X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=networking%2Fudhcp%2Fpacket.c;h=64af802a34c5c2cf3436fd4d6d5d19e1679ac384;hb=253c4e787a799a3e1f92957ed791b5222f8d2f64;hp=a3c7ae153010e34c9687c2392665c6830d3f4471;hpb=ad95373efcd7eaa4d641a7a821e5b05fb2d31e1d;p=oweals%2Fbusybox.git diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c index a3c7ae153..64af802a3 100644 --- a/networking/udhcp/packet.c +++ b/networking/udhcp/packet.c @@ -1,202 +1,238 @@ -#include -#include +/* vi: set sw=4 ts=4: */ +/* + * Packet ops + * + * Rewrite by Russ Dill July 2001 + * + * Licensed under GPLv2, see file LICENSE in this source tree. + */ +#include "common.h" +#include "dhcpd.h" #include -#include -#include -#include -#if __GLIBC__ >=2 && __GLIBC_MINOR >= 1 +#include #include -#include -#else -#include -#include -#include -#endif -#include - -#include "packet.h" -#include "dhcpd.h" -#include "options.h" -#include "common.h" - -void init_header(struct dhcpMessage *packet, char type) +#if ENABLE_UDHCPC || ENABLE_UDHCPD +void FAST_FUNC udhcp_init_header(struct dhcp_packet *packet, char type) { - memset(packet, 0, sizeof(struct dhcpMessage)); + memset(packet, 0, sizeof(*packet)); + packet->op = BOOTREQUEST; /* if client to a server */ switch (type) { - case DHCPDISCOVER: - case DHCPREQUEST: - case DHCPRELEASE: - case DHCPINFORM: - packet->op = BOOTREQUEST; - break; case DHCPOFFER: case DHCPACK: case DHCPNAK: - packet->op = BOOTREPLY; + packet->op = BOOTREPLY; /* if server to client */ } - packet->htype = ETH_10MB; - packet->hlen = ETH_10MB_LEN; + packet->htype = 1; /* ethernet */ + packet->hlen = 6; packet->cookie = htonl(DHCP_MAGIC); - packet->options[0] = DHCP_END; - add_simple_option(packet->options, DHCP_MESSAGE_TYPE, type); + if (DHCP_END != 0) + packet->options[0] = DHCP_END; + udhcp_add_simple_option(packet, DHCP_MESSAGE_TYPE, type); } +#endif +#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2 +void FAST_FUNC udhcp_dump_packet(struct dhcp_packet *packet) +{ + char buf[sizeof(packet->chaddr)*2 + 1]; + + if (dhcp_verbose < 2) + return; + + bb_info_msg( + //" op %x" + //" htype %x" + " hlen %x" + //" hops %x" + " xid %x" + //" secs %x" + //" flags %x" + " ciaddr %x" + " yiaddr %x" + " siaddr %x" + " giaddr %x" + //" sname %s" + //" file %s" + //" cookie %x" + //" options %s" + //, packet->op + //, packet->htype + , packet->hlen + //, packet->hops + , packet->xid + //, packet->secs + //, packet->flags + , packet->ciaddr + , packet->yiaddr + , packet->siaddr_nip + , packet->gateway_nip + //, packet->sname[64] + //, packet->file[128] + //, packet->cookie + //, packet->options[] + ); + *bin2hex(buf, (void *) packet->chaddr, sizeof(packet->chaddr)) = '\0'; + bb_info_msg(" chaddr %s", buf); +} +#endif -/* read a packet from socket fd, return -1 on read error, -2 on packet error */ -int get_packet(struct dhcpMessage *packet, int fd) +/* Read a packet from socket fd, return -1 on read error, -2 on packet error */ +int FAST_FUNC udhcp_recv_kernel_packet(struct dhcp_packet *packet, int fd) { int bytes; - int i; - const char broken_vendors[][8] = { - "MSFT 98", - "" - }; - char unsigned *vendor; - - memset(packet, 0, sizeof(struct dhcpMessage)); - bytes = read(fd, packet, sizeof(struct dhcpMessage)); + + memset(packet, 0, sizeof(*packet)); + bytes = safe_read(fd, packet, sizeof(*packet)); if (bytes < 0) { - DEBUG(LOG_INFO, "couldn't read on listening socket, ignoring"); - return -1; + log1("packet read error, ignoring"); + return bytes; /* returns -1 */ } - if (ntohl(packet->cookie) != DHCP_MAGIC) { - LOG(LOG_ERR, "received bogus message, ignoring"); + if (bytes < offsetof(struct dhcp_packet, options) + || packet->cookie != htonl(DHCP_MAGIC) + ) { + bb_info_msg("packet with bad magic, ignoring"); return -2; } - DEBUG(LOG_INFO, "Received a packet"); - - if (packet->op == BOOTREQUEST && (vendor = get_option(packet, DHCP_VENDOR))) { - for (i = 0; broken_vendors[i][0]; i++) { - if (vendor[OPT_LEN - 2] == (uint8_t) strlen(broken_vendors[i]) && - !strncmp(vendor, broken_vendors[i], vendor[OPT_LEN - 2])) { - DEBUG(LOG_INFO, "broken client (%s), forcing broadcast", - broken_vendors[i]); - packet->flags |= htons(BROADCAST_FLAG); - } - } - } - + log1("received %s", "a packet"); + udhcp_dump_packet(packet); return bytes; } - -uint16_t checksum(void *addr, int count) +/* Construct a ip/udp header for a packet, send packet */ +int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt, + uint32_t source_nip, int source_port, + uint32_t dest_nip, int dest_port, const uint8_t *dest_arp, + int ifindex) { - /* Compute Internet Checksum for "count" bytes - * beginning at location "addr". - */ - register int32_t sum = 0; - uint16_t *source = (uint16_t *) addr; + struct sockaddr_ll dest_sll; + struct ip_udp_dhcp_packet packet; + unsigned padding; + int fd; + int result = -1; + const char *msg; - while (count > 1) { - /* This is the inner loop */ - sum += *source++; - count -= 2; + fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP)); + if (fd < 0) { + msg = "socket(%s)"; + goto ret_msg; } - /* Add left-over byte, if any */ - if (count > 0) { - /* 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; - sum += tmp; + memset(&dest_sll, 0, sizeof(dest_sll)); + memset(&packet, 0, offsetof(struct ip_udp_dhcp_packet, data)); + packet.data = *dhcp_pkt; /* struct copy */ + + dest_sll.sll_family = AF_PACKET; + dest_sll.sll_protocol = htons(ETH_P_IP); + dest_sll.sll_ifindex = ifindex; + /*dest_sll.sll_hatype = ARPHRD_???;*/ + /*dest_sll.sll_pkttype = PACKET_???;*/ + dest_sll.sll_halen = 6; + memcpy(dest_sll.sll_addr, dest_arp, 6); + + if (bind(fd, (struct sockaddr *)&dest_sll, sizeof(dest_sll)) < 0) { + msg = "bind(%s)"; + goto ret_close; } - /* Fold 32-bit sum to 16 bits */ - while (sum >> 16) - sum = (sum & 0xffff) + (sum >> 16); - - return ~sum; -} - -/* Constuct a ip/udp header for a packet, and specify the source and dest hardware address */ -int raw_packet(struct dhcpMessage *payload, uint32_t source_ip, int source_port, - uint32_t dest_ip, int dest_port, uint8_t *dest_arp, int ifindex) -{ - int fd; - int result; - struct sockaddr_ll dest; - struct udp_dhcp_packet packet; - - if ((fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP))) < 0) { - DEBUG(LOG_ERR, "socket call failed: %m"); - return -1; - } - - memset(&dest, 0, sizeof(dest)); - memset(&packet, 0, sizeof(packet)); - - dest.sll_family = AF_PACKET; - dest.sll_protocol = htons(ETH_P_IP); - dest.sll_ifindex = ifindex; - dest.sll_halen = 6; - memcpy(dest.sll_addr, dest_arp, 6); - if (bind(fd, (struct sockaddr *)&dest, sizeof(struct sockaddr_ll)) < 0) { - DEBUG(LOG_ERR, "bind call failed: %m"); - close(fd); - return -1; - } + /* We were sending full-sized DHCP packets (zero padded), + * but some badly configured servers were seen dropping them. + * Apparently they drop all DHCP packets >576 *ethernet* octets big, + * whereas they may only drop packets >576 *IP* octets big + * (which for typical Ethernet II means 590 octets: 6+6+2 + 576). + * + * In order to work with those buggy servers, + * we truncate packets after end option byte. + * + * However, RFC 1542 says "The IP Total Length and UDP Length + * must be large enough to contain the minimal BOOTP header of 300 octets". + * Thus, we retain enough padding to not go below 300 BOOTP bytes. + * Some devices have filters which drop DHCP packets shorter than that. + */ + padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(packet.data.options); + if (padding > DHCP_SIZE - 300) + padding = DHCP_SIZE - 300; packet.ip.protocol = IPPROTO_UDP; - packet.ip.saddr = source_ip; - packet.ip.daddr = dest_ip; + packet.ip.saddr = source_nip; + packet.ip.daddr = dest_nip; 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(UDP_DHCP_SIZE - padding); + /* 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 = checksum(&packet, sizeof(struct udp_dhcp_packet)); - - packet.ip.tot_len = htons(sizeof(struct udp_dhcp_packet)); + packet.udp.check = inet_cksum((uint16_t *)&packet, + IP_UDP_DHCP_SIZE - padding); + /* but for sending, it is set to IP packet len */ + packet.ip.tot_len = htons(IP_UDP_DHCP_SIZE - padding); packet.ip.ihl = sizeof(packet.ip) >> 2; packet.ip.version = IPVERSION; packet.ip.ttl = IPDEFTTL; - packet.ip.check = checksum(&(packet.ip), sizeof(packet.ip)); + packet.ip.check = inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip)); - result = sendto(fd, &packet, sizeof(struct udp_dhcp_packet), 0, (struct sockaddr *) &dest, sizeof(dest)); - if (result <= 0) { - DEBUG(LOG_ERR, "write on socket failed: %m"); - } + udhcp_dump_packet(dhcp_pkt); + result = sendto(fd, &packet, IP_UDP_DHCP_SIZE - padding, /*flags:*/ 0, + (struct sockaddr *) &dest_sll, sizeof(dest_sll)); + msg = "sendto"; + ret_close: close(fd); + if (result < 0) { + ret_msg: + bb_perror_msg(msg, "PACKET"); + } return result; } - /* Let the kernel do all the work for packet generation */ -int kernel_packet(struct dhcpMessage *payload, uint32_t source_ip, int source_port, - uint32_t dest_ip, int dest_port) +int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt, + uint32_t source_nip, int source_port, + uint32_t dest_nip, int dest_port) { - int n = 1; - int fd, result; - struct sockaddr_in client; - - if ((fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) - return -1; - - if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, (char *) &n, sizeof(n)) == -1) - return -1; - - memset(&client, 0, sizeof(client)); - client.sin_family = AF_INET; - client.sin_port = htons(source_port); - client.sin_addr.s_addr = source_ip; - - if (bind(fd, (struct sockaddr *)&client, sizeof(struct sockaddr)) == -1) - return -1; - - memset(&client, 0, sizeof(client)); - client.sin_family = AF_INET; - client.sin_port = htons(dest_port); - client.sin_addr.s_addr = dest_ip; - - if (connect(fd, (struct sockaddr *)&client, sizeof(struct sockaddr)) == -1) - return -1; - - result = write(fd, payload, sizeof(struct dhcpMessage)); + struct sockaddr_in sa; + unsigned padding; + int fd; + int result = -1; + const char *msg; + + fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP); + if (fd < 0) { + msg = "socket(%s)"; + goto ret_msg; + } + setsockopt_reuseaddr(fd); + + memset(&sa, 0, sizeof(sa)); + sa.sin_family = AF_INET; + sa.sin_port = htons(source_port); + sa.sin_addr.s_addr = source_nip; + if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) { + msg = "bind(%s)"; + goto ret_close; + } + + memset(&sa, 0, sizeof(sa)); + sa.sin_family = AF_INET; + sa.sin_port = htons(dest_port); + sa.sin_addr.s_addr = dest_nip; + if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) { + msg = "connect"; + goto ret_close; + } + + udhcp_dump_packet(dhcp_pkt); + padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(dhcp_pkt->options); + if (padding > DHCP_SIZE - 300) + padding = DHCP_SIZE - 300; + result = safe_write(fd, dhcp_pkt, DHCP_SIZE - padding); + msg = "write"; + ret_close: close(fd); + if (result < 0) { + ret_msg: + bb_perror_msg(msg, "UDP"); + } return result; -} +}