Linux syscollector: retrieve MAC addresses from "/sys/class/net/<ifna…

…me>/address". (#2550)

* Linux syscollector: retrieve MAC addresses from "/sys/class/net/<ifname>/address".

* Fixed wrong fread() call + variable naming convention.

* Let Syscollector get a shorter MAC address.

Some tunneling interfaces have a shorter MAC, like "00:00:00:00"

src/wazuh_modules/syscollector/syscollector_linux.c

@@ -645,7 +645,7 @@ char * sys_deb_packages(int queue_fd, const char* LOCATION, int random_id){
                 if(object){
                     cJSON_Delete(object);
                 }
-                
+
                 object = cJSON_CreateObject();
                 package = cJSON_CreateObject();
                 cJSON_AddStringToObject(object, "type", "program");
@@ -1059,10 +1059,35 @@ void sys_network_linux(int queue_fd, const char* LOCATION){
             if (strcmp(ifaces_list[i], ifa->ifa_name)){
                 continue;
             }
+
             if (ifa->ifa_flags & IFF_LOOPBACK) {
                 continue;
             }
 
+            /* Get MAC address */
+            char addr_path[PATH_LENGTH] = {'\0'};
+            snprintf(addr_path, PATH_LENGTH, "%s%s/address", WM_SYS_IFDATA_DIR, ifaces_list[i]);
+
+            FILE *fs_if_addr = fopen(addr_path, "r");
+            if (fs_if_addr != NULL) {
+                char mac[MAC_LENGTH] = {'\0'};
+
+                if (fgets(mac, sizeof(mac), fs_if_addr)) {
+                    char * newline = strchr(mac, '\n');
+                    if (newline) {
+                        *newline = '\0';
+                    }
+
+                    cJSON_AddStringToObject(interface, "MAC", mac);
+                } else {
+                    mtdebug1(WM_SYS_LOGTAG, "Invalid MAC address length for interface \"%s\" at \"%s\": file is empty.", ifaces_list[i], addr_path);
+                }
+
+                fclose(fs_if_addr);
+            } else {
+                mtwarn(WM_SYS_LOGTAG, "Unable to read MAC address for interface \"%s\" from \"%s\": %s (%d)", ifaces_list[i], addr_path, strerror(errno), errno);
+            }
+
             if (ifa->ifa_addr) {
                 family = ifa->ifa_addr->sa_family;
 
@@ -1172,13 +1197,8 @@ void sys_network_linux(int queue_fd, const char* LOCATION){
                     }
 
                 } else if (family == AF_PACKET && ifa->ifa_data != NULL){
-
-                    /* Get MAC address and stats */
-                    char MAC[MAC_LENGTH];
+                    /* Get stats */
                     struct link_stats *stats = ifa->ifa_data;
-                    struct sockaddr_ll *addr = (struct sockaddr_ll*)ifa->ifa_addr;
-                    snprintf(MAC, MAC_LENGTH, "%02X:%02X:%02X:%02X:%02X:%02X", addr->sll_addr[0], addr->sll_addr[1], addr->sll_addr[2], addr->sll_addr[3], addr->sll_addr[4], addr->sll_addr[5]);
-                    cJSON_AddStringToObject(interface, "MAC", MAC);
                     cJSON_AddNumberToObject(interface, "tx_packets", stats->tx_packets);
                     cJSON_AddNumberToObject(interface, "rx_packets", stats->rx_packets);
                     cJSON_AddNumberToObject(interface, "tx_bytes", stats->tx_bytes);