udhcp: fix oversized packet sending (introduced by "slack for bad dhcp servers" options);
slight optimizations and function renaming
udhcp_send_raw_packet - 391 +391
udhcp_send_kernel_packet - 197 +197
udhcp_recv_packet - 134 +134
get_raw_packet 353 326 -27
udhcp_get_packet 134 - -134
udhcp_kernel_packet 197 - -197
udhcp_raw_packet 391 - -391
------------------------------------------------------------------------------
(add/remove: 3/3 grow/shrink: 0/1 up/down: 722/-749) Total: -27 bytes
diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c
index 0abe851..c389022 100644
--- a/networking/udhcp/packet.c
+++ b/networking/udhcp/packet.c
@@ -39,7 +39,7 @@
/* 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 @@
/* 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 @@
/* 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 @@
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 @@
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 @@
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 @@
/* 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 @@
return -1;
}
- result = write(fd, payload, sizeof(struct dhcpMessage));
+ result = write(fd, payload, DHCP_SIZE);
close(fd);
return result;
}