1/*********************************************************************** 2* 3* if.c 4* 5* Implementation of user-space PPPoE redirector for Linux. 6* 7* Functions for opening a raw socket and reading/writing raw Ethernet frames. 8* 9* Copyright (C) 2000 by Roaring Penguin Software Inc. 10* 11* This program may be distributed according to the terms of the GNU 12* General Public License, version 2 or (at your option) any later version. 13* 14***********************************************************************/ 15 16static char const RCSID[] = 17"$Id: if.c,v 1.2 2008/06/09 08:34:23 paulus Exp $"; 18 19#define _GNU_SOURCE 1 20#include "pppoe.h" 21#include "pppd/pppd.h" 22 23#ifdef HAVE_UNISTD_H 24#include <unistd.h> 25#endif 26 27#ifdef HAVE_NETPACKET_PACKET_H 28#include <netpacket/packet.h> 29#elif defined(HAVE_LINUX_IF_PACKET_H) 30#include <linux/if_packet.h> 31#endif 32 33#ifdef HAVE_NET_ETHERNET_H 34#include <net/ethernet.h> 35#endif 36 37#ifdef HAVE_ASM_TYPES_H 38#include <asm/types.h> 39#endif 40 41#ifdef HAVE_SYS_IOCTL_H 42#include <sys/ioctl.h> 43#endif 44 45#include <errno.h> 46#include <stdlib.h> 47#include <string.h> 48 49#ifdef HAVE_NET_IF_ARP_H 50#include <net/if_arp.h> 51#endif 52 53/* Initialize frame types to RFC 2516 values. Some broken peers apparently 54 use different frame types... sigh... */ 55 56UINT16_t Eth_PPPOE_Discovery = ETH_PPPOE_DISCOVERY; 57UINT16_t Eth_PPPOE_Session = ETH_PPPOE_SESSION; 58 59/********************************************************************** 60*%FUNCTION: etherType 61*%ARGUMENTS: 62* packet -- a received PPPoE packet 63*%RETURNS: 64* ethernet packet type (see /usr/include/net/ethertypes.h) 65*%DESCRIPTION: 66* Checks the ethernet packet header to determine its type. 67* We should only be receveing DISCOVERY and SESSION types if the BPF 68* is set up correctly. Logs an error if an unexpected type is received. 69* Note that the ethernet type names come from "pppoe.h" and the packet 70* packet structure names use the LINUX dialect to maintain consistency 71* with the rest of this file. See the BSD section of "pppoe.h" for 72* translations of the data structure names. 73***********************************************************************/ 74UINT16_t 75etherType(PPPoEPacket *packet) 76{ 77 UINT16_t type = (UINT16_t) ntohs(packet->ethHdr.h_proto); 78 if (type != Eth_PPPOE_Discovery && type != Eth_PPPOE_Session) { 79 error("Invalid ether type 0x%x", type); 80 } 81 return type; 82} 83 84/********************************************************************** 85*%FUNCTION: openInterface 86*%ARGUMENTS: 87* ifname -- name of interface 88* type -- Ethernet frame type 89* hwaddr -- if non-NULL, set to the hardware address 90*%RETURNS: 91* A raw socket for talking to the Ethernet card. Exits on error. 92*%DESCRIPTION: 93* Opens a raw Ethernet socket 94***********************************************************************/ 95int 96openInterface(char const *ifname, UINT16_t type, unsigned char *hwaddr) 97{ 98 int optval=1; 99 int fd; 100 struct ifreq ifr; 101 int domain, stype; 102 103#ifdef HAVE_STRUCT_SOCKADDR_LL 104 struct sockaddr_ll sa; 105#else 106 struct sockaddr sa; 107#endif 108 109 memset(&sa, 0, sizeof(sa)); 110 111#ifdef HAVE_STRUCT_SOCKADDR_LL 112 domain = PF_PACKET; 113 stype = SOCK_RAW; 114#else 115 domain = PF_INET; 116 stype = SOCK_PACKET; 117#endif 118 119 if ((fd = socket(domain, stype, htons(type))) < 0) { 120 /* Give a more helpful message for the common error case */ 121 if (errno == EPERM) { 122 fatal("Cannot create raw socket -- pppoe must be run as root."); 123 } 124 error("Can't open socket for pppoe: %m"); 125 return -1; 126 } 127 128 if (setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &optval, sizeof(optval)) < 0) { 129 error("Can't set socket options for pppoe: %m"); 130 close(fd); 131 return -1; 132 } 133 134 /* Fill in hardware address */ 135 if (hwaddr) { 136 strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)); 137 if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0) { 138 error("Can't get hardware address for %s: %m", ifname); 139 close(fd); 140 return -1; 141 } 142 memcpy(hwaddr, ifr.ifr_hwaddr.sa_data, ETH_ALEN); 143#ifdef ARPHRD_ETHER 144 if (ifr.ifr_hwaddr.sa_family != ARPHRD_ETHER) { 145 warn("Interface %.16s is not Ethernet", ifname); 146 } 147#endif 148 if (NOT_UNICAST(hwaddr)) { 149 fatal("Can't use interface %.16s: it has broadcast/multicast MAC address", 150 ifname); 151 } 152 } 153 154 /* Sanity check on MTU */ 155 strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)); 156 if (ioctl(fd, SIOCGIFMTU, &ifr) < 0) { 157 error("Can't get MTU for %s: %m", ifname); 158 } else if (ifr.ifr_mtu < ETH_DATA_LEN) { 159 error("Interface %.16s has MTU of %d -- should be at least %d.", 160 ifname, ifr.ifr_mtu, ETH_DATA_LEN); 161 error("This may cause serious connection problems."); 162 } 163 164#ifdef HAVE_STRUCT_SOCKADDR_LL 165 /* Get interface index */ 166 sa.sll_family = AF_PACKET; 167 sa.sll_protocol = htons(type); 168 169 strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)); 170 if (ioctl(fd, SIOCGIFINDEX, &ifr) < 0) { 171 error("Could not get interface index for %s: %m", ifname); 172 close(fd); 173 return -1; 174 } 175 sa.sll_ifindex = ifr.ifr_ifindex; 176 177#else 178 strcpy(sa.sa_data, ifname); 179#endif 180 181 /* We're only interested in packets on specified interface */ 182 if (bind(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0) { 183 error("Failed to bind to interface %s: %m", ifname); 184 close(fd); 185 return -1; 186 } 187 188 return fd; 189} 190 191 192/*********************************************************************** 193*%FUNCTION: sendPacket 194*%ARGUMENTS: 195* sock -- socket to send to 196* pkt -- the packet to transmit 197* size -- size of packet (in bytes) 198*%RETURNS: 199* 0 on success; -1 on failure 200*%DESCRIPTION: 201* Transmits a packet 202***********************************************************************/ 203int 204sendPacket(PPPoEConnection *conn, int sock, PPPoEPacket *pkt, int size) 205{ 206 int err; 207 208 if (debug) 209 pppoe_log_packet("Send ", pkt); 210#if defined(HAVE_STRUCT_SOCKADDR_LL) 211 err = send(sock, pkt, size, 0); 212#else 213 struct sockaddr sa; 214 215 strcpy(sa.sa_data, conn->ifName); 216 err = sendto(sock, pkt, size, 0, &sa, sizeof(sa)); 217#endif 218 if (err < 0) { 219 error("error sending pppoe packet: %m"); 220 return -1; 221 } 222 return 0; 223} 224 225/*********************************************************************** 226*%FUNCTION: receivePacket 227*%ARGUMENTS: 228* sock -- socket to read from 229* pkt -- place to store the received packet 230* size -- set to size of packet in bytes 231*%RETURNS: 232* >= 0 if all OK; < 0 if error 233*%DESCRIPTION: 234* Receives a packet 235***********************************************************************/ 236int 237receivePacket(int sock, PPPoEPacket *pkt, int *size) 238{ 239 if ((*size = recv(sock, pkt, sizeof(PPPoEPacket), 0)) < 0) { 240 error("error receiving pppoe packet: %m"); 241 return -1; 242 } 243 if (debug) 244 pppoe_log_packet("Recv ", pkt); 245 return 0; 246} 247