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- /*
- proxy.c -- Proxy handling functions.
- Copyright (C) 2015-2017 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;
- }
- // fallthrough
- 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:
- abort();
- default:
- logger(LOG_ERR, "Unknown proxy type");
- return false;
- }
- }
- int receive_proxy_meta(connection_t *c) {
- 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;
- c->status.proxy_passed = true;
- send_id(c);
- 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] == (char)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;
- c->status.proxy_passed = true;
- send_id(c);
- return replen;
- }
- case PROXY_HTTP: {
- char *p = memchr(c->buffer, '\n', c->buflen);
- if(!p || p - c->buffer >= c->buflen) {
- return 0;
- }
- while((p = memchr(p + 1, '\n', c->buflen - (p + 1 - c->buffer)))) {
- if(p > c->buffer + 3 && !memcmp(p - 3, "\r\n\r\n", 4)) {
- break;
- }
- }
- 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;
- c->status.proxy_passed = true;
- send_id(c);
- return replen;
- } else {
- p = memchr(c->buffer, '\n', c->buflen);
- p[-1] = 0;
- 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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