udhcp: add PXELINUX config file option (code 209) definition

[oweals/busybox.git] / networking / udhcp / packet.c

diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c
index bd754f76681ee6d13e4af8ce3cede378e7157d8b..148f52551a129e179ea8fe031ddb36a81eaa09a2 100644 (file)
--- a/networking/udhcp/packet.c
+++ b/networking/udhcp/packet.c
@@ -143,8 +143,15 @@ int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
         *
         * In order to work with those buggy servers,
         * we truncate packets after end option byte.
+        *
+        * However, RFC 1542 says "The IP Total Length and UDP Length
+        * must be large enough to contain the minimal BOOTP header of 300 octets".
+        * Thus, we retain enough padding to not go below 300 BOOTP bytes.
+        * Some devices have filters which drop DHCP packets shorter than that.
         */
        padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(packet.data.options);
+       if (padding > DHCP_SIZE - 300)
+               padding = DHCP_SIZE - 300;
 
        packet.ip.protocol = IPPROTO_UDP;
        packet.ip.saddr = source_nip;
@@ -182,7 +189,7 @@ int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
                uint32_t source_nip, int source_port,
                uint32_t dest_nip, int dest_port)
 {
-       struct sockaddr_in client;
+       struct sockaddr_in sa;
        unsigned padding;
        int fd;
        int result = -1;
@@ -195,27 +202,28 @@ int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
        }
        setsockopt_reuseaddr(fd);
 
-       memset(&client, 0, sizeof(client));
-       client.sin_family = AF_INET;
-       client.sin_port = htons(source_port);
-       client.sin_addr.s_addr = source_nip;
-       if (bind(fd, (struct sockaddr *)&client, sizeof(client)) == -1) {
+       memset(&sa, 0, sizeof(sa));
+       sa.sin_family = AF_INET;
+       sa.sin_port = htons(source_port);
+       sa.sin_addr.s_addr = source_nip;
+       if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
                msg = "bind(%s)";
                goto ret_close;
        }
 
-       memset(&client, 0, sizeof(client));
-       client.sin_family = AF_INET;
-       client.sin_port = htons(dest_port);
-       client.sin_addr.s_addr = dest_nip;
-       if (connect(fd, (struct sockaddr *)&client, sizeof(client)) == -1) {
+       memset(&sa, 0, sizeof(sa));
+       sa.sin_family = AF_INET;
+       sa.sin_port = htons(dest_port);
+       sa.sin_addr.s_addr = dest_nip;
+       if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
                msg = "connect";
                goto ret_close;
        }
 
        udhcp_dump_packet(dhcp_pkt);
-
        padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(dhcp_pkt->options);
+       if (padding > DHCP_SIZE - 300)
+               padding = DHCP_SIZE - 300;
        result = safe_write(fd, dhcp_pkt, DHCP_SIZE - padding);
        msg = "write";
  ret_close: