+/*
+ proxy.c -- Proxy handling functions.
+ Copyright (C) 2015 Guus Sliepen <guus@tinc-vpn.org>
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along
+ with this program; if not, write to the Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "system.h"
+
+#include "connection.h"
+#include "logger.h"
+#include "meta.h"
+#include "netutl.h"
+#include "protocol.h"
+#include "proxy.h"
+#include "utils.h" //
+
+proxytype_t proxytype;
+char *proxyhost;
+char *proxyport;
+char *proxyuser;
+char *proxypass;
+
+static void update_address_ipv4(connection_t *c, void *address, void *port) {
+ sockaddrfree(&c->address);
+ memset(&c->address, 0, sizeof c->address);
+ c->address.sa.sa_family = AF_INET;
+ if(address)
+ memcpy(&c->address.in.sin_addr, address, sizeof(ipv4_t));
+ if(port)
+ memcpy(&c->address.in.sin_port, port, sizeof(uint16_t));
+ // OpenSSH -D returns all zero address, set it to 0.0.0.1 to prevent spamming ourselves.
+ if(!memcmp(&c->address.in.sin_addr, "\0\0\0\0", 4))
+ memcpy(&c->address.in.sin_addr, "\0\0\0\01", 4);
+}
+
+static void update_address_ipv6(connection_t *c, void *address, void *port) {
+ sockaddrfree(&c->address);
+ memset(&c->address, 0, sizeof c->address);
+ c->address.sa.sa_family = AF_INET6;
+ if(address)
+ memcpy(&c->address.in6.sin6_addr, address, sizeof(ipv6_t));
+ if(port)
+ memcpy(&c->address.in6.sin6_port, port, sizeof(uint16_t));
+ // OpenSSH -D returns all zero address, set it to 0100:: to prevent spamming ourselves.
+ if(!memcmp(&c->address.in6.sin6_addr, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16))
+ memcpy(&c->address.in6.sin6_addr, "\01\0\0\0\0\0\0\0", 8);
+}
+
+bool send_proxyrequest(connection_t *c) {
+ switch(proxytype) {
+ case PROXY_SOCKS4:
+ if(c->address.sa.sa_family != AF_INET) {
+ logger(LOG_ERR, "Can only connect to numeric IPv4 addresses through a SOCKS 4 proxy!");
+ return false;
+ }
+ case PROXY_SOCKS4A: {
+ if(c->address.sa.sa_family != AF_INET && c->address.sa.sa_family != AF_UNKNOWN) {
+ logger(LOG_ERR, "Can only connect to IPv4 addresses or hostnames through a SOCKS 4a proxy!");
+ return false;
+ }
+ int len = 9;
+ if(proxyuser)
+ len += strlen(proxyuser);
+ if(c->address.sa.sa_family == AF_UNKNOWN)
+ len += 1 + strlen(c->address.unknown.address);
+ char s4req[len];
+ s4req[0] = 4;
+ s4req[1] = 1;
+ if(c->address.sa.sa_family == AF_INET) {
+ memcpy(s4req + 2, &c->address.in.sin_port, 2);
+ memcpy(s4req + 4, &c->address.in.sin_addr, 4);
+ } else {
+ uint16_t port = htons(atoi(c->address.unknown.port));
+ memcpy(s4req + 2, &port, 2);
+ memcpy(s4req + 4, "\0\0\0\1", 4);
+ strcpy(s4req + (9 + (proxyuser ? strlen(proxyuser) : 0)), c->address.unknown.address);
+ }
+ if(proxyuser)
+ strcpy(s4req + 8, proxyuser);
+ else
+ s4req[8] = 0;
+ s4req[sizeof s4req - 1] = 0;
+ c->allow_request = PROXY;
+ return send_meta(c, s4req, sizeof s4req);
+ }
+
+ case PROXY_SOCKS5: {
+ int len = 3 + 6;
+ if(c->address.sa.sa_family == AF_INET) {
+ len += 4;
+ } else if(c->address.sa.sa_family == AF_INET6) {
+ len += 16;
+ } else if(c->address.sa.sa_family == AF_UNKNOWN) {
+ len += 1 + strlen(c->address.unknown.address);
+ } else {
+ logger(LOG_ERR, "Address family %x not supported for SOCKS 5 proxies!", c->address.sa.sa_family);
+ return false;
+ }
+ if(proxypass)
+ len += 3 + strlen(proxyuser) + strlen(proxypass);
+ char s5req[len];
+ int i = 0;
+ s5req[i++] = 5;
+ s5req[i++] = 1;
+ if(proxypass) {
+ s5req[i++] = 2;
+ s5req[i++] = 1;
+ s5req[i++] = strlen(proxyuser);
+ strcpy(s5req + i, proxyuser);
+ i += strlen(proxyuser);
+ s5req[i++] = strlen(proxypass);
+ strcpy(s5req + i, proxypass);
+ i += strlen(proxypass);
+ } else {
+ s5req[i++] = 0;
+ }
+ s5req[i++] = 5;
+ s5req[i++] = 1;
+ s5req[i++] = 0;
+ if(c->address.sa.sa_family == AF_INET) {
+ s5req[i++] = 1;
+ memcpy(s5req + i, &c->address.in.sin_addr, 4);
+ i += 4;
+ memcpy(s5req + i, &c->address.in.sin_port, 2);
+ i += 2;
+ } else if(c->address.sa.sa_family == AF_INET6) {
+ s5req[i++] = 4;
+ memcpy(s5req + i, &c->address.in6.sin6_addr, 16);
+ i += 16;
+ memcpy(s5req + i, &c->address.in6.sin6_port, 2);
+ i += 2;
+ } else if(c->address.sa.sa_family == AF_UNKNOWN) {
+ s5req[i++] = 3;
+ int len = strlen(c->address.unknown.address);
+ s5req[i++] = len;
+ memcpy(s5req + i, c->address.unknown.address, len);
+ i += len;
+ uint16_t port = htons(atoi(c->address.unknown.port));
+ memcpy(s5req + i, &port, 2);
+ i += 2;
+ } else {
+ logger(LOG_ERR, "Unknown address family while trying to connect to SOCKS5 proxy");
+ return false;
+ }
+ if(i > len)
+ abort();
+ c->allow_request = PROXY;
+ return send_meta(c, s5req, sizeof s5req);
+ }
+
+ case PROXY_HTTP: {
+ char *host;
+ char *port;
+
+ sockaddr2str(&c->address, &host, &port);
+ send_request(c, "CONNECT %s:%s HTTP/1.1\r\n\r", host, port);
+ free(host);
+ free(port);
+ c->allow_request = PROXY;
+ return true;
+ }
+
+ case PROXY_EXEC:
+ return true;
+
+ default:
+ logger(LOG_ERR, "Unknown proxy type");
+ return false;
+ }
+}
+
+int receive_proxy_meta(connection_t *c, int start, int lenin) {
+ switch(proxytype) {
+ case PROXY_SOCKS4:
+ case PROXY_SOCKS4A:
+ if(c->buflen < 8)
+ return 0;
+ if(c->buffer[0] == 0 && c->buffer[1] == 0x5a) {
+ if(c->address.sa.sa_family == AF_UNKNOWN)
+ update_address_ipv4(c, c->buffer + 4, c->buffer + 2);
+
+ ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
+ c->allow_request = ID;
+ return 8;
+ } else {
+ logger(LOG_ERR, "Proxy request rejected");
+ return -1;
+ }
+
+ case PROXY_SOCKS5:
+ if(c->buflen < 2)
+ return 0;
+ if(c->buffer[0] != 0x05 || c->buffer[1] == 0xff) {
+ logger(LOG_ERR, "Proxy authentication method rejected");
+ return -1;
+ }
+ int offset = 2;
+ if(c->buffer[1] == 0x02) {
+ if(c->buflen < 4)
+ return 0;
+ if(c->buffer[2] != 0x05 || c->buffer[3] != 0x00) {
+ logger(LOG_ERR, "Proxy username/password rejected");
+ return -1;
+ }
+ offset += 2;
+ }
+ if(c->buflen - offset < 7)
+ return 0;
+ if(c->buffer[offset] != 0x05 || c->buffer[offset + 1] != 0x00) {
+ logger(LOG_ERR, "Proxy request rejected");
+ return -1;
+ }
+ int replen = offset + 6;
+ switch(c->buffer[offset + 3]) {
+ case 0x01: // IPv4
+ if(c->address.sa.sa_family == AF_UNKNOWN)
+ update_address_ipv4(c, c->buffer + offset + 4, c->buffer + offset + 8);
+ replen += 4;
+ break;
+ case 0x03: // Hostname
+ if(c->address.sa.sa_family == AF_UNKNOWN)
+ update_address_ipv4(c, "\0\0\0\1", "\0\0");
+ replen += ((uint8_t *)c->buffer)[offset + 4];
+ break;
+ case 0x04: // IPv6
+ if(c->address.sa.sa_family == AF_UNKNOWN)
+ update_address_ipv6(c, c->buffer + offset + 4, c->buffer + offset + 20);
+ replen += 16;
+ break;
+ default:
+ logger(LOG_ERR, "Proxy reply malformed");
+ return -1;
+ }
+ if(c->buflen < replen) {
+ return 0;
+ } else {
+ ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Proxy request granted");
+ c->allow_request = ID;
+ return replen;
+ }
+
+ case PROXY_HTTP: {
+ char *p = memchr(c->buffer, '\n', c->buflen);
+ if(!p || p - c->buffer >= c->buflen)
+ return 0;
+ p = memchr(p + 1, '\n', c->buflen - (p + 1 - c->buffer));
+ if(!p)
+ return 0;
+
+ if(c->buflen < 9)
+ return 0;
+
+ if(!strncasecmp(c->buffer, "HTTP/1.1 ", 9)) {
+ if(!strncmp(c->buffer + 9, "200", 3)) {
+ if(c->address.sa.sa_family == AF_UNKNOWN)
+ update_address_ipv4(c, "\0\0\0\1", "\0\0");
+ logger(LOG_DEBUG, "Proxy request granted");
+ replen = p + 1 - c->buffer;
+ c->allow_request = ID;
+ return replen;
+ } else {
+ logger(LOG_ERR, "Proxy request rejected: %s", c->buffer + 9);
+ return false;
+ }
+ } else {
+ logger(LOG_ERR, "Proxy reply malformed");
+ return -1;
+ }
+ }
+
+ default:
+ abort();
+ }
+}
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