*
* Copyright (C) 2000 Emmanuel Roger <winfield@freegates.be>
*
+ * 2005-08-05 Pablo Neira Ayuso <pablo@eurodev.net>
+ * - reimplemented to use new string matching iptables match
+ * - add functionality to match packets by using window offsets
+ * - add functionality to select the string matching algorithm
+ *
* ChangeLog
+ * 29.12.2003: Michael Rash <mbr@cipherdyne.org>
+ * Fixed iptables save/restore for ascii strings
+ * that contain space chars, and hex strings that
+ * contain embedded NULL chars. Updated to print
+ * strings in hex mode if any non-printable char
+ * is contained within the string.
+ *
* 27.01.2001: Gianni Tedesco <gianni@ecsc.co.uk>
* Changed --tos to --string in save(). Also
* updated to work with slightly modified
#include <stdlib.h>
#include <getopt.h>
#include <ctype.h>
-
#include <iptables.h>
+#include <stddef.h>
#include <linux/netfilter_ipv4/ipt_string.h>
-
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"STRING match v%s options:\n"
+"--from Offset to start searching from\n"
+"--to Offset to stop searching\n"
+"--algo Algorithm\n"
"--string [!] string Match a string in a packet\n"
"--hex-string [!] string Match a hex string in a packet\n",
IPTABLES_VERSION);
}
-
static struct option opts[] = {
- { .name = "string", .has_arg = 1, .flag = 0, .val = '1' },
- { .name = "hex-string", .has_arg = 1, .flag = 0, .val = '2' },
- { .name = 0 }
+ { "from", 1, 0, '1' },
+ { "to", 1, 0, '2' },
+ { "algo", 1, 0, '3' },
+ { "string", 1, 0, '4' },
+ { "hex-string", 1, 0, '5' },
+ {0}
};
-
-/* Initialize the match. */
static void
init(struct ipt_entry_match *m, unsigned int *nfcache)
{
- *nfcache |= NFC_UNKNOWN;
-}
+ struct ipt_string_info *i = (struct ipt_string_info *) m->data;
+ if (i->to_offset == 0)
+ i->to_offset = (u_int16_t) ~0UL;
+}
static void
-parse_string(const unsigned char *s, struct ipt_string_info *info)
+parse_string(const char *s, struct ipt_string_info *info)
{
- if (strlen(s) <= BM_MAX_NLEN) strcpy(info->string, s);
- else exit_error(PARAMETER_PROBLEM, "STRING too long `%s'", s);
+ if (strlen(s) <= IPT_STRING_MAX_PATTERN_SIZE) {
+ strncpy(info->pattern, s, IPT_STRING_MAX_PATTERN_SIZE);
+ info->patlen = strlen(s);
+ return;
+ }
+ exit_error(PARAMETER_PROBLEM, "STRING too long `%s'", s);
}
+static void
+parse_algo(const char *s, struct ipt_string_info *info)
+{
+ if (strlen(s) <= IPT_STRING_MAX_ALGO_NAME_SIZE) {
+ strncpy(info->algo, s, IPT_STRING_MAX_ALGO_NAME_SIZE);
+ return;
+ }
+ exit_error(PARAMETER_PROBLEM, "ALGO too long `%s'", s);
+}
static void
-parse_hex_string(const unsigned char *s, struct ipt_string_info *info)
+parse_hex_string(const char *s, struct ipt_string_info *info)
{
int i=0, slen, sindex=0, schar;
short hex_f = 0, literal_f = 0;
} else if (s[i] == '|') {
if (hex_f)
hex_f = 0;
- else
+ else {
hex_f = 1;
+ /* get past any initial whitespace just after the '|' */
+ while (s[i+1] == ' ')
+ i++;
+ }
if (i+1 >= slen)
break;
else
exit_error(PARAMETER_PROBLEM,
"Bad literal placement at end of string");
}
- info->string[sindex] = s[i+1];
+ info->pattern[sindex] = s[i+1];
i += 2; /* skip over literal char */
literal_f = 0;
} else if (hex_f) {
if (! sscanf(hextmp, "%x", &schar))
exit_error(PARAMETER_PROBLEM,
"Invalid hex char `%c'", s[i]);
- info->string[sindex] = (char) schar;
+ info->pattern[sindex] = (char) schar;
if (s[i+2] == ' ')
i += 3; /* spaces included in the hex block */
else
i += 2;
} else { /* the char is not part of hex data, so just copy */
- info->string[sindex] = s[i];
+ info->pattern[sindex] = s[i];
i++;
}
- if (sindex > BM_MAX_NLEN)
+ if (sindex > IPT_STRING_MAX_PATTERN_SIZE)
exit_error(PARAMETER_PROBLEM, "STRING too long `%s'", s);
sindex++;
}
- info->len = sindex;
+ info->patlen = sindex;
}
+#define STRING 0x1
+#define ALGO 0x2
+#define FROM 0x4
+#define TO 0x8
/* Function which parses command options; returns true if it
ate an option */
switch (c) {
case '1':
- if (*flags)
+ if (*flags & FROM)
exit_error(PARAMETER_PROBLEM,
- "Can't specify multiple strings");
-
+ "Can't specify multiple --from");
+ stringinfo->from_offset = atoi(optarg);
+ *flags |= FROM;
+ break;
+ case '2':
+ if (*flags & TO)
+ exit_error(PARAMETER_PROBLEM,
+ "Can't specify multiple --to");
+ stringinfo->to_offset = atoi(optarg);
+ *flags |= TO;
+ break;
+ case '3':
+ if (*flags & ALGO)
+ exit_error(PARAMETER_PROBLEM,
+ "Can't specify multiple --algo");
+ parse_algo(optarg, stringinfo);
+ *flags |= ALGO;
+ break;
+ case '4':
+ if (*flags & STRING)
+ exit_error(PARAMETER_PROBLEM,
+ "Can't specify multiple --string");
check_inverse(optarg, &invert, &optind, 0);
parse_string(argv[optind-1], stringinfo);
if (invert)
stringinfo->invert = 1;
- stringinfo->len=strlen((char *)&stringinfo->string);
- *flags = 1;
+ stringinfo->patlen=strlen((char *)&stringinfo->pattern);
+ *flags |= STRING;
break;
- case '2':
- if (*flags)
+ case '5':
+ if (*flags & STRING)
exit_error(PARAMETER_PROBLEM,
- "Can't specify multiple strings");
+ "Can't specify multiple --hex-string");
check_inverse(optarg, &invert, &optind, 0);
parse_hex_string(argv[optind-1], stringinfo); /* sets length */
if (invert)
stringinfo->invert = 1;
- *flags = 1;
+ *flags |= STRING;
break;
default:
static void
final_check(unsigned int flags)
{
- if (!flags)
+ if (!(flags & STRING))
+ exit_error(PARAMETER_PROBLEM,
+ "STRING match: You must specify `--string' or "
+ "`--hex-string'");
+ if (!(flags & ALGO))
exit_error(PARAMETER_PROBLEM,
- "STRING match: You must specify `--string'");
+ "STRING match: You must specify `--algo'");
}
+/* Test to see if the string contains non-printable chars or quotes */
+static unsigned short int
+is_hex_string(const char *str, const unsigned short int len)
+{
+ unsigned int i;
+ for (i=0; i < len; i++)
+ if (! isprint(str[i]))
+ return 1; /* string contains at least one non-printable char */
+ /* use hex output if the last char is a "\" */
+ if ((unsigned char) str[len-1] == 0x5c)
+ return 1;
+ return 0;
+}
+
+/* Print string with "|" chars included as one would pass to --hex-string */
+static void
+print_hex_string(const char *str, const unsigned short int len)
+{
+ unsigned int i;
+ /* start hex block */
+ printf("\"|");
+ for (i=0; i < len; i++) {
+ /* see if we need to prepend a zero */
+ if ((unsigned char) str[i] <= 0x0F)
+ printf("0%x", (unsigned char) str[i]);
+ else
+ printf("%x", (unsigned char) str[i]);
+ }
+ /* close hex block */
+ printf("|\" ");
+}
+
+static void
+print_string(const char *str, const unsigned short int len)
+{
+ unsigned int i;
+ printf("\"");
+ for (i=0; i < len; i++) {
+ if ((unsigned char) str[i] == 0x22) /* escape any embedded quotes */
+ printf("%c", 0x5c);
+ printf("%c", (unsigned char) str[i]);
+ }
+ printf("\" "); /* closing space and quote */
+}
/* Prints out the matchinfo. */
static void
const struct ipt_string_info *info =
(const struct ipt_string_info*) match->data;
- printf("STRING match %s%s ", (info->invert) ? "!" : "", info->string);
+ if (is_hex_string(info->pattern, info->patlen)) {
+ printf("STRING match %s", (info->invert) ? "!" : "");
+ print_hex_string(info->pattern, info->patlen);
+ } else {
+ printf("STRING match %s", (info->invert) ? "!" : "");
+ print_string(info->pattern, info->patlen);
+ }
+ printf("ALGO name %s ", info->algo);
+ if (info->from_offset != 0)
+ printf("FROM %u ", info->from_offset);
+ if (info->to_offset != 0)
+ printf("TO %u", info->to_offset);
}
const struct ipt_string_info *info =
(const struct ipt_string_info*) match->data;
- printf("--string %s%s ", (info->invert) ? "! ": "", info->string);
+ if (is_hex_string(info->pattern, info->patlen)) {
+ printf("--hex-string %s", (info->invert) ? "! ": "");
+ print_hex_string(info->pattern, info->patlen);
+ } else {
+ printf("--string %s", (info->invert) ? "! ": "");
+ print_string(info->pattern, info->patlen);
+ }
+ printf("--algo %s ", info->algo);
+ if (info->from_offset != 0)
+ printf("--from %u ", info->from_offset);
+ if (info->to_offset != 0)
+ printf("--to %u ", info->to_offset);
}
static struct iptables_match string = {
- .name = "string",
- .version = IPTABLES_VERSION,
- .size = IPT_ALIGN(sizeof(struct ipt_string_info)),
- .userspacesize = IPT_ALIGN(sizeof(struct ipt_string_info)),
- .help = &help,
- .init = &init,
- .parse = &parse,
- .final_check = &final_check,
- .print = &print,
- .save = &save,
- .extra_opts = opts
+ .name = "string",
+ .version = IPTABLES_VERSION,
+ .size = IPT_ALIGN(sizeof(struct ipt_string_info)),
+ .userspacesize = offsetof(struct ipt_string_info, config),
+ .help = help,
+ .init = init,
+ .parse = parse,
+ .final_check = final_check,
+ .print = print,
+ .save = save,
+ .extra_opts = opts
};
git://git.onelab.eu / iptables.git / blobdiff