Add get_src_mac_address() to utils.

Author: gamemann

src/utils.c

@@ -144,4 +144,41 @@ char *rand_ip(char *range, __u16 *pckt_count)
         free(cidr_str);
 
     return inet_ntoa(rand_ip_str);
+}
+
+/**
+ * Retrieves the source MAC address of an interface.
+ * 
+ * @param dev The interface/device name.
+ * @param src_mac A pointer to the source MAC address (__u8).
+ * 
+ * @return 0 on success or -1 on failure (path not found).
+**/
+int get_src_mac_address(const char *dev, __u8 *src_mac)
+{
+    // Format path to source MAC on file system using network class.
+    char path[255];
+    snprintf(path, sizeof(path) - 1, "/sys/class/net/%s/address", dev);
+
+    // Attempt to open path/file and check.
+    FILE *fp = fopen(path, "r");
+
+    if (!fp)
+    {
+        return -1;
+    }
+
+    // Create buffer to copy contents of file to.
+    char buffer[255];
+
+    // Copy contents of file to buffer.
+    fgets(buffer, sizeof(buffer), fp);
+
+    // Scan MAC address.
+    sscanf(buffer, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx", &src_mac[0], &src_mac[1], &src_mac[2], &src_mac[3], &src_mac[4], &src_mac[5]);
+
+    // Close file.
+    fclose(fp);
+
+    return 0;
 }