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/***********************************************************************
*
* if.c
*
* Implementation of user-space PPPoE redirector for Linux.
*
* Functions for opening a raw socket and reading/writing raw Ethernet frames.
*
* Copyright (C) 2000 by Roaring Penguin Software Inc.
*
* This program may be distributed according to the terms of the GNU
* General Public License, version 2 or (at your option) any later version.
*
***********************************************************************/
static char const RCSID[] =
"$Id: if.c,v 1.2 2008/06/09 08:34:23 paulus Exp $";
#define _GNU_SOURCE 1
#include "pppoe.h"
#include "pppd/pppd.h"
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_NETPACKET_PACKET_H
#include <netpacket/packet.h>
#elif defined(HAVE_LINUX_IF_PACKET_H)
#include <linux/if_packet.h>
#endif
#ifdef HAVE_NET_ETHERNET_H
#include <net/ethernet.h>
#endif
#ifdef HAVE_ASM_TYPES_H
#include <asm/types.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_NET_IF_ARP_H
#include <net/if_arp.h>
#endif
/* Initialize frame types to RFC 2516 values. Some broken peers apparently
use different frame types... sigh... */
UINT16_t Eth_PPPOE_Discovery = ETH_PPPOE_DISCOVERY;
UINT16_t Eth_PPPOE_Session = ETH_PPPOE_SESSION;
/**********************************************************************
*%FUNCTION: etherType
*%ARGUMENTS:
* packet -- a received PPPoE packet
*%RETURNS:
* ethernet packet type (see /usr/include/net/ethertypes.h)
*%DESCRIPTION:
* Checks the ethernet packet header to determine its type.
* We should only be receveing DISCOVERY and SESSION types if the BPF
* is set up correctly. Logs an error if an unexpected type is received.
* Note that the ethernet type names come from "pppoe.h" and the packet
* packet structure names use the LINUX dialect to maintain consistency
* with the rest of this file. See the BSD section of "pppoe.h" for
* translations of the data structure names.
***********************************************************************/
UINT16_t
etherType(PPPoEPacket *packet)
{
UINT16_t type = (UINT16_t) ntohs(packet->ethHdr.h_proto);
if (type != Eth_PPPOE_Discovery && type != Eth_PPPOE_Session) {
error("Invalid ether type 0x%x", type);
}
return type;
}
/**********************************************************************
*%FUNCTION: openInterface
*%ARGUMENTS:
* ifname -- name of interface
* type -- Ethernet frame type
* hwaddr -- if non-NULL, set to the hardware address
*%RETURNS:
* A raw socket for talking to the Ethernet card. Exits on error.
*%DESCRIPTION:
* Opens a raw Ethernet socket
***********************************************************************/
int
openInterface(char const *ifname, UINT16_t type, unsigned char *hwaddr)
{
int optval=1;
int fd;
struct ifreq ifr;
int domain, stype;
#ifdef HAVE_STRUCT_SOCKADDR_LL
struct sockaddr_ll sa;
#else
struct sockaddr sa;
#endif
memset(&sa, 0, sizeof(sa));
#ifdef HAVE_STRUCT_SOCKADDR_LL
domain = PF_PACKET;
stype = SOCK_RAW;
#else
domain = PF_INET;
stype = SOCK_PACKET;
#endif
if ((fd = socket(domain, stype, htons(type))) < 0) {
/* Give a more helpful message for the common error case */
if (errno == EPERM) {
fatal("Cannot create raw socket -- pppoe must be run as root.");
}
error("Can't open socket for pppoe: %m");
return -1;
}
if (setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &optval, sizeof(optval)) < 0) {
error("Can't set socket options for pppoe: %m");
close(fd);
return -1;
}
/* Fill in hardware address */
if (hwaddr) {
strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0) {
error("Can't get hardware address for %s: %m", ifname);
close(fd);
return -1;
}
memcpy(hwaddr, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
#ifdef ARPHRD_ETHER
if (ifr.ifr_hwaddr.sa_family != ARPHRD_ETHER) {
warn("Interface %.16s is not Ethernet", ifname);
}
#endif
if (NOT_UNICAST(hwaddr)) {
fatal("Can't use interface %.16s: it has broadcast/multicast MAC address",
ifname);
}
}
/* Sanity check on MTU */
strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
if (ioctl(fd, SIOCGIFMTU, &ifr) < 0) {
error("Can't get MTU for %s: %m", ifname);
} else if (ifr.ifr_mtu < ETH_DATA_LEN) {
error("Interface %.16s has MTU of %d -- should be at least %d.",
ifname, ifr.ifr_mtu, ETH_DATA_LEN);
error("This may cause serious connection problems.");
}
#ifdef HAVE_STRUCT_SOCKADDR_LL
/* Get interface index */
sa.sll_family = AF_PACKET;
sa.sll_protocol = htons(type);
strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
if (ioctl(fd, SIOCGIFINDEX, &ifr) < 0) {
error("Could not get interface index for %s: %m", ifname);
close(fd);
return -1;
}
sa.sll_ifindex = ifr.ifr_ifindex;
#else
strcpy(sa.sa_data, ifname);
#endif
/* We're only interested in packets on specified interface */
if (bind(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0) {
error("Failed to bind to interface %s: %m", ifname);
close(fd);
return -1;
}
return fd;
}
/***********************************************************************
*%FUNCTION: sendPacket
*%ARGUMENTS:
* sock -- socket to send to
* pkt -- the packet to transmit
* size -- size of packet (in bytes)
*%RETURNS:
* 0 on success; -1 on failure
*%DESCRIPTION:
* Transmits a packet
***********************************************************************/
int
sendPacket(PPPoEConnection *conn, int sock, PPPoEPacket *pkt, int size)
{
int err;
if (debug)
pppoe_log_packet("Send ", pkt);
#if defined(HAVE_STRUCT_SOCKADDR_LL)
err = send(sock, pkt, size, 0);
#else
struct sockaddr sa;
strcpy(sa.sa_data, conn->ifName);
err = sendto(sock, pkt, size, 0, &sa, sizeof(sa));
#endif
if (err < 0) {
error("error sending pppoe packet: %m");
return -1;
}
return 0;
}
/***********************************************************************
*%FUNCTION: receivePacket
*%ARGUMENTS:
* sock -- socket to read from
* pkt -- place to store the received packet
* size -- set to size of packet in bytes
*%RETURNS:
* >= 0 if all OK; < 0 if error
*%DESCRIPTION:
* Receives a packet
***********************************************************************/
int
receivePacket(int sock, PPPoEPacket *pkt, int *size)
{
if ((*size = recv(sock, pkt, sizeof(PPPoEPacket), 0)) < 0) {
error("error receiving pppoe packet: %m");
return -1;
}
if (debug)
pppoe_log_packet("Recv ", pkt);
return 0;
}
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