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 (file)
--- a/networking/udhcp/clientpacket.c
+++ b/networking/udhcp/clientpacket.c
@@ -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));
 }

diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index 55782b5..38ede01 100644 (file)
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -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);
 

diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 69c35ca..3de389f 100644 (file)
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -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) {

diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index 9679e08..45f445b 100644 (file)
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -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));

diff --git a/networking/udhcp/dhcprelay.c b/networking/udhcp/dhcprelay.c
index 42378d6..a6483fc 100644 (file)
--- a/networking/udhcp/dhcprelay.c
+++ b/networking/udhcp/dhcprelay.c
@@ -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);
                                }

diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c
index 0abe851..c389022 100644 (file)
--- 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;
 }

diff --git a/networking/udhcp/serverpacket.c b/networking/udhcp/serverpacket.c
index ecbf50a..764b9a8 100644 (file)
--- a/networking/udhcp/serverpacket.c
+++ b/networking/udhcp/serverpacket.c
@@ -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);
 }