Respond with 'Command not supported' SOCKS5 reply message upon reception of unsupported request.

This commit is contained in:
rl1987 2014-09-21 19:17:44 +03:00 committed by Nick Mathewson
parent e170205cd8
commit c5ad890904
3 changed files with 39 additions and 4 deletions

5
changes/bug12971 Normal file
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@ -0,0 +1,5 @@
o Bugfixes:
- Handle unsupported SOCKS5 requests properly by responding with
'Command not supported' reply message before closing a TCP connection
to the user. Fixes bug 12971.

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@ -55,6 +55,9 @@
* forever.
*/
static void send_socks5_error(socks_request_t *req,
socks5_reply_status_t reason);
static int parse_socks(const char *data, size_t datalen, socks_request_t *req,
int log_sockstype, int safe_socks, ssize_t *drain_out,
size_t *want_length_out);
@ -1831,6 +1834,21 @@ fetch_ext_or_command_from_evbuffer(struct evbuffer *buf, ext_or_cmd_t **out)
}
#endif
/** Create a SOCKS5 reply message with <b>reason</b> in its REP field and
* have Tor send it as error response to <b>req</b>.
*/
static void
send_socks5_error(socks_request_t *req,
socks5_reply_status_t reason)
{
req->replylen = 10;
memset(req->reply,0,10);
req->reply[0] = 0x05; // VER field.
req->reply[1] = reason; // REP field.
req->reply[3] = 0x01; // ATYP field.
}
/** Implementation helper to implement fetch_from_*_socks. Instead of looking
* at a buffer's contents, we look at the <b>datalen</b> bytes of data in
* <b>data</b>. Instead of removing data from the buffer, we set
@ -1966,6 +1984,8 @@ parse_socks(const char *data, size_t datalen, socks_request_t *req,
req->command != SOCKS_COMMAND_RESOLVE &&
req->command != SOCKS_COMMAND_RESOLVE_PTR) {
/* not a connect or resolve or a resolve_ptr? we don't support it. */
send_socks5_error(req,SOCKS5_COMMAND_NOT_SUPPORTED);
log_warn(LD_APP,"socks5: command %d not recognized. Rejecting.",
req->command);
return -1;

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@ -143,23 +143,33 @@ test_socks_5_unsupported_commands(void *ptr)
ADD_DATA(buf, "\x05\x02\x00\x01\x02\x02\x02\x01\x01\x01");
tt_int_op(fetch_from_buf_socks(buf, socks, get_options()->TestSocks,
get_options()->SafeSocks),==, -1);
/* XXX: shouldn't tor reply 'command not supported' [07]? */
tt_int_op(5,==,socks->socks_version);
tt_int_op(10,==,socks->replylen);
tt_int_op(5,==,socks->reply[0]);
tt_int_op(SOCKS5_COMMAND_NOT_SUPPORTED,==,socks->reply[1]);
tt_int_op(1,==,socks->reply[3]);
buf_clear(buf);
socks_request_clear(socks);
/* SOCKS 5 Send unsupported UDP_ASSOCIATE [03] command */
ADD_DATA(buf, "\x05\x03\x00\x01\x02");
ADD_DATA(buf, "\x05\x02\x00\x01");
tt_int_op(fetch_from_buf_socks(buf, socks, get_options()->TestSocks,
get_options()->SafeSocks),==, 0);
tt_int_op(5,==, socks->socks_version);
tt_int_op(2,==, socks->replylen);
tt_int_op(5,==, socks->reply[0]);
tt_int_op(2,==, socks->reply[1]);
tt_int_op(0,==, socks->reply[1]);
ADD_DATA(buf, "\x05\x03\x00\x01\x02\x02\x02\x01\x01\x01");
tt_int_op(fetch_from_buf_socks(buf, socks, get_options()->TestSocks,
get_options()->SafeSocks),==, -1);
/* XXX: shouldn't tor reply 'command not supported' [07]? */
tt_int_op(5,==,socks->socks_version);
tt_int_op(10,==,socks->replylen);
tt_int_op(5,==,socks->reply[0]);
tt_int_op(SOCKS5_COMMAND_NOT_SUPPORTED,==,socks->reply[1]);
tt_int_op(1,==,socks->reply[3]);
done:
;