pppoe-server.c

网上的一个开源代码

/***********************************************************************
*
* pppoe-server.c
*
* Implementation of a user-space PPPoE server
*
* Copyright (C) 2000 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.
*
* $Id: pppoe-server.c,v 1.91 2005/08/10 00:25:21 dfs Exp $
*
* LIC: GPL
*
***********************************************************************/

static char const RCSID[] =
"$Id: pppoe-server.c,v 1.91 2005/08/10 00:25:21 dfs Exp $";

#include "config.h"

#if defined(HAVE_NETPACKET_PACKET_H) || defined(HAVE_LINUX_IF_PACKET_H)
#define _POSIX_SOURCE 1 /* For sigaction defines */
#endif

#define _BSD_SOURCE 1 /* for gethostname */

#include "pppoe-server.h"
#include "md5.h"

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

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

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

#ifdef HAVE_GETOPT_H
#include <getopt.h>
#endif

#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif

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

#include <time.h>

#include <signal.h>

#ifdef HAVE_LICENSE
#include "license.h"
#include "licensed-only/servfuncs.h"
static struct License const *ServerLicense;
static struct License const *ClusterLicense;
#else
#define control_session_started(x) (void) 0
#define control_session_terminated(x) (void) 0
#define control_exit() (void) 0
#define realpeerip peerip
#endif

#ifdef HAVE_L2TP
extern PppoeSessionFunctionTable L2TPSessionFunctionTable;
extern void pppoe_to_l2tp_add_interface(EventSelector *es,
					Interface *interface);
#endif

static void InterfaceHandler(EventSelector *es,
			int fd, unsigned int flags, void *data);
static void startPPPD(ClientSession *sess);
static void sendErrorPADS(int sock, unsigned char *source, unsigned char *dest,
			  int errorTag, char *errorMsg);

#define CHECK_ROOM(cursor, start, len) \
do {\
    if (((cursor)-(start))+(len) > MAX_PPPOE_PAYLOAD) { \
	syslog(LOG_ERR, "Would create too-long packet"); \
	return; \
    } \
} while(0)

static void PppoeStopSession(ClientSession *ses, char const *reason);
static int PppoeSessionIsActive(ClientSession *ses);

/* Service-Names we advertise */
#define MAX_SERVICE_NAMES 64
static int NumServiceNames = 0;
static char const *ServiceNames[MAX_SERVICE_NAMES];

PppoeSessionFunctionTable DefaultSessionFunctionTable = {
    PppoeStopSession,
    PppoeSessionIsActive,
    NULL
};

/* An array of client sessions */
ClientSession *Sessions = NULL;
ClientSession *FreeSessions = NULL;
ClientSession *LastFreeSession = NULL;
ClientSession *BusySessions = NULL;

/* Interfaces we're listening on */
Interface interfaces[MAX_INTERFACES];
int NumInterfaces = 0;

/* The number of session slots */
size_t NumSessionSlots;

/* Number of active sessions */
size_t NumActiveSessions = 0;

/* Offset of first session */
size_t SessOffset = 0;

/* Event Selector */
EventSelector *event_selector;

/* Use Linux kernel-mode PPPoE? */
static int UseLinuxKernelModePPPoE = 0;

static int Debug = 0;
static int CheckPoolSyntax = 0;

/* Synchronous mode */
static int Synchronous = 0;

/* Random seed for cookie generation */
#define SEED_LEN 16
#define MD5_LEN 16
#define COOKIE_LEN (MD5_LEN + sizeof(pid_t)) /* Cookie is 16-byte MD5 + PID of server */

static unsigned char CookieSeed[SEED_LEN];

#define MAXLINE 512

/* Default interface if no -I option given */
#define DEFAULT_IF "eth0"

/* Access concentrator name */
char *ACName = NULL;

/* Options to pass to pppoe process */
char PppoeOptions[SMALLBUF] = "";

/* Our local IP address */
unsigned char LocalIP[IPV4ALEN] = {10, 0, 0, 1}; /* Counter optionally STARTS here */
unsigned char RemoteIP[IPV4ALEN] = {10, 67, 15, 1}; /* Counter STARTS here */

/* Do we increment local IP for each connection? */
int IncrLocalIP = 0;

/* Do we randomize session numbers? */
int RandomizeSessionNumbers = 0;

/* Do we pass the "unit" option to pppd?  (2.4 or greater) */
int PassUnitOptionToPPPD = 0;

static PPPoETag hostUniq;
static PPPoETag relayId;
static PPPoETag receivedCookie;
static PPPoETag requestedService;

#define HOSTNAMELEN 256

/**********************************************************************
*%FUNCTION: childHandler
*%ARGUMENTS:
* pid -- pid of child
* status -- exit status
* ses -- which session terminated
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Called synchronously when a child dies.  Remove from busy list.
***********************************************************************/
static void
childHandler(pid_t pid, int status, void *s)
{
    ClientSession *session = s;

    /* Temporary structure for sending PADT's. */
    PPPoEConnection conn;

#ifdef HAVE_L2TP
    /* We're acting as LAC, so when child exits, become a PPPoE <-> L2TP
       relay */
    if (session->flags & FLAG_ACT_AS_LAC) {
	syslog(LOG_INFO, "Session %d for client "
	       "%02x:%02x:%02x:%02x:%02x:%02x handed off to LNS %s",
	       ntohs(session->sess),
	       session->eth[0], session->eth[1], session->eth[2],
	       session->eth[3], session->eth[4], session->eth[5],
	       inet_ntoa(session->tunnel_endpoint.sin_addr));
	session->pid = 0;
	session->funcs = &L2TPSessionFunctionTable;
	return;
    }
#endif

    memset(&conn, 0, sizeof(conn));
    conn.useHostUniq = 0;

    syslog(LOG_INFO,
	   "Session %d closed for client "
	   "%02x:%02x:%02x:%02x:%02x:%02x (%d.%d.%d.%d) on %s",
	   ntohs(session->sess),
	   session->eth[0], session->eth[1], session->eth[2],
	   session->eth[3], session->eth[4], session->eth[5],
	   (int) session->realpeerip[0], (int) session->realpeerip[1],
	   (int) session->realpeerip[2], (int) session->realpeerip[3],
	   session->ethif->name);
    memcpy(conn.myEth, session->ethif->mac, ETH_ALEN);
    conn.discoverySocket = session->ethif->sock;
    conn.session = session->sess;
    memcpy(conn.peerEth, session->eth, ETH_ALEN);
    if (!(session->flags & FLAG_SENT_PADT)) {
	if (session->flags & FLAG_RECVD_PADT) {
	    sendPADT(&conn, "RP-PPPoE: Received PADT from peer");
	} else {
	    sendPADT(&conn, "RP-PPPoE: Child pppd process terminated");
	}
	session->flags |= FLAG_SENT_PADT;
    }

    session->serviceName = "";
    control_session_terminated(session);
    if (pppoe_free_session(session) < 0) {
	return;
    }

}

/**********************************************************************
*%FUNCTION: incrementIPAddress (static)
*%ARGUMENTS:
* addr -- a 4-byte array representing IP address
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Increments addr in-place
***********************************************************************/
static void
incrementIPAddress(unsigned char ip[IPV4ALEN])
{
    ip[3]++;
    if (!ip[3]) {
	ip[2]++;
	if (!ip[2]) {
	    ip[1]++;
	    if (!ip[1]) {
		ip[0]++;
	    }
	}
    }
}

/**********************************************************************
*%FUNCTION: killAllSessions
*%ARGUMENTS:
* None
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Kills all pppd processes (and hence all PPPoE sessions)
***********************************************************************/
void
killAllSessions(void)
{
    ClientSession *sess = BusySessions;
    while(sess) {
	sess->funcs->stop(sess, "Shutting Down");
	sess = sess->next;
    }
#ifdef HAVE_L2TP
    pppoe_close_l2tp_tunnels();
#endif
}

/**********************************************************************
*%FUNCTION: parseAddressPool
*%ARGUMENTS:
* fname -- name of file containing IP address pool.
* install -- if true, install IP addresses in sessions.
*%RETURNS:
* Number of valid IP addresses found.
*%DESCRIPTION:
* Reads a list of IP addresses from a file.
***********************************************************************/
static int
parseAddressPool(char const *fname, int install)
{
    FILE *fp = fopen(fname, "r");
    int numAddrs = 0;
    unsigned int a, b, c, d;
    unsigned int e, f, g, h;
    char line[MAXLINE];

    if (!fp) {
	sysErr("Cannot open address pool file");
	exit(1);
    }

    while (!feof(fp)) {
	if (!fgets(line, MAXLINE, fp)) {
	    break;
	}
	if ((sscanf(line, "%u.%u.%u.%u:%u.%u.%u.%u",
		    &a, &b, &c, &d, &e, &f, &g, &h) == 8) &&
	    a < 256 && b < 256 && c < 256 && d < 256 &&
	    e < 256 && f < 256 && g < 256 && h < 256) {

	    /* Both specified (local:remote) */
	    if (install) {
		Sessions[numAddrs].myip[0] = (unsigned char) a;
		Sessions[numAddrs].myip[1] = (unsigned char) b;
		Sessions[numAddrs].myip[2] = (unsigned char) c;
		Sessions[numAddrs].myip[3] = (unsigned char) d;
		Sessions[numAddrs].peerip[0] = (unsigned char) e;
		Sessions[numAddrs].peerip[1] = (unsigned char) f;
		Sessions[numAddrs].peerip[2] = (unsigned char) g;
		Sessions[numAddrs].peerip[3] = (unsigned char) h;
#ifdef HAVE_LICENSE
		memcpy(Sessions[numAddrs].realpeerip,
		       Sessions[numAddrs].peerip, IPV4ALEN);
#endif
	    }
	    numAddrs++;
	} else if ((sscanf(line, "%u.%u.%u.%u-%u", &a, &b, &c, &d, &e) == 5) &&
		   a < 256 && b < 256 && c < 256 && d < 256 && e < 256) {
	    /* Remote specied as a.b.c.d-e.  Example: 1.2.3.4-8 yields:
	       1.2.3.4, 1.2.3.5, 1.2.3.6, 1.2.3.7, 1.2.3.8 */
	    /* Swap d and e so that e >= d */
	    if (e < d) {
		f = d;
		d = e;
		e = f;
	    }
	    if (install) {
		while (d <= e) {
		    Sessions[numAddrs].peerip[0] = (unsigned char) a;
		    Sessions[numAddrs].peerip[1] = (unsigned char) b;
		    Sessions[numAddrs].peerip[2] = (unsigned char) c;
		    Sessions[numAddrs].peerip[3] = (unsigned char) d;
#ifdef HAVE_LICENSE
		    memcpy(Sessions[numAddrs].realpeerip,
			   Sessions[numAddrs].peerip, IPV4ALEN);
#endif
		d++;
		numAddrs++;
		}
	    } else {
		numAddrs += (e-d) + 1;
	    }
	} else if ((sscanf(line, "%u.%u.%u.%u", &a, &b, &c, &d) == 4) &&
		   a < 256 && b < 256 && c < 256 && d < 256) {
	    /* Only remote specified */
	    if (install) {
		Sessions[numAddrs].peerip[0] = (unsigned char) a;
		Sessions[numAddrs].peerip[1] = (unsigned char) b;
		Sessions[numAddrs].peerip[2] = (unsigned char) c;
		Sessions[numAddrs].peerip[3] = (unsigned char) d;
#ifdef HAVE_LICENSE
		memcpy(Sessions[numAddrs].realpeerip,
		       Sessions[numAddrs].peerip, IPV4ALEN);
#endif
	    }
	    numAddrs++;
	}
    }
    fclose(fp);
    if (!numAddrs) {
	rp_fatal("No valid ip addresses found in pool file");
    }
    return numAddrs;
}

/**********************************************************************
*%FUNCTION: parsePADITags
*%ARGUMENTS:
* type -- tag type
* len -- tag length
* data -- tag data
* extra -- extra user data.
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Picks interesting tags out of a PADI packet
***********************************************************************/
void
parsePADITags(UINT16_t type, UINT16_t len, unsigned char *data,
	      void *extra)
{
    switch(type) {
    case TAG_SERVICE_NAME:
	/* Copy requested service name */
	requestedService.type = htons(type);
	requestedService.length = htons(len);
	memcpy(requestedService.payload, data, len);
	break;
    case TAG_RELAY_SESSION_ID:
	relayId.type = htons(type);
	relayId.length = htons(len);
	memcpy(relayId.payload, data, len);
	break;
    case TAG_HOST_UNIQ:
	hostUniq.type = htons(type);
	hostUniq.length = htons(len);
	memcpy(hostUniq.payload, data, len);
	break;
    }
}

/**********************************************************************
*%FUNCTION: parsePADRTags
*%ARGUMENTS:
* type -- tag type
* len -- tag length
* data -- tag data
* extra -- extra user data.
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Picks interesting tags out of a PADR packet
***********************************************************************/
void
parsePADRTags(UINT16_t type, UINT16_t len, unsigned char *data,
	      void *extra)
{
    switch(type) {
    case TAG_RELAY_SESSION_ID:
	relayId.type = htons(type);
	relayId.length = htons(len);
	memcpy(relayId.payload, data, len);
	break;
    case TAG_HOST_UNIQ:
	hostUniq.type = htons(type);
	hostUniq.length = htons(len);
	memcpy(hostUniq.payload, data, len);
	break;
    case TAG_AC_COOKIE:
	receivedCookie.type = htons(type);
	receivedCookie.length = htons(len);
	memcpy(receivedCookie.payload, data, len);
	break;
    case TAG_SERVICE_NAME:
	requestedService.type = htons(type);
	requestedService.length = htons(len);
	memcpy(requestedService.payload, data, len);
	break;
    }
}

/**********************************************************************
*%FUNCTION: fatalSys
*%ARGUMENTS:
* str -- error message
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Prints a message plus the errno value to stderr and syslog and exits.
***********************************************************************/
void
fatalSys(char const *str)
{
    char buf[SMALLBUF];
    snprintf(buf, SMALLBUF, "%s: %s", str, strerror(errno));
    printErr(buf);
    control_exit();
    exit(EXIT_FAILURE);
}

/**********************************************************************
*%FUNCTION: sysErr
*%ARGUMENTS:
* str -- error message
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Prints a message plus the errno value to syslog.
***********************************************************************/
void
sysErr(char const *str)
{
    char buf[1024];
    sprintf(buf, "%.256s: %.256s", str, strerror(errno));
    printErr(buf);
}

/**********************************************************************
*%FUNCTION: rp_fatal
*%ARGUMENTS:
* str -- error message
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Prints a message to stderr and syslog and exits.
***********************************************************************/
void
rp_fatal(char const *str)
{
    printErr(str);
    control_exit();
    exit(EXIT_FAILURE);
}