add blacklist functionality

src/CMakeLists.txt

@@ -4,7 +4,7 @@ include_directories(${CMAKE_CURRENT_SOURCE_DIR} ${ALFREDJSON_BINARY_DIR}
   ${CMAKE_CURRENT_BINARY_DIR} ${ZLIB_INCLUDE_DIRS} ${JANSSON_INCLUDE_DIRS})
 link_directories(${JANSSON_LIBRARY_DIRS} ${ZLIB_LIBRARY_DIRS})
 
-add_executable(alfred-json main.c output_string.c output_json.c output_binary.c zcat.c)
+add_executable(alfred-json main.c output_string.c output_json.c output_binary.c zcat.c blacklist.c)
 
 set_target_properties(alfred-json PROPERTIES COMPILE_FLAGS "-std=gnu99 -Wall -pedantic" LINK_FLAGS "")
 target_link_libraries(alfred-json ${ZLIB_LIBRARIES} ${JANSSON_LIBRARIES})

src/blacklist.c

@@ -0,0 +1,93 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdio.h>
+#include <inttypes.h>
+#include <netinet/ether.h>
+#include "blacklist.h"
+
+struct mac {
+	uint8_t data[ETH_ALEN];
+};
+
+struct blacklist {
+	struct mac entry;
+	struct blacklist *next;
+};
+
+struct blacklist *blacklist_new() {
+	return calloc(sizeof(struct blacklist), 1);
+}
+
+struct mac *mac_from_string(const char *value) {
+	struct mac *result = calloc(sizeof(struct mac), 1);
+	if (NULL == result)
+		return NULL;
+	if (6 != sscanf(value, "%02" SCNx8 ":%02" SCNx8 ":%02" SCNx8 ":%02" SCNx8 ":%02" SCNx8 ":%02" SCNx8 "",
+		&result->data[0], &result->data[1],
+		&result->data[2], &result->data[3],
+		&result->data[4], &result->data[5])) {
+
+		free(result);
+		return NULL;
+	}
+	return result;
+}
+
+struct mac *mac_from_data(const void *value, size_t len) {
+	if (len != ETH_ALEN)
+		return NULL;
+
+	struct mac *result = calloc(sizeof(struct mac), 1);
+	if (NULL == result)
+		return NULL;
+	memcpy(result->data, value, sizeof(result->data));
+	return result;
+}
+
+bool blacklist_is_empty(const struct blacklist *blacklist) {
+	return NULL == blacklist->next;
+}
+
+void blacklist_append(struct blacklist *blacklist, const struct mac *mac) {
+	while (true) {
+		if (NULL == blacklist->next)
+			break;
+		blacklist = blacklist->next;
+	}
+	blacklist->entry = *mac;
+	blacklist->next = blacklist_new();
+}
+
+static inline bool mac_equals(const struct mac *mac1, const struct mac *mac2) {
+	return (0 == memcmp((const void *)mac1, (const void *)mac2, sizeof(struct mac)));
+}
+
+bool blacklist_match(const struct blacklist *blacklist, const struct mac *mac) {
+	while (true) {
+		if (NULL == blacklist->next)
+			break;
+
+		if (mac_equals(mac, &blacklist->entry)) {
+			return true;
+		}
+
+		blacklist = blacklist->next;
+	}
+
+	return false;
+}
+
+size_t blacklist_size(struct blacklist *blacklist) {
+	size_t result = 0;
+
+	while (true) {
+		if (NULL == blacklist->next)
+			break;
+
+		result++;
+		blacklist = blacklist->next;
+	}
+
+	return result;
+}

src/blacklist.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+
+struct blacklist;
+struct mac;
+
+struct mac *mac_from_string(const char *value);
+struct mac *mac_from_data(const void *value, size_t len);
+struct blacklist *blacklist_new();
+size_t blacklist_size(struct blacklist *blacklist);
+void blacklist_append(struct blacklist*, const struct mac *mac);
+bool blacklist_match(const struct blacklist *blacklist, const struct mac *mac);

src/main.c

@@ -26,6 +26,7 @@
 #include <string.h>
 #include <sys/un.h>
 #include <unistd.h>
+#include "blacklist.h"
 #include "output.h"
 #include "packet.h"
 #include "zcat.h"
@@ -40,6 +41,7 @@ static void alfred_usage(void)
 	printf("  -f, --format <format>       output format (\"json\" (default), \"string\" or \"binary\")\n");
 	printf("  -s, --socket <path>         path to alfred unix socket\n");
 	printf("  -z, --gzip                  enable transparent decompression (GZip)\n");
+        printf("  -i, --ignore <macaddress>   ignore data from given MAC Address (may be repeated)");
 	printf("  -h, --help                  this help\n");
 	printf("\n");
 }
@@ -63,7 +65,7 @@ int unix_sock_open(const char* path)
 }
 
 int request_data(int sock, int request_type, bool gzip,
-  const struct output_formatter *output_formatter)
+  const struct output_formatter *output_formatter, struct blacklist *blacklist)
 {
 	unsigned char buf[MAX_PAYLOAD], *pos;
 	struct alfred_request_v0 *request;
@@ -146,7 +148,8 @@ int request_data(int sock, int request_type, bool gzip,
 			}
 		}
 
-		output_formatter->push(formatter_ctx, data->source, ETH_ALEN, pos, data_len);
+		if (!blacklist_match(blacklist, mac_from_data(data->source, sizeof(data->source))))
+			output_formatter->push(formatter_ctx, data->source, ETH_ALEN, pos, data_len);
 
 		if (buffer_len > 0)
 			free(buffer);
@@ -178,18 +181,21 @@ int main(int argc, char *argv[])
 	bool gzip = false;
 	char *socket_path = "/var/run/alfred.sock";
   struct output_formatter output_formatter = output_formatter_json;
+	struct mac *blacklist_mac;
+	struct blacklist *blacklist = blacklist_new();
 
 	int opt, opt_ind, i;
 	struct option long_options[] = {
 		{"request",	required_argument,	NULL,	'r'},
 		{"format",	required_argument,	NULL,	'f'},
 		{"socket",	required_argument,	NULL,	's'},
 		{"gzip",	no_argument,	NULL,	'z'},
+		{"ignore",      required_argument, NULL, 'i'},
 		{"help",	no_argument,	NULL,	'h'},
 		{NULL,	0,	NULL,	0},
 	};
 
-	while ((opt = getopt_long(argc, argv, "r:f:s:hz", long_options, &opt_ind)) != -1) {
+	while ((opt = getopt_long(argc, argv, "r:f:s:i:hz", long_options, &opt_ind)) != -1) {
 		switch (opt) {
 		case 'r':
 			i = atoi(optarg);
@@ -215,6 +221,14 @@ int main(int argc, char *argv[])
 		case 's':
 			socket_path = optarg;
 			break;
+		case 'i':
+			blacklist_mac = mac_from_string(optarg);
+			if (NULL != blacklist_mac) {
+				blacklist_append(blacklist, blacklist_mac);
+			} else {
+				fprintf(stderr, "Ignoring invalid MAC address '%s'\n", optarg);
+			}
+			break;
 		case 'z':
 			gzip = true;
 			break;
@@ -234,7 +248,7 @@ int main(int argc, char *argv[])
 		if (sock < 0)
 			return 1;
 
-		ret = request_data(sock, request, gzip, &output_formatter);
+		ret = request_data(sock, request, gzip, &output_formatter, blacklist);
 		close(sock);
 
 		return ret;