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udhcp: fix oversized packet sending (introduced by "slack for bad dhcp servers" options);

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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
This commit is contained in:
Denis Vlasenko 2007-12-20 21:11:38 +00:00
parent f77f369ce8
commit fff145dba3
7 changed files with 49 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
networking/udhcp/clientpacket.c
View File

@ -86,7 +86,7 @@ int send_decline(uint32_t xid, uint32_t server)
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 @@ int send_discover(uint32_t xid, uint32_t requested)
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 @@ int send_selecting(uint32_t xid, uint32_t server, uint32_t requested)
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 @@ int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
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 @@ int send_release(uint32_t server, uint32_t ciaddr)
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 get_raw_packet(struct dhcpMessage *payload, int fd)
{
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 @@ int get_raw_packet(struct dhcpMessage *payload, int fd)
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));
}

10
networking/udhcp/common.h
View File

@ -54,14 +54,16 @@ struct BUG_bad_sizeof_struct_udp_dhcp_packet {
[(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);

2
networking/udhcp/dhcpc.c
View File

@ -451,7 +451,7 @@ int udhcpc_main(int argc, char **argv)
/* 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) {

2
networking/udhcp/dhcpd.c
View File

@ -133,7 +133,7 @@ int udhcpd_main(int argc, char **argv)
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));

2
networking/udhcp/dhcprelay.c
View File

@ -256,7 +256,7 @@ static void dhcprelay_loop(int *fds, int num_sockets, int max_socket, char **cli
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);
}

36
networking/udhcp/packet.c
View File

@ -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;
}

4
networking/udhcp/serverpacket.c
View File

@ -30,7 +30,7 @@ static int send_packet_to_relay(struct dhcpMessage *payload)
{
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 @@ static int send_packet_to_client(struct dhcpMessage *payload, int force_broadcas
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);
}