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

   1 diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c
   2 index 2b7528c..94e53dc 100644
   3 --- a/networking/udhcp/packet.c
   4 +++ b/networking/udhcp/packet.c
   5 @@ -165,6 +165,11 @@ uint16_t FAST_FUNC udhcp_checksum(void *addr, int count)
   6         return ~sum;
   7  }
   8
   9 +int udhcp_get_payload_len(struct dhcp_packet *dhcp_pkt)
  10 +{
  11 +       return sizeof(struct dhcp_packet) - DHCP_OPTIONS_BUFSIZE + udhcp_end_option(dhcp_pkt->options) + sizeof(dhcp_pkt->options[0]);
  12 +}
  13 +
  14  /* Construct a ip/udp header for a packet, send packet */
  15  int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
  16                 uint32_t source_nip, int source_port,
  17 @@ -173,10 +178,10 @@ int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
  18  {
  19         struct sockaddr_ll dest_sll;
  20         struct ip_udp_dhcp_packet packet;
  21 -       unsigned padding;
  22         int fd;
  23         int result = -1;
  24         const char *msg;
  25 +       int p_len = udhcp_get_payload_len(dhcp_pkt);
  26
  27         fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
  28         if (fd < 0) {
  29 @@ -185,8 +190,8 @@ int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
  30         }
  31
  32         memset(&dest_sll, 0, sizeof(dest_sll));
  33 -       memset(&packet, 0, offsetof(struct ip_udp_dhcp_packet, data));
  34 -       packet.data = *dhcp_pkt; /* struct copy */
  35 +       memset(&packet, 0, sizeof(packet));
  36 +       memcpy(&(packet.data), dhcp_pkt, p_len);
  37
  38         dest_sll.sll_family = AF_PACKET;
  39         dest_sll.sll_protocol = htons(ETH_P_IP);
  40 @@ -199,36 +204,24 @@ int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
  41                 goto ret_close;
  42         }
  43
  44 -       /* We were sending full-sized DHCP packets (zero padded),
  45 -        * but some badly configured servers were seen dropping them.
  46 -        * Apparently they drop all DHCP packets >576 *ethernet* octets big,
  47 -        * whereas they may only drop packets >576 *IP* octets big
  48 -        * (which for typical Ethernet II means 590 octets: 6+6+2 + 576).
  49 -        *
  50 -        * In order to work with those buggy servers,
  51 -        * we truncate packets after end option byte.
  52 -        */
  53 -       padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(packet.data.options);
  54 -
  55         packet.ip.protocol = IPPROTO_UDP;
  56         packet.ip.saddr = source_nip;
  57         packet.ip.daddr = dest_nip;
  58         packet.udp.source = htons(source_port);
  59         packet.udp.dest = htons(dest_port);
  60 -       /* size, excluding IP header: */
  61 -       packet.udp.len = htons(UDP_DHCP_SIZE - padding);
  62 -       /* for UDP checksumming, ip.len is set to UDP packet len */
  63 +       p_len += sizeof(packet.udp);
  64 +       packet.udp.len = htons(p_len);
  65         packet.ip.tot_len = packet.udp.len;
  66 -       packet.udp.check = udhcp_checksum(&packet, IP_UDP_DHCP_SIZE - padding);
  67 -       /* but for sending, it is set to IP packet len */
  68 -       packet.ip.tot_len = htons(IP_UDP_DHCP_SIZE - padding);
  69 +       p_len += sizeof(packet.ip);
  70 +       packet.udp.check = udhcp_checksum(&packet, p_len);
  71 +       packet.ip.tot_len = htons(p_len);
  72         packet.ip.ihl = sizeof(packet.ip) >> 2;
  73         packet.ip.version = IPVERSION;
  74         packet.ip.ttl = IPDEFTTL;
  75         packet.ip.check = udhcp_checksum(&packet.ip, sizeof(packet.ip));
  76
  77         udhcp_dump_packet(dhcp_pkt);
  78 -       result = sendto(fd, &packet, IP_UDP_DHCP_SIZE - padding, /*flags:*/ 0,
  79 +       result = sendto(fd, &packet, p_len, /*flags:*/ 0,
  80                         (struct sockaddr *) &dest_sll, sizeof(dest_sll));
  81         msg = "sendto";
  82   ret_close:
  83 @@ -246,7 +239,6 @@ int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
  84                 uint32_t dest_nip, int dest_port)
  85  {
  86         struct sockaddr_in client;
  87 -       unsigned padding;
  88         int fd;
  89         int result = -1;
  90         const char *msg;
  91 @@ -277,9 +269,7 @@ int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
  92         }
  93
  94         udhcp_dump_packet(dhcp_pkt);
  95 -
  96 -       padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(dhcp_pkt->options);
  97 -       result = safe_write(fd, dhcp_pkt, DHCP_SIZE - padding);
  98 +       result = safe_write(fd, dhcp_pkt, udhcp_get_payload_len(dhcp_pkt));
  99         msg = "write";
 100   ret_close:
 101         close(fd);