2 * Dropbear - a SSH2 server
4 * Copyright (c) 2002-2004 Matt Johnston
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
38 #define MAX_UNAUTH_PACKET_TYPE SSH_MSG_USERAUTH_PK_OK
40 static void recv_unimplemented(void);
42 /* process a decrypted packet, call the appropriate handler */
43 void process_packet() {
49 TRACE2(("enter process_packet"))
51 type
= buf_getbyte(ses
.payload
);
52 TRACE(("process_packet: packet type = %d, len %d", type
, ses
.payload
->len
))
54 ses
.lastpacket
= type
;
56 now
= monotonic_now();
57 ses
.last_packet_time_keepalive_recv
= now
;
59 /* These packets we can receive at any time */
67 case SSH_MSG_UNIMPLEMENTED
:
69 TRACE(("SSH_MSG_UNIMPLEMENTED"))
72 case SSH_MSG_DISCONNECT
:
74 dropbear_close("Disconnect received");
77 /* Ignore these packet types so that keepalives don't interfere with
78 idle detection. This is slightly incorrect since a tcp forwarded
79 global request with failure won't trigger the idle timeout,
80 but that's probably acceptable */
81 if (!(type
== SSH_MSG_GLOBAL_REQUEST
|| type
== SSH_MSG_REQUEST_FAILURE
)) {
82 ses
.last_packet_time_idle
= now
;
85 /* This applies for KEX, where the spec says the next packet MUST be
87 if (ses
.requirenext
!= 0) {
88 if (ses
.requirenext
== type
)
90 /* Got what we expected */
91 TRACE(("got expected packet %d during kexinit", type
))
95 /* RFC4253 7.1 - various messages are allowed at this point.
96 The only ones we know about have already been handled though,
97 so just return "unimplemented" */
98 if (type
>= 1 && type
<= 49
99 && type
!= SSH_MSG_SERVICE_REQUEST
100 && type
!= SSH_MSG_SERVICE_ACCEPT
101 && type
!= SSH_MSG_KEXINIT
)
103 TRACE(("unknown allowed packet during kexinit"))
104 recv_unimplemented();
109 TRACE(("disallowed packet during kexinit"))
110 dropbear_exit("Unexpected packet type %d, expected %d", type
,
116 /* Check if we should ignore this packet. Used currently only for
117 * KEX code, with first_kex_packet_follows */
118 if (ses
.ignorenext
) {
119 TRACE(("Ignoring packet, type = %d", type
))
124 /* Only clear the flag after we have checked ignorenext */
125 if (ses
.requirenext
!= 0 && ses
.requirenext
== type
)
131 /* Kindly the protocol authors gave all the preauth packets type values
132 * less-than-or-equal-to 60 ( == MAX_UNAUTH_PACKET_TYPE ).
133 * NOTE: if the protocol changes and new types are added, revisit this
135 if ( !ses
.authstate
.authdone
&& type
> MAX_UNAUTH_PACKET_TYPE
) {
136 dropbear_exit("Received message %d before userauth", type
);
140 if (ses
.packettypes
[i
].type
== 0) {
145 if (ses
.packettypes
[i
].type
== type
) {
146 ses
.packettypes
[i
].handler();
152 /* TODO do something more here? */
153 TRACE(("preauth unknown packet"))
154 recv_unimplemented();
157 buf_free(ses
.payload
);
160 TRACE2(("leave process_packet"))
165 /* This must be called directly after receiving the unimplemented packet.
166 * Isn't the most clean implementation, it relies on packet processing
167 * occurring directly after decryption (direct use of ses.recvseq).
168 * This is reasonably valid, since there is only a single decryption buffer */
169 static void recv_unimplemented() {
173 buf_putbyte(ses
.writepayload
, SSH_MSG_UNIMPLEMENTED
);
174 /* the decryption routine increments the sequence number, we must
176 buf_putint(ses
.writepayload
, ses
.recvseq
- 1);