accum_buf
;
66 static size_t accum_used
, accum_avail
;
68 static time_t nextsendka
;
71 void arg_assert_fail(const char *msg
) {
72 fprintf(stderr
, PROGRAM
": argument error: %s\n",msg
);
76 void sysfail(const char *msg
) {
77 fprintf(stderr
, "%s: fatal system error: %s: %s\n", programid
, msg
, strerror(errno
));
81 void fail(const char *msg
) {
82 fprintf(stderr
, "%s: fatal error: %s\n", programid
, msg
);
86 void sysdiag(const char *msg
) {
87 fprintf(stderr
, "%s: system/network error: %s: %s\n", programid
, msg
, strerror(errno
));
90 void diag(const char *msg
) {
91 fprintf(stderr
, "%s: %s\n", programid
, msg
);
96 if (time(&r
) == (time_t)-1) sysfail("get time of day");
100 void *xmalloc(size_t sz
) {
103 if (!r
) sysfail("allocate memory");
107 void get_random(void *ptr
, size_t sz
) {
108 static FILE *randfile
;
113 randfile
= fopen("/dev/urandom","rb");
114 if (!randfile
&& errno
==ENOENT
) randfile
= fopen("/dev/random","rb");
115 if (!randfile
) sysfail("open random number generator");
118 r
= fread(ptr
,1,sz
,randfile
);
120 (ferror(randfile
) ? sysfail
: fail
)("cannot read random number generator");
123 const char *getarg_string(void) {
131 unsigned long getarg_ulong(void) {
135 ul
= strtoul(getarg_string(),&ep
,0);
140 static void setnonblock(int fd
, int nonblock
) {
143 r
= fcntl(fd
,F_GETFL
);
144 if (r
==-1) sysfail("fcntl F_GETFL");
145 r
= fcntl(fd
,F_SETFL
, nonblock ? r
|O_NONBLOCK
: r
&~O_NONBLOCK
);
146 if (r
==-1) sysfail("fcntl F_SETFL");
149 static const struct mechanism
*getarg_mech(void) {
151 const struct mechanism
*mech
, *const *mechlist
;
153 name
= getarg_string();
155 for (mechlist
= mechanismlists
;
158 for (mech
= *mechlist
; mech
->name
; mech
++)
159 if (!strcmp(mech
->name
,name
)) return mech
;
161 fprintf(stderr
,"%s: unknown mechanism: %s\n",programid
,name
);
165 static void inbound(void) {
166 static int any_recvd
;
168 struct sockaddr_in this_saddr
;
169 int r
, i
, different
, this_saddrlen
;
174 setnonblock(public_local_fd
,1);
175 this_saddrlen
= sizeof(this_saddr
);
176 r
= recvfrom(public_local_fd
, buf_in
.base
, buffer_size
-1, 0,
177 &this_saddr
, &this_saddrlen
);
178 if (!r
) { diag("empty ciphertext"); return; }
181 if (errno
!= EAGAIN
&& errno
!= EINTR
) sysdiag("receive");
184 if (this_saddr
.sin_family
!= AF_INET
) {
185 fprintf(stderr
,"%s: received unknown AF %lu",
186 programid
, (unsigned long)this_saddr
.sin_family
);
189 assert(this_saddrlen
== sizeof(this_saddr
));
191 buf_in
.size
= buffer_size
;
192 buf_in
.start
= buf_in
.base
;
193 for (i
=n_mechs
-1; i
>=0; i
--) {
194 emsg
= mechs
[i
]->decode(md_in
[i
],&buf_in
);
196 fprintf(stderr
, "%s: bad packet: %s: %s\n", programid
, mechs
[i
]->name
, emsg
);
201 different
= !public_remote_specd
||
202 memcmp(&this_saddr
,&public_remote
,sizeof(this_saddr
));
206 if (public_remote_specd
==2) {
207 fprintf(stderr
, "%s: packet from unexpected sender %s:%lu",
208 programid
, inet_ntoa(this_saddr
.sin_addr
),
209 (unsigned long)this_saddr
.sin_port
);
213 fprintf(stderr
, "%s: tunnel open with peer %s:%lu",
214 programid
, inet_ntoa(this_saddr
.sin_addr
),
215 (unsigned long)this_saddr
.sin_port
);
217 public_remote_specd
= 1;
218 memcpy(&public_remote
,&this_saddr
,sizeof(public_remote
));
220 } else if (!any_recvd
) {
228 buf_in
.start
[buf_in
.size
]= 0300;
229 *--buf_in
.start
= 0300;
232 setnonblock(private_in_fd
,0);
233 while (buf_in
.size
) {
234 r
= write(private_in_fd
, buf_in
.start
, buf_in
.size
);
235 assert(r
&& r
<= buf_in
.size
);
237 if (errno
== EINTR
) continue;
238 sysfail("write down");
245 static void sendpacket(const unsigned char *message
, size_t size
) {
248 buf_out
.start
= buf_out
.base
+maxprefix
;
250 memcpy(buf_out
.start
, message
, size
);
252 nextsendka
= now() + keepalive
;
254 for (i
=0; i
<n_mechs
; i
++) mechs
[i
]->encode(md_out
[i
],&buf_out
);
255 assert(public_remote_specd
);
257 setnonblock(public_local_fd
,1);
259 r
= sendto(public_local_fd
, buf_out
.start
, buf_out
.size
, 0,
260 &public_remote
, sizeof(public_remote
));
261 if (r
== buf_out
.size
) break;
262 if (r
>= 0) { diag("unexpected short send"); return; }
263 if (errno
!= EINTR
) { sysdiag("send"); return; }
267 static void outbound(void) {
269 unsigned char *after_eaten
, *delim
;
272 setnonblock(private_out_fd
,1);
275 r
= read(private_out_fd
, accum_buf
+ accum_used
, accum_avail
- accum_used
);
276 if (!r
) { diag("outbound datastream closed, quitting"); exit(0); }
278 if (errno
== EAGAIN
) return;
279 if (errno
== EINTR
) continue;
282 assert(accum_used
<=accum_avail
);
284 after_eaten
= accum_buf
;
285 while ((delim
= memchr(after_eaten
, 0300, accum_used
))) {
286 this_packet
= delim
- after_eaten
;
287 sendpacket(after_eaten
, this_packet
);
288 accum_used
-= this_packet
+1;
289 after_eaten
= delim
+1;
291 memmove(accum_buf
, after_eaten
, accum_used
);
293 if (accum_used
== accum_avail
) {
294 diag("missing interpacket delimiter in output datastream");
300 int main(int argc
, const char *const *const argv_in
) {
302 struct pollfd pollfds
[2];
303 struct utsname uname_result
;
304 int i
, polltimeout
, r
;
309 if (uname(&uname_result
)) { perror(PROGRAM
": uname failed"); exit(16); }
310 sprintf(programid
, PROGRAM
": %.*s", SYS_NMLN
, uname_result
.nodename
);
312 public_local_fd
= getarg_ulong();
313 mtu2
= getarg_ulong() * 2;
314 keepalive
= getarg_ulong();
315 timeout
= getarg_ulong();
316 private_in_fd
= getarg_ulong();
317 private_out_fd
= getarg_ulong();
319 arg
= getarg_string();
321 public_remote_specd
= 1;
322 arg_assert(inet_aton(arg
,&public_remote
.sin_addr
));
323 public_remote
.sin_port
= getarg_ulong();
326 encdec_keys_fd
= getarg_ulong();
327 encdec_keys_write
= !!*getarg_string();
330 for (i
=0; i
<n_mechs
; i
++) mechs
[i
]= getarg_mech();
331 for (i
=0; i
<n_mechs
; i
++) mechs
[i
]->encsetup(&md_in
[i
], &maxprefix
, &maxsuffix
);
332 for (i
=0; i
<n_mechs
; i
++) mechs
[i
]->decsetup(&md_out
[i
]);
334 if (maxprefix
<1) maxprefix
= 1;
335 if (maxsuffix
<1) maxsuffix
= 1;
336 buffer_size
= mtu2
+ maxprefix
+ maxsuffix
;
337 buf_in
.base
= xmalloc(buffer_size
);
338 buf_out
.base
= xmalloc(buffer_size
);
339 accum_avail
= mtu2
+ 1;
340 accum_buf
= xmalloc(accum_avail
);
344 pollfds
[0].fd
= public_local_fd
;
345 pollfds
[0].events
= POLLIN
;
346 pollfds
[1].fd
= private_out_fd
;
348 pollfds
[1].events
= public_remote_specd ? POLLIN
: 0;
349 pollfds
[0].revents
= 0;
350 pollfds
[1].revents
= 0;
354 if (tnow
>= nextsendka
) sendpacket("\300",1);
355 polltimeout
= (nextsendka
- tnow
)*1000;
360 r
= poll(pollfds
,2,polltimeout
);
362 if (r
==-1 && errno
==EINTR
) continue;
363 if (r
==-1) sysfail("poll");
365 if (pollfds
[0].revents
& POLLIN
) inbound();
366 if (pollfds
[1].revents
& POLLOUT
) outbound();