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Don't send IUTF8 to servers that don't like them.

Some SSH servers eg "ConfD" drop the connection if the client sends the
new IUTF8 (RFC8160) terminal mode even if it's not set.  Add a bug bit
for such servers and avoid sending IUTF8 to them.  ok djm@

/* $OpenBSD: compat.c,v 1.106 2018/02/16 04:43:11 dtucker Exp $ */
/*
 * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/types.h>

#include <stdlib.h>
#include <string.h>
#include <stdarg.h>

#include "xmalloc.h"
#include "buffer.h"
#include "packet.h"
#include "compat.h"
#include "log.h"
#include "match.h"
#include "kex.h"

int datafellows = 0;

/* datafellows bug compatibility */
u_int
compat_datafellows(const char *version)
{
	int i;
	static struct {
		char	*pat;
		int	bugs;
	} check[] = {
		{ "OpenSSH_2.*,"
		  "OpenSSH_3.0*,"
		  "OpenSSH_3.1*",	SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
		{ "OpenSSH_3.*",	SSH_OLD_FORWARD_ADDR },
		{ "Sun_SSH_1.0*",	SSH_BUG_NOREKEY|SSH_BUG_EXTEOF},
		{ "OpenSSH_2*,"
		  "OpenSSH_3*,"
		  "OpenSSH_4*",		0 },
		{ "OpenSSH_5*",		SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT},
		{ "OpenSSH_6.6.1*",	SSH_NEW_OPENSSH},
		{ "OpenSSH_6.5*,"
		  "OpenSSH_6.6*",	SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD},
		{ "OpenSSH*",		SSH_NEW_OPENSSH },
		{ "*MindTerm*",		0 },
		{ "3.0.*",		SSH_BUG_DEBUG },
		{ "3.0 SecureCRT*",	SSH_OLD_SESSIONID },
		{ "1.7 SecureFX*",	SSH_OLD_SESSIONID },
		{ "1.2.18*,"
		  "1.2.19*,"
		  "1.2.20*,"
		  "1.2.21*,"
		  "1.2.22*",		SSH_BUG_IGNOREMSG },
		{ "1.3.2*",		/* F-Secure */
					SSH_BUG_IGNOREMSG },
		{ "Cisco-1.*",		SSH_BUG_DHGEX_LARGE|
					SSH_BUG_HOSTKEYS },
		{ "*SSH Compatible Server*",			/* Netscreen */
					SSH_BUG_PASSWORDPAD },
		{ "*OSU_0*,"
		  "OSU_1.0*,"
		  "OSU_1.1*,"
		  "OSU_1.2*,"
		  "OSU_1.3*,"
		  "OSU_1.4*,"
		  "OSU_1.5alpha1*,"
		  "OSU_1.5alpha2*,"
		  "OSU_1.5alpha3*",	SSH_BUG_PASSWORDPAD },
		{ "*SSH_Version_Mapper*",
					SSH_BUG_SCANNER },
		{ "PuTTY_Local:*,"	/* dev versions < Sep 2014 */
		  "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
		  "PuTTY_Release_0.5*,"	/* 0.58-0.59 */
		  "PuTTY_Release_0.60*,"
		  "PuTTY_Release_0.61*,"
		  "PuTTY_Release_0.62*,"
		  "PuTTY_Release_0.63*,"
		  "PuTTY_Release_0.64*",
					SSH_OLD_DHGEX },
		{ "FuTTY*",		SSH_OLD_DHGEX }, /* Putty Fork */
		{ "Probe-*",
					SSH_BUG_PROBE },
		{ "TeraTerm SSH*,"
		  "TTSSH/1.5.*,"
		  "TTSSH/2.1*,"
		  "TTSSH/2.2*,"
		  "TTSSH/2.3*,"
		  "TTSSH/2.4*,"
		  "TTSSH/2.5*,"
		  "TTSSH/2.6*,"
		  "TTSSH/2.70*,"
		  "TTSSH/2.71*,"
		  "TTSSH/2.72*",	SSH_BUG_HOSTKEYS },
		{ "WinSCP_release_4*,"
		  "WinSCP_release_5.0*,"
		  "WinSCP_release_5.1,"
		  "WinSCP_release_5.1.*,"
		  "WinSCP_release_5.5,"
		  "WinSCP_release_5.5.*,"
		  "WinSCP_release_5.6,"
		  "WinSCP_release_5.6.*,"
		  "WinSCP_release_5.7,"
		  "WinSCP_release_5.7.1,"
		  "WinSCP_release_5.7.2,"
		  "WinSCP_release_5.7.3,"
		  "WinSCP_release_5.7.4",
					SSH_OLD_DHGEX },
		{ "ConfD-*",
					SSH_BUG_UTF8TTYMODE },
		{ NULL,			0 }
	};

	/* process table, return first match */
	for (i = 0; check[i].pat; i++) {
		if (match_pattern_list(version, check[i].pat, 0) == 1) {
			debug("match: %s pat %s compat 0x%08x",
			    version, check[i].pat, check[i].bugs);
			datafellows = check[i].bugs;	/* XXX for now */
			return check[i].bugs;
		}
	}
	debug("no match: %s", version);
	return 0;
}

#define	SEP	","
int
proto_spec(const char *spec)
{
	char *s, *p, *q;
	int ret = SSH_PROTO_UNKNOWN;

	if (spec == NULL)
		return ret;
	q = s = strdup(spec);
	if (s == NULL)
		return ret;
	for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) {
		switch (atoi(p)) {
		case 2:
			ret |= SSH_PROTO_2;
			break;
		default:
			logit("ignoring bad proto spec: '%s'.", p);
			break;
		}
	}
	free(s);
	return ret;
}

char *
compat_cipher_proposal(char *cipher_prop)
{
	if (!(datafellows & SSH_BUG_BIGENDIANAES))
		return cipher_prop;
	debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
	if ((cipher_prop = match_filter_list(cipher_prop, "aes*")) == NULL)
		fatal("match_filter_list failed");
	debug2("%s: compat cipher proposal: %s", __func__, cipher_prop);
	if (*cipher_prop == '\0')
		fatal("No supported ciphers found");
	return cipher_prop;
}

char *
compat_pkalg_proposal(char *pkalg_prop)
{
	if (!(datafellows & SSH_BUG_RSASIGMD5))
		return pkalg_prop;
	debug2("%s: original public key proposal: %s", __func__, pkalg_prop);
	if ((pkalg_prop = match_filter_list(pkalg_prop, "ssh-rsa")) == NULL)
		fatal("match_filter_list failed");
	debug2("%s: compat public key proposal: %s", __func__, pkalg_prop);
	if (*pkalg_prop == '\0')
		fatal("No supported PK algorithms found");
	return pkalg_prop;
}

char *
compat_kex_proposal(char *p)
{
	if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
		return p;
	debug2("%s: original KEX proposal: %s", __func__, p);
	if ((datafellows & SSH_BUG_CURVE25519PAD) != 0)
		if ((p = match_filter_list(p,
		    "curve25519-sha256@libssh.org")) == NULL)
			fatal("match_filter_list failed");
	if ((datafellows & SSH_OLD_DHGEX) != 0) {
		if ((p = match_filter_list(p,
		    "diffie-hellman-group-exchange-sha256,"
		    "diffie-hellman-group-exchange-sha1")) == NULL)
			fatal("match_filter_list failed");
	}
	debug2("%s: compat KEX proposal: %s", __func__, p);
	if (*p == '\0')
		fatal("No supported key exchange algorithms found");
	return p;
}