discovery.c

实现点到点的以太网协议,用于拨号上网,是拨号上网的基础部分软件模块.

/***********************************************************************
*
* discovery.c
*
* Perform PPPoE discovery
*
* Copyright (C) 1999 by Roaring Penguin Software Inc.
*
***********************************************************************/

static char const RCSID[] =
"$Id: discovery.c,v 1.4 2005/03/22 10:22:32 paulus Exp $";

#include "pppoe.h"

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

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

#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif

#ifdef HAVE_SYS_UIO_H
#include <sys/uio.h>
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef USE_LINUX_PACKET
#include <sys/ioctl.h>
#include <fcntl.h>
#endif

#include <signal.h>

/**********************************************************************
*%FUNCTION: parseForHostUniq
*%ARGUMENTS:
* type -- tag type
* len -- tag length
* data -- tag data.
* extra -- user-supplied pointer.  This is assumed to be a pointer to int.
*%RETURNS:
* Nothing
*%DESCRIPTION:
* If a HostUnique tag is found which matches our PID, sets *extra to 1.
***********************************************************************/
void
parseForHostUniq(UINT16_t type, UINT16_t len, unsigned char *data,
		 void *extra)
{
    int *val = (int *) extra;
    if (type == TAG_HOST_UNIQ && len == sizeof(pid_t)) {
	pid_t tmp;
	memcpy(&tmp, data, len);
	if (tmp == getpid()) {
	    *val = 1;
	}
    }
}

/**********************************************************************
*%FUNCTION: packetIsForMe
*%ARGUMENTS:
* conn -- PPPoE connection info
* packet -- a received PPPoE packet
*%RETURNS:
* 1 if packet is for this PPPoE daemon; 0 otherwise.
*%DESCRIPTION:
* If we are using the Host-Unique tag, verifies that packet contains
* our unique identifier.
***********************************************************************/
int
packetIsForMe(PPPoEConnection *conn, PPPoEPacket *packet)
{
    int forMe = 0;

    /* If packet is not directed to our MAC address, forget it */
    if (memcmp(packet->ethHdr.h_dest, conn->myEth, ETH_ALEN)) return 0;

    /* If we're not using the Host-Unique tag, then accept the packet */
    if (!conn->useHostUniq) return 1;

    parsePacket(packet, parseForHostUniq, &forMe);
    return forMe;
}

/**********************************************************************
*%FUNCTION: parsePADOTags
*%ARGUMENTS:
* type -- tag type
* len -- tag length
* data -- tag data
* extra -- extra user data.  Should point to a PacketCriteria structure
*          which gets filled in according to selected AC name and service
*          name.
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Picks interesting tags out of a PADO packet
***********************************************************************/
void
parsePADOTags(UINT16_t type, UINT16_t len, unsigned char *data,
	      void *extra)
{
    struct PacketCriteria *pc = (struct PacketCriteria *) extra;
    PPPoEConnection *conn = pc->conn;
    int i;

    switch(type) {
    case TAG_AC_NAME:
	pc->seenACName = 1;
	if (conn->printACNames) {
	    printf("Access-Concentrator: %.*s\n", (int) len, data);
	}
	if (conn->acName && len == strlen(conn->acName) &&
	    !strncmp((char *) data, conn->acName, len)) {
	    pc->acNameOK = 1;
	}
	break;
    case TAG_SERVICE_NAME:
	pc->seenServiceName = 1;
	if (conn->printACNames && len > 0) {
	    printf("       Service-Name: %.*s\n", (int) len, data);
	}
	if (conn->serviceName && len == strlen(conn->serviceName) &&
	    !strncmp((char *) data, conn->serviceName, len)) {
	    pc->serviceNameOK = 1;
	}
	break;
    case TAG_AC_COOKIE:
	if (conn->printACNames) {
	    printf("Got a cookie:");
	    /* Print first 20 bytes of cookie */
	    for (i=0; i<len && i < 20; i++) {
		printf(" %02x", (unsigned) data[i]);
	    }
	    if (i < len) printf("...");
	    printf("\n");
	}
	conn->cookie.type = htons(type);
	conn->cookie.length = htons(len);
	memcpy(conn->cookie.payload, data, len);
	break;
    case TAG_RELAY_SESSION_ID:
	if (conn->printACNames) {
	    printf("Got a Relay-ID:");
	    /* Print first 20 bytes of relay ID */
	    for (i=0; i<len && i < 20; i++) {
		printf(" %02x", (unsigned) data[i]);
	    }
	    if (i < len) printf("...");
	    printf("\n");
	}
	conn->relayId.type = htons(type);
	conn->relayId.length = htons(len);
	memcpy(conn->relayId.payload, data, len);
	break;
    case TAG_SERVICE_NAME_ERROR:
	if (conn->printACNames) {
	    printf("Got a Service-Name-Error tag: %.*s\n", (int) len, data);
	} else {
	    syslog(LOG_ERR, "PADO: Service-Name-Error: %.*s", (int) len, data);
	    exit(1);
	}
	break;
    case TAG_AC_SYSTEM_ERROR:
	if (conn->printACNames) {
	    printf("Got a System-Error tag: %.*s\n", (int) len, data);
	} else {
	    syslog(LOG_ERR, "PADO: System-Error: %.*s", (int) len, data);
	    exit(1);
	}
	break;
    case TAG_GENERIC_ERROR:
	if (conn->printACNames) {
	    printf("Got a Generic-Error tag: %.*s\n", (int) len, data);
	} else {
	    syslog(LOG_ERR, "PADO: Generic-Error: %.*s", (int) len, data);
	    exit(1);
	}
	break;
    }
}

/**********************************************************************
*%FUNCTION: parsePADSTags
*%ARGUMENTS:
* type -- tag type
* len -- tag length
* data -- tag data
* extra -- extra user data (pointer to PPPoEConnection structure)
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Picks interesting tags out of a PADS packet
***********************************************************************/
void
parsePADSTags(UINT16_t type, UINT16_t len, unsigned char *data,
	      void *extra)
{
    PPPoEConnection *conn = (PPPoEConnection *) extra;
    switch(type) {
    case TAG_SERVICE_NAME:
	syslog(LOG_DEBUG, "PADS: Service-Name: '%.*s'", (int) len, data);
	break;
    case TAG_SERVICE_NAME_ERROR:
	syslog(LOG_ERR, "PADS: Service-Name-Error: %.*s", (int) len, data);
	fprintf(stderr, "PADS: Service-Name-Error: %.*s\n", (int) len, data);
	exit(1);
    case TAG_AC_SYSTEM_ERROR:
	syslog(LOG_ERR, "PADS: System-Error: %.*s", (int) len, data);
	fprintf(stderr, "PADS: System-Error: %.*s\n", (int) len, data);
	exit(1);
    case TAG_GENERIC_ERROR:
	syslog(LOG_ERR, "PADS: Generic-Error: %.*s", (int) len, data);
	fprintf(stderr, "PADS: Generic-Error: %.*s\n", (int) len, data);
	exit(1);
    case TAG_RELAY_SESSION_ID:
	conn->relayId.type = htons(type);
	conn->relayId.length = htons(len);
	memcpy(conn->relayId.payload, data, len);
	break;
    }
}

/***********************************************************************
*%FUNCTION: sendPADI
*%ARGUMENTS:
* conn -- PPPoEConnection structure
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Sends a PADI packet
***********************************************************************/
void
sendPADI(PPPoEConnection *conn)
{
    PPPoEPacket packet;
    unsigned char *cursor = packet.payload;
    PPPoETag *svc = (PPPoETag *) (&packet.payload);
    UINT16_t namelen = 0;
    UINT16_t plen;

    if (conn->serviceName) {
	namelen = (UINT16_t) strlen(conn->serviceName);
    }
    plen = TAG_HDR_SIZE + namelen;
    CHECK_ROOM(cursor, packet.payload, plen);

    /* Set destination to Ethernet broadcast address */
    memset(packet.ethHdr.h_dest, 0xFF, ETH_ALEN);
    memcpy(packet.ethHdr.h_source, conn->myEth, ETH_ALEN);

    packet.ethHdr.h_proto = htons(Eth_PPPOE_Discovery);
    packet.ver = 1;
    packet.type = 1;
    packet.code = CODE_PADI;
    packet.session = 0;

    svc->type = TAG_SERVICE_NAME;
    svc->length = htons(namelen);
    CHECK_ROOM(cursor, packet.payload, namelen+TAG_HDR_SIZE);

    if (conn->serviceName) {
	memcpy(svc->payload, conn->serviceName, strlen(conn->serviceName));
    }
    cursor += namelen + TAG_HDR_SIZE;

    /* If we're using Host-Uniq, copy it over */
    if (conn->useHostUniq) {
	PPPoETag hostUniq;
	pid_t pid = getpid();
	hostUniq.type = htons(TAG_HOST_UNIQ);
	hostUniq.length = htons(sizeof(pid));
	memcpy(hostUniq.payload, &pid, sizeof(pid));
	CHECK_ROOM(cursor, packet.payload, sizeof(pid) + TAG_HDR_SIZE);
	memcpy(cursor, &hostUniq, sizeof(pid) + TAG_HDR_SIZE);
	cursor += sizeof(pid) + TAG_HDR_SIZE;
	plen += sizeof(pid) + TAG_HDR_SIZE;
    }

    packet.length = htons(plen);

    sendPacket(conn, conn->discoverySocket, &packet, (int) (plen + HDR_SIZE));
    if (conn->debugFile) {
	dumpPacket(conn->debugFile, &packet, "SENT");
	fprintf(conn->debugFile, "\n");
	fflush(conn->debugFile);
    }
}

/**********************************************************************
*%FUNCTION: waitForPADO
*%ARGUMENTS:
* conn -- PPPoEConnection structure
* timeout -- how long to wait (in seconds)
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Waits for a PADO packet and copies useful information
***********************************************************************/
void
waitForPADO(PPPoEConnection *conn, int timeout)
{
    fd_set readable;
    int r;
    struct timeval tv;
    PPPoEPacket packet;
    int len;

    struct PacketCriteria pc;
    pc.conn          = conn;
    pc.acNameOK      = (conn->acName)      ? 0 : 1;
    pc.serviceNameOK = (conn->serviceName) ? 0 : 1;
    pc.seenACName    = 0;