/* * SSH port forwarding. */ #include #include #include "putty.h" #include "ssh.h" #ifndef FALSE #define FALSE 0 #endif #ifndef TRUE #define TRUE 1 #endif struct PFwdPrivate { const struct plug_function_table *fn; /* the above variable absolutely *must* be the first in this structure */ void *c; /* (channel) data used by ssh.c */ void *backhandle; /* instance of SSH backend itself */ /* Note that backhandle need not be filled in if c is non-NULL */ Socket s; int throttled, throttle_override; int ready; /* * `dynamic' does double duty. It's set to 0 for an ordinary * forwarded port, and nonzero for SOCKS-style dynamic port * forwarding; but it also represents the state of the SOCKS * exchange. */ int dynamic; /* * `hostname' and `port' are the real hostname and port, once * we know what we're connecting to; they're unused for this * purpose while conducting a local SOCKS exchange, which means * we can also use them as a buffer and pointer for reading * data from the SOCKS client. */ char hostname[256+8]; int port; /* * When doing dynamic port forwarding, we can receive * connection data before we are actually able to send it; so * we may have to temporarily hold some in a dynamically * allocated buffer here. */ void *buffer; int buflen; }; static void pfd_log(Plug plug, int type, SockAddr addr, int port, const char *error_msg, int error_code) { /* we have to dump these since we have no interface to logging.c */ } static int pfd_closing(Plug plug, const char *error_msg, int error_code, int calling_back) { struct PFwdPrivate *pr = (struct PFwdPrivate *) plug; /* * We have no way to communicate down the forwarded connection, * so if an error occurred on the socket, we just ignore it * and treat it like a proper close. */ if (pr->c) sshfwd_close(pr->c); pfd_close(pr->s); return 1; } static int pfd_receive(Plug plug, int urgent, char *data, int len) { struct PFwdPrivate *pr = (struct PFwdPrivate *) plug; if (pr->dynamic) { while (len--) { /* * Throughout SOCKS negotiation, "hostname" is re-used as a * random protocol buffer with "port" storing the length. */ if (pr->port >= lenof(pr->hostname)) { /* Request too long. */ if ((pr->dynamic >> 12) == 4) { /* Send back a SOCKS 4 error before closing. */ char data[8]; memset(data, 0, sizeof(data)); data[1] = 91; /* generic `request rejected' */ sk_write(pr->s, data, 8); } pfd_close(pr->s); return 1; } pr->hostname[pr->port++] = *data++; /* * Now check what's in the buffer to see if it's a * valid and complete message in the SOCKS exchange. */ if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) && pr->hostname[0] == 4) { /* * SOCKS 4. */ if (pr->dynamic == 1) pr->dynamic = 0x4000; if (pr->port < 2) continue;/* don't have command code yet */ if (pr->hostname[1] != 1) { /* Not CONNECT. */ /* Send back a SOCKS 4 error before closing. */ char data[8]; memset(data, 0, sizeof(data)); data[1] = 91; /* generic `request rejected' */ sk_write(pr->s, data, 8); pfd_close(pr->s); return 1; } if (pr->port <= 8) continue; /* haven't started user/hostname */ if (pr->hostname[pr->port-1] != 0) continue; /* haven't _finished_ user/hostname */ /* * Now we have a full SOCKS 4 request. Check it to * see if it's a SOCKS 4A request. */ if (pr->hostname[4] == 0 && pr->hostname[5] == 0 && pr->hostname[6] == 0 && pr->hostname[7] != 0) { /* * It's SOCKS 4A. So if we haven't yet * collected the host name, we should continue * waiting for data in order to do so; if we * have, we can go ahead. */ int len; if (pr->dynamic == 0x4000) { pr->dynamic = 0x4001; pr->port = 8; /* reset buffer to overwrite name */ continue; } pr->hostname[0] = 0; /* reply version code */ pr->hostname[1] = 90; /* request granted */ sk_write(pr->s, pr->hostname, 8); len= pr->port - 8; pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2); memmove(pr->hostname, pr->hostname + 8, len); goto connect; } else { /* * It's SOCKS 4, which means we should format * the IP address into the hostname string and * then just go. */ pr->hostname[0] = 0; /* reply version code */ pr->hostname[1] = 90; /* request granted */ sk_write(pr->s, pr->hostname, 8); pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2); sprintf(pr->hostname, "%d.%d.%d.%d", (unsigned char)pr->hostname[4], (unsigned char)pr->hostname[5], (unsigned char)pr->hostname[6], (unsigned char)pr->hostname[7]); goto connect; } } if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) && pr->hostname[0] == 5) { /* * SOCKS 5. */ if (pr->dynamic == 1) pr->dynamic = 0x5000; if (pr->dynamic == 0x5000) { int i, method; char data[2]; /* * We're receiving a set of method identifiers. */ if (pr->port < 2) continue;/* no method count yet */ if (pr->port < 2 + (unsigned char)pr->hostname[1]) continue; /* no methods yet */ method = 0xFF; /* invalid */ for (i = 0; i < (unsigned char)pr->hostname[1]; i++) if (pr->hostname[2+i] == 0) { method = 0;/* no auth */ break; } data[0] = 5; data[1] = method; sk_write(pr->s, data, 2); pr->dynamic = 0x5001; pr->port = 0; /* re-empty the buffer */ continue; } if (pr->dynamic == 0x5001) { /* * We're receiving a SOCKS request. */ unsigned char reply[10]; /* SOCKS5 atyp=1 reply */ int atype, alen = 0; /* * Pre-fill reply packet. * In all cases, we set BND.{HOST,ADDR} to 0.0.0.0:0 * (atyp=1) in the reply; if we succeed, we don't know * the right answers, and if we fail, they should be * ignored. */ memset(reply, 0, lenof(reply)); reply[0] = 5; /* VER */ reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */ if (pr->port < 6) continue; atype = (unsigned char)pr->hostname[3]; if (atype == 1) /* IPv4 address */ alen = 4; if (atype == 4) /* IPv6 address */ alen = 16; if (atype == 3) /* domain name has leading length */ alen = 1 + (unsigned char)pr->hostname[4]; if (pr->port < 6 + alen) continue; if (pr->hostname[1] != 1 || pr->hostname[2] != 0) { /* Not CONNECT or reserved field nonzero - error */ reply[1] = 1; /* generic failure */ sk_write(pr->s, (char *) reply, lenof(reply)); pfd_close(pr->s); return 1; } /* * Now we have a viable connect request. Switch * on atype. */ pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen); if (atype == 1) { /* REP=0 (success) already */ sk_write(pr->s, (char *) reply, lenof(reply)); sprintf(pr->hostname, "%d.%d.%d.%d", (unsigned char)pr->hostname[4], (unsigned char)pr->hostname[5], (unsigned char)pr->hostname[6], (unsigned char)pr->hostname[7]); goto connect; } else if (atype == 3) { /* REP=0 (success) already */ sk_write(pr->s, (char *) reply, lenof(reply)); memmove(pr->hostname, pr->hostname + 5, alen-1); pr->hostname[alen-1] = '\0'; goto connect; } else { /* * Unknown address type. (FIXME: support IPv6!) */ reply[1] = 8; /* atype not supported */ sk_write(pr->s, (char *) reply, lenof(reply)); pfd_close(pr->s); return 1; } } } /* * If we get here without either having done `continue' * or `goto connect', it must be because there is no * sensible interpretation of what's in our buffer. So * close the connection rudely. */ pfd_close(pr->s); return 1; } return 1; /* * We come here when we're ready to make an actual * connection. */ connect: /* * Freeze the socket until the SSH server confirms the * connection. */ sk_set_frozen(pr->s, 1); pr->c = new_sock_channel(pr->backhandle, pr->s); if (pr->c == NULL) { pfd_close(pr->s); return 1; } else { /* asks to forward to the specified host/port for this */ ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding"); } pr->dynamic = 0; /* * If there's any data remaining in our current buffer, * save it to be sent on pfd_confirm(). */ if (len > 0) { pr->buffer = snewn(len, char); memcpy(pr->buffer, data, len); pr->buflen = len; } } if (pr->ready) { if (sshfwd_write(pr->c, data, len) > 0) { pr->throttled = 1; sk_set_frozen(pr->s, 1); } } return 1; } static void pfd_sent(Plug plug, int bufsize) { struct PFwdPrivate *pr = (struct PFwdPrivate *) plug; if (pr->c) sshfwd_unthrottle(pr->c, bufsize); } /* * Called when receiving a PORT OPEN from the server */ const char *pfd_newconnect(Socket *s, char *hostname, int port, void *c, const Config *cfg, int addressfamily) { static const struct plug_function_table fn_table = { pfd_log, pfd_closing, pfd_receive, pfd_sent, NULL }; SockAddr addr; const char *err; char *dummy_realhost; struct PFwdPrivate *pr; /* * Try to find host. */ addr = name_lookup(hostname, port, &dummy_realhost, cfg, addressfamily); if ((err = sk_addr_error(addr)) != NULL) { sk_addr_free(addr); return err; } /* * Open socket. */ pr = snew(struct PFwdPrivate); pr->buffer = NULL; pr->fn = &fn_table; pr->throttled = pr->throttle_override = 0; pr->ready = 1; pr->c = c; pr->backhandle = NULL; /* we shouldn't need this */ pr->dynamic = 0; pr->s = *s = new_connection(addr, dummy_realhost, port, 0, 1, 0, 0, (Plug) pr, cfg); if ((err = sk_socket_error(*s)) != NULL) { sfree(pr); return err; } sk_set_private_ptr(*s, pr); return NULL; } /* called when someone connects to the local port */ static int pfd_accepting(Plug p, OSSocket sock) { static const struct plug_function_table fn_table = { pfd_log, pfd_closing, pfd_receive, pfd_sent, NULL }; struct PFwdPrivate *pr, *org; Socket s; const char *err; org = (struct PFwdPrivate *)p; pr = snew(struct PFwdPrivate); pr->buffer = NULL; pr->fn = &fn_table; pr->c = NULL; pr->backhandle = org->backhandle; pr->s = s = sk_register(sock, (Plug) pr); if ((err = sk_socket_error(s)) != NULL) { sfree(pr); return err != NULL; } sk_set_private_ptr(s, pr); pr->throttled = pr->throttle_override = 0; pr->ready = 0; if (org->dynamic) { pr->dynamic = 1; pr->port = 0; /* "hostname" buffer is so far empty */ sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */ } else { pr->dynamic = 0; strcpy(pr->hostname, org->hostname); pr->port = org->port; pr->c = new_sock_channel(org->backhandle, s); if (pr->c == NULL) { sfree(pr); return 1; } else { /* asks to forward to the specified host/port for this */ ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding"); } } return 0; } /* Add a new forwarding from port -> desthost:destport sets up a listener on the local machine on (srcaddr:)port */ const char *pfd_addforward(char *desthost, int destport, char *srcaddr, int port, void *backhandle, const Config *cfg, void **sockdata, int address_family) { static const struct plug_function_table fn_table = { pfd_log, pfd_closing, pfd_receive, /* should not happen... */ pfd_sent, /* also should not happen */ pfd_accepting }; const char *err; struct PFwdPrivate *pr; Socket s; /* * Open socket. */ pr = snew(struct PFwdPrivate); pr->buffer = NULL; pr->fn = &fn_table; pr->c = NULL; if (desthost) { strcpy(pr->hostname, desthost); pr->port = destport; pr->dynamic = 0; } else pr->dynamic = 1; pr->throttled = pr->throttle_override = 0; pr->ready = 0; pr->backhandle = backhandle; pr->s = s = new_listener(srcaddr, port, (Plug) pr, !cfg->lport_acceptall, cfg, address_family); if ((err = sk_socket_error(s)) != NULL) { sfree(pr); return err; } sk_set_private_ptr(s, pr); *sockdata = (void *)s; return NULL; } void pfd_close(Socket s) { struct PFwdPrivate *pr; if (!s) return; pr = (struct PFwdPrivate *) sk_get_private_ptr(s); sfree(pr->buffer); sfree(pr); sk_close(s); } /* * Terminate a listener. */ void pfd_terminate(void *sv) { pfd_close((Socket)sv); } void pfd_unthrottle(Socket s) { struct PFwdPrivate *pr; if (!s) return; pr = (struct PFwdPrivate *) sk_get_private_ptr(s); pr->throttled = 0; sk_set_frozen(s, pr->throttled || pr->throttle_override); } void pfd_override_throttle(Socket s, int enable) { struct PFwdPrivate *pr; if (!s) return; pr = (struct PFwdPrivate *) sk_get_private_ptr(s); pr->throttle_override = enable; sk_set_frozen(s, pr->throttled || pr->throttle_override); } /* * Called to send data down the raw connection. */ int pfd_send(Socket s, char *data, int len) { if (s == NULL) return 0; return sk_write(s, data, len); } void pfd_confirm(Socket s) { struct PFwdPrivate *pr; if (s == NULL) return; pr = (struct PFwdPrivate *) sk_get_private_ptr(s); pr->ready = 1; sk_set_frozen(s, 0); sk_write(s, NULL, 0); if (pr->buffer) { sshfwd_write(pr->c, pr->buffer, pr->buflen); sfree(pr->buffer); pr->buffer = NULL; } }