[ipv4] Use broadcast link-layer address for all broadcast IPv4 addresses

When transmitting, use the broadcast link-layer address for any
broadcast address (e.g. 192.168.0.255), not just INADDR_BROADCAST
(255.255.255.255).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/net/ipv4.c b/src/net/ipv4.c
index aee3bc355b2acc90179b22e8b6d7ccf4b43c04e7..5bb01a1cc4f88ddaa4a9c35fe7c0d8c039cf982d 100644 (file)
--- a/src/net/ipv4.c
+++ b/src/net/ipv4.c
@@ -110,10 +110,6 @@ static struct ipv4_miniroute * ipv4_route ( struct in_addr *dest ) {
        int local;
        int has_gw;
 
-       /* Never attempt to route the broadcast address */
-       if ( dest->s_addr == INADDR_BROADCAST )
-               return NULL;
-
        /* Find first usable route in routing table */
        list_for_each_entry ( miniroute, &ipv4_miniroutes, list ) {
                if ( ! netdev_is_open ( miniroute->netdev ) )
@@ -260,15 +256,17 @@ static uint16_t ipv4_pshdr_chksum ( struct io_buffer *iobuf, uint16_t csum ) {
  *
  * @v dest             IPv4 destination address
  * @v src              IPv4 source address
+ * @v netmask          IPv4 subnet mask
  * @v netdev           Network device
  * @v ll_dest          Link-layer destination address buffer
  * @ret rc             Return status code
  */
 static int ipv4_ll_addr ( struct in_addr dest, struct in_addr src,
-                         struct net_device *netdev, uint8_t *ll_dest ) {
+                         struct in_addr netmask, struct net_device *netdev,
+                         uint8_t *ll_dest ) {
        struct ll_protocol *ll_protocol = netdev->ll_protocol;
 
-       if ( dest.s_addr == INADDR_BROADCAST ) {
+       if ( ( ( dest.s_addr ^ INADDR_BROADCAST ) & ~netmask.s_addr ) == 0 ) {
                /* Broadcast address */
                memcpy ( ll_dest, netdev->ll_broadcast,
                         ll_protocol->ll_addr_len );
@@ -306,6 +304,7 @@ static int ipv4_tx ( struct io_buffer *iobuf,
        struct sockaddr_in *sin_dest = ( ( struct sockaddr_in * ) st_dest );
        struct ipv4_miniroute *miniroute;
        struct in_addr next_hop;
+       struct in_addr netmask = { .s_addr = 0 };
        uint8_t ll_dest[MAX_LL_ADDR_LEN];
        int rc;
 
@@ -326,6 +325,7 @@ static int ipv4_tx ( struct io_buffer *iobuf,
             ( ! IN_MULTICAST ( ntohl ( next_hop.s_addr ) ) ) &&
             ( ( miniroute = ipv4_route ( &next_hop ) ) != NULL ) ) {
                iphdr->src = miniroute->address;
+               netmask = miniroute->netmask;
                netdev = miniroute->netdev;
        }
        if ( ! netdev ) {
@@ -343,7 +343,7 @@ static int ipv4_tx ( struct io_buffer *iobuf,
                               ( ( netdev->rx_stats.good & 0xf ) << 0 ) );
 
        /* Determine link-layer destination address */
-       if ( ( rc = ipv4_ll_addr ( next_hop, iphdr->src, netdev,
+       if ( ( rc = ipv4_ll_addr ( next_hop, iphdr->src, netmask, netdev,
                                   ll_dest ) ) != 0 ) {
                DBG ( "IPv4 has no link-layer address for %s: %s\n",
                      inet_ntoa ( next_hop ), strerror ( rc ) );