/*************************************************************************** * proxy_socks4.c -- SOCKS4 proxying. * * * ***********************IMPORTANT NSOCK LICENSE TERMS*********************** * * * The nsock parallel socket event library is (C) 1999-2015 Insecure.Com * * LLC This library is free software; you may redistribute and/or * * modify it under the terms of the GNU General Public License as * * published by the Free Software Foundation; Version 2. This guarantees * * your right to use, modify, and redistribute this software under certain * * conditions. If this license is unacceptable to you, Insecure.Com LLC * * may be willing to sell alternative licenses (contact * * sales@insecure.com ). * * * * As a special exception to the GPL terms, Insecure.Com LLC grants * * permission to link the code of this program with any version of the * * OpenSSL library which is distributed under a license identical to that * * listed in the included docs/licenses/OpenSSL.txt file, and distribute * * linked combinations including the two. You must obey the GNU GPL in all * * respects for all of the code used other than OpenSSL. If you modify * * this file, you may extend this exception to your version of the file, * * but you are not obligated to do so. * * * * If you received these files with a written license agreement stating * * terms other than the (GPL) terms above, then that alternative license * * agreement takes precedence over this comment. * * * * Source is provided to this software because we believe users have a * * right to know exactly what a program is going to do before they run it. * * This also allows you to audit the software for security holes. * * * * Source code also allows you to port Nmap to new platforms, fix bugs, * * and add new features. You are highly encouraged to send your changes * * to the dev@nmap.org mailing list for possible incorporation into the * * main distribution. By sending these changes to Fyodor or one of the * * Insecure.Org development mailing lists, or checking them into the Nmap * * source code repository, it is understood (unless you specify otherwise) * * that you are offering the Nmap Project (Insecure.Com LLC) the * * unlimited, non-exclusive right to reuse, modify, and relicense the * * code. Nmap will always be available Open Source, but this is important * * because the inability to relicense code has caused devastating problems * * for other Free Software projects (such as KDE and NASM). We also * * occasionally relicense the code to third parties as discussed above. * * If you wish to specify special license conditions of your * * contributions, just say so when you send them. * * * * 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 v2.0 for more details * * (http://www.gnu.org/licenses/gpl-2.0.html). * * * ***************************************************************************/ /* $Id $ */ #define _GNU_SOURCE #include #include "nsock.h" #include "nsock_internal.h" #include "nsock_log.h" #include #define DEFAULT_PROXY_PORT_SOCKS4 1080 extern struct timeval nsock_tod; extern const struct proxy_spec ProxySpecSocks4; struct socks4_data { uint8_t version; uint8_t type; uint16_t port; uint32_t address; uint8_t null; } __attribute__((packed)); static int proxy_socks4_node_new(struct proxy_node **node, const struct uri *uri) { int rc; struct proxy_node *proxy; proxy = (struct proxy_node *)safe_zalloc(sizeof(struct proxy_node)); proxy->spec = &ProxySpecSocks4; rc = proxy_resolve(uri->host, (struct sockaddr *)&proxy->ss, &proxy->sslen); if (rc < 0) goto err_out; if (proxy->ss.ss_family != AF_INET) { rc = -1; goto err_out; } if (uri->port == -1) proxy->port = DEFAULT_PROXY_PORT_SOCKS4; else proxy->port = (unsigned short)uri->port; rc = asprintf(&proxy->nodestr, "socks4://%s:%d", uri->host, proxy->port); if (rc < 0) { /* asprintf() failed for some reason but this is not a disaster (yet). * Set nodestr to NULL and try to keep on going. */ proxy->nodestr = NULL; } rc = 1; err_out: if (rc < 0) { free(proxy); proxy = NULL; } *node = proxy; return rc; } static void proxy_socks4_node_delete(struct proxy_node *node) { if (!node) return; if (node->nodestr) free(node->nodestr); free(node); } static inline void socks4_data_init(struct socks4_data *socks4, struct sockaddr_storage *ss, size_t sslen, unsigned short port) { struct sockaddr_in *sin = (struct sockaddr_in *)ss; memset(socks4, 0x00, sizeof(struct socks4_data)); socks4->version = 4; socks4->type = 1; socks4->port = htons(port); assert(ss->ss_family == AF_INET); socks4->address = sin->sin_addr.s_addr; } static int handle_state_initial(struct npool *nsp, struct nevent *nse, void *udata) { struct proxy_chain_context *px_ctx = nse->iod->px_ctx; struct sockaddr_storage *ss; size_t sslen; unsigned short port; struct proxy_node *next; struct socks4_data socks4; int timeout; px_ctx->px_state = PROXY_STATE_SOCKS4_TCP_CONNECTED; next = proxy_ctx_node_next(px_ctx); if (next) { ss = &next->ss; sslen = next->sslen; port = next->port; } else { ss = &px_ctx->target_ss; sslen = px_ctx->target_sslen; port = px_ctx->target_port; } socks4_data_init(&socks4, ss, sslen, port); timeout = TIMEVAL_MSEC_SUBTRACT(nse->timeout, nsock_tod); nsock_write(nsp, (nsock_iod)nse->iod, nsock_proxy_ev_dispatch, timeout, udata, (char *)&socks4, sizeof(socks4)); nsock_readbytes(nsp, (nsock_iod)nse->iod, nsock_proxy_ev_dispatch, timeout, udata, 8); return 0; } static int handle_state_tcp_connected(struct npool *nsp, struct nevent *nse, void *udata) { struct proxy_chain_context *px_ctx = nse->iod->px_ctx; char *res; int reslen; res = nse_readbuf(nse, &reslen); if (!(reslen == 8 && res[1] == 90)) { struct proxy_node *node = px_ctx->px_current; nsock_log_debug(nsp, "Ignoring invalid socks4 reply from proxy %s", node->nodestr); return -EINVAL; } px_ctx->px_state = PROXY_STATE_SOCKS4_TUNNEL_ESTABLISHED; if (proxy_ctx_node_next(px_ctx) == NULL) { forward_event(nsp, nse, udata); } else { px_ctx->px_current = proxy_ctx_node_next(px_ctx); px_ctx->px_state = PROXY_STATE_INITIAL; nsock_proxy_ev_dispatch(nsp, nse, udata); } return 0; } static void proxy_socks4_handler(nsock_pool nspool, nsock_event nsevent, void *udata) { int rc = 0; struct npool *nsp = (struct npool *)nspool; struct nevent *nse = (struct nevent *)nsevent; switch (nse->iod->px_ctx->px_state) { case PROXY_STATE_INITIAL: rc = handle_state_initial(nsp, nse, udata); break; case PROXY_STATE_SOCKS4_TCP_CONNECTED: if (nse->type == NSE_TYPE_READ) rc = handle_state_tcp_connected(nsp, nse, udata); break; case PROXY_STATE_SOCKS4_TUNNEL_ESTABLISHED: forward_event(nsp, nse, udata); break; default: fatal("Invalid proxy state!"); } if (rc) { nse->status = NSE_STATUS_PROXYERROR; forward_event(nsp, nse, udata); } } /* ---- PROXY DEFINITION ---- */ static const struct proxy_op ProxyOpsSocks4 = { proxy_socks4_node_new, proxy_socks4_node_delete, proxy_socks4_handler, }; const struct proxy_spec ProxySpecSocks4 = { "socks4://", PROXY_TYPE_SOCKS4, &ProxyOpsSocks4, };