Mercurial > dropbear

comparison process-packet.c @ 285:1b9e69c058d2

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propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3) to branch 'au.asn.ucc.matt.dropbear' (head fdf4a7a3b97ae5046139915de7e40399cceb2c01)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:58 +0000
parents 0cfba3034be5
children 695413c59b6a
comparison
equal deleted inserted replaced
281:997e6f7dc01e 285:1b9e69c058d2
1 /*
2 * Dropbear - a SSH2 server
3 *
4 * Copyright (c) 2002-2004 Matt Johnston
5 * All rights reserved.
6 *
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:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
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
23 * SOFTWARE. */
24
25 #include "includes.h"
26 #include "packet.h"
27 #include "session.h"
28 #include "dbutil.h"
29 #include "ssh.h"
30 #include "algo.h"
31 #include "buffer.h"
32 #include "kex.h"
33 #include "random.h"
34 #include "service.h"
35 #include "auth.h"
36 #include "channel.h"
37
38 #define MAX_UNAUTH_PACKET_TYPE SSH_MSG_USERAUTH_PK_OK
39
40 static void recv_unimplemented();
41
42 /* process a decrypted packet, call the appropriate handler */
43 void process_packet() {
44
45 unsigned char type;
46 unsigned int i;
47
48 TRACE(("enter process_packet"))
49
50 type = buf_getbyte(ses.payload);
51 TRACE(("process_packet: packet type = %d", type))
52
53 ses.lastpacket = type;
54
55 /* These packets we can receive at any time */
56 switch(type) {
57
58 case SSH_MSG_IGNORE:
59 case SSH_MSG_DEBUG:
60 TRACE(("received SSH_MSG_IGNORE or SSH_MSG_DEBUG"))
61 goto out;
62
63 case SSH_MSG_UNIMPLEMENTED:
64 /* debugging XXX */
65 TRACE(("SSH_MSG_UNIMPLEMENTED"))
66 dropbear_exit("received SSH_MSG_UNIMPLEMENTED");
67
68 case SSH_MSG_DISCONNECT:
69 /* TODO cleanup? */
70 dropbear_close("Disconnect received");
71 }
72
73
74 /* This applies for KEX, where the spec says the next packet MUST be
75 * NEWKEYS */
76 if (ses.requirenext != 0) {
77 if (ses.requirenext != type) {
78 /* TODO send disconnect? */
79 dropbear_exit("unexpected packet type %d, expected %d", type,
80 ses.requirenext);
81 } else {
82 /* Got what we expected */
83 ses.requirenext = 0;
84 }
85 }
86
87 /* Check if we should ignore this packet. Used currently only for
88 * KEX code, with first_kex_packet_follows */
89 if (ses.ignorenext) {
90 TRACE(("Ignoring packet, type = %d", type))
91 ses.ignorenext = 0;
92 goto out;
93 }
94
95
96 /* Kindly the protocol authors gave all the preauth packets type values
97 * less-than-or-equal-to 60 ( == MAX_UNAUTH_PACKET_TYPE ).
98 * NOTE: if the protocol changes and new types are added, revisit this
99 * assumption */
100 if ( !ses.authstate.authdone && type > MAX_UNAUTH_PACKET_TYPE ) {
101 dropbear_exit("received message %d before userauth", type);
102 }
103
104 for (i = 0; ; i++) {
105 if (ses.packettypes[i].type == 0) {
106 /* end of list */
107 break;
108 }
109
110 if (ses.packettypes[i].type == type) {
111 ses.packettypes[i].handler();
112 goto out;
113 }
114 }
115
116
117 /* TODO do something more here? */
118 TRACE(("preauth unknown packet"))
119 recv_unimplemented();
120
121 out:
122 buf_burn(ses.payload); /* Clear the memory to avoid swapping it out */
123 buf_free(ses.payload);
124 ses.payload = NULL;
125
126 TRACE(("leave process_packet"))
127 }
128
129
130
131 /* This must be called directly after receiving the unimplemented packet.
132 * Isn't the most clean implementation, it relies on packet processing
133 * occurring directly after decryption (direct use of ses.recvseq).
134 * This is reasonably valid, since there is only a single decryption buffer */
135 static void recv_unimplemented() {
136
137 CHECKCLEARTOWRITE();
138
139 buf_putbyte(ses.writepayload, SSH_MSG_UNIMPLEMENTED);
140 /* the decryption routine increments the sequence number, we must
141 * decrement */
142 buf_putint(ses.writepayload, ses.recvseq - 1);
143
144 encrypt_packet();
145 }