diff --git a/ndhc/arp.c b/ndhc/arp.c index c9ad90a..f8cfb99 100644 --- a/ndhc/arp.c +++ b/ndhc/arp.c @@ -1,5 +1,5 @@ /* arp.c - arp ping checking - * Time-stamp: <2011-06-02 10:48:31 njk> + * Time-stamp: <2011-06-11 11:12:58 njk> * * Copyright 2010-2011 Nicholas J. Kain * @@ -32,7 +32,6 @@ #include #include #include "arp.h" -#include "dhcpmsg.h" #include "packet.h" #include "socket.h" #include "sys.h" diff --git a/ndhc/dhcpmsg.c b/ndhc/dhcpmsg.c deleted file mode 100644 index 52666eb..0000000 --- a/ndhc/dhcpmsg.c +++ /dev/null @@ -1,281 +0,0 @@ -/* dhcpmsg.c - dhcp packet generation and sending functions - * Time-stamp: <2011-06-11 04:47:46 njk> - * - * (c) 2004-2011 Nicholas J. Kain - * (c) 2001 Russ Dill - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - */ - -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - -#include "dhcpmsg.h" -#include "packet.h" -#include "options.h" -#include "config.h" -#include "log.h" -#include "io.h" - -/* Create a random xid */ -uint32_t random_xid(void) -{ - static int initialized; - if (initialized) - return rand(); - - uint32_t seed; - int fd = open("/dev/urandom", O_RDONLY); - if (fd != -1) { - int r = safe_read(fd, (char *)&seed, sizeof seed); - if (r == -1) { - log_warning("Could not read /dev/urandom: %s", strerror(errno)); - close(fd); - seed = time(0); - } - } else { - log_warning("Could not open /dev/urandom: %s", - strerror(errno)); - seed = time(0); - } - srand(seed); - initialized = 1; - return rand(); -} - -/* Initializes dhcp packet header for a -client- packet. */ -static void init_header(struct dhcpMessage *packet, char type) -{ - memset(packet, 0, DHCP_SIZE); - packet->op = 1; // BOOTREQUEST (client) - packet->htype = 1; // ETH_10MB - packet->hlen = 6; // ETH_10MB_LEN - packet->cookie = htonl(DHCP_MAGIC); - packet->options[0] = DHCP_END; - add_u32_option(packet->options, DHCP_OPTIONS_BUFSIZE, DHCP_MESSAGE_TYPE, - type); -} - -/* initialize a packet with the proper defaults */ -static void init_packet(struct dhcpMessage *packet, char type) -{ - struct vendor { - char vendor; - char length; - char str[sizeof "ndhc"]; - } vendor_id = { DHCP_VENDOR, sizeof "ndhc" - 1, "ndhc"}; - - init_header(packet, type); - memcpy(packet->chaddr, client_config.arp, 6); - add_option_string(packet->options, DHCP_OPTIONS_BUFSIZE, - client_config.clientid); - if (client_config.hostname) - add_option_string(packet->options, DHCP_OPTIONS_BUFSIZE, - client_config.hostname); - add_option_string(packet->options, DHCP_OPTIONS_BUFSIZE, - (uint8_t *)&vendor_id); -} - -#define MAC_BCAST_ADDR (uint8_t *)"\xff\xff\xff\xff\xff\xff" -/* Wrapper that broadcasts a raw dhcp packet on the bound interface. */ -static int bcast_raw_packet(struct dhcpMessage *packet) -{ - return raw_packet(packet, INADDR_ANY, DHCP_CLIENT_PORT, INADDR_BROADCAST, - DHCP_SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); -} -#undef MAC_BCAST_ADDR - -/* Broadcast a DHCP discover packet to the network, with an optionally - * requested IP */ -int send_discover(uint32_t xid, uint32_t requested) -{ - struct dhcpMessage packet; - - init_packet(&packet, DHCPDISCOVER); - packet.xid = xid; - if (requested) - add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP, - requested); - - /* Request a RFC-specified max size to work around buggy servers. */ - add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, - DHCP_MAX_SIZE, htons(576)); - add_option_request_list(packet.options, DHCP_OPTIONS_BUFSIZE); - log_line("Sending discover..."); - return bcast_raw_packet(&packet); -} - -/* Broadcasts a DHCP request message */ -int send_selecting(uint32_t xid, uint32_t server, uint32_t requested) -{ - struct dhcpMessage packet; - struct in_addr addr; - - init_packet(&packet, DHCPREQUEST); - packet.xid = xid; - - add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP, - requested); - add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_SERVER_ID, server); - - add_option_request_list(packet.options, DHCP_OPTIONS_BUFSIZE); - addr.s_addr = requested; - log_line("Sending select for %s...", inet_ntoa(addr)); - return bcast_raw_packet(&packet); -} - -/* Unicasts or broadcasts a DHCP renew message */ -int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr) -{ - struct dhcpMessage packet; - - init_packet(&packet, DHCPREQUEST); - packet.xid = xid; - packet.ciaddr = ciaddr; - - add_option_request_list(packet.options, DHCP_OPTIONS_BUFSIZE); - log_line("Sending renew..."); - if (server) - return kernel_packet(&packet, ciaddr, DHCP_CLIENT_PORT, server, - DHCP_SERVER_PORT); - else - return bcast_raw_packet(&packet); -} - -/* Broadcast a DHCP decline message */ -int send_decline(uint32_t xid, uint32_t server, uint32_t requested) -{ - struct dhcpMessage packet; - - /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields, - * client-id option (unless -C), message type option: - */ - init_packet(&packet, DHCPDECLINE); - - /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client, - * but in case the server is buggy and wants DHCPDECLINE's xid - * to match the xid which started entire handshake, - * we use the same xid we used in initial DHCPDISCOVER: - */ - packet.xid = xid; - /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */ - add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP, - requested); - add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_SERVER_ID, server); - - log_line("Sending decline..."); - return bcast_raw_packet(&packet); -} - -/* Unicasts a DHCP release message */ -int send_release(uint32_t server, uint32_t ciaddr) -{ - struct dhcpMessage packet; - - init_packet(&packet, DHCPRELEASE); - packet.xid = random_xid(); - packet.ciaddr = ciaddr; - - add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP, - ciaddr); - add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_SERVER_ID, server); - - log_line("Sending release..."); - return kernel_packet(&packet, ciaddr, DHCP_CLIENT_PORT, server, - DHCP_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) -{ - struct ip_udp_dhcp_packet packet; - uint16_t check; - - memset(&packet, 0, IP_UPD_DHCP_SIZE); - int len = safe_read(fd, (char *)&packet, IP_UPD_DHCP_SIZE); - if (len == -1) { - if (errno == EAGAIN || errno == EWOULDBLOCK) - return -2; - log_line("get_raw_packet: read error %s", strerror(errno)); - return -1; - } - - /* ignore any extra garbage bytes */ - len = ntohs(packet.ip.tot_len); - - // Validate the IP and UDP headers. - if (packet.ip.protocol != IPPROTO_UDP) { - log_line("IP header is not UDP: %d", packet.ip.protocol); - return -2; - } - if (packet.ip.version != IPVERSION) { - log_line("IP version is not IPv4"); - return -2; - } - if (packet.ip.ihl != sizeof packet.ip >> 2) { - log_line("IP header length incorrect"); - return -2; - } - check = packet.ip.check; - packet.ip.check = 0; - if (check != checksum(&packet.ip, sizeof packet.ip)) { - log_line("IP header checksum incorrect"); - return -2; - } - if (packet.udp.dest != htons(DHCP_CLIENT_PORT)) { - log_line("UDP destination port incorrect: %d", ntohs(packet.udp.dest)); - return -2; - } - if (len > IP_UPD_DHCP_SIZE) { - log_line("Data longer than that of a IP+UDP+DHCP message: %d", len); - return -2; - } - if (ntohs(packet.udp.len) != (short)(len - sizeof packet.ip)) { - log_line("UDP header length incorrect"); - return -2; - } - - /* verify the UDP checksum by replacing the header with a psuedo header */ - memset(&packet.ip, 0, offsetof(struct iphdr, protocol)); - /* preserved fields: protocol, check, saddr, daddr */ - packet.ip.tot_len = packet.udp.len; /* cheat on the psuedo-header */ - check = packet.udp.check; - packet.udp.check = 0; - if (check && check != checksum(&packet, len)) { - log_error("Packet with bad UDP checksum received, ignoring"); - return -2; - } - - memcpy(payload, &packet.data, - len - sizeof packet.ip - sizeof packet.udp); - - log_line("Received a packet via raw socket."); - return len - sizeof packet.ip - sizeof packet.udp; -} diff --git a/ndhc/dhcpmsg.h b/ndhc/dhcpmsg.h deleted file mode 100644 index d2c2e47..0000000 --- a/ndhc/dhcpmsg.h +++ /dev/null @@ -1,50 +0,0 @@ -/* dhcpmsg.c - dhcp packet generation and sending functions - * Time-stamp: <2011-06-11 11:03:22 njk> - * - * (c) 2004-2011 Nicholas J. Kain - * (c) 2001 Russ Dill - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - */ - -#ifndef DHCPMSG_H_ -#define DHCPMSG_H_ - -#include -#include "packet.h" - -#define DHCP_SERVER_PORT 67 -#define DHCP_CLIENT_PORT 68 -#define DHCP_MAGIC 0x63825363 - -enum { - DHCPDISCOVER = 1, - DHCPOFFER = 2, - DHCPREQUEST = 3, - DHCPDECLINE = 4, - DHCPACK = 5, - DHCPNAK = 6, - DHCPRELEASE = 7, - DHCPINFORM = 8 -}; - -uint32_t random_xid(void); -int send_discover(uint32_t xid, uint32_t requested); -int send_selecting(uint32_t xid, uint32_t server, uint32_t requested); -int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr); -int send_decline(uint32_t xid, uint32_t server, uint32_t requested); -int send_release(uint32_t server, uint32_t ciaddr); - -#endif diff --git a/ndhc/ndhc.c b/ndhc/ndhc.c index f139456..c187fda 100644 --- a/ndhc/ndhc.c +++ b/ndhc/ndhc.c @@ -1,5 +1,5 @@ /* ndhc.c - DHCP client - * Time-stamp: <2011-04-19 16:04:53 njk> + * Time-stamp: <2011-06-11 11:13:32 njk> * * (c) 2004-2011 Nicholas J. Kain * @@ -41,7 +41,6 @@ #include "ndhc-defines.h" #include "config.h" #include "options.h" -#include "dhcpmsg.h" #include "packet.h" #include "timeout.h" #include "sys.h" diff --git a/ndhc/packet.c b/ndhc/packet.c index 0e0a892..1162e31 100644 --- a/ndhc/packet.c +++ b/ndhc/packet.c @@ -1,5 +1,5 @@ /* packet.c - send and react to DHCP message packets - * Time-stamp: <2011-06-11 11:03:05 njk> + * Time-stamp: <2011-06-11 11:15:09 njk> * * (c) 2004-2011 Nicholas J. Kain * (c) 2001 Russ Dill @@ -23,15 +23,18 @@ #include #include #include +#include #include +#include #include +#include #include #include #include +#include #include #include "packet.h" -#include "dhcpmsg.h" #include "socket.h" #include "arp.h" #include "ifchange.h" @@ -433,3 +436,171 @@ void handle_packet(struct client_state_t *cs) break; } } + +/* Create a random xid */ +uint32_t random_xid(void) +{ + static int initialized; + if (initialized) + return rand(); + + uint32_t seed; + int fd = open("/dev/urandom", O_RDONLY); + if (fd != -1) { + int r = safe_read(fd, (char *)&seed, sizeof seed); + if (r == -1) { + log_warning("Could not read /dev/urandom: %s", strerror(errno)); + close(fd); + seed = time(0); + } + } else { + log_warning("Could not open /dev/urandom: %s", + strerror(errno)); + seed = time(0); + } + srand(seed); + initialized = 1; + return rand(); +} + +/* Initializes dhcp packet header for a -client- packet. */ +static void init_header(struct dhcpMessage *packet, char type) +{ + memset(packet, 0, DHCP_SIZE); + packet->op = 1; // BOOTREQUEST (client) + packet->htype = 1; // ETH_10MB + packet->hlen = 6; // ETH_10MB_LEN + packet->cookie = htonl(DHCP_MAGIC); + packet->options[0] = DHCP_END; + add_u32_option(packet->options, DHCP_OPTIONS_BUFSIZE, DHCP_MESSAGE_TYPE, + type); +} + +/* initialize a packet with the proper defaults */ +static void init_packet(struct dhcpMessage *packet, char type) +{ + struct vendor { + char vendor; + char length; + char str[sizeof "ndhc"]; + } vendor_id = { DHCP_VENDOR, sizeof "ndhc" - 1, "ndhc"}; + + init_header(packet, type); + memcpy(packet->chaddr, client_config.arp, 6); + add_option_string(packet->options, DHCP_OPTIONS_BUFSIZE, + client_config.clientid); + if (client_config.hostname) + add_option_string(packet->options, DHCP_OPTIONS_BUFSIZE, + client_config.hostname); + add_option_string(packet->options, DHCP_OPTIONS_BUFSIZE, + (uint8_t *)&vendor_id); +} + +#define MAC_BCAST_ADDR (uint8_t *)"\xff\xff\xff\xff\xff\xff" +/* Wrapper that broadcasts a raw dhcp packet on the bound interface. */ +static int bcast_raw_packet(struct dhcpMessage *packet) +{ + return raw_packet(packet, INADDR_ANY, DHCP_CLIENT_PORT, INADDR_BROADCAST, + DHCP_SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); +} +#undef MAC_BCAST_ADDR + +/* Broadcast a DHCP discover packet to the network, with an optionally + * requested IP */ +int send_discover(uint32_t xid, uint32_t requested) +{ + struct dhcpMessage packet; + + init_packet(&packet, DHCPDISCOVER); + packet.xid = xid; + if (requested) + add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP, + requested); + + /* Request a RFC-specified max size to work around buggy servers. */ + add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, + DHCP_MAX_SIZE, htons(576)); + add_option_request_list(packet.options, DHCP_OPTIONS_BUFSIZE); + log_line("Sending discover..."); + return bcast_raw_packet(&packet); +} + +/* Broadcasts a DHCP request message */ +int send_selecting(uint32_t xid, uint32_t server, uint32_t requested) +{ + struct dhcpMessage packet; + struct in_addr addr; + + init_packet(&packet, DHCPREQUEST); + packet.xid = xid; + + add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP, + requested); + add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_SERVER_ID, server); + + add_option_request_list(packet.options, DHCP_OPTIONS_BUFSIZE); + addr.s_addr = requested; + log_line("Sending select for %s...", inet_ntoa(addr)); + return bcast_raw_packet(&packet); +} + +/* Unicasts or broadcasts a DHCP renew message */ +int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr) +{ + struct dhcpMessage packet; + + init_packet(&packet, DHCPREQUEST); + packet.xid = xid; + packet.ciaddr = ciaddr; + + add_option_request_list(packet.options, DHCP_OPTIONS_BUFSIZE); + log_line("Sending renew..."); + if (server) + return kernel_packet(&packet, ciaddr, DHCP_CLIENT_PORT, server, + DHCP_SERVER_PORT); + else + return bcast_raw_packet(&packet); +} + +/* Broadcast a DHCP decline message */ +int send_decline(uint32_t xid, uint32_t server, uint32_t requested) +{ + struct dhcpMessage packet; + + /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields, + * client-id option (unless -C), message type option: + */ + init_packet(&packet, DHCPDECLINE); + + /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client, + * but in case the server is buggy and wants DHCPDECLINE's xid + * to match the xid which started entire handshake, + * we use the same xid we used in initial DHCPDISCOVER: + */ + packet.xid = xid; + /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */ + add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP, + requested); + add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_SERVER_ID, server); + + log_line("Sending decline..."); + return bcast_raw_packet(&packet); +} + +/* Unicasts a DHCP release message */ +int send_release(uint32_t server, uint32_t ciaddr) +{ + struct dhcpMessage packet; + + init_packet(&packet, DHCPRELEASE); + packet.xid = random_xid(); + packet.ciaddr = ciaddr; + + add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_REQUESTED_IP, + ciaddr); + add_u32_option(packet.options, DHCP_OPTIONS_BUFSIZE, DHCP_SERVER_ID, server); + + log_line("Sending release..."); + return kernel_packet(&packet, ciaddr, DHCP_CLIENT_PORT, server, + DHCP_SERVER_PORT); +} diff --git a/ndhc/packet.h b/ndhc/packet.h index 9e7473b..21c8dbd 100644 --- a/ndhc/packet.h +++ b/ndhc/packet.h @@ -1,5 +1,5 @@ /* packet.h - send and react to DHCP message packets - * Time-stamp: <2011-06-11 11:03:14 njk> + * Time-stamp: <2011-06-11 11:12:26 njk> * * (c) 2004-2011 Nicholas J. Kain * (c) 2001 Russ Dill @@ -27,6 +27,21 @@ #include "config.h" +#define DHCP_SERVER_PORT 67 +#define DHCP_CLIENT_PORT 68 +#define DHCP_MAGIC 0x63825363 + +enum { + DHCPDISCOVER = 1, + DHCPOFFER = 2, + DHCPREQUEST = 3, + DHCPDECLINE = 4, + DHCPACK = 5, + DHCPNAK = 6, + DHCPRELEASE = 7, + DHCPINFORM = 8 +}; + struct dhcpMessage { uint8_t op; // Message type: 1 = BOOTREQUEST for clients. uint8_t htype; // ARP HW address type: always '1' for 10MB ethernet. @@ -74,4 +89,11 @@ int kernel_packet(struct dhcpMessage *payload, uint32_t source_ip, int source_port, uint32_t dest_ip, int dest_port); void change_listen_mode(struct client_state_t *cs, int new_mode); void handle_packet(struct client_state_t *cs); +uint32_t random_xid(void); +int send_discover(uint32_t xid, uint32_t requested); +int send_selecting(uint32_t xid, uint32_t server, uint32_t requested); +int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr); +int send_decline(uint32_t xid, uint32_t server, uint32_t requested); +int send_release(uint32_t server, uint32_t ciaddr); + #endif diff --git a/ndhc/timeout.c b/ndhc/timeout.c index 87d0717..401f039 100644 --- a/ndhc/timeout.c +++ b/ndhc/timeout.c @@ -1,5 +1,5 @@ /* timeout.c - callbacks to react to event timeouts - * Time-stamp: <2011-03-31 15:18:41 nk> + * Time-stamp: <2011-06-11 11:13:22 njk> * * (c) 2004-2011 Nicholas J. Kain * @@ -25,7 +25,6 @@ #include "config.h" #include "ifchange.h" #include "packet.h" -#include "dhcpmsg.h" #include "arp.h" #include "log.h"