decode.c

/*
 * decode.c
 *
 * Copyright (c) 2000 Dug Song <dugsong@monkey.org>
 * 
 * $Id: decode.c,v 1.13 2001/03/15 08:32:59 dugsong Exp $
 */

#include "config.h"

#include <sys/types.h>
#include <arpa/telnet.h>
#include <rpc/rpc.h>

#include <stdio.h>
#include <string.h>
#include <ctype.h>

#include "decode.h"

extern int decode_hex(u_char *, int, u_char *, int);
extern int decode_ftp(u_char *, int, u_char *, int);
extern int decode_telnet(u_char *, int, u_char *, int);
extern int decode_smtp(u_char *, int, u_char *, int);
extern int decode_pptp(u_char *, int, u_char *, int);
extern int decode_http(u_char *, int, u_char *, int);
extern int decode_ospf(u_char *, int, u_char *, int);
extern int decode_poppass(u_char *, int, u_char *, int);
extern int decode_pop(u_char *, int, u_char *, int);
extern int decode_nntp(u_char *, int, u_char *, int);
extern int decode_smb(u_char *, int, u_char *, int);
extern int decode_imap(u_char *, int, u_char *, int);
extern int decode_snmp(u_char *, int, u_char *, int);
extern int decode_ldap(u_char *, int, u_char *, int);
extern int decode_mmxp(u_char *, int, u_char *, int);
extern int decode_rlogin(u_char *, int, u_char *, int);
extern int decode_rip(u_char *, int, u_char *, int);
extern int decode_socks(u_char *, int, u_char *, int);
extern int decode_citrix(u_char *, int, u_char *, int);
extern int decode_oracle(u_char *, int, u_char *, int);
extern int decode_tds(u_char *, int, u_char *, int);
extern int decode_sniffer(u_char *, int, u_char *, int);
extern int decode_cvs(u_char *, int, u_char *, int);
extern int decode_icq(u_char *, int, u_char *, int);
extern int decode_napster(u_char *, int, u_char *, int);
extern int decode_aim(u_char *, int, u_char *, int);
extern int decode_postgresql(u_char *, int, u_char *, int);
extern int decode_pcanywhere(u_char *, int, u_char *, int);
extern int decode_x11(u_char *, int, u_char *, int);
extern int decode_irc(u_char *, int, u_char *, int);
extern int decode_portmap(u_char *, int, u_char *, int);
extern int decode_mountd(u_char *, int, u_char *, int);
extern int decode_vrrp(u_char *, int, u_char *, int);
extern int decode_ypserv(u_char *, int, u_char *, int);
extern int decode_yppasswd(u_char *, int, u_char *, int);

static struct decode decodes[] = {
	{ "hex",	decode_hex },
	{ "ftp",	decode_ftp },
	{ "telnet",	decode_telnet },
	{ "smtp",	decode_smtp },
	{ "pptp",	decode_pptp },
	{ "http",	decode_http },
	{ "ospf",	decode_ospf },
	{ "poppass",	decode_poppass },
	{ "pop2",	decode_pop },
	{ "pop3",	decode_pop },
	{ "nntp",	decode_nntp },
	{ "smb",	decode_smb },
	{ "imap",	decode_imap },
	{ "snmp",	decode_snmp },
	{ "ldap",	decode_ldap },
	{ "mmxp",	decode_mmxp },
	{ "rlogin",	decode_rlogin },
	{ "rip",	decode_rip },
	{ "socks",	decode_socks },
	{ "citrix",	decode_citrix },
	{ "oracle",	decode_oracle },
	{ "tds",	decode_tds },
	{ "sniffer",	decode_sniffer },
	{ "cvs",	decode_cvs },
	{ "icq",	decode_icq },
	{ "napster",	decode_napster },
	{ "aim",	decode_aim },
	{ "postgresql",	decode_postgresql },
	{ "pcanywhere", decode_pcanywhere },
	{ "vrrp",	decode_vrrp },
	{ "x11",	decode_x11 },
	{ "irc",	decode_irc },
	{ "portmap",	decode_portmap },
	{ "mountd",	decode_mountd },
	{ "ypserv",	decode_ypserv },
	{ "yppasswd",	decode_yppasswd },
	{ NULL }
};

struct decode *
getdecodebyname(const char *name)
{
	struct decode *dc;
	
	for (dc = decodes; dc->dc_name != NULL; dc++) {
		if (strcasecmp(dc->dc_name, name) == 0)
			return (dc);
	}
	return (NULL);
}

/* Strip telnet options, as well as suboption data. */
int
strip_telopts(u_char *buf, int len)
{
	int i, j, subopt = 0;
	char *p, *q;
	
	for (i = j = 0; i < len; i++) {
		if (buf[i] == IAC) {
			if (++i >= len) break;
			else if (buf[i] > SB)
				i++;
			else if (buf[i] == SB) {
				/* XXX - check for autologin username. */
				p = buf + i + 1;
				if ((q = bufbuf(p, len - i, "\xff", 1))
				    != NULL) {
					if ((p = bufbuf(p, q - p, "USER\x01",
							5)) != NULL) {
						p += 5;
						buf[j++] = '[';
						memcpy(buf + j, p, q - p);
						j += q - p;
						buf[j++] = ']';
						buf[j++] = '\n';
					}
				}
				subopt = 1;
			}
			else if (buf[i] == SE) {
				if (!subopt) j = 0;
				subopt = 0;
			}
		}
		else if (!subopt) {
			/* XXX - convert isolated returns to newlines. */
			if (buf[i] == '\r' && i + 1 < len &&
			    buf[i + 1] != '\n')
				buf[j++] = '\n';
			/* XXX - strip binary nulls. */
			else if (buf[i] != '\0')
				buf[j++] = buf[i];
		}
	}
	buf[j] = '\0';
	
	return (j);
}

/* Strip a string buffer down to a maximum number of lines. */
int
strip_lines(char *buf, int max_lines)
{
	char *p;
	int lines, nonascii;
	
	if (!buf) return (0);
	
	lines = nonascii = 0;
	
	for (p = buf; *p && lines < max_lines; p++) {
		if (*p == '\n') lines++;
		if (!isascii(*p)) nonascii++;
	}
	if (*p) *p = '\0';
	
	/* XXX - lame ciphertext heuristic */
	if (nonascii * 3 > p - buf)
		return (0);
	
	return (lines);
}

int
is_ascii_string(char *buf, int len)
{
	int i;
	
	for (i = 0; i < len; i++)
		if (!isascii(buf[i])) return (0);
	
	return (1);
}

u_char *
bufbuf(u_char *big, int blen, u_char *little, int llen)
{
	u_char *p;
	
         for (p = big; p <= big + blen - llen; p++) {
		 if (memcmp(p, little, llen) == 0)
			 return (p);
	 }
	 return (NULL);
}