3 files changed, 42 insertions, 2 deletions
diff --git a/options.c b/options.c
index ca9b9e1..ebccd7f 100644
--- a/options.c
+++ b/options.c
@@ -3436,11 +3436,11 @@ add_option (struct options *options,
   else if (streq (p[0], "lladdr") && p[1])
     {
       VERIFY_PERMISSION (OPT_P_UP);
-      if (ip_addr_dotted_quad_safe (p[1])) /* FQDN -- IP address only */
+      if (mac_addr_safe (p[1])) /* MAC address only */
 	options->lladdr = p[1];
       else
 	{
-	  msg (msglevel, "lladdr parm '%s' must be an IP address", p[1]);
+	  msg (msglevel, "lladdr parm '%s' must be a MAC address", p[1]);
 	  goto err;
 	}
     }
diff --git a/socket.c b/socket.c
index df922a9..fe58c3e 100644
--- a/socket.c
+++ b/socket.c
@@ -317,6 +317,45 @@ ip_or_dns_addr_safe (const char *addr, const bool allow_fqdn)
     return false;
 }
 
+bool
+mac_addr_safe (const char *mac_addr)
+{
+  /* verify non-NULL */
+  if (!mac_addr)
+    return false;
+
+  /* verify length is within limits */
+  if (strlen (mac_addr) > 17)
+    return false;
+
+  /* verify that all chars are either alphanumeric or ':' and that no
+     alphanumeric substring is greater than 2 chars */
+  {
+    int nnum = 0;
+    const char *p = mac_addr;
+    int c;
+
+    while ((c = *p++))
+      {
+	if ( (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F') )
+	  {
+	    ++nnum;
+	    if (nnum > 2)
+	      return false;
+	  }
+	else if (c == ':')
+	  {
+	    nnum = 0;
+	  }
+	else
+	  return false;
+      }
+  }
+
+  /* error-checking is left to script invoked in lladdr.c */
+  return true;
+}
+
 static void
 update_remote (const char* host,
 	       struct openvpn_sockaddr *addr,
diff --git a/socket.h b/socket.h
index f6ec570..980322d 100644
--- a/socket.h
+++ b/socket.h
@@ -400,6 +400,7 @@ int openvpn_inet_aton (const char *dotted_quad, struct in_addr *addr);
 /* integrity validation on pulled options */
 bool ip_addr_dotted_quad_safe (const char *dotted_quad);
 bool ip_or_dns_addr_safe (const char *addr, const bool allow_fqdn);
+bool mac_addr_safe (const char *mac_addr);
 
 socket_descriptor_t create_socket_tcp (void);