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/***********************************************************************
*
* common.c
*
* Implementation of user-space PPPoE redirector for Linux.
*
* Common functions used by PPPoE client and server
*
* 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: common.c,v 1.3 2008/06/09 08:34:23 paulus Exp $";
#define _GNU_SOURCE 1
#include "pppoe.h"
#include "pppd/pppd.h"
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <syslog.h> /* for LOG_DEBUG */
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
/**********************************************************************
*%FUNCTION: parsePacket
*%ARGUMENTS:
* packet -- the PPPoE discovery packet to parse
* func -- function called for each tag in the packet
* extra -- an opaque data pointer supplied to parsing function
*%RETURNS:
* 0 if everything went well; -1 if there was an error
*%DESCRIPTION:
* Parses a PPPoE discovery packet, calling "func" for each tag in the packet.
* "func" is passed the additional argument "extra".
***********************************************************************/
int
parsePacket(PPPoEPacket *packet, ParseFunc *func, void *extra)
{
UINT16_t len = ntohs(packet->length);
unsigned char *curTag;
UINT16_t tagType, tagLen;
if (PPPOE_VER(packet->vertype) != 1) {
error("Invalid PPPoE version (%d)", PPPOE_VER(packet->vertype));
return -1;
}
if (PPPOE_TYPE(packet->vertype) != 1) {
error("Invalid PPPoE type (%d)", PPPOE_TYPE(packet->vertype));
return -1;
}
/* Do some sanity checks on packet */
if (len > ETH_JUMBO_LEN - PPPOE_OVERHEAD) { /* 6-byte overhead for PPPoE header */
error("Invalid PPPoE packet length (%u)", len);
return -1;
}
/* Step through the tags */
curTag = packet->payload;
while(curTag - packet->payload < len) {
/* Alignment is not guaranteed, so do this by hand... */
tagType = (curTag[0] << 8) + curTag[1];
tagLen = (curTag[2] << 8) + curTag[3];
if (tagType == TAG_END_OF_LIST) {
return 0;
}
if ((curTag - packet->payload) + tagLen + TAG_HDR_SIZE > len) {
error("Invalid PPPoE tag length (%u)", tagLen);
return -1;
}
func(tagType, tagLen, curTag+TAG_HDR_SIZE, extra);
curTag = curTag + TAG_HDR_SIZE + tagLen;
}
return 0;
}
/***********************************************************************
*%FUNCTION: sendPADT
*%ARGUMENTS:
* conn -- PPPoE connection
* msg -- if non-NULL, extra error message to include in PADT packet.
*%RETURNS:
* Nothing
*%DESCRIPTION:
* Sends a PADT packet
***********************************************************************/
void
sendPADT(PPPoEConnection *conn, char const *msg)
{
PPPoEPacket packet;
unsigned char *cursor = packet.payload;
UINT16_t plen = 0;
/* Do nothing if no session established yet */
if (!conn->session) return;
/* Do nothing if no discovery socket */
if (conn->discoverySocket < 0) return;
memcpy(packet.ethHdr.h_dest, conn->peerEth, ETH_ALEN);
memcpy(packet.ethHdr.h_source, conn->myEth, ETH_ALEN);
packet.ethHdr.h_proto = htons(Eth_PPPOE_Discovery);
packet.vertype = PPPOE_VER_TYPE(1, 1);
packet.code = CODE_PADT;
packet.session = conn->session;
/* Reset Session to zero so there is no possibility of
recursive calls to this function by any signal handler */
conn->session = 0;
/* 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));
memcpy(cursor, &hostUniq, sizeof(pid) + TAG_HDR_SIZE);
cursor += sizeof(pid) + TAG_HDR_SIZE;
plen += sizeof(pid) + TAG_HDR_SIZE;
}
/* Copy error message */
if (msg) {
PPPoETag err;
size_t elen = strlen(msg);
err.type = htons(TAG_GENERIC_ERROR);
err.length = htons(elen);
strcpy(err.payload, msg);
memcpy(cursor, &err, elen + TAG_HDR_SIZE);
cursor += elen + TAG_HDR_SIZE;
plen += elen + TAG_HDR_SIZE;
}
/* Copy cookie and relay-ID if needed */
if (conn->cookie.type) {
CHECK_ROOM(cursor, packet.payload,
ntohs(conn->cookie.length) + TAG_HDR_SIZE);
memcpy(cursor, &conn->cookie, ntohs(conn->cookie.length) + TAG_HDR_SIZE);
cursor += ntohs(conn->cookie.length) + TAG_HDR_SIZE;
plen += ntohs(conn->cookie.length) + TAG_HDR_SIZE;
}
if (conn->relayId.type) {
CHECK_ROOM(cursor, packet.payload,
ntohs(conn->relayId.length) + TAG_HDR_SIZE);
memcpy(cursor, &conn->relayId, ntohs(conn->relayId.length) + TAG_HDR_SIZE);
cursor += ntohs(conn->relayId.length) + TAG_HDR_SIZE;
plen += ntohs(conn->relayId.length) + TAG_HDR_SIZE;
}
packet.length = htons(plen);
sendPacket(conn, conn->discoverySocket, &packet, (int) (plen + HDR_SIZE));
info("Sent PADT");
}
#define EH(x) (x)[0], (x)[1], (x)[2], (x)[3], (x)[4], (x)[5]
/* Print out a PPPOE packet for debugging */
void pppoe_printpkt(PPPoEPacket *packet,
void (*printer)(void *, char *, ...), void *arg)
{
int len = ntohs(packet->length);
int i, tag, tlen, text;
switch (ntohs(packet->ethHdr.h_proto)) {
case ETH_PPPOE_DISCOVERY:
printer(arg, "PPPOE Discovery V%dT%d ", PPPOE_VER(packet->vertype),
PPPOE_TYPE(packet->vertype));
switch (packet->code) {
case CODE_PADI:
printer(arg, "PADI");
break;
case CODE_PADO:
printer(arg, "PADO");
break;
case CODE_PADR:
printer(arg, "PADR");
break;
case CODE_PADS:
printer(arg, "PADS");
break;
case CODE_PADT:
printer(arg, "PADT");
break;
default:
printer(arg, "unknown code %x", packet->code);
}
printer(arg, " session 0x%x length %d\n", ntohs(packet->session), len);
break;
case ETH_PPPOE_SESSION:
printer(arg, "PPPOE Session V%dT%d", PPPOE_VER(packet->vertype),
PPPOE_TYPE(packet->vertype));
printer(arg, " code 0x%x session 0x%x length %d\n", packet->code,
ntohs(packet->session), len);
break;
default:
printer(arg, "Unknown ethernet frame with proto = 0x%x\n",
ntohs(packet->ethHdr.h_proto));
}
printer(arg, " dst %02x:%02x:%02x:%02x:%02x:%02x ", EH(packet->ethHdr.h_dest));
printer(arg, " src %02x:%02x:%02x:%02x:%02x:%02x\n", EH(packet->ethHdr.h_source));
if (ntohs(packet->ethHdr.h_proto) != ETH_PPPOE_DISCOVERY)
return;
for (i = 0; i + TAG_HDR_SIZE <= len; i += tlen) {
tag = (packet->payload[i] << 8) + packet->payload[i+1];
tlen = (packet->payload[i+2] << 8) + packet->payload[i+3];
if (i + tlen + TAG_HDR_SIZE > len)
break;
text = 0;
i += TAG_HDR_SIZE;
printer(arg, " [");
switch (tag) {
case TAG_END_OF_LIST:
printer(arg, "end-of-list");
break;
case TAG_SERVICE_NAME:
printer(arg, "service-name");
text = 1;
break;
case TAG_AC_NAME:
printer(arg, "AC-name");
text = 1;
break;
case TAG_HOST_UNIQ:
printer(arg, "host-uniq");
break;
case TAG_AC_COOKIE:
printer(arg, "AC-cookie");
break;
case TAG_VENDOR_SPECIFIC:
printer(arg, "vendor-specific");
break;
case TAG_RELAY_SESSION_ID:
printer(arg, "relay-session-id");
break;
case TAG_PPP_MAX_PAYLOAD:
printer(arg, "PPP-max-payload");
break;
case TAG_SERVICE_NAME_ERROR:
printer(arg, "service-name-error");
text = 1;
break;
case TAG_AC_SYSTEM_ERROR:
printer(arg, "AC-system-error");
text = 1;
break;
case TAG_GENERIC_ERROR:
printer(arg, "generic-error");
text = 1;
break;
default:
printer(arg, "unknown tag 0x%x", tag);
}
if (tlen) {
if (text)
printer(arg, " %.*v", tlen, &packet->payload[i]);
else if (tlen <= 32)
printer(arg, " %.*B", tlen, &packet->payload[i]);
else
printer(arg, " %.32B... (length %d)",
&packet->payload[i], tlen);
}
printer(arg, "]");
}
printer(arg, "\n");
}
void pppoe_log_packet(const char *prefix, PPPoEPacket *packet)
{
init_pr_log(prefix, LOG_DEBUG);
pppoe_printpkt(packet, pr_log, NULL);
end_pr_log();
}
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