2 * SSH port forwarding.
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18 struct PortForwarding {
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19 const struct plug_function_table *fn;
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20 /* the above variable absolutely *must* be the first in this structure */
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21 struct ssh_channel *c; /* channel structure held by ssh.c */
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22 void *backhandle; /* instance of SSH backend itself */
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23 /* Note that backhandle need not be filled in if c is non-NULL */
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25 int throttled, throttle_override;
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28 * `dynamic' does double duty. It's set to 0 for an ordinary
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29 * forwarded port, and nonzero for SOCKS-style dynamic port
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30 * forwarding; but the nonzero values are also a state machine
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31 * tracking where the SOCKS exchange has got to.
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35 * `hostname' and `port' are the real hostname and port, once
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36 * we know what we're connecting to.
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41 * `socksbuf' is the buffer we use to accumulate a SOCKS request.
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44 int sockslen, sockssize;
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46 * When doing dynamic port forwarding, we can receive
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47 * connection data before we are actually able to send it; so
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48 * we may have to temporarily hold some in a dynamically
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49 * allocated buffer here.
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55 struct PortListener {
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56 const struct plug_function_table *fn;
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57 /* the above variable absolutely *must* be the first in this structure */
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58 void *backhandle; /* instance of SSH backend itself */
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61 * `dynamic' is set to 0 for an ordinary forwarded port, and
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62 * nonzero for SOCKS-style dynamic port forwarding.
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66 * `hostname' and `port' are the real hostname and port, for
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67 * ordinary forwardings.
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73 static struct PortForwarding *new_portfwd_state(void)
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75 struct PortForwarding *pf = snew(struct PortForwarding);
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76 pf->hostname = NULL;
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77 pf->socksbuf = NULL;
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78 pf->sockslen = pf->sockssize = 0;
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83 static void free_portfwd_state(struct PortForwarding *pf)
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87 sfree(pf->hostname);
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88 sfree(pf->socksbuf);
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93 static struct PortListener *new_portlistener_state(void)
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95 struct PortListener *pl = snew(struct PortListener);
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96 pl->hostname = NULL;
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100 static void free_portlistener_state(struct PortListener *pl)
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104 sfree(pl->hostname);
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108 static void pfd_log(Plug plug, int type, SockAddr addr, int port,
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109 const char *error_msg, int error_code)
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111 /* we have to dump these since we have no interface to logging.c */
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114 static void pfl_log(Plug plug, int type, SockAddr addr, int port,
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115 const char *error_msg, int error_code)
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117 /* we have to dump these since we have no interface to logging.c */
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120 static int pfd_closing(Plug plug, const char *error_msg, int error_code,
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123 struct PortForwarding *pf = (struct PortForwarding *) plug;
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127 * Socket error. Slam the connection instantly shut.
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130 sshfwd_unclean_close(pf->c, error_msg);
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133 * We might not have an SSH channel, if a socket error
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134 * occurred during SOCKS negotiation. If not, we must
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135 * clean ourself up without sshfwd_unclean_close's call
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136 * back to pfd_close.
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142 * Ordinary EOF received on socket. Send an EOF on the SSH
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146 sshfwd_write_eof(pf->c);
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152 static int pfl_closing(Plug plug, const char *error_msg, int error_code,
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155 struct PortListener *pl = (struct PortListener *) plug;
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160 static void wrap_send_port_open(void *channel, char *hostname, int port,
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163 char *peerinfo, *description;
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164 peerinfo = sk_peer_info(s);
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166 description = dupprintf("forwarding from %s", peerinfo);
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169 description = dupstr("forwarding");
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171 ssh_send_port_open(channel, hostname, port, description);
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172 sfree(description);
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175 static int pfd_receive(Plug plug, int urgent, char *data, int len)
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177 struct PortForwarding *pf = (struct PortForwarding *) plug;
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180 if (pf->sockslen >= pf->sockssize) {
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181 pf->sockssize = pf->sockslen * 5 / 4 + 256;
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182 pf->socksbuf = sresize(pf->socksbuf, pf->sockssize, char);
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184 pf->socksbuf[pf->sockslen++] = *data++;
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187 * Now check what's in the buffer to see if it's a
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188 * valid and complete message in the SOCKS exchange.
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190 if ((pf->dynamic == 1 || (pf->dynamic >> 12) == 4) &&
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191 pf->socksbuf[0] == 4) {
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195 if (pf->dynamic == 1)
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196 pf->dynamic = 0x4000;
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197 if (pf->sockslen < 2)
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198 continue; /* don't have command code yet */
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199 if (pf->socksbuf[1] != 1) {
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201 /* Send back a SOCKS 4 error before closing. */
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203 memset(data, 0, sizeof(data));
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204 data[1] = 91; /* generic `request rejected' */
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205 sk_write(pf->s, data, 8);
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209 if (pf->sockslen <= 8)
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210 continue; /* haven't started user/hostname */
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211 if (pf->socksbuf[pf->sockslen-1] != 0)
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212 continue; /* haven't _finished_ user/hostname */
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214 * Now we have a full SOCKS 4 request. Check it to
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215 * see if it's a SOCKS 4A request.
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217 if (pf->socksbuf[4] == 0 && pf->socksbuf[5] == 0 &&
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218 pf->socksbuf[6] == 0 && pf->socksbuf[7] != 0) {
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220 * It's SOCKS 4A. So if we haven't yet
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221 * collected the host name, we should continue
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222 * waiting for data in order to do so; if we
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223 * have, we can go ahead.
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226 if (pf->dynamic == 0x4000) {
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227 pf->dynamic = 0x4001;
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228 pf->sockslen = 8; /* reset buffer to overwrite name */
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231 pf->socksbuf[0] = 0; /* reply version code */
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232 pf->socksbuf[1] = 90; /* request granted */
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233 sk_write(pf->s, pf->socksbuf, 8);
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234 len = pf->sockslen - 8;
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235 pf->port = GET_16BIT_MSB_FIRST(pf->socksbuf+2);
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236 pf->hostname = snewn(len+1, char);
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237 pf->hostname[len] = '\0';
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238 memcpy(pf->hostname, pf->socksbuf + 8, len);
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242 * It's SOCKS 4, which means we should format
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243 * the IP address into the hostname string and
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246 pf->socksbuf[0] = 0; /* reply version code */
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247 pf->socksbuf[1] = 90; /* request granted */
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248 sk_write(pf->s, pf->socksbuf, 8);
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249 pf->port = GET_16BIT_MSB_FIRST(pf->socksbuf+2);
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250 pf->hostname = dupprintf("%d.%d.%d.%d",
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251 (unsigned char)pf->socksbuf[4],
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252 (unsigned char)pf->socksbuf[5],
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253 (unsigned char)pf->socksbuf[6],
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254 (unsigned char)pf->socksbuf[7]);
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259 if ((pf->dynamic == 1 || (pf->dynamic >> 12) == 5) &&
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260 pf->socksbuf[0] == 5) {
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264 if (pf->dynamic == 1)
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265 pf->dynamic = 0x5000;
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267 if (pf->dynamic == 0x5000) {
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271 * We're receiving a set of method identifiers.
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273 if (pf->sockslen < 2)
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274 continue; /* no method count yet */
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275 if (pf->sockslen < 2 + (unsigned char)pf->socksbuf[1])
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276 continue; /* no methods yet */
\r
277 method = 0xFF; /* invalid */
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278 for (i = 0; i < (unsigned char)pf->socksbuf[1]; i++)
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279 if (pf->socksbuf[2+i] == 0) {
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280 method = 0;/* no auth */
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285 sk_write(pf->s, data, 2);
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286 pf->dynamic = 0x5001;
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287 pf->sockslen = 0; /* re-empty the buffer */
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291 if (pf->dynamic == 0x5001) {
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293 * We're receiving a SOCKS request.
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295 unsigned char reply[10]; /* SOCKS5 atyp=1 reply */
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296 int atype, alen = 0;
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299 * Pre-fill reply packet.
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300 * In all cases, we set BND.{HOST,ADDR} to 0.0.0.0:0
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301 * (atyp=1) in the reply; if we succeed, we don't know
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302 * the right answers, and if we fail, they should be
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305 memset(reply, 0, lenof(reply));
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306 reply[0] = 5; /* VER */
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307 reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */
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309 if (pf->sockslen < 6) continue;
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310 atype = (unsigned char)pf->socksbuf[3];
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311 if (atype == 1) /* IPv4 address */
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313 if (atype == 4) /* IPv6 address */
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315 if (atype == 3) /* domain name has leading length */
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316 alen = 1 + (unsigned char)pf->socksbuf[4];
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317 if (pf->sockslen < 6 + alen) continue;
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318 if (pf->socksbuf[1] != 1 || pf->socksbuf[2] != 0) {
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319 /* Not CONNECT or reserved field nonzero - error */
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320 reply[1] = 1; /* generic failure */
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321 sk_write(pf->s, (char *) reply, lenof(reply));
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326 * Now we have a viable connect request. Switch
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329 pf->port = GET_16BIT_MSB_FIRST(pf->socksbuf+4+alen);
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331 /* REP=0 (success) already */
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332 sk_write(pf->s, (char *) reply, lenof(reply));
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333 pf->hostname = dupprintf("%d.%d.%d.%d",
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334 (unsigned char)pf->socksbuf[4],
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335 (unsigned char)pf->socksbuf[5],
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336 (unsigned char)pf->socksbuf[6],
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337 (unsigned char)pf->socksbuf[7]);
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339 } else if (atype == 3) {
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340 /* REP=0 (success) already */
\r
341 sk_write(pf->s, (char *) reply, lenof(reply));
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342 pf->hostname = snewn(alen, char);
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343 pf->hostname[alen-1] = '\0';
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344 memcpy(pf->hostname, pf->socksbuf + 5, alen-1);
\r
348 * Unknown address type. (FIXME: support IPv6!)
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350 reply[1] = 8; /* atype not supported */
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351 sk_write(pf->s, (char *) reply, lenof(reply));
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359 * If we get here without either having done `continue'
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360 * or `goto connect', it must be because there is no
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361 * sensible interpretation of what's in our buffer. So
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362 * close the connection rudely.
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370 * We come here when we're ready to make an actual
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374 sfree(pf->socksbuf);
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375 pf->socksbuf = NULL;
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378 * Freeze the socket until the SSH server confirms the
\r
381 sk_set_frozen(pf->s, 1);
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383 pf->c = new_sock_channel(pf->backhandle, pf);
\r
384 if (pf->c == NULL) {
\r
388 /* asks to forward to the specified host/port for this */
\r
389 wrap_send_port_open(pf->c, pf->hostname, pf->port, pf->s);
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394 * If there's any data remaining in our current buffer,
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395 * save it to be sent on pfd_confirm().
\r
398 pf->buffer = snewn(len, char);
\r
399 memcpy(pf->buffer, data, len);
\r
404 if (sshfwd_write(pf->c, data, len) > 0) {
\r
406 sk_set_frozen(pf->s, 1);
\r
412 static void pfd_sent(Plug plug, int bufsize)
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414 struct PortForwarding *pf = (struct PortForwarding *) plug;
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417 sshfwd_unthrottle(pf->c, bufsize);
\r
421 * Called when receiving a PORT OPEN from the server to make a
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422 * connection to a destination host.
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424 * On success, returns NULL and fills in *pf_ret. On error, returns a
\r
425 * dynamically allocated error message string.
\r
427 char *pfd_connect(struct PortForwarding **pf_ret, char *hostname,int port,
\r
428 void *c, Conf *conf, int addressfamily)
\r
430 static const struct plug_function_table fn_table = {
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440 char *dummy_realhost;
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441 struct PortForwarding *pf;
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444 * Try to find host.
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446 addr = name_lookup(hostname, port, &dummy_realhost, conf, addressfamily);
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447 if ((err = sk_addr_error(addr)) != NULL) {
\r
448 char *err_ret = dupstr(err);
\r
449 sk_addr_free(addr);
\r
450 sfree(dummy_realhost);
\r
457 pf = *pf_ret = new_portfwd_state();
\r
458 pf->fn = &fn_table;
\r
459 pf->throttled = pf->throttle_override = 0;
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462 pf->backhandle = NULL; /* we shouldn't need this */
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465 pf->s = new_connection(addr, dummy_realhost, port,
\r
466 0, 1, 0, 0, (Plug) pf, conf);
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467 sfree(dummy_realhost);
\r
468 if ((err = sk_socket_error(pf->s)) != NULL) {
\r
469 char *err_ret = dupstr(err);
\r
471 free_portfwd_state(pf);
\r
480 called when someone connects to the local port
\r
483 static int pfl_accepting(Plug p, accept_fn_t constructor, accept_ctx_t ctx)
\r
485 static const struct plug_function_table fn_table = {
\r
492 struct PortForwarding *pf;
\r
493 struct PortListener *pl;
\r
497 pl = (struct PortListener *)p;
\r
498 pf = new_portfwd_state();
\r
499 pf->fn = &fn_table;
\r
502 pf->backhandle = pl->backhandle;
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504 pf->s = s = constructor(ctx, (Plug) pf);
\r
505 if ((err = sk_socket_error(s)) != NULL) {
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506 free_portfwd_state(pf);
\r
507 return err != NULL;
\r
510 pf->throttled = pf->throttle_override = 0;
\r
515 pf->port = 0; /* "hostname" buffer is so far empty */
\r
516 sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */
\r
519 pf->hostname = dupstr(pl->hostname);
\r
520 pf->port = pl->port;
\r
521 pf->c = new_sock_channel(pl->backhandle, pf);
\r
523 if (pf->c == NULL) {
\r
524 free_portfwd_state(pf);
\r
527 /* asks to forward to the specified host/port for this */
\r
528 wrap_send_port_open(pf->c, pf->hostname, pf->port, s);
\r
537 * Add a new port-forwarding listener from srcaddr:port -> desthost:destport.
\r
539 * On success, returns NULL and fills in *pl_ret. On error, returns a
\r
540 * dynamically allocated error message string.
\r
542 char *pfl_listen(char *desthost, int destport, char *srcaddr,
\r
543 int port, void *backhandle, Conf *conf,
\r
544 struct PortListener **pl_ret, int address_family)
\r
546 static const struct plug_function_table fn_table = {
\r
555 struct PortListener *pl;
\r
560 pl = *pl_ret = new_portlistener_state();
\r
561 pl->fn = &fn_table;
\r
563 pl->hostname = dupstr(desthost);
\r
564 pl->port = destport;
\r
568 pl->backhandle = backhandle;
\r
570 pl->s = new_listener(srcaddr, port, (Plug) pl,
\r
571 !conf_get_int(conf, CONF_lport_acceptall),
\r
572 conf, address_family);
\r
573 if ((err = sk_socket_error(pl->s)) != NULL) {
\r
574 char *err_ret = dupstr(err);
\r
576 free_portlistener_state(pl);
\r
584 void pfd_close(struct PortForwarding *pf)
\r
590 free_portfwd_state(pf);
\r
594 * Terminate a listener.
\r
596 void pfl_terminate(struct PortListener *pl)
\r
602 free_portlistener_state(pl);
\r
605 void pfd_unthrottle(struct PortForwarding *pf)
\r
611 sk_set_frozen(pf->s, pf->throttled || pf->throttle_override);
\r
614 void pfd_override_throttle(struct PortForwarding *pf, int enable)
\r
619 pf->throttle_override = enable;
\r
620 sk_set_frozen(pf->s, pf->throttled || pf->throttle_override);
\r
624 * Called to send data down the raw connection.
\r
626 int pfd_send(struct PortForwarding *pf, char *data, int len)
\r
630 return sk_write(pf->s, data, len);
\r
633 void pfd_send_eof(struct PortForwarding *pf)
\r
635 sk_write_eof(pf->s);
\r
638 void pfd_confirm(struct PortForwarding *pf)
\r
644 sk_set_frozen(pf->s, 0);
\r
645 sk_write(pf->s, NULL, 0);
\r
647 sshfwd_write(pf->c, pf->buffer, pf->buflen);
\r