if.c

Linux平台下的pppoe拨号程序

/***********************************************************************
*
* 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.
*
* LIC: GPL
*
***********************************************************************/

static char const RCSID[] =
"$Id: if.c,v 1.16 2002/07/08 14:28:40 dfs Exp $";

#include "pppoe.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

#ifdef HAVE_SYSLOG_H
#include <syslog.h>
#endif

#include <errno.h>
#include <stdlib.h>
#include <string.h>

#ifdef HAVE_NET_IF_ARP_H
#include <net/if_arp.h>
#endif

#ifdef USE_DLPI

#include <limits.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/stream.h>
#include <sys/stropts.h>
#include <sys/dlpi.h>
#include <sys/bufmod.h>
#include <stdio.h>
#include <signal.h>
#include <stropts.h>

/* function declarations */

void dlpromisconreq( int fd, u_long  level);
void dlinforeq(int fd);
void dlunitdatareq(int fd, u_char *addrp, int addrlen, u_long minpri, u_long maxpri, u_char *datap, int datalen);
void dlinfoack(int fd, char *bufp);
void dlbindreq(int fd, u_long sap, u_long max_conind, u_long service_mode, u_long conn_mgmt, u_long xidtest);
void dlattachreq(int fd, u_long ppa);
void dlokack(int fd, char *bufp);
void dlbindack(int fd, char *bufp);
int strioctl(int fd, int cmd, int timout, int len, char *dp);
void strgetmsg(int fd, struct strbuf *ctlp, struct strbuf *datap, int *flagsp, char *caller);
void sigalrm(int sig);
void expecting(int prim, union DL_primitives *dlp);
char *dlprim(u_long prim);

/* #define DL_DEBUG */

static	int     dl_abssaplen;
static	int     dl_saplen;
static	int	dl_addrlen;

#endif

#ifdef USE_BPF
#include <net/bpf.h>
#include <fcntl.h>

unsigned char *bpfBuffer;	/* Packet filter buffer */
int bpfLength = 0;		/* Packet filter buffer length */
int bpfSize = 0;		/* Number of unread bytes in buffer */
int bpfOffset = 0;		/* Current offset in bpfBuffer */
#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) {
	syslog(LOG_ERR, "Invalid ether type 0x%x", type);
    }
    return type;
}

#ifdef USE_BPF
/**********************************************************************
*%FUNCTION: getHWaddr
*%ARGUMENTS:
* ifname -- name of interface
* hwaddr -- buffer for ehthernet address
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Locates the Ethernet hardware address for an interface.
***********************************************************************/
void
getHWaddr(int sock, char const *ifname, unsigned char *hwaddr)
{
    char inbuf[8192];
    const struct sockaddr_dl *sdl;
    struct ifconf ifc;
    struct ifreq ifreq, *ifr;
    int i;
    int found = 0;

    ifc.ifc_len = sizeof(inbuf);
    ifc.ifc_buf = inbuf;
    if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
	fatalSys("SIOCGIFCONF");
    }
    ifr = ifc.ifc_req;
    ifreq.ifr_name[0] = '\0';
    for (i = 0; i < ifc.ifc_len; ) {
	ifr = (struct ifreq *)((caddr_t)ifc.ifc_req + i);
	i += sizeof(ifr->ifr_name) +
		    (ifr->ifr_addr.sa_len > sizeof(struct sockaddr)
		    ? ifr->ifr_addr.sa_len
		    : sizeof(struct sockaddr));
	if (ifr->ifr_addr.sa_family == AF_LINK) {
	    sdl = (const struct sockaddr_dl *) &ifr->ifr_addr;
	    if ((sdl->sdl_type == IFT_ETHER) &&
		(sdl->sdl_alen == ETH_ALEN) &&
		!strncmp(ifname, ifr->ifr_name, sizeof(ifr->ifr_name))) {
		if (found) {
		    char buffer[256];
		    sprintf(buffer, "interface %.16s has more than one ethernet address", ifname);
		    rp_fatal(buffer);
		} else {
		    found = 1;
		    memcpy(hwaddr, LLADDR(sdl), ETH_ALEN);
		}
	    }
	}
    }
    if (!found) {
	char buffer[256];
	sprintf(buffer, "interface %.16s has no ethernet address", ifname);
	rp_fatal(buffer);
    }
}

/**********************************************************************
*%FUNCTION: initFilter
*%ARGUMENTS:
* fd -- file descriptor of BSD device
* type -- Ethernet frame type (0 for watch mode)
* hwaddr -- buffer with ehthernet address
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Initializes the packet filter rules.
***********************************************************************/
void
initFilter(int fd, UINT16_t type, unsigned char *hwaddr)
{
    /* Packet Filter Instructions:
     * Note that the ethernet type names come from "pppoe.h" and are
     * used here to maintain consistency with the rest of this file. */
    static struct bpf_insn bpfRun[] = {         /* run PPPoE */
	BPF_STMT(BPF_LD+BPF_H+BPF_ABS, 12),     /* ethernet type */
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, ETH_PPPOE_SESSION, 5, 0),
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, ETH_PPPOE_DISCOVERY, 0, 9),
	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, 0),      /* first word of dest. addr */
#define PPPOE_BCAST_CMPW 4                     /* offset of word compare */
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0, 0, 2),
	BPF_STMT(BPF_LD+BPF_H+BPF_ABS, 4),      /* next 1/2 word of dest. */
#define PPPOE_BCAST_CMPH 6                     /* offset of 1/2 word compare */
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0, 4, 0),
	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, 0),      /* first word of dest. addr */
#define PPPOE_FILTER_CMPW 8                     /* offset of word compare */
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0, 0, 3),
	BPF_STMT(BPF_LD+BPF_H+BPF_ABS, 4),      /* next 1/2 word of dest. */
#define PPPOE_FILTER_CMPH 10                    /* offset of 1/rd compare */
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0, 0, 1),
	BPF_STMT(BPF_RET+BPF_K, (u_int) -1),    /* keep packet */
	BPF_STMT(BPF_RET+BPF_K, 0),             /* drop packet */
    };

    /* Fix the potentially varying parts */
    bpfRun[1].code = (u_short) BPF_JMP+BPF_JEQ+BPF_K;
    bpfRun[1].jt   = 5;
    bpfRun[1].jf   = 0;
    bpfRun[1].k    = Eth_PPPOE_Session;

    bpfRun[2].code = (u_short) BPF_JMP+BPF_JEQ+BPF_K;
    bpfRun[2].jt   = 0;
    bpfRun[2].jf   = 9;
    bpfRun[2].k    = Eth_PPPOE_Discovery;

    {
      struct bpf_insn bpfInsn[sizeof(bpfRun) / sizeof(bpfRun[0])];
      struct bpf_program bpfProgram;
      memcpy(bpfInsn, bpfRun, sizeof(bpfRun));
      bpfInsn[PPPOE_BCAST_CMPW].k = ((0xff << 24) | (0xff << 16) |
				     (0xff << 8) | 0xff);
      bpfInsn[PPPOE_BCAST_CMPH].k = ((0xff << 8) | 0xff);
      bpfInsn[PPPOE_FILTER_CMPW].k = ((hwaddr[0] << 24) | (hwaddr[1] << 16) |
				      (hwaddr[2] << 8) | hwaddr[3]);
      bpfInsn[PPPOE_FILTER_CMPH].k = ((hwaddr[4] << 8) | hwaddr[5]);
      bpfProgram.bf_len = (sizeof(bpfInsn) / sizeof(bpfInsn[0]));
      bpfProgram.bf_insns = &bpfInsn[0];

      /* Apply the filter */
      if (ioctl(fd, BIOCSETF, &bpfProgram) < 0) {
	fatalSys("ioctl(BIOCSETF)");
      }
    }
}

/**********************************************************************
*%FUNCTION: openInterface
*%ARGUMENTS:
* ifname -- name of interface
* type -- Ethernet frame type (0 for any frame type)
* hwaddr -- if non-NULL, set to the hardware address
*%RETURNS:
* A file descriptor for talking with the Ethernet card.  Exits on error.
* Note that the Linux version of this routine returns a socket instead.
*%DESCRIPTION:
* Opens a BPF on an interface for all PPPoE traffic (discovery and
* session).  If 'type' is 0, uses promiscuous mode to watch any PPPoE
* traffic on this network.
***********************************************************************/
int
openInterface(char const *ifname, UINT16_t type, unsigned char *hwaddr)
{
    static int fd = -1;
    char bpfName[32];
    u_int optval;
    struct bpf_version bpf_ver;
    struct ifreq ifr;
    int sock;
    int i;

    /* BSD only opens one socket for both Discovery and Session packets */
    if (fd >= 0) {
	return fd;
    }

    /* Find a free BPF device */
    for (i = 0; i < 256; i++) {
	sprintf(bpfName, "/dev/bpf%d", i);
	if (((fd = open(bpfName, O_RDWR, 0)) >= 0) ||
	    (errno != EBUSY)) {
	    break;
	}
    }
    if (fd < 0) {
	switch (errno) {
	case EACCES:		/* permission denied */
	    {
		char buffer[256];
		sprintf(buffer, "Cannot open %.32s -- pppoe must be run as root.", bpfName);
		rp_fatal(buffer);
	    }
	    break;
	case EBUSY:
	case ENOENT:		/* no such file */
	    if (i == 0) {
		rp_fatal("No /dev/bpf* devices (check your kernel configuration for BPF support)");
	    } else {
		rp_fatal("All /dev/bpf* devices are in use");
	    }
	    break;
	}
	fatalSys(bpfName);
    }

    if ((sock = socket(AF_LOCAL, SOCK_DGRAM, 0)) < 0) {
	fatalSys("socket");
    }

    /* Check that the interface is up */
    strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
    if (ioctl(sock, SIOCGIFFLAGS, &ifr) < 0) {
	fatalSys("ioctl(SIOCGIFFLAGS)");
    }
    if ((ifr.ifr_flags & IFF_UP) == 0) {
	char buffer[256];
	sprintf(buffer, "Interface %.16s is not up\n", ifname);
	rp_fatal(buffer);
    }

    /* Fill in hardware address and initialize the packet filter rules */
    if (hwaddr == NULL) {
	rp_fatal("openInterface: no hwaddr arg.");
    }
    getHWaddr(sock, ifname, hwaddr);
    initFilter(fd, type, hwaddr);

    /* Sanity check on MTU -- apparently does not work on OpenBSD */
#if !defined(__OpenBSD__)
    strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
    if (ioctl(sock, SIOCGIFMTU, &ifr) < 0) {
	fatalSys("ioctl(SIOCGIFMTU)");
    }
    if (ifr.ifr_mtu < ETH_DATA_LEN) {
	char buffer[256];
	sprintf(buffer, "Interface %.16s has MTU of %d -- should be %d.  You may have serious connection problems.",
		ifname, ifr.ifr_mtu, ETH_DATA_LEN);
	printErr(buffer);
    }
#endif

    /* done with the socket */
    if (close(sock) < 0) {
	fatalSys("close");
    }

    /* Check the BPF version number */
    if (ioctl(fd, BIOCVERSION, &bpf_ver) < 0) {
	fatalSys("ioctl(BIOCVERSION)");
    }
    if ((bpf_ver.bv_major != BPF_MAJOR_VERSION) ||
	(bpf_ver.bv_minor < BPF_MINOR_VERSION)) {
	char buffer[256];
	sprintf(buffer, "Unsupported BPF version: %d.%d (kernel: %d.%d)",
			BPF_MAJOR_VERSION, BPF_MINOR_VERSION,
			bpf_ver.bv_major, bpf_ver.bv_minor);
	rp_fatal(buffer);