[ebtables-compat PATCH 2/2] ebtables-compat: add log watcher extension

[Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>]

This patch adds the log 'watcher' extension.

The work was started by Giuseppe Longo <giuseppelng@gmail.com> and finised
by me.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
---
 extensions/libebt_log.c |  197 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 197 insertions(+)
 create mode 100644 extensions/libebt_log.c

diff --git a/extensions/libebt_log.c b/extensions/libebt_log.c
new file mode 100644
index 0000000..0799185
--- /dev/null
+++ b/extensions/libebt_log.c
@@ -0,0 +1,197 @@
+/*
+ * Bart De Schuymer <bdschuym@pandora.be>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Giuseppe Longo <giuseppelng@gmail.com> adapted the original code to the
+ * xtables-compat environment in 2015.
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <syslog.h>
+#include <string.h>
+#include <getopt.h>
+#include <xtables.h>
+#include <linux/netfilter_bridge/ebt_log.h>
+
+#define LOG_DEFAULT_LEVEL LOG_INFO
+
+#define LOG_PREFIX '1'
+#define LOG_LEVEL  '2'
+#define LOG_ARP    '3'
+#define LOG_IP     '4'
+#define LOG_LOG    '5'
+#define LOG_IP6    '6'
+
+typedef struct _code {
+	char *c_name;
+	int c_val;
+} CODE;
+
+static CODE eight_priority[] = {
+	{ "emerg", LOG_EMERG },
+	{ "alert", LOG_ALERT },
+	{ "crit", LOG_CRIT },
+	{ "error", LOG_ERR },
+	{ "warning", LOG_WARNING },
+	{ "notice", LOG_NOTICE },
+	{ "info", LOG_INFO },
+	{ "debug", LOG_DEBUG }
+};
+
+static int name_to_loglevel(const char *arg)
+{
+	int i;
+
+	for (i = 0; i < 8; i++)
+		if (!strcmp(arg, eight_priority[i].c_name))
+			return eight_priority[i].c_val;
+
+	/* return bad loglevel */
+	return 9;
+}
+
+static const struct option brlog_opts[] = {
+	{ .name = "log-prefix",		.has_arg = true,  .val = LOG_PREFIX },
+	{ .name = "log-level",		.has_arg = true,  .val = LOG_LEVEL  },
+	{ .name = "log-arp",		.has_arg = false, .val = LOG_ARP    },
+	{ .name = "log-ip",		.has_arg = false, .val = LOG_IP     },
+	{ .name = "log",		.has_arg = false, .val = LOG_LOG    },
+	{ .name = "log-ip6",		.has_arg = false, .val = LOG_IP6    },
+	XT_GETOPT_TABLEEND,
+};
+
+static void brlog_help(void)
+{
+	int i;
+
+	printf(
+"log options:\n"
+"--log               : use this if you're not specifying anything\n"
+"--log-level level   : level = [1-8] or a string\n"
+"--log-prefix prefix : max. %d chars.\n"
+"--log-ip            : put ip info. in the log for ip packets\n"
+"--log-arp           : put (r)arp info. in the log for (r)arp packets\n"
+"--log-ip6           : put ip6 info. in the log for ip6 packets\n"
+	, EBT_LOG_PREFIX_SIZE - 1);
+	for (i = 0; i < 8; i++)
+		printf("%d = %s\n", eight_priority[i].c_val,
+				    eight_priority[i].c_name);
+}
+
+static void brlog_init(struct xt_entry_target *t)
+{
+	struct ebt_log_info *loginfo = (struct ebt_log_info *)t->data;
+
+	loginfo->bitmask = 0;
+	loginfo->prefix[0] = '\0';
+	loginfo->loglevel = LOG_NOTICE;
+}
+
+static int brlog_parse(int c, char **argv, int invert, unsigned int *flags,
+		       const void *entry, struct xt_entry_target **target)
+{
+	struct ebt_log_info *loginfo = (struct ebt_log_info *)(*target)->data;
+	long int i;
+	char *end;
+
+	switch (c) {
+	case LOG_PREFIX:
+		if (invert)
+			xtables_error(PARAMETER_PROBLEM,
+				      "Unexpected `!` after --log-prefix");
+		if (strlen(optarg) > sizeof(loginfo->prefix) - 1)
+			xtables_error(PARAMETER_PROBLEM,
+				      "Prefix too long");
+		if (strchr(optarg, '\"'))
+			xtables_error(PARAMETER_PROBLEM,
+				      "Use of \\\" is not allowed"
+				      " in the prefix");
+		strcpy((char *)loginfo->prefix, (char *)optarg);
+		break;
+	case LOG_LEVEL:
+		i = strtol(optarg, &end, 16);
+		if (*end != '\0' || i < 0 || i > 7)
+			loginfo->loglevel = name_to_loglevel(optarg);
+		else
+			loginfo->loglevel = i;
+
+		if (loginfo->loglevel == 9)
+			xtables_error(PARAMETER_PROBLEM,
+				      "Problem with the log-level");
+		break;
+	case LOG_IP:
+		if (invert)
+			xtables_error(PARAMETER_PROBLEM,
+				      "Unexpected `!' after --log-ip");
+		loginfo->bitmask |= EBT_LOG_IP;
+		break;
+	case LOG_ARP:
+		if (invert)
+			xtables_error(PARAMETER_PROBLEM,
+				      "Unexpected `!' after --log-arp");
+		loginfo->bitmask |= EBT_LOG_ARP;
+	case LOG_LOG:
+		if (invert)
+			xtables_error(PARAMETER_PROBLEM,
+				      "Unexpected `!' after --log");
+		break;
+	case LOG_IP6:
+		if (invert)
+			xtables_error(PARAMETER_PROBLEM,
+				      "Unexpected `!' after --log-ip6");
+		loginfo->bitmask |= EBT_LOG_IP6;
+		break;
+	default:
+		return 0;
+	}
+
+	*flags |= loginfo->bitmask;
+	return 1;
+}
+
+static void brlog_final_check(unsigned int flags)
+{
+}
+
+static void brlog_print(const void *ip, const struct xt_entry_target *target,
+			int numeric)
+{
+	struct ebt_log_info *loginfo = (struct ebt_log_info *)target->data;
+
+	printf("--log-level %s --log-prefix \"%s\"",
+		eight_priority[loginfo->loglevel].c_name,
+		loginfo->prefix);
+
+	if (loginfo->bitmask & EBT_LOG_IP)
+		printf(" --log-ip");
+	if (loginfo->bitmask & EBT_LOG_ARP)
+		printf(" --log-arp");
+	if (loginfo->bitmask & EBT_LOG_IP6)
+		printf(" --log-ip6");
+	printf(" ");
+}
+
+static struct xtables_target brlog_target = {
+	.name		= "log",
+	.revision	= 0,
+	.version	= XTABLES_VERSION,
+	.family		= NFPROTO_BRIDGE,
+	.size		= XT_ALIGN(sizeof(struct ebt_log_info)),
+	.userspacesize	= XT_ALIGN(sizeof(struct ebt_log_info)),
+	.init		= brlog_init,
+	.help		= brlog_help,
+	.parse		= brlog_parse,
+	.final_check	= brlog_final_check,
+	.print		= brlog_print,
+	.extra_opts	= brlog_opts,
+};
+
+void _init(void)
+{
+	xtables_register_target(&brlog_target);
+}