[dhcp] Allow multiple interfaces in dhcp command

The "dhcp" command now accepts a list of interfaces to try until one
succeeds.  For example:

 iPXE> dhcp net0 net1 net2

If no interfaces are specified, all interfaces will be tried.

Note that interfaces that fail to DHCP are closed in order to avoid
memory exhaustion.  This behavior differs from the previous "dhcp"
command implementation but should not affect any existing scripts
since a "dhcp" command failure would in any case cause the script to
abort.

Originally-implemented-by: Lars Kellogg-Stedman <lars@oddbit.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/hci/commands/dhcp_cmd.c b/src/hci/commands/dhcp_cmd.c
index 82869d62482b2cf0f95c4ad77d50fd550e386961..6da0d6377459116d922b694f41c2032793f1bcec 100644 (file)
--- a/src/hci/commands/dhcp_cmd.c
+++ b/src/hci/commands/dhcp_cmd.c
@@ -45,12 +45,52 @@ FILE_LICENCE ( GPL2_OR_LATER );
  */
 static void dhcp_syntax ( char **argv ) {
        printf ( "Usage:\n"
-                "  %s <interface>\n"
+                "  %s [<interface>] [<interface>...]\n"
                 "\n"
                 "Configure a network interface using DHCP\n",
                 argv[0] );
 }
 
+/**
+ * Execute "dhcp" command for a network device
+ *
+ * @v netdev           Network device
+ * @ret rc             Exit code
+ */
+static int dhcp_exec_netdev ( struct net_device *netdev ) {
+       int rc;
+
+       if ( ( rc = dhcp ( netdev ) ) != 0 ) {
+               printf ( "Could not configure %s: %s\n",
+                        netdev->name, strerror ( rc ) );
+
+               /* Close device on failure, to avoid memory exhaustion */
+               netdev_close ( netdev );
+
+               return 1;
+       }
+
+       return 0;
+}
+
+/**
+ * Execute "dhcp" command for a named network device
+ *
+ * @v netdev_name      Network device name
+ * @ret rc             Exit code
+ */
+static int dhcp_exec_name ( const char *netdev_name ) {
+       struct net_device *netdev;
+
+       netdev = find_netdev ( netdev_name );
+       if ( ! netdev ) {
+               printf ( "No such interface \"%s\"\n", netdev_name );
+               return 1;
+       }
+
+       return dhcp_exec_netdev ( netdev );
+}
+
 /**
  * The "dhcp" command
  *
@@ -63,7 +103,7 @@ static int dhcp_exec ( int argc, char **argv ) {
                { "help", 0, NULL, 'h' },
                { NULL, 0, NULL, 0 },
        };
-       const char *netdev_txt;
+       const char *netdev_name;
        struct net_device *netdev;
        int c;
        int rc;
@@ -80,28 +120,22 @@ static int dhcp_exec ( int argc, char **argv ) {
                }
        }
 
-       /* Need exactly one interface name remaining after the options */
-       if ( optind != ( argc - 1 ) ) {
-               dhcp_syntax ( argv );
-               return 1;
-       }
-       netdev_txt = argv[optind];
-
-       /* Parse arguments */
-       netdev = find_netdev ( netdev_txt );
-       if ( ! netdev ) {
-               printf ( "No such interface: %s\n", netdev_txt );
-               return 1;
-       }
-
-       /* Perform DHCP */
-       if ( ( rc = dhcp ( netdev ) ) != 0 ) {
-               printf ( "Could not configure %s: %s\n", netdev->name,
-                        strerror ( rc ) );
-               return 1;
+       if ( optind != argc ) {
+               /* Treat arguments as a list of interfaces to try */
+               while ( optind != argc ) {
+                       netdev_name = argv[optind++];
+                       if ( ( rc = dhcp_exec_name ( netdev_name ) ) == 0 )
+                               return 0;
+               }
+       } else {
+               /* Try all interfaces */
+               for_each_netdev ( netdev ) {
+                       if ( ( rc = dhcp_exec_netdev ( netdev ) ) == 0 )
+                               return 0;
+               }
        }
 
-       return 0;
+       return 1;
 }
 
 /**