+++ /dev/null
-/***********************************************************************
-*
-* 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 1.2 2004/01/13 04:03:58 paulus Exp $";
-
-#include "pppoe.h"
-
-#ifdef HAVE_SYSLOG_H
-#include <syslog.h>
-#endif
-
-#include <string.h>
-#include <errno.h>
-#include <stdlib.h>
-
-#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 (packet->ver != 1) {
- syslog(LOG_ERR, "Invalid PPPoE version (%d)", (int) packet->ver);
- return -1;
- }
- if (packet->type != 1) {
- syslog(LOG_ERR, "Invalid PPPoE type (%d)", (int) packet->type);
- return -1;
- }
-
- /* Do some sanity checks on packet */
- if (len > ETH_DATA_LEN - 6) { /* 6-byte overhead for PPPoE header */
- syslog(LOG_ERR, "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 = (((UINT16_t) curTag[0]) << 8) +
- (UINT16_t) curTag[1];
- tagLen = (((UINT16_t) curTag[2]) << 8) +
- (UINT16_t) curTag[3];
- if (tagType == TAG_END_OF_LIST) {
- return 0;
- }
- if ((curTag - packet->payload) + tagLen + TAG_HDR_SIZE > len) {
- syslog(LOG_ERR, "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: findTag
-*%ARGUMENTS:
-* packet -- the PPPoE discovery packet to parse
-* type -- the type of the tag to look for
-* tag -- will be filled in with tag contents
-*%RETURNS:
-* A pointer to the tag if one of the specified type is found; NULL
-* otherwise.
-*%DESCRIPTION:
-* Looks for a specific tag type.
-***********************************************************************/
-unsigned char *
-findTag(PPPoEPacket *packet, UINT16_t type, PPPoETag *tag)
-{
- UINT16_t len = ntohs(packet->length);
- unsigned char *curTag;
- UINT16_t tagType, tagLen;
-
- if (packet->ver != 1) {
- syslog(LOG_ERR, "Invalid PPPoE version (%d)", (int) packet->ver);
- return NULL;
- }
- if (packet->type != 1) {
- syslog(LOG_ERR, "Invalid PPPoE type (%d)", (int) packet->type);
- return NULL;
- }
-
- /* Do some sanity checks on packet */
- if (len > ETH_DATA_LEN - 6) { /* 6-byte overhead for PPPoE header */
- syslog(LOG_ERR, "Invalid PPPoE packet length (%u)", len);
- return NULL;
- }
-
- /* Step through the tags */
- curTag = packet->payload;
- while(curTag - packet->payload < len) {
- /* Alignment is not guaranteed, so do this by hand... */
- tagType = (((UINT16_t) curTag[0]) << 8) +
- (UINT16_t) curTag[1];
- tagLen = (((UINT16_t) curTag[2]) << 8) +
- (UINT16_t) curTag[3];
- if (tagType == TAG_END_OF_LIST) {
- return NULL;
- }
- if ((curTag - packet->payload) + tagLen + TAG_HDR_SIZE > len) {
- syslog(LOG_ERR, "Invalid PPPoE tag length (%u)", tagLen);
- return NULL;
- }
- if (tagType == type) {
- memcpy(tag, curTag, tagLen + TAG_HDR_SIZE);
- return curTag;
- }
- curTag = curTag + TAG_HDR_SIZE + tagLen;
- }
- return NULL;
-}
-
-/**********************************************************************
-*%FUNCTION: printErr
-*%ARGUMENTS:
-* str -- error message
-*%RETURNS:
-* Nothing
-*%DESCRIPTION:
-* Prints a message to stderr and syslog.
-***********************************************************************/
-void
-printErr(char const *str)
-{
- fprintf(stderr, "pppoe: %s\n", str);
- syslog(LOG_ERR, "%s", str);
-}
-
-
-/**********************************************************************
-*%FUNCTION: strDup
-*%ARGUMENTS:
-* str -- string to copy
-*%RETURNS:
-* A malloc'd copy of str. Exits if malloc fails.
-***********************************************************************/
-char *
-strDup(char const *str)
-{
- char *copy = malloc(strlen(str)+1);
- if (!copy) {
- rp_fatal("strdup failed");
- }
- strcpy(copy, str);
- return copy;
-}
-
-#ifdef PPPOE_STANDALONE
-/**********************************************************************
-*%FUNCTION: computeTCPChecksum
-*%ARGUMENTS:
-* ipHdr -- pointer to IP header
-* tcpHdr -- pointer to TCP header
-*%RETURNS:
-* The computed TCP checksum
-***********************************************************************/
-UINT16_t
-computeTCPChecksum(unsigned char *ipHdr, unsigned char *tcpHdr)
-{
- UINT32_t sum = 0;
- UINT16_t count = ipHdr[2] * 256 + ipHdr[3];
- unsigned char *addr = tcpHdr;
- unsigned char pseudoHeader[12];
-
- /* Count number of bytes in TCP header and data */
- count -= (ipHdr[0] & 0x0F) * 4;
-
- memcpy(pseudoHeader, ipHdr+12, 8);
- pseudoHeader[8] = 0;
- pseudoHeader[9] = ipHdr[9];
- pseudoHeader[10] = (count >> 8) & 0xFF;
- pseudoHeader[11] = (count & 0xFF);
-
- /* Checksum the pseudo-header */
- sum += * (UINT16_t *) pseudoHeader;
- sum += * ((UINT16_t *) (pseudoHeader+2));
- sum += * ((UINT16_t *) (pseudoHeader+4));
- sum += * ((UINT16_t *) (pseudoHeader+6));
- sum += * ((UINT16_t *) (pseudoHeader+8));
- sum += * ((UINT16_t *) (pseudoHeader+10));
-
- /* Checksum the TCP header and data */
- while (count > 1) {
- sum += * (UINT16_t *) addr;
- addr += 2;
- count -= 2;
- }
- if (count > 0) {
- sum += *addr;
- }
-
- while(sum >> 16) {
- sum = (sum & 0xffff) + (sum >> 16);
- }
- return (UINT16_t) (~sum & 0xFFFF);
-}
-
-/**********************************************************************
-*%FUNCTION: clampMSS
-*%ARGUMENTS:
-* packet -- PPPoE session packet
-* dir -- either "incoming" or "outgoing"
-* clampMss -- clamp value
-*%RETURNS:
-* Nothing
-*%DESCRIPTION:
-* Clamps MSS option if TCP SYN flag is set.
-***********************************************************************/
-void
-clampMSS(PPPoEPacket *packet, char const *dir, int clampMss)
-{
- unsigned char *tcpHdr;
- unsigned char *ipHdr;
- unsigned char *opt;
- unsigned char *endHdr;
- unsigned char *mssopt = NULL;
- UINT16_t csum;
-
- int len, minlen;
-
- /* check PPP protocol type */
- if (packet->payload[0] & 0x01) {
- /* 8 bit protocol type */
-
- /* Is it IPv4? */
- if (packet->payload[0] != 0x21) {
- /* Nope, ignore it */
- return;
- }
-
- ipHdr = packet->payload + 1;
- minlen = 41;
- } else {
- /* 16 bit protocol type */
-
- /* Is it IPv4? */
- if (packet->payload[0] != 0x00 ||
- packet->payload[1] != 0x21) {
- /* Nope, ignore it */
- return;
- }
-
- ipHdr = packet->payload + 2;
- minlen = 42;
- }
-
- /* Is it too short? */
- len = (int) ntohs(packet->length);
- if (len < minlen) {
- /* 20 byte IP header; 20 byte TCP header; at least 1 or 2 byte PPP protocol */
- return;
- }
-
- /* Verify once more that it's IPv4 */
- if ((ipHdr[0] & 0xF0) != 0x40) {
- return;
- }
-
- /* Is it a fragment that's not at the beginning of the packet? */
- if ((ipHdr[6] & 0x1F) || ipHdr[7]) {
- /* Yup, don't touch! */
- return;
- }
- /* Is it TCP? */
- if (ipHdr[9] != 0x06) {
- return;
- }
-
- /* Get start of TCP header */
- tcpHdr = ipHdr + (ipHdr[0] & 0x0F) * 4;
-
- /* Is SYN set? */
- if (!(tcpHdr[13] & 0x02)) {
- return;
- }
-
- /* Compute and verify TCP checksum -- do not touch a packet with a bad
- checksum */
- csum = computeTCPChecksum(ipHdr, tcpHdr);
- if (csum) {
- syslog(LOG_ERR, "Bad TCP checksum %x", (unsigned int) csum);
-
- /* Upper layers will drop it */
- return;
- }
-
- /* Look for existing MSS option */
- endHdr = tcpHdr + ((tcpHdr[12] & 0xF0) >> 2);
- opt = tcpHdr + 20;
- while (opt < endHdr) {
- if (!*opt) break; /* End of options */
- switch(*opt) {
- case 1:
- opt++;
- break;
-
- case 2:
- if (opt[1] != 4) {
- /* Something fishy about MSS option length. */
- syslog(LOG_ERR,
- "Bogus length for MSS option (%u) from %u.%u.%u.%u",
- (unsigned int) opt[1],
- (unsigned int) ipHdr[12],
- (unsigned int) ipHdr[13],
- (unsigned int) ipHdr[14],
- (unsigned int) ipHdr[15]);
- return;
- }
- mssopt = opt;
- break;
- default:
- if (opt[1] < 2) {
- /* Someone's trying to attack us? */
- syslog(LOG_ERR,
- "Bogus TCP option length (%u) from %u.%u.%u.%u",
- (unsigned int) opt[1],
- (unsigned int) ipHdr[12],
- (unsigned int) ipHdr[13],
- (unsigned int) ipHdr[14],
- (unsigned int) ipHdr[15]);
- return;
- }
- opt += (opt[1]);
- break;
- }
- /* Found existing MSS option? */
- if (mssopt) break;
- }
-
- /* If MSS exists and it's low enough, do nothing */
- if (mssopt) {
- unsigned mss = mssopt[2] * 256 + mssopt[3];
- if (mss <= clampMss) {
- return;
- }
-
- mssopt[2] = (((unsigned) clampMss) >> 8) & 0xFF;
- mssopt[3] = ((unsigned) clampMss) & 0xFF;
- } else {
- /* No MSS option. Don't add one; we'll have to use 536. */
- return;
- }
-
- /* Recompute TCP checksum */
- tcpHdr[16] = 0;
- tcpHdr[17] = 0;
- csum = computeTCPChecksum(ipHdr, tcpHdr);
- (* (UINT16_t *) (tcpHdr+16)) = csum;
-}
-#endif /* PPPOE_STANDALONE */
-
-/***********************************************************************
-*%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.ver = 1;
- packet.type = 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));
- if (conn->debugFile) {
- dumpPacket(conn->debugFile, &packet, "SENT");
- fprintf(conn->debugFile, "\n");
- fflush(conn->debugFile);
- }
- syslog(LOG_INFO,"Sent PADT");
-}
-
-/**********************************************************************
-*%FUNCTION: parseLogErrs
-*%ARGUMENTS:
-* type -- tag type
-* len -- tag length
-* data -- tag data
-* extra -- extra user data
-*%RETURNS:
-* Nothing
-*%DESCRIPTION:
-* Picks error tags out of a packet and logs them.
-***********************************************************************/
-void
-parseLogErrs(UINT16_t type, UINT16_t len, unsigned char *data,
- void *extra)
-{
- switch(type) {
- case TAG_SERVICE_NAME_ERROR:
- syslog(LOG_ERR, "PADT: Service-Name-Error: %.*s", (int) len, data);
- fprintf(stderr, "PADT: Service-Name-Error: %.*s\n", (int) len, data);
- break;
- case TAG_AC_SYSTEM_ERROR:
- syslog(LOG_ERR, "PADT: System-Error: %.*s", (int) len, data);
- fprintf(stderr, "PADT: System-Error: %.*s\n", (int) len, data);
- break;
- case TAG_GENERIC_ERROR:
- syslog(LOG_ERR, "PADT: Generic-Error: %.*s", (int) len, data);
- fprintf(stderr, "PADT: Generic-Error: %.*s\n", (int) len, data);
- break;
- }
-}
-
projects / ppp.git / blobdiff