text: /* $OpenBSD: compat.c,v 1.113 2018/08/13 02:41:05 djm 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 "includes.h"
  
  #include <sys/types.h>
  
  #include <stdlib.h>
  #include <string.h>
  #include <stdarg.h>
  
  #include "xmalloc.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|
  					SSH_BUG_SIGTYPE},
  		{ "OpenSSH_3.*",	SSH_OLD_FORWARD_ADDR|SSH_BUG_SIGTYPE },
  		{ "Sun_SSH_1.0*",	SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
  					SSH_BUG_SIGTYPE},
  		{ "OpenSSH_2*,"
  		  "OpenSSH_3*,"
  		  "OpenSSH_4*",		SSH_BUG_SIGTYPE },
  		{ "OpenSSH_5*",		SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT|
  					SSH_BUG_SIGTYPE},
  		{ "OpenSSH_6.6.1*",	SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
  		{ "OpenSSH_6.5*,"
  		  "OpenSSH_6.6*",	SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD|
  					SSH_BUG_SIGTYPE},
  		{ "OpenSSH_7.0*,"
  		  "OpenSSH_7.1*,"
  		  "OpenSSH_7.2*,"
  		  "OpenSSH_7.3*,"
  		  "OpenSSH_7.4*,"
  		  "OpenSSH_7.5*,"
  		  "OpenSSH_7.6*,"
  		  "OpenSSH_7.7*",	SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
  		{ "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 },
  		{ "Twisted_*",		0 },
  		{ "Twisted*",		SSH_BUG_DEBUG },
  		{ 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_blacklist(cipher_prop, "aes*")) == NULL)
  		fatal("match_filter_blacklist 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_blacklist(pkalg_prop, "ssh-rsa")) == NULL)
  		fatal("match_filter_blacklist 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_blacklist(p,
  		    "curve25519-sha256@libssh.org")) == NULL)
  			fatal("match_filter_blacklist failed");
  	if ((datafellows & SSH_OLD_DHGEX) != 0) {
  		if ((p = match_filter_blacklist(p,
  		    "diffie-hellman-group-exchange-sha256,"
  		    "diffie-hellman-group-exchange-sha1")) == NULL)
  			fatal("match_filter_blacklist failed");
  	}
  	debug2("%s: compat KEX proposal: %s", __func__, p);
  	if (*p == '\0')
  		fatal("No supported key exchange algorithms found");
  	return p;
  }
  
  