X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;ds=sidebyside;f=networking%2Fudhcp%2Fclientpacket.c;h=21c1a7bd56a15987ee70aa17f66cd051797eba4d;hb=bcbd37df2495359195b0deda7c85deacc9b3ff13;hp=58b26c171571c89452de8e7510556112e962e46c;hpb=e1a0d486e4804eae098571f1a6788394c2ee51ae;p=oweals%2Fbusybox.git diff --git a/networking/udhcp/clientpacket.c b/networking/udhcp/clientpacket.c index 58b26c171..21c1a7bd5 100644 --- a/networking/udhcp/clientpacket.c +++ b/networking/udhcp/clientpacket.c @@ -8,10 +8,8 @@ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. */ -#include -#include #include -#if (__GLIBC__ >= 2 && __GLIBC_MINOR >= 1) || defined _NEWLIB_VERSION +#if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined _NEWLIB_VERSION #include #include #else @@ -19,92 +17,140 @@ #include #include #endif -#include -#include -#include -#include -#include -#include - +#include "common.h" #include "dhcpd.h" -#include "clientpacket.h" -#include "options.h" #include "dhcpc.h" -#include "common.h" +#include "options.h" /* Create a random xid */ -unsigned long random_xid(void) +uint32_t FAST_FUNC random_xid(void) { - static int initialized; - if (!initialized) { - unsigned long seed; + static smallint initialized; - if (open_read_close("/dev/urandom", &seed, sizeof(seed)) < 0) { - bb_info_msg("Cannot load seed " - "from /dev/urandom: %s", strerror(errno)); - seed = time(0); - } - srand(seed); - initialized++; + if (!initialized) { + srand(monotonic_us()); + initialized = 1; } return rand(); } -/* initialize a packet with the proper defaults */ -static void init_packet(struct dhcpMessage *packet, char type) +/* Initialize the packet with the proper defaults */ +static void init_packet(struct dhcp_packet *packet, char type) { udhcp_init_header(packet, type); - memcpy(packet->chaddr, client_config.arp, 6); + memcpy(packet->chaddr, client_config.client_mac, 6); if (client_config.clientid) - add_option_string(packet->options, client_config.clientid); - if (client_config.hostname) add_option_string(packet->options, client_config.hostname); - if (client_config.fqdn) add_option_string(packet->options, client_config.fqdn); - add_option_string(packet->options, client_config.vendorclass); + add_option_string(packet->options, client_config.clientid); + if (client_config.hostname) + add_option_string(packet->options, client_config.hostname); + if (client_config.fqdn) + add_option_string(packet->options, client_config.fqdn); + if ((type != DHCPDECLINE) && (type != DHCPRELEASE)) + add_option_string(packet->options, client_config.vendorclass); } /* Add a parameter request list for stubborn DHCP servers. Pull the data * from the struct in options.c. Don't do bounds checking here because it * goes towards the head of the packet. */ -static void add_requests(struct dhcpMessage *packet) +static void add_param_req_option(struct dhcp_packet *packet) { + uint8_t c; int end = end_option(packet->options); int i, len = 0; - packet->options[end + OPT_CODE] = DHCP_PARAM_REQ; - for (i = 0; dhcp_options[i].code; i++) - if (dhcp_options[i].flags & OPTION_REQ) - packet->options[end + OPT_DATA + len++] = dhcp_options[i].code; - packet->options[end + OPT_LEN] = len; - packet->options[end + OPT_DATA + len] = DHCP_END; + for (i = 0; (c = dhcp_options[i].code) != 0; i++) { + if (((dhcp_options[i].flags & OPTION_REQ) + && !client_config.no_default_options) + || (client_config.opt_mask[c >> 3] & (1 << (c & 7))) + ) { + packet->options[end + OPT_DATA + len] = c; + len++; + } + } + if (len) { + packet->options[end + OPT_CODE] = DHCP_PARAM_REQ; + packet->options[end + OPT_LEN] = len; + packet->options[end + OPT_DATA + len] = DHCP_END; + } +} + +/* RFC 2131 + * 4.4.4 Use of broadcast and unicast + * + * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM + * messages, unless the client knows the address of a DHCP server. + * The client unicasts DHCPRELEASE messages to the server. Because + * the client is declining the use of the IP address supplied by the server, + * the client broadcasts DHCPDECLINE messages. + * + * When the DHCP client knows the address of a DHCP server, in either + * INIT or REBOOTING state, the client may use that address + * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address. + * The client may also use unicast to send DHCPINFORM messages + * to a known DHCP server. If the client receives no response to DHCP + * messages sent to the IP address of a known DHCP server, the DHCP + * client reverts to using the IP broadcast address. + */ +static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet) +{ + return udhcp_send_raw_packet(packet, + /*src*/ INADDR_ANY, CLIENT_PORT, + /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR, + client_config.ifindex); } +#if ENABLE_FEATURE_UDHCPC_ARPING +/* Broadcast a DHCP decline message */ +int FAST_FUNC send_decline(uint32_t xid, uint32_t server, uint32_t requested) +{ + struct dhcp_packet packet; + + init_packet(&packet, DHCPDECLINE); + packet.xid = xid; + add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); + add_simple_option(packet.options, DHCP_SERVER_ID, server); + + bb_info_msg("Sending decline..."); + + return raw_bcast_from_client_config_ifindex(&packet); +} +#endif + + /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */ -int send_discover(unsigned long xid, unsigned long requested) +int FAST_FUNC send_discover(uint32_t xid, uint32_t requested) { - struct dhcpMessage packet; + struct dhcp_packet packet; init_packet(&packet, DHCPDISCOVER); packet.xid = xid; if (requested) add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); - add_requests(&packet); + /* Explicitly saying that we want RFC-compliant packets helps + * some buggy DHCP servers to NOT send bigger packets */ + add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576)); + + add_param_req_option(&packet); + bb_info_msg("Sending discover..."); - return udhcp_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, - SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); + return raw_bcast_from_client_config_ifindex(&packet); } -/* Broadcasts a DHCP request message */ -int send_selecting(unsigned long xid, unsigned long server, unsigned long requested) +/* Broadcast a DHCP request message */ +/* RFC 2131 3.1 paragraph 3: + * "The client _broadcasts_ a DHCPREQUEST message..." + */ +int FAST_FUNC send_select(uint32_t xid, uint32_t server, uint32_t requested) { - struct dhcpMessage packet; + struct dhcp_packet packet; struct in_addr addr; init_packet(&packet, DHCPREQUEST); @@ -112,121 +158,116 @@ int send_selecting(unsigned long xid, unsigned long server, unsigned long reques add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); add_simple_option(packet.options, DHCP_SERVER_ID, server); + add_param_req_option(&packet); - 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, - SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); + return raw_bcast_from_client_config_ifindex(&packet); } /* Unicasts or broadcasts a DHCP renew message */ -int send_renew(unsigned long xid, unsigned long server, unsigned long ciaddr) +int FAST_FUNC send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr) { - struct dhcpMessage packet; - int ret = 0; + struct dhcp_packet packet; init_packet(&packet, DHCPREQUEST); packet.xid = xid; packet.ciaddr = ciaddr; - add_requests(&packet); + add_param_req_option(&packet); bb_info_msg("Sending renew..."); if (server) - ret = udhcp_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT); - else ret = udhcp_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, - SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); - return ret; + return udhcp_send_kernel_packet(&packet, + ciaddr, CLIENT_PORT, + server, SERVER_PORT); + + return raw_bcast_from_client_config_ifindex(&packet); } /* Unicasts a DHCP release message */ -int send_release(unsigned long server, unsigned long ciaddr) +int FAST_FUNC send_release(uint32_t server, uint32_t ciaddr) { - struct dhcpMessage packet; + struct dhcp_packet packet; init_packet(&packet, DHCPRELEASE); packet.xid = random_xid(); packet.ciaddr = ciaddr; - add_simple_option(packet.options, DHCP_REQUESTED_IP, 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); } -/* return -1 on errors that are fatal for the socket, -2 for those that aren't */ -int get_raw_packet(struct dhcpMessage *payload, int fd) +/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */ +int FAST_FUNC udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd) { int bytes; - struct udp_dhcp_packet packet; - uint32_t source, dest; + struct ip_udp_dhcp_packet packet; uint16_t check; - memset(&packet, 0, sizeof(struct udp_dhcp_packet)); - bytes = read(fd, &packet, sizeof(struct udp_dhcp_packet)); + memset(&packet, 0, sizeof(packet)); + bytes = safe_read(fd, &packet, sizeof(packet)); if (bytes < 0) { - DEBUG("Cannot read on raw listening socket - ignoring"); - usleep(500000); /* possible down interface, looping condition */ - return -1; + log1("Packet read error, ignoring"); + /* NB: possible down interface, etc. Caller should pause. */ + return bytes; /* returns -1 */ } - if (bytes < (int) (sizeof(struct iphdr) + sizeof(struct udphdr))) { - DEBUG("Message too short, ignoring"); + if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) { + log1("Packet is too short, ignoring"); return -2; } if (bytes < ntohs(packet.ip.tot_len)) { - DEBUG("Truncated packet"); + /* packet is bigger than sizeof(packet), we did partial read */ + log1("Oversized packet, ignoring"); return -2; } /* ignore any extra garbage bytes */ bytes = ntohs(packet.ip.tot_len); - /* Make sure its the right packet for us, and that it passes sanity checks */ - if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION || - packet.ip.ihl != sizeof(packet.ip) >> 2 || packet.udp.dest != htons(CLIENT_PORT) || - bytes > (int) sizeof(struct udp_dhcp_packet) || - ntohs(packet.udp.len) != (uint16_t) (bytes - sizeof(packet.ip))) { - DEBUG("Unrelated/bogus packet"); + /* make sure its the right packet for us, and that it passes sanity checks */ + if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION + || packet.ip.ihl != (sizeof(packet.ip) >> 2) + || packet.udp.dest != htons(CLIENT_PORT) + /* || bytes > (int) sizeof(packet) - can't happen */ + || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip)) + ) { + log1("Unrelated/bogus packet, ignoring"); 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"); - return -1; + if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) { + log1("Bad IP header checksum, ignoring"); + return -2; } - /* verify the UDP checksum by replacing the header with a psuedo 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)); + /* ip.xx 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"); + log1("Packet with bad UDP checksum received, ignoring"); return -2; } - memcpy(payload, &(packet.data), bytes - (sizeof(packet.ip) + sizeof(packet.udp))); + memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp))); - if (ntohl(payload->cookie) != DHCP_MAGIC) { - bb_error_msg("received bogus message (bad magic) - ignoring"); + if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) { + bb_info_msg("Packet with bad magic, ignoring"); return -2; } - DEBUG("oooooh!!! got some!"); + log1("Got valid DHCP packet"); + udhcp_dump_packet(dhcp_pkt); return bytes - (sizeof(packet.ip) + sizeof(packet.udp)); - }