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Probable support for first_kex_packet_follows in KEXINIT. Not significantly

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tested since none of the common key-exchange protocols starts with a packet
from the server, so I don't have a server that implements this.

[originally from svn r5162]
This commit is contained in:
Ben Harris 2005-01-22 13:32:41 +00:00
parent c29e61381a
commit 5140b67435
1 changed files with 36 additions and 1 deletions
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37
ssh.c
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@ -4652,6 +4652,28 @@ static int in_commasep_string(char *needle, char *haystack, int haylen)
} }
} }
/*
* Similar routine for checking whether we have the first string in a list.
*/
static int first_in_commasep_string(char *needle, char *haystack, int haylen)
{
int needlen;
if (!needle || !haystack) /* protect against null pointers */
return 0;
needlen = strlen(needle);
/*
* Is it at the start of the string?
*/
if (haylen >= needlen && /* haystack is long enough */
!memcmp(needle, haystack, needlen) && /* initial match */
(haylen == needlen || haystack[needlen] == ',')
/* either , or EOS follows */
)
return 1;
return 0;
}
/* /*
* SSH2 key creation method. * SSH2 key creation method.
*/ */
@ -4920,7 +4942,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
*/ */
{ {
char *str; char *str;
int i, j, len; int i, j, len, guessok;
if (pktin->type != SSH2_MSG_KEXINIT) { if (pktin->type != SSH2_MSG_KEXINIT) {
bombout(("expected key exchange packet from server")); bombout(("expected key exchange packet from server"));
@ -4959,6 +4981,13 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
str ? str : "(null)")); str ? str : "(null)"));
crStop(0); crStop(0);
} }
/*
* Note that the server's guess is considered wrong if it doesn't match
* the first algorithm in our list, even if it's still the algorithm
* we end up using.
*/
guessok =
first_in_commasep_string(s->preferred_kex[0]->name, str, len);
ssh_pkt_getstring(pktin, &str, &len); /* host key algorithms */ ssh_pkt_getstring(pktin, &str, &len); /* host key algorithms */
for (i = 0; i < lenof(hostkey_algs); i++) { for (i = 0; i < lenof(hostkey_algs); i++) {
if (in_commasep_string(hostkey_algs[i]->name, str, len)) { if (in_commasep_string(hostkey_algs[i]->name, str, len)) {
@ -4966,6 +4995,8 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
break; break;
} }
} }
guessok = guessok &&
first_in_commasep_string(hostkey_algs[0]->name, str, len);
ssh_pkt_getstring(pktin, &str, &len); /* client->server cipher */ ssh_pkt_getstring(pktin, &str, &len); /* client->server cipher */
s->warn = 0; s->warn = 0;
for (i = 0; i < s->n_preferred_ciphers; i++) { for (i = 0; i < s->n_preferred_ciphers; i++) {
@ -5058,6 +5089,10 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
break; break;
} }
} }
ssh_pkt_getstring(pktin, &str, &len); /* client->server language */
ssh_pkt_getstring(pktin, &str, &len); /* server->client language */
if (ssh2_pkt_getbool(pktin) && !guessok) /* first_kex_packet_follows */
crWaitUntil(pktin); /* Ignore packet */
} }
/* /*