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-rw-r--r--nsock/src/proxy_socks4.c241
1 files changed, 241 insertions, 0 deletions
diff --git a/nsock/src/proxy_socks4.c b/nsock/src/proxy_socks4.c
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+++ b/nsock/src/proxy_socks4.c
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+/***************************************************************************
+ * proxy_socks4.c -- SOCKS4 proxying. *
+ * *
+ ***********************IMPORTANT NSOCK LICENSE TERMS***********************
+ *
+ * The nsock parallel socket event library is (C) 1999-2023 Nmap Software 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, Nmap Software LLC may be willing to sell alternative
+ * licenses (contact sales@nmap.com ).
+ *
+ * As a special exception to the GPL terms, Nmap Software 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 (Nmap Software 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 <stdio.h>
+
+#include "nsock.h"
+#include "nsock_internal.h"
+#include "nsock_log.h"
+
+#include <string.h>
+
+#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, AF_INET);
+ 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;
+
+ 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("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,
+};
+
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-11 19:45:03 +0000