1 files changed, 23 insertions, 13 deletions

diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c
index 0abe851a4..c3890229f 100644
--- a/networking/udhcp/packet.c
+++ b/networking/udhcp/packet.c
@@ -39,7 +39,7 @@ void udhcp_init_header(struct dhcpMessage *packet, char type)
 
 
 /* read a packet from socket fd, return -1 on read error, -2 on packet error */
-int udhcp_get_packet(struct dhcpMessage *packet, int fd)
+int udhcp_recv_packet(struct dhcpMessage *packet, int fd)
 {
 #if 0
         static const char broken_vendors[][8] = {
@@ -111,7 +111,7 @@ uint16_t udhcp_checksum(void *addr, int count)
                 /* Make sure that the left-over byte is added correctly both
                  * with little and big endian hosts */
                 uint16_t tmp = 0;
-                *(uint8_t *) (&tmp) = * (uint8_t *) source;
+                *(uint8_t*)&tmp = *(uint8_t*)source;
                 sum += tmp;
         }
         /*  Fold 32-bit sum to 16 bits */
@@ -123,7 +123,7 @@ uint16_t udhcp_checksum(void *addr, int count)
 
 
 /* Construct a ip/udp header for a packet, and specify the source and dest hardware address */
-int udhcp_raw_packet(struct dhcpMessage *payload,
+int udhcp_send_raw_packet(struct dhcpMessage *payload,
                 uint32_t source_ip, int source_port,
                 uint32_t dest_ip, int dest_port, const uint8_t *dest_arp, int ifindex)
 {
@@ -132,6 +132,11 @@ int udhcp_raw_packet(struct dhcpMessage *payload,
         struct sockaddr_ll dest;
         struct udp_dhcp_packet packet;
 
+        enum {
+                IP_UPD_DHCP_SIZE = sizeof(struct udp_dhcp_packet) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
+                UPD_DHCP_SIZE    = IP_UPD_DHCP_SIZE - offsetof(struct udp_dhcp_packet, udp),
+        };
+
         fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
         if (fd < 0) {
                 bb_perror_msg("socket");
@@ -140,6 +145,7 @@ int udhcp_raw_packet(struct dhcpMessage *payload,
 
         memset(&dest, 0, sizeof(dest));
         memset(&packet, 0, sizeof(packet));
+        packet.data = *payload; /* struct copy */
 
         dest.sll_family = AF_PACKET;
         dest.sll_protocol = htons(ETH_P_IP);
@@ -157,19 +163,19 @@ int udhcp_raw_packet(struct dhcpMessage *payload,
         packet.ip.daddr = dest_ip;
         packet.udp.source = htons(source_port);
         packet.udp.dest = htons(dest_port);
-        packet.udp.len = htons(sizeof(packet.udp) + sizeof(struct dhcpMessage)); /* cheat on the psuedo-header */
+        /* size, excluding IP header: */
+        packet.udp.len = htons(UPD_DHCP_SIZE);
+        /* for UDP checksumming, ip.len is set to UDP packet len */
         packet.ip.tot_len = packet.udp.len;
-        memcpy(&(packet.data), payload, sizeof(struct dhcpMessage));
-        packet.udp.check = udhcp_checksum(&packet, sizeof(struct udp_dhcp_packet));
-
-        packet.ip.tot_len = htons(sizeof(struct udp_dhcp_packet));
+        packet.udp.check = udhcp_checksum(&packet, IP_UPD_DHCP_SIZE);
+        /* but for sending, it is set to IP packet len */
+        packet.ip.tot_len = htons(IP_UPD_DHCP_SIZE);
         packet.ip.ihl = sizeof(packet.ip) >> 2;
         packet.ip.version = IPVERSION;
         packet.ip.ttl = IPDEFTTL;
-        packet.ip.check = udhcp_checksum(&(packet.ip), sizeof(packet.ip));
+        packet.ip.check = udhcp_checksum(&packet.ip, sizeof(packet.ip));
 
-        result = sendto(fd, &packet, sizeof(struct udp_dhcp_packet), 0,
-                        (struct sockaddr *) &dest, sizeof(dest));
+        result = sendto(fd, &packet, IP_UPD_DHCP_SIZE, 0, (struct sockaddr *) &dest, sizeof(dest));
         if (result <= 0) {
                 bb_perror_msg("sendto");
         }
@@ -179,13 +185,17 @@ int udhcp_raw_packet(struct dhcpMessage *payload,
 
 
 /* Let the kernel do all the work for packet generation */
-int udhcp_kernel_packet(struct dhcpMessage *payload,
+int udhcp_send_kernel_packet(struct dhcpMessage *payload,
                 uint32_t source_ip, int source_port,
                 uint32_t dest_ip, int dest_port)
 {
         int fd, result;
         struct sockaddr_in client;
 
+        enum {
+                DHCP_SIZE = sizeof(struct dhcpMessage) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
+        };
+
         fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
         if (fd < 0)
                 return -1;
@@ -212,7 +222,7 @@ int udhcp_kernel_packet(struct dhcpMessage *payload,
                 return -1;
         }
 
-        result = write(fd, payload, sizeof(struct dhcpMessage));
+        result = write(fd, payload, DHCP_SIZE);
         close(fd);
         return result;
 }