/* * Network proxy abstraction in PuTTY * * A proxy layer, if necessary, wedges itself between the network * code and the higher level backend. */ #include #include #include #include "putty.h" #include "network.h" #include "proxy.h" #define do_proxy_dns(conf) \ (conf_get_int(conf, CONF_proxy_dns) == FORCE_ON || \ (conf_get_int(conf, CONF_proxy_dns) == AUTO && \ conf_get_int(conf, CONF_proxy_type) != PROXY_SOCKS4)) /* * Call this when proxy negotiation is complete, so that this * socket can begin working normally. */ void proxy_activate (ProxySocket *p) { size_t output_before, output_after; p->state = PROXY_STATE_ACTIVE; /* we want to ignore new receive events until we have sent * all of our buffered receive data. */ sk_set_frozen(p->sub_socket, true); /* how many bytes of output have we buffered? */ output_before = bufchain_size(&p->pending_oob_output_data) + bufchain_size(&p->pending_output_data); /* and keep track of how many bytes do not get sent. */ output_after = 0; /* send buffered OOB writes */ while (bufchain_size(&p->pending_oob_output_data) > 0) { ptrlen data = bufchain_prefix(&p->pending_oob_output_data); output_after += sk_write_oob(p->sub_socket, data.ptr, data.len); bufchain_consume(&p->pending_oob_output_data, data.len); } /* send buffered normal writes */ while (bufchain_size(&p->pending_output_data) > 0) { ptrlen data = bufchain_prefix(&p->pending_output_data); output_after += sk_write(p->sub_socket, data.ptr, data.len); bufchain_consume(&p->pending_output_data, data.len); } /* if we managed to send any data, let the higher levels know. */ if (output_after < output_before) plug_sent(p->plug, output_after); /* if we have a pending EOF to send, send it */ if (p->pending_eof) sk_write_eof(p->sub_socket); /* if the backend wanted the socket unfrozen, try to unfreeze. * our set_frozen handler will flush buffered receive data before * unfreezing the actual underlying socket. */ if (!p->freeze) sk_set_frozen(&p->sock, false); } /* basic proxy socket functions */ static Plug *sk_proxy_plug (Socket *s, Plug *p) { ProxySocket *ps = container_of(s, ProxySocket, sock); Plug *ret = ps->plug; if (p) ps->plug = p; return ret; } static void sk_proxy_close (Socket *s) { ProxySocket *ps = container_of(s, ProxySocket, sock); sk_close(ps->sub_socket); sk_addr_free(ps->remote_addr); sfree(ps); } static size_t sk_proxy_write (Socket *s, const void *data, size_t len) { ProxySocket *ps = container_of(s, ProxySocket, sock); if (ps->state != PROXY_STATE_ACTIVE) { bufchain_add(&ps->pending_output_data, data, len); return bufchain_size(&ps->pending_output_data); } return sk_write(ps->sub_socket, data, len); } static size_t sk_proxy_write_oob (Socket *s, const void *data, size_t len) { ProxySocket *ps = container_of(s, ProxySocket, sock); if (ps->state != PROXY_STATE_ACTIVE) { bufchain_clear(&ps->pending_output_data); bufchain_clear(&ps->pending_oob_output_data); bufchain_add(&ps->pending_oob_output_data, data, len); return len; } return sk_write_oob(ps->sub_socket, data, len); } static void sk_proxy_write_eof (Socket *s) { ProxySocket *ps = container_of(s, ProxySocket, sock); if (ps->state != PROXY_STATE_ACTIVE) { ps->pending_eof = true; return; } sk_write_eof(ps->sub_socket); } static void sk_proxy_set_frozen (Socket *s, bool is_frozen) { ProxySocket *ps = container_of(s, ProxySocket, sock); if (ps->state != PROXY_STATE_ACTIVE) { ps->freeze = is_frozen; return; } /* handle any remaining buffered recv data first */ if (bufchain_size(&ps->pending_input_data) > 0) { ps->freeze = is_frozen; /* loop while we still have buffered data, and while we are * unfrozen. the plug_receive call in the loop could result * in a call back into this function refreezing the socket, * so we have to check each time. */ while (!ps->freeze && bufchain_size(&ps->pending_input_data) > 0) { char databuf[512]; ptrlen data = bufchain_prefix(&ps->pending_input_data); if (data.len > lenof(databuf)) data.len = lenof(databuf); memcpy(databuf, data.ptr, data.len); bufchain_consume(&ps->pending_input_data, data.len); plug_receive(ps->plug, 0, databuf, data.len); } /* if we're still frozen, we'll have to wait for another * call from the backend to finish unbuffering the data. */ if (ps->freeze) return; } sk_set_frozen(ps->sub_socket, is_frozen); } static const char * sk_proxy_socket_error (Socket *s) { ProxySocket *ps = container_of(s, ProxySocket, sock); if (ps->error != NULL || ps->sub_socket == NULL) { return ps->error; } return sk_socket_error(ps->sub_socket); } /* basic proxy plug functions */ static void plug_proxy_log(Plug *plug, PlugLogType type, SockAddr *addr, int port, const char *error_msg, int error_code) { ProxySocket *ps = container_of(plug, ProxySocket, plugimpl); plug_log(ps->plug, type, addr, port, error_msg, error_code); } static void plug_proxy_closing (Plug *p, const char *error_msg, int error_code, bool calling_back) { ProxySocket *ps = container_of(p, ProxySocket, plugimpl); if (ps->state != PROXY_STATE_ACTIVE) { ps->closing_error_msg = error_msg; ps->closing_error_code = error_code; ps->closing_calling_back = calling_back; ps->negotiate(ps, PROXY_CHANGE_CLOSING); } else { plug_closing(ps->plug, error_msg, error_code, calling_back); } } static void plug_proxy_receive( Plug *p, int urgent, const char *data, size_t len) { ProxySocket *ps = container_of(p, ProxySocket, plugimpl); if (ps->state != PROXY_STATE_ACTIVE) { /* we will lose the urgentness of this data, but since most, * if not all, of this data will be consumed by the negotiation * process, hopefully it won't affect the protocol above us */ bufchain_add(&ps->pending_input_data, data, len); ps->receive_urgent = (urgent != 0); ps->receive_data = data; ps->receive_len = len; ps->negotiate(ps, PROXY_CHANGE_RECEIVE); } else { plug_receive(ps->plug, urgent, data, len); } } static void plug_proxy_sent (Plug *p, size_t bufsize) { ProxySocket *ps = container_of(p, ProxySocket, plugimpl); if (ps->state != PROXY_STATE_ACTIVE) { ps->negotiate(ps, PROXY_CHANGE_SENT); return; } plug_sent(ps->plug, bufsize); } static int plug_proxy_accepting(Plug *p, accept_fn_t constructor, accept_ctx_t ctx) { ProxySocket *ps = container_of(p, ProxySocket, plugimpl); if (ps->state != PROXY_STATE_ACTIVE) { ps->accepting_constructor = constructor; ps->accepting_ctx = ctx; return ps->negotiate(ps, PROXY_CHANGE_ACCEPTING); } return plug_accepting(ps->plug, constructor, ctx); } /* * This function can accept a NULL pointer as `addr', in which case * it will only check the host name. */ static bool proxy_for_destination(SockAddr *addr, const char *hostname, int port, Conf *conf) { int s = 0, e = 0; char hostip[64]; int hostip_len, hostname_len; const char *exclude_list; /* * Special local connections such as Unix-domain sockets * unconditionally cannot be proxied, even in proxy-localhost * mode. There just isn't any way to ask any known proxy type for * them. */ if (addr && sk_address_is_special_local(addr)) return false; /* do not proxy */ /* * Check the host name and IP against the hard-coded * representations of `localhost'. */ if (!conf_get_bool(conf, CONF_even_proxy_localhost) && (sk_hostname_is_local(hostname) || (addr && sk_address_is_local(addr)))) return false; /* do not proxy */ /* we want a string representation of the IP address for comparisons */ if (addr) { sk_getaddr(addr, hostip, 64); hostip_len = strlen(hostip); } else hostip_len = 0; /* placate gcc; shouldn't be required */ hostname_len = strlen(hostname); exclude_list = conf_get_str(conf, CONF_proxy_exclude_list); /* now parse the exclude list, and see if either our IP * or hostname matches anything in it. */ while (exclude_list[s]) { while (exclude_list[s] && (isspace((unsigned char)exclude_list[s]) || exclude_list[s] == ',')) s++; if (!exclude_list[s]) break; e = s; while (exclude_list[e] && (isalnum((unsigned char)exclude_list[e]) || exclude_list[e] == '-' || exclude_list[e] == '.' || exclude_list[e] == '*')) e++; if (exclude_list[s] == '*') { /* wildcard at beginning of entry */ if ((addr && strnicmp(hostip + hostip_len - (e - s - 1), exclude_list + s + 1, e - s - 1) == 0) || strnicmp(hostname + hostname_len - (e - s - 1), exclude_list + s + 1, e - s - 1) == 0) { /* IP/hostname range excluded. do not use proxy. */ return false; } } else if (exclude_list[e-1] == '*') { /* wildcard at end of entry */ if ((addr && strnicmp(hostip, exclude_list + s, e - s - 1) == 0) || strnicmp(hostname, exclude_list + s, e - s - 1) == 0) { /* IP/hostname range excluded. do not use proxy. */ return false; } } else { /* no wildcard at either end, so let's try an absolute * match (ie. a specific IP) */ if (addr && strnicmp(hostip, exclude_list + s, e - s) == 0) return false; /* IP/hostname excluded. do not use proxy. */ if (strnicmp(hostname, exclude_list + s, e - s) == 0) return false; /* IP/hostname excluded. do not use proxy. */ } s = e; /* Make sure we really have reached the next comma or end-of-string */ while (exclude_list[s] && !isspace((unsigned char)exclude_list[s]) && exclude_list[s] != ',') s++; } /* no matches in the exclude list, so use the proxy */ return true; } static char *dns_log_msg(const char *host, int addressfamily, const char *reason) { return dupprintf("Looking up host \"%s\"%s for %s", host, (addressfamily == ADDRTYPE_IPV4 ? " (IPv4)" : addressfamily == ADDRTYPE_IPV6 ? " (IPv6)" : ""), reason); } SockAddr *name_lookup(const char *host, int port, char **canonicalname, Conf *conf, int addressfamily, LogContext *logctx, const char *reason) { if (conf_get_int(conf, CONF_proxy_type) != PROXY_NONE && do_proxy_dns(conf) && proxy_for_destination(NULL, host, port, conf)) { if (logctx) logeventf(logctx, "Leaving host lookup to proxy of \"%s\"" " (for %s)", host, reason); *canonicalname = dupstr(host); return sk_nonamelookup(host); } else { if (logctx) logevent_and_free( logctx, dns_log_msg(host, addressfamily, reason)); return sk_namelookup(host, canonicalname, addressfamily); } } static const SocketVtable ProxySocket_sockvt = { .plug = sk_proxy_plug, .close = sk_proxy_close, .write = sk_proxy_write, .write_oob = sk_proxy_write_oob, .write_eof = sk_proxy_write_eof, .set_frozen = sk_proxy_set_frozen, .socket_error = sk_proxy_socket_error, .peer_info = NULL, }; static const PlugVtable ProxySocket_plugvt = { .log = plug_proxy_log, .closing = plug_proxy_closing, .receive = plug_proxy_receive, .sent = plug_proxy_sent, .accepting = plug_proxy_accepting }; Socket *new_connection(SockAddr *addr, const char *hostname, int port, bool privport, bool oobinline, bool nodelay, bool keepalive, Plug *plug, Conf *conf) { if (conf_get_int(conf, CONF_proxy_type) != PROXY_NONE && proxy_for_destination(addr, hostname, port, conf)) { ProxySocket *ret; SockAddr *proxy_addr; char *proxy_canonical_name; const char *proxy_type; Socket *sret; int type; if ((sret = platform_new_connection(addr, hostname, port, privport, oobinline, nodelay, keepalive, plug, conf)) != NULL) return sret; ret = snew(ProxySocket); ret->sock.vt = &ProxySocket_sockvt; ret->plugimpl.vt = &ProxySocket_plugvt; ret->conf = conf_copy(conf); ret->plug = plug; ret->remote_addr = addr; /* will need to be freed on close */ ret->remote_port = port; ret->error = NULL; ret->pending_eof = false; ret->freeze = false; bufchain_init(&ret->pending_input_data); bufchain_init(&ret->pending_output_data); bufchain_init(&ret->pending_oob_output_data); ret->sub_socket = NULL; ret->state = PROXY_STATE_NEW; ret->negotiate = NULL; type = conf_get_int(conf, CONF_proxy_type); if (type == PROXY_HTTP) { ret->negotiate = proxy_http_negotiate; proxy_type = "HTTP"; } else if (type == PROXY_SOCKS4) { ret->negotiate = proxy_socks4_negotiate; proxy_type = "SOCKS 4"; } else if (type == PROXY_SOCKS5) { ret->negotiate = proxy_socks5_negotiate; proxy_type = "SOCKS 5"; } else if (type == PROXY_TELNET) { ret->negotiate = proxy_telnet_negotiate; proxy_type = "Telnet"; } else { ret->error = "Proxy error: Unknown proxy method"; return &ret->sock; } { char *logmsg = dupprintf("Will use %s proxy at %s:%d to connect" " to %s:%d", proxy_type, conf_get_str(conf, CONF_proxy_host), conf_get_int(conf, CONF_proxy_port), hostname, port); plug_log(plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0); sfree(logmsg); } { char *logmsg = dns_log_msg(conf_get_str(conf, CONF_proxy_host), conf_get_int(conf, CONF_addressfamily), "proxy"); plug_log(plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0); sfree(logmsg); } /* look-up proxy */ proxy_addr = sk_namelookup(conf_get_str(conf, CONF_proxy_host), &proxy_canonical_name, conf_get_int(conf, CONF_addressfamily)); if (sk_addr_error(proxy_addr) != NULL) { ret->error = "Proxy error: Unable to resolve proxy host name"; sk_addr_free(proxy_addr); return &ret->sock; } sfree(proxy_canonical_name); { char addrbuf[256], *logmsg; sk_getaddr(proxy_addr, addrbuf, lenof(addrbuf)); logmsg = dupprintf("Connecting to %s proxy at %s port %d", proxy_type, addrbuf, conf_get_int(conf, CONF_proxy_port)); plug_log(plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0); sfree(logmsg); } /* create the actual socket we will be using, * connected to our proxy server and port. */ ret->sub_socket = sk_new(proxy_addr, conf_get_int(conf, CONF_proxy_port), privport, oobinline, nodelay, keepalive, &ret->plugimpl); if (sk_socket_error(ret->sub_socket) != NULL) return &ret->sock; /* start the proxy negotiation process... */ sk_set_frozen(ret->sub_socket, false); ret->negotiate(ret, PROXY_CHANGE_NEW); return &ret->sock; } /* no proxy, so just return the direct socket */ return sk_new(addr, port, privport, oobinline, nodelay, keepalive, plug); } Socket *new_listener(const char *srcaddr, int port, Plug *plug, bool local_host_only, Conf *conf, int addressfamily) { /* TODO: SOCKS (and potentially others) support inbound * TODO: connections via the proxy. support them. */ return sk_newlistener(srcaddr, port, plug, local_host_only, addressfamily); } /* ---------------------------------------------------------------------- * HTTP CONNECT proxy type. */ static bool get_line_end(char *data, size_t len, size_t *out) { size_t off = 0; while (off < len) { if (data[off] == '\n') { /* we have a newline */ off++; /* is that the only thing on this line? */ if (off <= 2) { *out = off; return true; } /* if not, then there is the possibility that this header * continues onto the next line, if it starts with a space * or a tab. */ if (off + 1 < len && data[off+1] != ' ' && data[off+1] != '\t') { *out = off; return true; } /* the line does continue, so we have to keep going * until we see an the header's "real" end of line. */ off++; } off++; } return false; } int proxy_http_negotiate (ProxySocket *p, int change) { if (p->state == PROXY_STATE_NEW) { /* we are just beginning the proxy negotiate process, * so we'll send off the initial bits of the request. * for this proxy method, it's just a simple HTTP * request */ char *buf, dest[512]; char *username, *password; sk_getaddr(p->remote_addr, dest, lenof(dest)); buf = dupprintf("CONNECT %s:%i HTTP/1.1\r\nHost: %s:%i\r\n", dest, p->remote_port, dest, p->remote_port); sk_write(p->sub_socket, buf, strlen(buf)); sfree(buf); username = conf_get_str(p->conf, CONF_proxy_username); password = conf_get_str(p->conf, CONF_proxy_password); if (username[0] || password[0]) { char *buf, *buf2; int i, j, len; buf = dupprintf("%s:%s", username, password); len = strlen(buf); buf2 = snewn(len * 4 / 3 + 100, char); sprintf(buf2, "Proxy-Authorization: Basic "); for (i = 0, j = strlen(buf2); i < len; i += 3, j += 4) base64_encode_atom((unsigned char *)(buf+i), (len-i > 3 ? 3 : len-i), buf2+j); strcpy(buf2+j, "\r\n"); sk_write(p->sub_socket, buf2, strlen(buf2)); sfree(buf); sfree(buf2); } sk_write(p->sub_socket, "\r\n", 2); p->state = 1; return 0; } if (change == PROXY_CHANGE_CLOSING) { /* if our proxy negotiation process involves closing and opening * new sockets, then we would want to intercept this closing * callback when we were expecting it. if we aren't anticipating * a socket close, then some error must have occurred. we'll * just pass those errors up to the backend. */ plug_closing(p->plug, p->closing_error_msg, p->closing_error_code, p->closing_calling_back); return 0; /* ignored */ } if (change == PROXY_CHANGE_SENT) { /* some (or all) of what we wrote to the proxy was sent. * we don't do anything new, however, until we receive the * proxy's response. we might want to set a timer so we can * timeout the proxy negotiation after a while... */ return 0; } if (change == PROXY_CHANGE_ACCEPTING) { /* we should _never_ see this, as we are using our socket to * connect to a proxy, not accepting inbound connections. * what should we do? close the socket with an appropriate * error message? */ return plug_accepting(p->plug, p->accepting_constructor, p->accepting_ctx); } if (change == PROXY_CHANGE_RECEIVE) { /* we have received data from the underlying socket, which * we'll need to parse, process, and respond to appropriately. */ char *data, *datap; size_t len, eol; if (p->state == 1) { int min_ver, maj_ver, status; /* get the status line */ len = bufchain_size(&p->pending_input_data); assert(len > 0); /* or we wouldn't be here */ data = snewn(len+1, char); bufchain_fetch(&p->pending_input_data, data, len); /* * We must NUL-terminate this data, because Windows * sscanf appears to require a NUL at the end of the * string because it strlens it _first_. Sigh. */ data[len] = '\0'; if (!get_line_end(data, len, &eol)) { sfree(data); return 1; } status = -1; /* We can't rely on whether the %n incremented the sscanf return */ if (sscanf((char *)data, "HTTP/%i.%i %n", &maj_ver, &min_ver, &status) < 2 || status == -1) { plug_closing(p->plug, "Proxy error: HTTP response was absent", PROXY_ERROR_GENERAL, 0); sfree(data); return 1; } /* remove the status line from the input buffer. */ bufchain_consume(&p->pending_input_data, eol); if (data[status] != '2') { /* error */ char *buf; data[eol] = '\0'; while (eol > status && (data[eol-1] == '\r' || data[eol-1] == '\n')) data[--eol] = '\0'; buf = dupprintf("Proxy error: %s", data+status); plug_closing(p->plug, buf, PROXY_ERROR_GENERAL, 0); sfree(buf); sfree(data); return 1; } sfree(data); p->state = 2; } if (p->state == 2) { /* get headers. we're done when we get a * header of length 2, (ie. just "\r\n") */ len = bufchain_size(&p->pending_input_data); assert(len > 0); /* or we wouldn't be here */ data = snewn(len, char); datap = data; bufchain_fetch(&p->pending_input_data, data, len); if (!get_line_end(datap, len, &eol)) { sfree(data); return 1; } while (eol > 2) { bufchain_consume(&p->pending_input_data, eol); datap += eol; len -= eol; if (!get_line_end(datap, len, &eol)) eol = 0; /* terminate the loop */ } if (eol == 2) { /* we're done */ bufchain_consume(&p->pending_input_data, 2); proxy_activate(p); /* proxy activate will have dealt with * whatever is left of the buffer */ sfree(data); return 1; } sfree(data); return 1; } } plug_closing(p->plug, "Proxy error: unexpected proxy error", PROXY_ERROR_UNEXPECTED, 0); return 1; } /* ---------------------------------------------------------------------- * SOCKS proxy type. */ /* SOCKS version 4 */ int proxy_socks4_negotiate (ProxySocket *p, int change) { if (p->state == PROXY_CHANGE_NEW) { /* request format: * version number (1 byte) = 4 * command code (1 byte) * 1 = CONNECT * 2 = BIND * dest. port (2 bytes) [network order] * dest. address (4 bytes) * user ID (variable length, null terminated string) */ strbuf *command = strbuf_new(); char hostname[512]; bool write_hostname = false; put_byte(command, 4); /* SOCKS version 4 */ put_byte(command, 1); /* CONNECT command */ put_uint16(command, p->remote_port); switch (sk_addrtype(p->remote_addr)) { case ADDRTYPE_IPV4: { char addr[4]; sk_addrcopy(p->remote_addr, addr); put_data(command, addr, 4); break; } case ADDRTYPE_NAME: sk_getaddr(p->remote_addr, hostname, lenof(hostname)); put_uint32(command, 1); write_hostname = true; break; case ADDRTYPE_IPV6: p->error = "Proxy error: SOCKS version 4 does not support IPv6"; strbuf_free(command); return 1; } put_asciz(command, conf_get_str(p->conf, CONF_proxy_username)); if (write_hostname) put_asciz(command, hostname); sk_write(p->sub_socket, command->s, command->len); strbuf_free(command); p->state = 1; return 0; } if (change == PROXY_CHANGE_CLOSING) { /* if our proxy negotiation process involves closing and opening * new sockets, then we would want to intercept this closing * callback when we were expecting it. if we aren't anticipating * a socket close, then some error must have occurred. we'll * just pass those errors up to the backend. */ plug_closing(p->plug, p->closing_error_msg, p->closing_error_code, p->closing_calling_back); return 0; /* ignored */ } if (change == PROXY_CHANGE_SENT) { /* some (or all) of what we wrote to the proxy was sent. * we don't do anything new, however, until we receive the * proxy's response. we might want to set a timer so we can * timeout the proxy negotiation after a while... */ return 0; } if (change == PROXY_CHANGE_ACCEPTING) { /* we should _never_ see this, as we are using our socket to * connect to a proxy, not accepting inbound connections. * what should we do? close the socket with an appropriate * error message? */ return plug_accepting(p->plug, p->accepting_constructor, p->accepting_ctx); } if (change == PROXY_CHANGE_RECEIVE) { /* we have received data from the underlying socket, which * we'll need to parse, process, and respond to appropriately. */ if (p->state == 1) { /* response format: * version number (1 byte) = 4 * reply code (1 byte) * 90 = request granted * 91 = request rejected or failed * 92 = request rejected due to lack of IDENTD on client * 93 = request rejected due to difference in user ID * (what we sent vs. what IDENTD said) * dest. port (2 bytes) * dest. address (4 bytes) */ char data[8]; if (bufchain_size(&p->pending_input_data) < 8) return 1; /* not got anything yet */ /* get the response */ bufchain_fetch(&p->pending_input_data, data, 8); if (data[0] != 0) { plug_closing(p->plug, "Proxy error: SOCKS proxy responded with " "unexpected reply code version", PROXY_ERROR_GENERAL, 0); return 1; } if (data[1] != 90) { switch (data[1]) { case 92: plug_closing(p->plug, "Proxy error: SOCKS server wanted IDENTD on client", PROXY_ERROR_GENERAL, 0); break; case 93: plug_closing(p->plug, "Proxy error: Username and IDENTD on client don't agree", PROXY_ERROR_GENERAL, 0); break; case 91: default: plug_closing(p->plug, "Proxy error: Error while communicating with proxy", PROXY_ERROR_GENERAL, 0); break; } return 1; } bufchain_consume(&p->pending_input_data, 8); /* we're done */ proxy_activate(p); /* proxy activate will have dealt with * whatever is left of the buffer */ return 1; } } plug_closing(p->plug, "Proxy error: unexpected proxy error", PROXY_ERROR_UNEXPECTED, 0); return 1; } /* SOCKS version 5 */ int proxy_socks5_negotiate (ProxySocket *p, int change) { if (p->state == PROXY_CHANGE_NEW) { /* initial command: * version number (1 byte) = 5 * number of available authentication methods (1 byte) * available authentication methods (1 byte * previous value) * authentication methods: * 0x00 = no authentication * 0x01 = GSSAPI * 0x02 = username/password * 0x03 = CHAP */ strbuf *command; char *username, *password; int method_count_offset, methods_start; command = strbuf_new(); put_byte(command, 5); /* SOCKS version 5 */ username = conf_get_str(p->conf, CONF_proxy_username); password = conf_get_str(p->conf, CONF_proxy_password); method_count_offset = command->len; put_byte(command, 0); methods_start = command->len; put_byte(command, 0x00); /* no authentication */ if (username[0] || password[0]) { proxy_socks5_offerencryptedauth(BinarySink_UPCAST(command)); put_byte(command, 0x02); /* username/password */ } command->u[method_count_offset] = command->len - methods_start; sk_write(p->sub_socket, command->s, command->len); strbuf_free(command); p->state = 1; return 0; } if (change == PROXY_CHANGE_CLOSING) { /* if our proxy negotiation process involves closing and opening * new sockets, then we would want to intercept this closing * callback when we were expecting it. if we aren't anticipating * a socket close, then some error must have occurred. we'll * just pass those errors up to the backend. */ plug_closing(p->plug, p->closing_error_msg, p->closing_error_code, p->closing_calling_back); return 0; /* ignored */ } if (change == PROXY_CHANGE_SENT) { /* some (or all) of what we wrote to the proxy was sent. * we don't do anything new, however, until we receive the * proxy's response. we might want to set a timer so we can * timeout the proxy negotiation after a while... */ return 0; } if (change == PROXY_CHANGE_ACCEPTING) { /* we should _never_ see this, as we are using our socket to * connect to a proxy, not accepting inbound connections. * what should we do? close the socket with an appropriate * error message? */ return plug_accepting(p->plug, p->accepting_constructor, p->accepting_ctx); } if (change == PROXY_CHANGE_RECEIVE) { /* we have received data from the underlying socket, which * we'll need to parse, process, and respond to appropriately. */ if (p->state == 1) { /* initial response: * version number (1 byte) = 5 * authentication method (1 byte) * authentication methods: * 0x00 = no authentication * 0x01 = GSSAPI * 0x02 = username/password * 0x03 = CHAP * 0xff = no acceptable methods */ char data[2]; if (bufchain_size(&p->pending_input_data) < 2) return 1; /* not got anything yet */ /* get the response */ bufchain_fetch(&p->pending_input_data, data, 2); if (data[0] != 5) { plug_closing(p->plug, "Proxy error: SOCKS proxy returned unexpected version", PROXY_ERROR_GENERAL, 0); return 1; } if (data[1] == 0x00) p->state = 2; /* no authentication needed */ else if (data[1] == 0x01) p->state = 4; /* GSSAPI authentication */ else if (data[1] == 0x02) p->state = 5; /* username/password authentication */ else if (data[1] == 0x03) p->state = 6; /* CHAP authentication */ else { plug_closing(p->plug, "Proxy error: SOCKS proxy did not accept our authentication", PROXY_ERROR_GENERAL, 0); return 1; } bufchain_consume(&p->pending_input_data, 2); } if (p->state == 7) { /* password authentication reply format: * version number (1 bytes) = 1 * reply code (1 byte) * 0 = succeeded * >0 = failed */ char data[2]; if (bufchain_size(&p->pending_input_data) < 2) return 1; /* not got anything yet */ /* get the response */ bufchain_fetch(&p->pending_input_data, data, 2); if (data[0] != 1) { plug_closing(p->plug, "Proxy error: SOCKS password " "subnegotiation contained wrong version number", PROXY_ERROR_GENERAL, 0); return 1; } if (data[1] != 0) { plug_closing(p->plug, "Proxy error: SOCKS proxy refused" " password authentication", PROXY_ERROR_GENERAL, 0); return 1; } bufchain_consume(&p->pending_input_data, 2); p->state = 2; /* now proceed as authenticated */ } if (p->state == 8) { int ret; ret = proxy_socks5_handlechap(p); if (ret) return ret; } if (p->state == 2) { /* request format: * version number (1 byte) = 5 * command code (1 byte) * 1 = CONNECT * 2 = BIND * 3 = UDP ASSOCIATE * reserved (1 byte) = 0x00 * address type (1 byte) * 1 = IPv4 * 3 = domainname (first byte has length, no terminating null) * 4 = IPv6 * dest. address (variable) * dest. port (2 bytes) [network order] */ strbuf *command = strbuf_new(); put_byte(command, 5); /* SOCKS version 5 */ put_byte(command, 1); /* CONNECT command */ put_byte(command, 0x00); /* reserved byte */ switch (sk_addrtype(p->remote_addr)) { case ADDRTYPE_IPV4: put_byte(command, 1); /* IPv4 */ sk_addrcopy(p->remote_addr, strbuf_append(command, 4)); break; case ADDRTYPE_IPV6: put_byte(command, 4); /* IPv6 */ sk_addrcopy(p->remote_addr, strbuf_append(command, 16)); break; case ADDRTYPE_NAME: { char hostname[512]; put_byte(command, 3); /* domain name */ sk_getaddr(p->remote_addr, hostname, lenof(hostname)); if (!put_pstring(command, hostname)) { p->error = "Proxy error: SOCKS 5 cannot " "support host names longer than 255 chars"; strbuf_free(command); return 1; } break; } } put_uint16(command, p->remote_port); sk_write(p->sub_socket, command->s, command->len); strbuf_free(command); p->state = 3; return 1; } if (p->state == 3) { /* reply format: * version number (1 bytes) = 5 * reply code (1 byte) * 0 = succeeded * 1 = general SOCKS server failure * 2 = connection not allowed by ruleset * 3 = network unreachable * 4 = host unreachable * 5 = connection refused * 6 = TTL expired * 7 = command not supported * 8 = address type not supported * reserved (1 byte) = x00 * address type (1 byte) * 1 = IPv4 * 3 = domainname (first byte has length, no terminating null) * 4 = IPv6 * server bound address (variable) * server bound port (2 bytes) [network order] */ char data[5]; int len; /* First 5 bytes of packet are enough to tell its length. */ if (bufchain_size(&p->pending_input_data) < 5) return 1; /* not got anything yet */ /* get the response */ bufchain_fetch(&p->pending_input_data, data, 5); if (data[0] != 5) { plug_closing(p->plug, "Proxy error: SOCKS proxy returned wrong version number", PROXY_ERROR_GENERAL, 0); return 1; } if (data[1] != 0) { char buf[256]; strcpy(buf, "Proxy error: "); switch (data[1]) { case 1: strcat(buf, "General SOCKS server failure"); break; case 2: strcat(buf, "Connection not allowed by ruleset"); break; case 3: strcat(buf, "Network unreachable"); break; case 4: strcat(buf, "Host unreachable"); break; case 5: strcat(buf, "Connection refused"); break; case 6: strcat(buf, "TTL expired"); break; case 7: strcat(buf, "Command not supported"); break; case 8: strcat(buf, "Address type not supported"); break; default: sprintf(buf+strlen(buf), "Unrecognised SOCKS error code %d", data[1]); break; } plug_closing(p->plug, buf, PROXY_ERROR_GENERAL, 0); return 1; } /* * Eat the rest of the reply packet. */ len = 6; /* first 4 bytes, last 2 */ switch (data[3]) { case 1: len += 4; break; /* IPv4 address */ case 4: len += 16; break;/* IPv6 address */ case 3: len += 1+(unsigned char)data[4]; break; /* domain name */ default: plug_closing(p->plug, "Proxy error: SOCKS proxy returned " "unrecognised address format", PROXY_ERROR_GENERAL, 0); return 1; } if (bufchain_size(&p->pending_input_data) < len) return 1; /* not got whole reply yet */ bufchain_consume(&p->pending_input_data, len); /* we're done */ proxy_activate(p); return 1; } if (p->state == 4) { /* TODO: Handle GSSAPI authentication */ plug_closing(p->plug, "Proxy error: We don't support GSSAPI authentication", PROXY_ERROR_GENERAL, 0); return 1; } if (p->state == 5) { const char *username = conf_get_str(p->conf, CONF_proxy_username); const char *password = conf_get_str(p->conf, CONF_proxy_password); if (username[0] || password[0]) { strbuf *auth = strbuf_new_nm(); put_byte(auth, 1); /* version number of subnegotiation */ if (!put_pstring(auth, username)) { p->error = "Proxy error: SOCKS 5 authentication cannot " "support usernames longer than 255 chars"; strbuf_free(auth); return 1; } if (!put_pstring(auth, password)) { p->error = "Proxy error: SOCKS 5 authentication cannot " "support passwords longer than 255 chars"; strbuf_free(auth); return 1; } sk_write(p->sub_socket, auth->s, auth->len); strbuf_free(auth); p->state = 7; } else plug_closing(p->plug, "Proxy error: Server chose " "username/password authentication but we " "didn't offer it!", PROXY_ERROR_GENERAL, 0); return 1; } if (p->state == 6) { int ret; ret = proxy_socks5_selectchap(p); if (ret) return ret; } } plug_closing(p->plug, "Proxy error: Unexpected proxy error", PROXY_ERROR_UNEXPECTED, 0); return 1; } /* ---------------------------------------------------------------------- * `Telnet' proxy type. * * (This is for ad-hoc proxies where you connect to the proxy's * telnet port and send a command such as `connect host port'. The * command is configurable, since this proxy type is typically not * standardised or at all well-defined.) */ char *format_telnet_command(SockAddr *addr, int port, Conf *conf) { char *fmt = conf_get_str(conf, CONF_proxy_telnet_command); int so = 0, eo = 0; strbuf *buf = strbuf_new(); /* we need to escape \\, \%, \r, \n, \t, \x??, \0???, * %%, %host, %port, %user, and %pass */ while (fmt[eo] != 0) { /* scan forward until we hit end-of-line, * or an escape character (\ or %) */ while (fmt[eo] != 0 && fmt[eo] != '%' && fmt[eo] != '\\') eo++; /* if we hit eol, break out of our escaping loop */ if (fmt[eo] == 0) break; /* if there was any unescaped text before the escape * character, send that now */ if (eo != so) put_data(buf, fmt + so, eo - so); so = eo++; /* if the escape character was the last character of * the line, we'll just stop and send it. */ if (fmt[eo] == 0) break; if (fmt[so] == '\\') { /* we recognize \\, \%, \r, \n, \t, \x??. * anything else, we just send unescaped (including the \). */ switch (fmt[eo]) { case '\\': put_byte(buf, '\\'); eo++; break; case '%': put_byte(buf, '%'); eo++; break; case 'r': put_byte(buf, '\r'); eo++; break; case 'n': put_byte(buf, '\n'); eo++; break; case 't': put_byte(buf, '\t'); eo++; break; case 'x': case 'X': { /* escaped hexadecimal value (ie. \xff) */ unsigned char v = 0; int i = 0; for (;;) { eo++; if (fmt[eo] >= '0' && fmt[eo] <= '9') v += fmt[eo] - '0'; else if (fmt[eo] >= 'a' && fmt[eo] <= 'f') v += fmt[eo] - 'a' + 10; else if (fmt[eo] >= 'A' && fmt[eo] <= 'F') v += fmt[eo] - 'A' + 10; else { /* non hex character, so we abort and just * send the whole thing unescaped (including \x) */ put_byte(buf, '\\'); eo = so + 1; break; } /* we only extract two hex characters */ if (i == 1) { put_byte(buf, v); eo++; break; } i++; v <<= 4; } break; } default: put_data(buf, fmt + so, 2); eo++; break; } } else { /* % escape. we recognize %%, %host, %port, %user, %pass. * %proxyhost, %proxyport. Anything else we just send * unescaped (including the %). */ if (fmt[eo] == '%') { put_byte(buf, '%'); eo++; } else if (strnicmp(fmt + eo, "host", 4) == 0) { char dest[512]; sk_getaddr(addr, dest, lenof(dest)); put_data(buf, dest, strlen(dest)); eo += 4; } else if (strnicmp(fmt + eo, "port", 4) == 0) { strbuf_catf(buf, "%d", port); eo += 4; } else if (strnicmp(fmt + eo, "user", 4) == 0) { const char *username = conf_get_str(conf, CONF_proxy_username); put_data(buf, username, strlen(username)); eo += 4; } else if (strnicmp(fmt + eo, "pass", 4) == 0) { const char *password = conf_get_str(conf, CONF_proxy_password); put_data(buf, password, strlen(password)); eo += 4; } else if (strnicmp(fmt + eo, "proxyhost", 9) == 0) { const char *host = conf_get_str(conf, CONF_proxy_host); put_data(buf, host, strlen(host)); eo += 9; } else if (strnicmp(fmt + eo, "proxyport", 9) == 0) { int port = conf_get_int(conf, CONF_proxy_port); strbuf_catf(buf, "%d", port); eo += 9; } else { /* we don't escape this, so send the % now, and * don't advance eo, so that we'll consider the * text immediately following the % as unescaped. */ put_byte(buf, '%'); } } /* resume scanning for additional escapes after this one. */ so = eo; } /* if there is any unescaped text at the end of the line, send it */ if (eo != so) { put_data(buf, fmt + so, eo - so); } return strbuf_to_str(buf); } int proxy_telnet_negotiate (ProxySocket *p, int change) { if (p->state == PROXY_CHANGE_NEW) { char *formatted_cmd; formatted_cmd = format_telnet_command(p->remote_addr, p->remote_port, p->conf); { /* * Re-escape control chars in the command, for logging. */ char *reescaped = snewn(4*strlen(formatted_cmd) + 1, char); const char *in; char *out; char *logmsg; for (in = formatted_cmd, out = reescaped; *in; in++) { if (*in == '\n') { *out++ = '\\'; *out++ = 'n'; } else if (*in == '\r') { *out++ = '\\'; *out++ = 'r'; } else if (*in == '\t') { *out++ = '\\'; *out++ = 't'; } else if (*in == '\\') { *out++ = '\\'; *out++ = '\\'; } else if ((unsigned)(((unsigned char)*in) - 0x20) < (0x7F-0x20)) { *out++ = *in; } else { out += sprintf(out, "\\x%02X", (unsigned)*in & 0xFF); } } *out = '\0'; logmsg = dupprintf("Sending Telnet proxy command: %s", reescaped); plug_log(p->plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0); sfree(logmsg); sfree(reescaped); } sk_write(p->sub_socket, formatted_cmd, strlen(formatted_cmd)); sfree(formatted_cmd); p->state = 1; return 0; } if (change == PROXY_CHANGE_CLOSING) { /* if our proxy negotiation process involves closing and opening * new sockets, then we would want to intercept this closing * callback when we were expecting it. if we aren't anticipating * a socket close, then some error must have occurred. we'll * just pass those errors up to the backend. */ plug_closing(p->plug, p->closing_error_msg, p->closing_error_code, p->closing_calling_back); return 0; /* ignored */ } if (change == PROXY_CHANGE_SENT) { /* some (or all) of what we wrote to the proxy was sent. * we don't do anything new, however, until we receive the * proxy's response. we might want to set a timer so we can * timeout the proxy negotiation after a while... */ return 0; } if (change == PROXY_CHANGE_ACCEPTING) { /* we should _never_ see this, as we are using our socket to * connect to a proxy, not accepting inbound connections. * what should we do? close the socket with an appropriate * error message? */ return plug_accepting(p->plug, p->accepting_constructor, p->accepting_ctx); } if (change == PROXY_CHANGE_RECEIVE) { /* we have received data from the underlying socket, which * we'll need to parse, process, and respond to appropriately. */ /* we're done */ proxy_activate(p); /* proxy activate will have dealt with * whatever is left of the buffer */ return 1; } plug_closing(p->plug, "Proxy error: Unexpected proxy error", PROXY_ERROR_UNEXPECTED, 0); return 1; }