/* * 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)) static void proxy_negotiator_cleanup(ProxySocket *ps) { if (ps->pn) { proxy_negotiator_free(ps->pn); ps->pn = NULL; } if (ps->clientseat) { interactor_return_seat(ps->clientitr); ps->clientitr = NULL; ps->clientseat = NULL; } } /* * Call this when proxy negotiation is complete, so that this * socket can begin working normally. */ static void proxy_activate(ProxySocket *ps) { size_t output_before, output_after; proxy_negotiator_cleanup(ps); plug_log(ps->plug, &ps->sock, PLUGLOG_CONNECT_SUCCESS, NULL, 0, NULL, 0); /* we want to ignore new receive events until we have sent * all of our buffered receive data. */ sk_set_frozen(ps->sub_socket, true); /* how many bytes of output have we buffered? */ output_before = bufchain_size(&ps->pending_oob_output_data) + bufchain_size(&ps->pending_output_data); /* and keep track of how many bytes do not get sent. */ output_after = 0; /* send buffered OOB writes */ while (bufchain_size(&ps->pending_oob_output_data) > 0) { ptrlen data = bufchain_prefix(&ps->pending_oob_output_data); output_after += sk_write_oob(ps->sub_socket, data.ptr, data.len); bufchain_consume(&ps->pending_oob_output_data, data.len); } /* send buffered normal writes */ while (bufchain_size(&ps->pending_output_data) > 0) { ptrlen data = bufchain_prefix(&ps->pending_output_data); output_after += sk_write(ps->sub_socket, data.ptr, data.len); bufchain_consume(&ps->pending_output_data, data.len); } /* if we managed to send any data, let the higher levels know. */ if (output_after < output_before) plug_sent(ps->plug, output_after); /* if we have a pending EOF to send, send it */ if (ps->pending_eof) sk_write_eof(ps->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 (!ps->freeze) sk_set_frozen(&ps->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->proxy_addr); sk_addr_free(ps->remote_addr); proxy_negotiator_cleanup(ps); bufchain_clear(&ps->output_from_negotiator); 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->pn) { 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->pn) { 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->pn) { 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->pn) { 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, Socket *s, PlugLogType type, SockAddr *addr, int port, const char *error_msg, int error_code) { ProxySocket *ps = container_of(plug, ProxySocket, plugimpl); plug_log(ps->plug, &ps->sock, type, addr, port, error_msg, error_code); } static void plug_proxy_closing(Plug *p, PlugCloseType type, const char *error_msg) { ProxySocket *ps = container_of(p, ProxySocket, plugimpl); proxy_negotiator_cleanup(ps); plug_closing(ps->plug, type, error_msg); } static void proxy_negotiate(ProxySocket *ps) { assert(ps->pn); proxy_negotiator_process_queue(ps->pn); if (ps->pn->error) { char *err = dupprintf("Proxy error: %s", ps->pn->error); sfree(ps->pn->error); proxy_negotiator_cleanup(ps); plug_closing_error(ps->plug, err); sfree(err); return; } else if (ps->pn->aborted) { proxy_negotiator_cleanup(ps); plug_closing_user_abort(ps->plug); return; } if (ps->pn->reconnect) { sk_close(ps->sub_socket); SockAddr *proxy_addr = sk_addr_dup(ps->proxy_addr); ps->sub_socket = sk_new(proxy_addr, ps->proxy_port, ps->proxy_privport, ps->proxy_oobinline, ps->proxy_nodelay, ps->proxy_keepalive, &ps->plugimpl); ps->pn->reconnect = false; /* If the negotiator has asked us to reconnect, they are * expecting that on the next call their input queue will * consist entirely of data from the _new_ connection, without * any remaining data buffered from the old one. (If they'd * wanted the latter, they could have read it out of the input * queue before asking us to close the connection.) */ bufchain_clear(&ps->pending_input_data); } while (bufchain_size(&ps->output_from_negotiator)) { ptrlen data = bufchain_prefix(&ps->output_from_negotiator); sk_write(ps->sub_socket, data.ptr, data.len); bufchain_consume(&ps->output_from_negotiator, data.len); } if (ps->pn->done) proxy_activate(ps); } static void plug_proxy_receive( Plug *p, int urgent, const char *data, size_t len) { ProxySocket *ps = container_of(p, ProxySocket, plugimpl); if (ps->pn) { /* 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); proxy_negotiate(ps); } 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->pn) return; plug_sent(ps->plug, bufsize); } static int plug_proxy_accepting(Plug *p, accept_fn_t constructor, accept_ctx_t ctx) { unreachable("ProxySockets never create listening Sockets"); } /* * 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 SocketEndpointInfo *sk_proxy_endpoint_info(Socket *s, bool peer) { ProxySocket *ps = container_of(s, ProxySocket, sock); /* We can't reliably find out where we ended up connecting _to_: * that's at the far end of the proxy, and might be anything. */ if (peer) return NULL; /* But we can at least tell where we're coming _from_. */ return sk_endpoint_info(ps->sub_socket, false); } 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, .endpoint_info = sk_proxy_endpoint_info, }; 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 }; static char *proxy_description(Interactor *itr) { ProxySocket *ps = container_of(itr, ProxySocket, interactor); assert(ps->pn); return dupprintf("%s connection to %s port %d", ps->pn->vt->type, conf_get_str(ps->conf, CONF_proxy_host), conf_get_int(ps->conf, CONF_proxy_port)); } static LogPolicy *proxy_logpolicy(Interactor *itr) { ProxySocket *ps = container_of(itr, ProxySocket, interactor); return ps->clientlp; } static Seat *proxy_get_seat(Interactor *itr) { ProxySocket *ps = container_of(itr, ProxySocket, interactor); return ps->clientseat; } static void proxy_set_seat(Interactor *itr, Seat *seat) { ProxySocket *ps = container_of(itr, ProxySocket, interactor); ps->clientseat = seat; } static const InteractorVtable ProxySocket_interactorvt = { .description = proxy_description, .logpolicy = proxy_logpolicy, .get_seat = proxy_get_seat, .set_seat = proxy_set_seat, }; static void proxy_prompts_callback(void *ctx) { proxy_negotiate((ProxySocket *)ctx); } prompts_t *proxy_new_prompts(ProxySocket *ps) { prompts_t *prs = new_prompts(); prs->callback = proxy_prompts_callback; prs->callback_ctx = ps; return prs; } void proxy_spr_abort(ProxyNegotiator *pn, SeatPromptResult spr) { if (spr.kind == SPRK_SW_ABORT) { pn->error = spr_get_error_message(spr); } else { assert(spr.kind == SPRK_USER_ABORT); pn->aborted = true; } } Socket *new_connection(SockAddr *addr, const char *hostname, int port, bool privport, bool oobinline, bool nodelay, bool keepalive, Plug *plug, Conf *conf, Interactor *itr) { int type = conf_get_int(conf, CONF_proxy_type); if (type != PROXY_NONE && proxy_for_destination(addr, hostname, port, conf)) { ProxySocket *ps; SockAddr *proxy_addr; char *proxy_canonical_name; Socket *sret; if ((type == PROXY_SSH_TCPIP || type == PROXY_SSH_EXEC || type == PROXY_SSH_SUBSYSTEM) && (sret = sshproxy_new_connection(addr, hostname, port, privport, oobinline, nodelay, keepalive, plug, conf, itr)) != NULL) return sret; if ((sret = platform_new_connection(addr, hostname, port, privport, oobinline, nodelay, keepalive, plug, conf, itr)) != NULL) return sret; ps = snew(ProxySocket); ps->sock.vt = &ProxySocket_sockvt; ps->plugimpl.vt = &ProxySocket_plugvt; ps->interactor.vt = &ProxySocket_interactorvt; ps->conf = conf_copy(conf); ps->plug = plug; ps->remote_addr = addr; /* will need to be freed on close */ ps->remote_port = port; ps->error = NULL; ps->pending_eof = false; ps->freeze = false; bufchain_init(&ps->pending_input_data); bufchain_init(&ps->pending_output_data); bufchain_init(&ps->pending_oob_output_data); bufchain_init(&ps->output_from_negotiator); ps->sub_socket = NULL; /* * If we've been given an Interactor by the caller, set ourselves * up to work with it. */ if (itr) { ps->clientitr = itr; interactor_set_child(ps->clientitr, &ps->interactor); ps->clientlp = interactor_logpolicy(ps->clientitr); ps->clientseat = interactor_borrow_seat(ps->clientitr); } const ProxyNegotiatorVT *vt; switch (type) { case PROXY_HTTP: vt = &http_proxy_negotiator_vt; break; case PROXY_SOCKS4: vt = &socks4_proxy_negotiator_vt; break; case PROXY_SOCKS5: vt = &socks5_proxy_negotiator_vt; break; case PROXY_TELNET: vt = &telnet_proxy_negotiator_vt; break; default: ps->error = "Proxy error: Unknown proxy method"; return &ps->sock; } ps->pn = proxy_negotiator_new(vt); ps->pn->ps = ps; ps->pn->done = false; ps->pn->error = NULL; ps->pn->aborted = false; ps->pn->input = &ps->pending_input_data; /* Provide an Interactor to the negotiator if and only if we * are usefully able to ask interactive questions of the user */ ps->pn->itr = ps->clientseat ? &ps->interactor : NULL; bufchain_sink_init(ps->pn->output, &ps->output_from_negotiator); { char *logmsg = dupprintf("Will use %s proxy at %s:%d to connect" " to %s:%d", vt->type, conf_get_str(conf, CONF_proxy_host), conf_get_int(conf, CONF_proxy_port), hostname, port); plug_log(plug, &ps->sock, 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, &ps->sock, 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) { ps->error = "Proxy error: Unable to resolve proxy host name"; sk_addr_free(proxy_addr); return &ps->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", vt->type, addrbuf, conf_get_int(conf, CONF_proxy_port)); plug_log(plug, &ps->sock, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0); sfree(logmsg); } /* create the actual socket we will be using, * connected to our proxy server and port. */ ps->proxy_addr = sk_addr_dup(proxy_addr); ps->proxy_port = conf_get_int(conf, CONF_proxy_port); ps->proxy_privport = privport; ps->proxy_oobinline = oobinline; ps->proxy_nodelay = nodelay; ps->proxy_keepalive = keepalive; ps->sub_socket = sk_new(proxy_addr, ps->proxy_port, ps->proxy_privport, ps->proxy_oobinline, ps->proxy_nodelay, ps->proxy_keepalive, &ps->plugimpl); if (sk_socket_error(ps->sub_socket) != NULL) return &ps->sock; /* start the proxy negotiation process... */ sk_set_frozen(ps->sub_socket, false); proxy_negotiate(ps); return &ps->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); }