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/clientpacket.c b/networking/udhcp/clientpacket.c
index 54f3f0e..0347310 100644
--- a/networking/udhcp/clientpacket.c
+++ b/networking/udhcp/clientpacket.c
@@ -86,7 +86,7 @@
bb_info_msg("Sending decline...");
- return udhcp_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
+ return udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
}
#endif
@@ -106,7 +106,7 @@
add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576));
add_requests(&packet);
bb_info_msg("Sending discover...");
- return udhcp_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
+ return udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
}
@@ -126,7 +126,7 @@
add_requests(&packet);
addr.s_addr = requested;
bb_info_msg("Sending select for %s...", inet_ntoa(addr));
- return udhcp_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
+ return udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
}
@@ -143,9 +143,9 @@
add_requests(&packet);
bb_info_msg("Sending renew...");
if (server)
- return udhcp_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
+ return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
- return udhcp_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
+ return udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
}
@@ -163,7 +163,7 @@
add_simple_option(packet.options, DHCP_SERVER_ID, server);
bb_info_msg("Sending release...");
- return udhcp_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
+ return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
}
@@ -172,7 +172,6 @@
{
int bytes;
struct udp_dhcp_packet packet;
- uint32_t source, dest;
uint16_t check;
memset(&packet, 0, sizeof(struct udp_dhcp_packet));
@@ -207,36 +206,31 @@
return -2;
}
- /* check IP checksum */
+ /* verify IP checksum */
check = packet.ip.check;
packet.ip.check = 0;
- if (check != udhcp_checksum(&(packet.ip), sizeof(packet.ip))) {
- DEBUG("bad IP header checksum, ignoring");
+ if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
+ DEBUG("Bad IP header checksum, ignoring");
return -1;
}
- /* verify the UDP checksum by replacing the header with a pseudo header */
- source = packet.ip.saddr;
- dest = packet.ip.daddr;
+ /* verify UDP checksum. IP header has to be modified for this */
+ memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
+ /* fields which are not memset: protocol, check, saddr, daddr */
+ packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
check = packet.udp.check;
packet.udp.check = 0;
- memset(&packet.ip, 0, sizeof(packet.ip));
-
- packet.ip.protocol = IPPROTO_UDP;
- packet.ip.saddr = source;
- packet.ip.daddr = dest;
- packet.ip.tot_len = packet.udp.len; /* cheat on the psuedo-header */
if (check && check != udhcp_checksum(&packet, bytes)) {
bb_error_msg("packet with bad UDP checksum received, ignoring");
return -2;
}
- memcpy(payload, &(packet.data), bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
+ memcpy(payload, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
if (payload->cookie != htonl(DHCP_MAGIC)) {
bb_error_msg("received bogus message (bad magic) - ignoring");
return -2;
}
- DEBUG("oooooh!!! got some!");
+ DEBUG("Got valid DHCP packet");
return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
}
diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index 55782b5..38ede01 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -54,14 +54,16 @@
[(sizeof(struct udp_dhcp_packet) != 576 + CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS) ? -1 : 1];
};
-void udhcp_init_header(struct dhcpMessage *packet, char type);
-int udhcp_get_packet(struct dhcpMessage *packet, int fd);
uint16_t udhcp_checksum(void *addr, int count);
-int udhcp_raw_packet(struct dhcpMessage *payload,
+
+void udhcp_init_header(struct dhcpMessage *packet, char type);
+
+int udhcp_recv_packet(struct dhcpMessage *packet, int fd);
+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);
-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);
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 69c35ca..3de389f 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -451,7 +451,7 @@
/* A packet is ready, read it */
if (listen_mode == LISTEN_KERNEL)
- len = udhcp_get_packet(&packet, sockfd);
+ len = udhcp_recv_packet(&packet, sockfd);
else len = get_raw_packet(&packet, sockfd);
if (len == -1 && errno != EINTR) {
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index 9679e08..45f445b 100644
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -133,7 +133,7 @@
default: continue; /* signal or error (probably EINTR) */
}
- bytes = udhcp_get_packet(&packet, server_socket); /* this waits for a packet - idle */
+ bytes = udhcp_recv_packet(&packet, server_socket); /* this waits for a packet - idle */
if (bytes < 0) {
if (bytes == -1 && errno != EINTR) {
DEBUG("error on read, %s, reopening socket", strerror(errno));
diff --git a/networking/udhcp/dhcprelay.c b/networking/udhcp/dhcprelay.c
index 42378d6..a6483fc 100644
--- a/networking/udhcp/dhcprelay.c
+++ b/networking/udhcp/dhcprelay.c
@@ -256,7 +256,7 @@
if (select(max_socket + 1, &rfds, NULL, NULL, &tv) > 0) {
/* server */
if (FD_ISSET(fds[0], &rfds)) {
- packlen = udhcp_get_packet(&dhcp_msg, fds[0]);
+ packlen = udhcp_recv_packet(&dhcp_msg, fds[0]);
if (packlen > 0) {
pass_back(&dhcp_msg, packlen, fds);
}
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;
}
diff --git a/networking/udhcp/serverpacket.c b/networking/udhcp/serverpacket.c
index ecbf50a..764b9a8 100644
--- a/networking/udhcp/serverpacket.c
+++ b/networking/udhcp/serverpacket.c
@@ -30,7 +30,7 @@
{
DEBUG("Forwarding packet to relay");
- return udhcp_kernel_packet(payload, server_config.server, SERVER_PORT,
+ return udhcp_send_kernel_packet(payload, server_config.server, SERVER_PORT,
payload->giaddr, SERVER_PORT);
}
@@ -58,7 +58,7 @@
ciaddr = payload->yiaddr;
chaddr = payload->chaddr;
}
- return udhcp_raw_packet(payload, server_config.server, SERVER_PORT,
+ return udhcp_send_raw_packet(payload, server_config.server, SERVER_PORT,
ciaddr, CLIENT_PORT, chaddr, server_config.ifindex);
}