package/busybox/patches/241-udhcpc-oversized_packets.patch

   1 --- a/networking/udhcp/packet.c
   2 +++ b/networking/udhcp/packet.c
   3 @@ -165,6 +165,11 @@ uint16_t FAST_FUNC udhcp_checksum(void *
   4         return ~sum;
   5  }
   6
   7 +int udhcp_get_payload_len(struct dhcp_packet *dhcp_pkt)
   8 +{
   9 +       return sizeof(struct dhcp_packet) - DHCP_OPTIONS_BUFSIZE + udhcp_end_option(dhcp_pkt->options) + sizeof(dhcp_pkt->options[0]);
  10 +}
  11 +
  12  /* Construct a ip/udp header for a packet, send packet */
  13  int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
  14                 uint32_t source_nip, int source_port,
  15 @@ -173,10 +178,10 @@ int FAST_FUNC udhcp_send_raw_packet(stru
  16  {
  17         struct sockaddr_ll dest_sll;
  18         struct ip_udp_dhcp_packet packet;
  19 -       unsigned padding;
  20         int fd;
  21         int result = -1;
  22         const char *msg;
  23 +       int p_len = udhcp_get_payload_len(dhcp_pkt);
  24
  25         fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
  26         if (fd < 0) {
  27 @@ -185,8 +190,8 @@ int FAST_FUNC udhcp_send_raw_packet(stru
  28         }
  29
  30         memset(&dest_sll, 0, sizeof(dest_sll));
  31 -       memset(&packet, 0, offsetof(struct ip_udp_dhcp_packet, data));
  32 -       packet.data = *dhcp_pkt; /* struct copy */
  33 +       memset(&packet, 0, sizeof(packet));
  34 +       memcpy(&(packet.data), dhcp_pkt, p_len);
  35
  36         dest_sll.sll_family = AF_PACKET;
  37         dest_sll.sll_protocol = htons(ETH_P_IP);
  38 @@ -199,36 +204,24 @@ int FAST_FUNC udhcp_send_raw_packet(stru
  39                 goto ret_close;
  40         }
  41
  42 -       /* We were sending full-sized DHCP packets (zero padded),
  43 -        * but some badly configured servers were seen dropping them.
  44 -        * Apparently they drop all DHCP packets >576 *ethernet* octets big,
  45 -        * whereas they may only drop packets >576 *IP* octets big
  46 -        * (which for typical Ethernet II means 590 octets: 6+6+2 + 576).
  47 -        *
  48 -        * In order to work with those buggy servers,
  49 -        * we truncate packets after end option byte.
  50 -        */
  51 -       padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(packet.data.options);
  52 -
  53         packet.ip.protocol = IPPROTO_UDP;
  54         packet.ip.saddr = source_nip;
  55         packet.ip.daddr = dest_nip;
  56         packet.udp.source = htons(source_port);
  57         packet.udp.dest = htons(dest_port);
  58 -       /* size, excluding IP header: */
  59 -       packet.udp.len = htons(UDP_DHCP_SIZE - padding);
  60 -       /* for UDP checksumming, ip.len is set to UDP packet len */
  61 +       p_len += sizeof(packet.udp);
  62 +       packet.udp.len = htons(p_len);
  63         packet.ip.tot_len = packet.udp.len;
  64 -       packet.udp.check = udhcp_checksum(&packet, IP_UDP_DHCP_SIZE - padding);
  65 -       /* but for sending, it is set to IP packet len */
  66 -       packet.ip.tot_len = htons(IP_UDP_DHCP_SIZE - padding);
  67 +       p_len += sizeof(packet.ip);
  68 +       packet.udp.check = udhcp_checksum(&packet, p_len);
  69 +       packet.ip.tot_len = htons(p_len);
  70         packet.ip.ihl = sizeof(packet.ip) >> 2;
  71         packet.ip.version = IPVERSION;
  72         packet.ip.ttl = IPDEFTTL;
  73         packet.ip.check = udhcp_checksum(&packet.ip, sizeof(packet.ip));
  74
  75         udhcp_dump_packet(dhcp_pkt);
  76 -       result = sendto(fd, &packet, IP_UDP_DHCP_SIZE - padding, /*flags:*/ 0,
  77 +       result = sendto(fd, &packet, p_len, /*flags:*/ 0,
  78                         (struct sockaddr *) &dest_sll, sizeof(dest_sll));
  79         msg = "sendto";
  80   ret_close:
  81 @@ -246,7 +239,6 @@ int FAST_FUNC udhcp_send_kernel_packet(s
  82                 uint32_t dest_nip, int dest_port)
  83  {
  84         struct sockaddr_in client;
  85 -       unsigned padding;
  86         int fd;
  87         int result = -1;
  88         const char *msg;
  89 @@ -277,9 +269,7 @@ int FAST_FUNC udhcp_send_kernel_packet(s
  90         }
  91
  92         udhcp_dump_packet(dhcp_pkt);
  93 -
  94 -       padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(dhcp_pkt->options);
  95 -       result = safe_write(fd, dhcp_pkt, DHCP_SIZE - padding);
  96 +       result = safe_write(fd, dhcp_pkt, udhcp_get_payload_len(dhcp_pkt));
  97         msg = "write";
  98   ret_close:
  99         close(fd);