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-rw-r--r--socks.c411
1 files changed, 411 insertions, 0 deletions
diff --git a/socks.c b/socks.c
new file mode 100644
index 0000000..22bdfa4
--- /dev/null
+++ b/socks.c
@@ -0,0 +1,411 @@
+/*
+ * OpenVPN -- An application to securely tunnel IP networks
+ * over a single TCP/UDP port, with support for SSL/TLS-based
+ * session authentication and key exchange,
+ * packet encryption, packet authentication, and
+ * packet compression.
+ *
+ * Copyright (C) 2002-2005 OpenVPN Solutions LLC <info@openvpn.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * 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 (see the file COPYING included with this
+ * distribution); if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+/*
+ * 2004-01-30: Added Socks5 proxy support
+ * (Christof Meerwald, http://cmeerw.org)
+ *
+ * see RFC 1928, only supports "no authentication"
+ */
+
+#ifdef WIN32
+#include "config-win32.h"
+#else
+#include "config.h"
+#endif
+
+#ifdef ENABLE_SOCKS
+
+#include "syshead.h"
+
+#include "common.h"
+#include "misc.h"
+#include "win32.h"
+#include "socket.h"
+#include "fdmisc.h"
+#include "proxy.h"
+
+#include "memdbg.h"
+
+
+void
+socks_adjust_frame_parameters (struct frame *frame, int proto)
+{
+ if (proto == PROTO_UDPv4)
+ frame_add_to_extra_link (frame, 10);
+}
+
+struct socks_proxy_info *
+new_socks_proxy (const char *server,
+ int port,
+ bool retry,
+ struct gc_arena *gc)
+{
+ struct socks_proxy_info *p;
+ ALLOC_OBJ_CLEAR_GC (p, struct socks_proxy_info, gc);
+ ASSERT (server);
+ ASSERT (legal_ipv4_port (port));
+
+ strncpynt (p->server, server, sizeof (p->server));
+ p->port = port;
+ p->retry = retry;
+ p->defined = true;
+
+ return p;
+}
+
+static bool
+socks_handshake (socket_descriptor_t sd, volatile int *signal_received)
+{
+ char buf[2];
+ int len = 0;
+ const int timeout_sec = 5;
+
+ /* VER = 5, NMETHODS = 1, METHODS = [0] */
+ const ssize_t size = send (sd, "\x05\x01\x00", 3, MSG_NOSIGNAL);
+ if (size != 3)
+ {
+ msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_handshake: TCP port write failed on send()");
+ return false;
+ }
+
+ while (len < 2)
+ {
+ int status;
+ ssize_t size;
+ fd_set reads;
+ struct timeval tv;
+ char c;
+
+ FD_ZERO (&reads);
+ FD_SET (sd, &reads);
+ tv.tv_sec = timeout_sec;
+ tv.tv_usec = 0;
+
+ status = select (sd + 1, &reads, NULL, NULL, &tv);
+
+ get_signal (signal_received);
+ if (*signal_received)
+ return false;
+
+ /* timeout? */
+ if (status == 0)
+ {
+ msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_handshake: TCP port read timeout expired");
+ return false;
+ }
+
+ /* error */
+ if (status < 0)
+ {
+ msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_handshake: TCP port read failed on select()");
+ return false;
+ }
+
+ /* read single char */
+ size = recv(sd, &c, 1, MSG_NOSIGNAL);
+
+ /* error? */
+ if (size != 1)
+ {
+ msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_handshake: TCP port read failed on recv()");
+ return false;
+ }
+
+ /* store char in buffer */
+ buf[len++] = c;
+ }
+
+ /* VER == 5 && METHOD == 0 */
+ if (buf[0] != '\x05' || buf[1] != '\x00')
+ {
+ msg (D_LINK_ERRORS, "socks_handshake: Socks proxy returned bad status");
+ return false;
+ }
+
+ return true;
+}
+
+static bool
+recv_socks_reply (socket_descriptor_t sd, struct sockaddr_in *addr,
+ volatile int *signal_received)
+{
+ char atyp = '\0';
+ int alen = 0;
+ int len = 0;
+ char buf[22];
+ const int timeout_sec = 5;
+
+ if (addr != NULL)
+ {
+ addr->sin_family = AF_INET;
+ addr->sin_addr.s_addr = htonl (INADDR_ANY);
+ addr->sin_port = htons (0);
+ }
+
+ while (len < 4 + alen + 2)
+ {
+ int status;
+ ssize_t size;
+ fd_set reads;
+ struct timeval tv;
+ char c;
+
+ FD_ZERO (&reads);
+ FD_SET (sd, &reads);
+ tv.tv_sec = timeout_sec;
+ tv.tv_usec = 0;
+
+ status = select (sd + 1, &reads, NULL, NULL, &tv);
+
+ get_signal (signal_received);
+ if (*signal_received)
+ return false;
+
+ /* timeout? */
+ if (status == 0)
+ {
+ msg (D_LINK_ERRORS | M_ERRNO_SOCK, "recv_socks_reply: TCP port read timeout expired");
+ return false;
+ }
+
+ /* error */
+ if (status < 0)
+ {
+ msg (D_LINK_ERRORS | M_ERRNO_SOCK, "recv_socks_reply: TCP port read failed on select()");
+ return false;
+ }
+
+ /* read single char */
+ size = recv(sd, &c, 1, MSG_NOSIGNAL);
+
+ /* error? */
+ if (size != 1)
+ {
+ msg (D_LINK_ERRORS | M_ERRNO_SOCK, "recv_socks_reply: TCP port read failed on recv()");
+ return false;
+ }
+
+ if (len == 3)
+ atyp = c;
+
+ if (len == 4)
+ {
+ switch (atyp)
+ {
+ case '\x01': /* IP V4 */
+ alen = 4;
+ break;
+
+ case '\x03': /* DOMAINNAME */
+ alen = (unsigned char) c;
+ break;
+
+ case '\x04': /* IP V6 */
+ alen = 16;
+ break;
+
+ default:
+ msg (D_LINK_ERRORS, "recv_socks_reply: Socks proxy returned bad address type");
+ return false;
+ }
+ }
+
+ /* store char in buffer */
+ if (len < (int)sizeof(buf))
+ buf[len] = c;
+ ++len;
+ }
+
+ /* VER == 5 && REP == 0 (succeeded) */
+ if (buf[0] != '\x05' || buf[1] != '\x00')
+ {
+ msg (D_LINK_ERRORS, "recv_socks_reply: Socks proxy returned bad reply");
+ return false;
+ }
+
+ /* ATYP == 1 (IP V4 address) */
+ if (atyp == '\x01' && addr != NULL)
+ {
+ memcpy (&addr->sin_addr, buf + 4, sizeof (addr->sin_addr));
+ memcpy (&addr->sin_port, buf + 8, sizeof (addr->sin_port));
+ }
+
+
+ return true;
+}
+
+void
+establish_socks_proxy_passthru (struct socks_proxy_info *p,
+ socket_descriptor_t sd, /* already open to proxy */
+ const char *host, /* openvpn server remote */
+ const int port, /* openvpn server port */
+ volatile int *signal_received)
+{
+ char buf[128];
+ size_t len;
+
+ if (!socks_handshake (sd, signal_received))
+ goto error;
+
+ /* format Socks CONNECT message */
+ buf[0] = '\x05'; /* VER = 5 */
+ buf[1] = '\x01'; /* CMD = 1 (CONNECT) */
+ buf[2] = '\x00'; /* RSV */
+ buf[3] = '\x03'; /* ATYP = 3 (DOMAINNAME) */
+
+ len = strlen(host);
+ len = (5 + len + 2 > sizeof(buf)) ? (sizeof(buf) - 5 - 2) : len;
+
+ buf[4] = (char) len;
+ memcpy(buf + 5, host, len);
+
+ buf[5 + len] = (char) (port >> 8);
+ buf[5 + len + 1] = (char) (port & 0xff);
+
+ {
+ const ssize_t size = send (sd, buf, 5 + len + 2, MSG_NOSIGNAL);
+ if ((int)size != 5 + (int)len + 2)
+ {
+ msg (D_LINK_ERRORS | M_ERRNO_SOCK, "establish_socks_proxy_passthru: TCP port write failed on send()");
+ goto error;
+ }
+ }
+
+ /* receive reply from Socks proxy and discard */
+ if (!recv_socks_reply (sd, NULL, signal_received))
+ goto error;
+
+ return;
+
+ error:
+ /* on error, should we exit or restart? */
+ if (!*signal_received)
+ *signal_received = (p->retry ? SIGUSR1 : SIGTERM); /* SOFT-SIGUSR1 -- socks error */
+ return;
+}
+
+void
+establish_socks_proxy_udpassoc (struct socks_proxy_info *p,
+ socket_descriptor_t ctrl_sd, /* already open to proxy */
+ socket_descriptor_t udp_sd,
+ struct sockaddr_in *relay_addr,
+ volatile int *signal_received)
+{
+ if (!socks_handshake (ctrl_sd, signal_received))
+ goto error;
+
+ {
+ /* send Socks UDP ASSOCIATE message */
+ /* VER = 5, CMD = 3 (UDP ASSOCIATE), RSV = 0, ATYP = 1 (IP V4),
+ BND.ADDR = 0, BND.PORT = 0 */
+ const ssize_t size = send (ctrl_sd,
+ "\x05\x03\x00\x01\x00\x00\x00\x00\x00\x00",
+ 10, MSG_NOSIGNAL);
+ if (size != 10)
+ {
+ msg (D_LINK_ERRORS | M_ERRNO_SOCK, "establish_socks_proxy_passthru: TCP port write failed on send()");
+ goto error;
+ }
+ }
+
+ /* receive reply from Socks proxy */
+ CLEAR (*relay_addr);
+ if (!recv_socks_reply (ctrl_sd, relay_addr, signal_received))
+ goto error;
+
+ return;
+
+ error:
+ /* on error, should we exit or restart? */
+ if (!*signal_received)
+ *signal_received = (p->retry ? SIGUSR1 : SIGTERM); /* SOFT-SIGUSR1 -- socks error */
+ return;
+}
+
+/*
+ * Remove the 10 byte socks5 header from an incoming
+ * UDP packet, setting *from to the source address.
+ *
+ * Run after UDP read.
+ */
+void
+socks_process_incoming_udp (struct buffer *buf,
+ struct sockaddr_in *from)
+{
+ int atyp;
+
+ if (BLEN (buf) < 10)
+ goto error;
+
+ buf_read_u16 (buf);
+ if (buf_read_u8 (buf) != 0)
+ goto error;
+
+ atyp = buf_read_u8 (buf);
+ if (atyp != 1) /* ATYP == 1 (IP V4) */
+ goto error;
+
+ buf_read (buf, &from->sin_addr, sizeof (from->sin_addr));
+ buf_read (buf, &from->sin_port, sizeof (from->sin_port));
+
+ return;
+
+ error:
+ buf->len = 0;
+}
+
+/*
+ * Add a 10 byte socks header prior to UDP write.
+ * *to is the destination address.
+ *
+ * Run before UDP write.
+ * Returns the size of the header.
+ */
+int
+socks_process_outgoing_udp (struct buffer *buf,
+ struct sockaddr_in *to)
+{
+ /*
+ * Get a 10 byte subset buffer prepended to buf --
+ * we expect these bytes will be here because
+ * we allocated frame space in socks_adjust_frame_parameters.
+ */
+ struct buffer head = buf_sub (buf, 10, true);
+
+ /* crash if not enough headroom in buf */
+ ASSERT (buf_defined (&head));
+
+ buf_write_u16 (&head, 0); /* RSV = 0 */
+ buf_write_u8 (&head, 0); /* FRAG = 0 */
+ buf_write_u8 (&head, '\x01'); /* ATYP = 1 (IP V4) */
+ buf_write (&head, &to->sin_addr, sizeof (to->sin_addr));
+ buf_write (&head, &to->sin_port, sizeof (to->sin_port));
+
+ return 10;
+}
+
+#else
+static void dummy(void) {}
+#endif /* ENABLE_SOCKS */
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