/* imtcp.c
 * This is the implementation of the TCP input module.
 *
 * NOTE: read comments in module-template.h to understand how this file
 *       works!
 *
 * File begun on 2007-12-21 by RGerhards (extracted from syslogd.c)
 *
 * Copyright 2007 Rainer Gerhards and Adiscon GmbH.
 *
 * This file is part of rsyslog.
 *
 * Rsyslog is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Rsyslog is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Rsyslog.  If not, see <http://www.gnu.org/licenses/>.
 *
 * A copy of the GPL can be found in the file "COPYING" in this distribution.
 */

#include "config.h"
#ifdef FORCE_NO_GSS
  #ifdef USE_GSSAPI
    #undef USE_GSSAPI
  #endif
#endif

#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <stdarg.h>
#include <ctype.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#if HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef USE_GSSAPI
#include <gssapi/gssapi.h>
#endif
#include "rsyslog.h"
#include "syslogd.h"
#include "cfsysline.h"
#include "module-template.h"
#include "net.h"
#ifdef USE_GSSAPI
#include "gss-misc.h"
#endif
#include "srUtils.h"

MODULE_TYPE_INPUT

/* defines */
#ifdef USE_GSSAPI
#define ALLOWEDMETHOD_GSS 2
#endif
#define ALLOWEDMETHOD_TCP 1

#define TCPSESS_MAX_DEFAULT 200 /* default for nbr of tcp sessions if no number is given */

/* Module static data */
DEF_IMOD_STATIC_DATA

typedef struct _instanceData {
} instanceData;

typedef enum _TCPFRAMINGMODE {
		TCP_FRAMING_OCTET_STUFFING = 0, /* traditional LF-delimited */
		TCP_FRAMING_OCTET_COUNTING = 1  /* -transport-tls like octet count */
	} TCPFRAMINGMODE;

struct TCPSession {
	int sock;
	int iMsg; /* index of next char to store in msg */
	int bAtStrtOfFram;	/* are we at the very beginning of a new frame? */
	int iOctetsRemain;	/* Number of Octets remaining in message */
	TCPFRAMINGMODE eFraming;
	char msg[MAXLINE+1];
	char *fromHost;
#ifdef USE_GSSAPI
	OM_uint32 gss_flags;
	gss_ctx_id_t gss_context;
	char allowedMethods;
#endif
};

static int iTCPSessMax = TCPSESS_MAX_DEFAULT;	/* actual number of sessions */
static char *TCPLstnPort = "0"; /* read-only after startup */
static int bEnableTCP = 0; /* read-only after startup */
static int  *sockTCPLstn = NULL; /* read-only after startup, modified by restart */
static struct TCPSession *pTCPSessions;
/* The thread-safeness of the sesion table is doubtful */
#ifdef USE_GSSAPI
static gss_cred_id_t gss_server_creds = GSS_C_NO_CREDENTIAL;
static char *gss_listen_service_name = NULL;
#endif

/* config settings */


/* code to free all sockets within a socket table.
 * A socket table is a descriptor table where the zero
 * element has the count of elements. This is used for
 * listening sockets. The socket table itself is also
 * freed.
 * A POINTER to this structure must be provided, thus
 * double indirection!
 * rgerhards, 2007-06-28
 */
static void freeAllSockets(int **socks)
{
	assert(socks != NULL);
	assert(*socks != NULL);
	while(**socks) {
		dbgprintf("Closing socket %d.\n", (*socks)[**socks]);
		close((*socks)[**socks]);
		(**socks)--;
	}
	free(*socks);
	socks = NULL;
}


/* configure TCP listener settings. This is called during command
 * line parsing. The argument following -t is supplied as an argument.
 * The format of this argument is
 * "<port-to-use>, <nbr-of-sessions>"
 * Typically, there is no whitespace between port and session number.
 * (but it may be...).
 * NOTE: you can not use dbgprintf() in here - the dbgprintf() system is
 * not yet initilized when this function is called.
 * rgerhards, 2007-06-21
 * We can also not use logerror(), as that system is also not yet
 * initialized... rgerhards, 2007-06-28
 */
void configureTCPListen(char *cOptarg)
{
	register int i;
	register char *pArg = cOptarg;

	assert(cOptarg != NULL);

	/* extract port */
	i = 0;
	while(isdigit((int) *pArg)) {
		i = i * 10 + *pArg++ - '0';
	}

	if( i >= 0 && i <= 65535) {
		TCPLstnPort = cOptarg;
	} else {
		logerrorSz("Invalid TCP listen port %s - changed to 514.\n", cOptarg);
		TCPLstnPort = "514";
	}
}


void configureTCPListenSessMax(char *cOptarg)
{
	register int i;
	register char *pArg = cOptarg;

	assert(cOptarg != NULL);

	/* number of sessions */
	i = 0;
	while(isdigit((int) *pArg)) {
		i = i * 10 + *pArg++ - '0';
	}

	if(i > 0)
		iTCPSessMax = i;
	else {
		/* too small, need to adjust */
		logerrorSz("TCP session max configured to %s - changing to 1.\n", cOptarg);
		iTCPSessMax = 1;
	}
}


/* Initialize the session table
 * returns 0 if OK, somewhat else otherwise
 */
static int TCPSessInit(void)
{
	register int i;

	assert(pTCPSessions == NULL);
	dbgprintf("Allocating buffer for %d TCP sessions.\n", iTCPSessMax);
	if((pTCPSessions = (struct TCPSession *) malloc(sizeof(struct TCPSession) * iTCPSessMax))
	    == NULL) {
		dbgprintf("Error: TCPSessInit() could not alloc memory for TCP session table.\n");
		return(1);
	}

	for(i = 0 ; i < iTCPSessMax ; ++i) {
		pTCPSessions[i].sock = -1; /* no sock */
		pTCPSessions[i].iMsg = 0; /* just make sure... */
		pTCPSessions[i].bAtStrtOfFram = 1; /* indicate frame header expected */
		pTCPSessions[i].eFraming = TCP_FRAMING_OCTET_STUFFING; /* just make sure... */
#ifdef USE_GSSAPI
		pTCPSessions[i].gss_flags = 0;
		pTCPSessions[i].gss_context = GSS_C_NO_CONTEXT;
		pTCPSessions[i].allowedMethods = 0;
#endif
	}
	return(0);
}


/* find a free spot in the session table. If the table
 * is full, -1 is returned, else the index of the free
 * entry (0 or higher).
 */
static int TCPSessFindFreeSpot(void)
{
	register int i;

	for(i = 0 ; i < iTCPSessMax ; ++i) {
		if(pTCPSessions[i].sock == -1)
			break;
	}

	return((i < iTCPSessMax) ? i : -1);
}


/* Get the next session index. Free session tables entries are
 * skipped. This function is provided the index of the last
 * session entry, or -1 if no previous entry was obtained. It
 * returns the index of the next session or -1, if there is no
 * further entry in the table. Please note that the initial call
 * might as well return -1, if there is no session at all in the
 * session table.
 */
int TCPSessGetNxtSess(int iCurr)
{
	register int i;

	for(i = iCurr + 1 ; i < iTCPSessMax ; ++i)
		if(pTCPSessions[i].sock != -1)
			break;

	return((i < iTCPSessMax) ? i : -1);
}


/* De-Initialize TCP listner sockets.
 * This function deinitializes everything, including freeing the
 * session table. No TCP listen receive operations are permitted
 * unless the subsystem is reinitialized.
 * rgerhards, 2007-06-21
 */
void deinit_tcp_listener(void)
{
	int iTCPSess;

	assert(pTCPSessions != NULL);
	/* close all TCP connections! */
	iTCPSess = TCPSessGetNxtSess(-1);
	while(iTCPSess != -1) {
		int fd;
		fd = pTCPSessions[iTCPSess].sock;
		dbgprintf("Closing TCP Session %d\n", fd);
		close(fd);
		free(pTCPSessions[iTCPSess].fromHost);
#ifdef USE_GSSAPI
		if(bEnableTCP & ALLOWEDMETHOD_GSS) {
			OM_uint32 maj_stat, min_stat;
			maj_stat = gss_delete_sec_context(&min_stat, &pTCPSessions[iTCPSess].gss_context, GSS_C_NO_BUFFER);
			if (maj_stat != GSS_S_COMPLETE)
				display_status("deleting context", maj_stat, min_stat);
		}
#endif
		/* now get next... */
		iTCPSess = TCPSessGetNxtSess(iTCPSess);
	}
	
	/* we are done with the session table - so get rid of it...
	*/
	free(pTCPSessions);
	pTCPSessions = NULL; /* just to make sure... */

	/* finally close the listen sockets themselfs */
	freeAllSockets(&sockTCPLstn);
}


/* Initialize TCP sockets (for listener)
 * This function returns either NULL (which means it failed) or 
 * a pointer to an array of file descriptiors. If the pointer is
 * returned, the zeroest element [0] contains the count of valid
 * descriptors. The descriptors themself follow in range
 * [1] ... [num-descriptors]. It is guaranteed that each of these
 * descriptors is valid, at least when this function returns.
 * Please note that technically the array may be larger than the number
 * of valid pointers stored in it. The memory overhead is minimal, so
 * we do not bother to re-allocate an array of the exact size. Logically,
 * the array still contains the exactly correct number of descriptors.
 */
int *create_tcp_socket(void)
{
        struct addrinfo hints, *res, *r;
        int error, maxs, *s, *socks, on = 1;

	if(!strcmp(TCPLstnPort, "0"))
		TCPLstnPort = "514";
		/* use default - we can not do service db update, because there is
		 * no IANA-assignment for syslog/tcp. In the long term, we might
		 * re-use RFC 3195 port of 601, but that would probably break to
		 * many existing configurations.
		 * rgerhards, 2007-06-28
		 */
	dbgprintf("creating tcp socket on port %s\n", TCPLstnPort);
        memset(&hints, 0, sizeof(hints));
        hints.ai_flags = AI_PASSIVE | AI_NUMERICSERV;
        hints.ai_family = family;
        hints.ai_socktype = SOCK_STREAM;

        error = getaddrinfo(NULL, TCPLstnPort, &hints, &res);
        if(error) {
               logerror((char*) gai_strerror(error));
	       return NULL;
	}

        /* Count max number of sockets we may open */
        for (maxs = 0, r = res; r != NULL ; r = r->ai_next, maxs++)
		/* EMPTY */;
        socks = malloc((maxs+1) * sizeof(int));
        if (socks == NULL) {
               logerror("couldn't allocate memory for TCP listen sockets, suspending TCP message reception.");
               freeaddrinfo(res);
               return NULL;
        }

        *socks = 0;   /* num of sockets counter at start of array */
        s = socks + 1;
	for (r = res; r != NULL ; r = r->ai_next) {
               *s = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
        	if (*s < 0) {
			if(!(r->ai_family == PF_INET6 && errno == EAFNOSUPPORT))
				logerror("create_udp_socket(), socket");
				/* it is debatable if PF_INET with EAFNOSUPPORT should
				 * also be ignored...
				 */
                        continue;
                }

#ifdef IPV6_V6ONLY
                if (r->ai_family == AF_INET6) {
                	int iOn = 1;
			if (setsockopt(*s, IPPROTO_IPV6, IPV6_V6ONLY,
			      (char *)&iOn, sizeof (iOn)) < 0) {
			logerror("TCP setsockopt");
			close(*s);
			*s = -1;
			continue;
                	}
                }
#endif
       		if (setsockopt(*s, SOL_SOCKET, SO_REUSEADDR,
			       (char *) &on, sizeof(on)) < 0 ) {
			logerror("TCP setsockopt(REUSEADDR)");
                        close(*s);
			*s = -1;
			continue;
		}

		/* We need to enable BSD compatibility. Otherwise an attacker
		 * could flood our log files by sending us tons of ICMP errors.
		 */
#ifndef BSD	
		if (should_use_so_bsdcompat()) {
			if (setsockopt(*s, SOL_SOCKET, SO_BSDCOMPAT,
					(char *) &on, sizeof(on)) < 0) {
				logerror("TCP setsockopt(BSDCOMPAT)");
                                close(*s);
				*s = -1;
				continue;
			}
		}
#endif

	        if( (bind(*s, r->ai_addr, r->ai_addrlen) < 0)
#ifndef IPV6_V6ONLY
		     && (errno != EADDRINUSE)
#endif
	           ) {
                        logerror("TCP bind");
                	close(*s);
			*s = -1;
                        continue;
                }

		if( listen(*s,iTCPSessMax / 10 + 5) < 0) {
			/* If the listen fails, it most probably fails because we ask
			 * for a too-large backlog. So in this case we first set back
			 * to a fixed, reasonable, limit that should work. Only if
			 * that fails, too, we give up.
			 */
			logerrorInt("listen with a backlog of %d failed - retrying with default of 32.",
				    iTCPSessMax / 10 + 5);
			if(listen(*s, 32) < 0) {
				logerror("TCP listen, suspending tcp inet");
	                	close(*s);
				*s = -1;
               		        continue;
			}
		}

		(*socks)++;
		s++;
	}

        if(res != NULL)
               freeaddrinfo(res);

	if(Debug && *socks != maxs)
		dbgprintf("We could initialize %d TCP listen sockets out of %d we received "
		 	"- this may or may not be an error indication.\n", *socks, maxs);

        if(*socks == 0) {
		logerror("No TCP listen socket could successfully be initialized, "
			 "message reception via TCP disabled.\n");
        	free(socks);
		return(NULL);
	}

	/* OK, we had success. Now it is also time to
	 * initialize our connections
	 */
	if(TCPSessInit() != 0) {
		/* OK, we are in some trouble - we could not initialize the
		 * session table, so we can not continue. We need to free all
		 * we have assigned so far, because we can not really use it...
		 */
		logerror("Could not initialize TCP session table, suspending TCP message reception.");
		freeAllSockets(&socks); /* prevent a socket leak */
		return(NULL);
	}

	return(socks);
}


/* Accept new TCP connection; make entry in session table. If there
 * is no more space left in the connection table, the new TCP
 * connection is immediately dropped.
 */
int TCPSessAccept(int fd)
{
	int newConn;
	int iSess;
	struct sockaddr_storage addr;
	socklen_t addrlen = sizeof(struct sockaddr_storage);
	size_t lenHostName;
	uchar fromHost[NI_MAXHOST];
	uchar fromHostFQDN[NI_MAXHOST];
	char *pBuf;
#ifdef USE_GSSAPI
	char allowedMethods = 0;
#endif

	newConn = accept(fd, (struct sockaddr*) &addr, &addrlen);
	if (newConn < 0) {
		logerror("tcp accept, ignoring error and connection request");
		return -1;
	}

	/* Add to session list */
	iSess = TCPSessFindFreeSpot();
	if(iSess == -1) {
		errno = 0;
		logerror("too many tcp sessions - dropping incoming request");
		close(newConn);
		return -1;
	}

	/* OK, we have a "good" index... */
	/* get the host name */
	if(cvthname(&addr, fromHost, fromHostFQDN) != RS_RET_OK) {
		/* we seem to have something malicous - at least we
		 * are now told to discard the connection request.
		 * Error message has been generated by cvthname.
		 */
		close (newConn);
		return -1;
	}

	/* Here we check if a host is permitted to send us
	 * syslog messages. If it isn't, we do not further
	 * process the message but log a warning (if we are
	 * configured to do this).
	 * rgerhards, 2005-09-26
	 */
#ifdef USE_GSSAPI
	if((bEnableTCP & ALLOWEDMETHOD_TCP) &&
	   isAllowedSender(pAllowedSenders_TCP, (struct sockaddr *)&addr, (char*)fromHostFQDN))
		allowedMethods |= ALLOWEDMETHOD_TCP;
	if((bEnableTCP & ALLOWEDMETHOD_GSS) &&
	   isAllowedSender(pAllowedSenders_GSS, (struct sockaddr *)&addr, (char*)fromHostFQDN))
		allowedMethods |= ALLOWEDMETHOD_GSS;
	if(allowedMethods)
		pTCPSessions[iSess].allowedMethods = allowedMethods;
	else
#else
	if(!isAllowedSender(pAllowedSenders_TCP, (struct sockaddr *)&addr, (char*)fromHostFQDN))
#endif
	{
		dbgprintf("%s is not an allowed sender\n", (char *) fromHostFQDN);
		if(option_DisallowWarning) {
			errno = 0;
			logerrorSz("TCP message from disallowed sender %s discarded",
				   (char*)fromHost);
		}
		close(newConn);
		return -1;
	}

	/* OK, we have an allowed sender, so let's continue */
	lenHostName = strlen((char*)fromHost) + 1; /* for \0 byte */
	if((pBuf = (char*) malloc(sizeof(char) * lenHostName)) == NULL) {
		glblHadMemShortage = 1;
		pTCPSessions[iSess].fromHost = "NO-MEMORY-FOR-HOSTNAME";
	} else {
		memcpy(pBuf, fromHost, lenHostName);
		pTCPSessions[iSess].fromHost = pBuf;
	}

	pTCPSessions[iSess].sock = newConn;
	pTCPSessions[iSess].iMsg = 0; /* init msg buffer! */
	return iSess;
}


/* This should be called before a normal (non forced) close
 * of a TCP session. This function checks if there is any unprocessed
 * message left in the TCP stream. Such a message is probably a
 * fragement. If evrything goes well, we must be right at the
 * beginnig of a new frame without any data received from it. If
 * not, there is some kind of a framing error. I think I remember that
 * some legacy syslog/TCP implementations have non-LF terminated
 * messages at the end of the stream. For now, we allow this behaviour.
 * Later, it should probably become a configuration option.
 * rgerhards, 2006-12-07
 */
void TCPSessPrepareClose(int iTCPSess)
{
	if(iTCPSess < 0 || iTCPSess > iTCPSessMax) {
		errno = 0;
		logerror("internal error, trying to close an invalid TCP session!");
		return;
	}
	
	if(pTCPSessions[iTCPSess].bAtStrtOfFram == 1) {
		/* this is how it should be. There is no unprocessed
		 * data left and such we have nothing to do. For simplicity
		 * reasons, we immediately return in that case.
		 */
		 return;
	}

	/* we have some data left! */
	if(pTCPSessions[iTCPSess].eFraming == TCP_FRAMING_OCTET_COUNTING) {
		/* In this case, we have an invalid frame count and thus
		 * generate an error message and discard the frame.
		 */
		logerrorInt("Incomplete frame at end of stream in session %d - "
			    "ignoring extra data (a message may be lost).\n",
			    pTCPSessions[iTCPSess].sock);
		/* nothing more to do */
	} else { /* here, we have traditional framing. Missing LF at the end
		 * of message may occur. As such, we process the message in
		 * this case.
		 */
		dbgprintf("Extra data at end of stream in legacy syslog/tcp message - processing\n");
		parseAndSubmitMessage(pTCPSessions[iTCPSess].fromHost, pTCPSessions[iTCPSess].msg,
			              pTCPSessions[iTCPSess].iMsg, MSG_PARSE_HOSTNAME);
		pTCPSessions[iTCPSess].bAtStrtOfFram = 1;
	}
}


/* Closes a TCP session and marks its slot in the session
 * table as unused. No attention is paid to the return code
 * of close, so potential-double closes are not detected.
 */
void TCPSessClose(int iSess)
{
	if(iSess < 0 || iSess > iTCPSessMax) {
		errno = 0;
		logerror("internal error, trying to close an invalid TCP session!");
		return;
	}

	close(pTCPSessions[iSess].sock);
	pTCPSessions[iSess].sock = -1;
	free(pTCPSessions[iSess].fromHost);
	pTCPSessions[iSess].fromHost = NULL; /* not really needed, but... */
}


/* Processes the data received via a TCP session. If there
 * is no other way to handle it, data is discarded.
 * Input parameter data is the data received, iLen is its
 * len as returned from recv(). iLen must be 1 or more (that
 * is errors must be handled by caller!). iTCPSess must be
 * the index of the TCP session that received the data.
 * rgerhards 2005-07-04
 * Changed this functions interface. We now return a status of
 * what shall happen with the session. This is information for
 * the caller. If 1 is returned, the session should remain open
 * and additional data be accepted. If we return 0, the TCP
 * session is to be closed by the caller. This functionality is
 * needed in order to support framing errors, from which there
 * is no recovery possible other than session termination and
 * re-establishment. The need for this functionality thus is
 * primarily rooted in support for -transport-tls I-D framing.
 * rgerhards, 2006-12-07
 */
int TCPSessDataRcvd(int iTCPSess, char *pData, int iLen)
{
	register int iMsg;
	char *pMsg;
	char *pEnd;
	assert(pData != NULL);
	assert(iLen > 0);
	assert(iTCPSess >= 0);
	assert(iTCPSess < iTCPSessMax);
	assert(pTCPSessions[iTCPSess].sock != -1);

	 /* We now copy the message to the session buffer. As
	  * it looks, we need to do this in any case because
	  * we might run into multiple messages inside a single
	  * buffer. Of course, we could think about optimizations,
	  * but as this code is to be replaced by liblogging, it
	  * probably doesn't make so much sense...
	  * rgerhards 2005-07-04
	  *
	  * Algo:
	  * - copy message to buffer until the first LF is found
	  * - printline() the buffer
	  * - continue with copying
	  */
	iMsg = pTCPSessions[iTCPSess].iMsg; /* copy for speed */
	pMsg = pTCPSessions[iTCPSess].msg; /* just a shortcut */
	pEnd = pData + iLen; /* this is one off, which is intensional */

	while(pData < pEnd) {
		/* Check if we are at a new frame */
		if(pTCPSessions[iTCPSess].bAtStrtOfFram) {
			/* we need to look at the message and detect
			 * the framing mode used
			 *//*
			 * Contrary to -transport-tls, we accept leading zeros in the message
			 * length. We do this in the spirit of "Be liberal in what you accept,
			 * and conservative in what you send". We expect that including leading
			 * zeros could be a common coding error.
			 * rgerhards, 2006-12-07
			 * The chairs of the IETF syslog-sec WG have announced that it is
			 * consensus to do the octet count on the SYSLOG-MSG part only. I am
			 * now changing the code to reflect this. Hopefully, it will not change
			 * once again (there can no compatibility layer programmed for this).
			 * To be on the save side, I just comment the code out. I mark these
			 * comments with "IETF20061218".
			 * rgerhards, 2006-12-19
			 */
			if(isdigit((int) *pData)) {
				int iCnt;	/* the frame count specified */
				pTCPSessions[iTCPSess].eFraming = TCP_FRAMING_OCTET_COUNTING;
				/* in this mode, we have OCTET-COUNT SP MSG - so we now need
				 * to extract the OCTET-COUNT and the SP and then extract
				 * the msg.
				 */
				iCnt = 0;
				/* IETF20061218 int iNbrOctets = 0; / * number of octets already consumed */
				while(isdigit((int) *pData)) {
					iCnt = iCnt * 10 + *pData - '0';
					/* IETF20061218 ++iNbrOctets; */
					++pData;
				}
				dbgprintf("TCP Message with octet-counter, size %d.\n", iCnt);
				if(*pData == ' ') {
					++pData;	/* skip over SP */
					/* IETF20061218 ++iNbrOctets; */
				} else {
					/* TODO: handle "invalid frame" case */
					logerrorInt("Framing Error in received TCP message: "
					            "delimiter is not SP but has ASCII value %d.\n",
						    *pData);
					return(0); /* unconditional error exit */
				}
				/* IETF20061218 pTCPSessions[iTCPSess].iOctetsRemain = iCnt - iNbrOctets; */
				pTCPSessions[iTCPSess].iOctetsRemain = iCnt;
				if(pTCPSessions[iTCPSess].iOctetsRemain < 1) {
					/* TODO: handle the case where the octet count is 0 or negative! */
					dbgprintf("Framing Error: invalid octet count\n");
					logerrorInt("Framing Error in received TCP message: "
					            "invalid octet count %d.\n",
				 		    pTCPSessions[iTCPSess].iOctetsRemain);
					return(0); /* unconditional error exit */
				}
			} else {
				pTCPSessions[iTCPSess].eFraming = TCP_FRAMING_OCTET_STUFFING;
				/* No need to do anything else here in this case */
			}
			pTCPSessions[iTCPSess].bAtStrtOfFram = 0; /* done frame header */
		}
	
		/* now copy message until end of record */

		if(iMsg >= MAXLINE) {
			/* emergency, we now need to flush, no matter if
			 * we are at end of message or not...
			 */
			parseAndSubmitMessage(pTCPSessions[iTCPSess].fromHost, pMsg, iMsg, MSG_PARSE_HOSTNAME);
			iMsg = 0;
			/* we might think if it is better to ignore the rest of the
		 	 * message than to treat it as a new one. Maybe this is a good
			 * candidate for a configuration parameter...
			 * rgerhards, 2006-12-04
			 */
		}

		if(*pData == '\n' &&
		   pTCPSessions[iTCPSess].eFraming == TCP_FRAMING_OCTET_STUFFING) { /* record delemiter? */
			parseAndSubmitMessage(pTCPSessions[iTCPSess].fromHost, pMsg, iMsg, MSG_PARSE_HOSTNAME);
			iMsg = 0;
			pTCPSessions[iTCPSess].bAtStrtOfFram = 1;
			++pData;
		} else {
			/* IMPORTANT: here we copy the actual frame content to the message! */
			*(pMsg + iMsg++) = *pData++;
		}

		if(pTCPSessions[iTCPSess].eFraming == TCP_FRAMING_OCTET_COUNTING) {
			/* do we need to find end-of-frame via octet counting? */
			pTCPSessions[iTCPSess].iOctetsRemain--;
			if(pTCPSessions[iTCPSess].iOctetsRemain < 1) {
				/* we have end of frame! */
				parseAndSubmitMessage(pTCPSessions[iTCPSess].fromHost, pMsg, iMsg, MSG_PARSE_HOSTNAME);
				iMsg = 0;
				pTCPSessions[iTCPSess].bAtStrtOfFram = 1;
			}
		}
	}

	pTCPSessions[iTCPSess].iMsg = iMsg; /* persist value */

	return(1);	/* successful return */
}


static rsRetVal addTCPListener(void __attribute__((unused)) *pVal, uchar *pNewVal)
{
	if (!bEnableTCP)
		configureTCPListen((char *) pNewVal);
	bEnableTCP |= ALLOWEDMETHOD_TCP;

	return RS_RET_OK;
}


#ifdef USE_GSSAPI
static rsRetVal addGSSListener(void __attribute__((unused)) *pVal, uchar *pNewVal)
{
	if (!bEnableTCP)
		configureTCPListen((char *) pNewVal);
	bEnableTCP |= ALLOWEDMETHOD_GSS;

	return RS_RET_OK;
}


/* returns 0 if all went OK, -1 if it failed */
int TCPSessGSSInit(void)
{
	gss_buffer_desc name_buf;
	gss_name_t server_name;
	OM_uint32 maj_stat, min_stat;

	if (gss_server_creds != GSS_C_NO_CREDENTIAL)
		return 0;

	name_buf.value = (gss_listen_service_name == NULL) ? "host" : gss_listen_service_name;
	name_buf.length = strlen(name_buf.value) + 1;
	maj_stat = gss_import_name(&min_stat, &name_buf, GSS_C_NT_HOSTBASED_SERVICE, &server_name);
	if (maj_stat != GSS_S_COMPLETE) {
		display_status("importing name", maj_stat, min_stat);
		return -1;
	}

	maj_stat = gss_acquire_cred(&min_stat, server_name, 0,
				    GSS_C_NULL_OID_SET, GSS_C_ACCEPT,
				    &gss_server_creds, NULL, NULL);
	if (maj_stat != GSS_S_COMPLETE) {
		display_status("acquiring credentials", maj_stat, min_stat);
		return -1;
	}

	gss_release_name(&min_stat, &server_name);
	dbgprintf("GSS-API initialized\n");
	return 0;
}


/* returns 0 if all went OK, -1 if it failed */
int TCPSessGSSAccept(int fd)
{
	gss_buffer_desc send_tok, recv_tok;
	gss_name_t client;
	OM_uint32 maj_stat, min_stat, acc_sec_min_stat;
	int iSess;
	gss_ctx_id_t *context;
	OM_uint32 *sess_flags;
	int fdSess;
	char allowedMethods;

	if ((iSess = TCPSessAccept(fd)) == -1)
		return -1;

	allowedMethods = pTCPSessions[iSess].allowedMethods;
	if (allowedMethods & ALLOWEDMETHOD_GSS) {
		/* Buffer to store raw message in case that
		 * gss authentication fails halfway through.
		 */
		char buf[MAXLINE];
		int ret = 0;

		dbgprintf("GSS-API Trying to accept TCP session %d\n", iSess);

		fdSess = pTCPSessions[iSess].sock;
		if (allowedMethods & ALLOWEDMETHOD_TCP) {
			int len;
			fd_set  fds;
			struct timeval tv;
		
			do {
				FD_ZERO(&fds);
				FD_SET(fdSess, &fds);
				tv.tv_sec = 1;
				tv.tv_usec = 0;
				ret = select(fdSess + 1, &fds, NULL, NULL, &tv);
			} while (ret < 0 && errno == EINTR);
			if (ret < 0) {
				logerrorInt("TCP session %d will be closed, error ignored\n", iSess);
				TCPSessClose(iSess);
				return -1;
			} else if (ret == 0) {
				dbgprintf("GSS-API Reverting to plain TCP\n");
				pTCPSessions[iSess].allowedMethods = ALLOWEDMETHOD_TCP;
				return 0;
			}

			do {
				ret = recv(fdSess, buf, sizeof (buf), MSG_PEEK);
			} while (ret < 0 && errno == EINTR);
			if (ret <= 0) {
				if (ret == 0)
					dbgprintf("GSS-API Connection closed by peer\n");
				else
					logerrorInt("TCP session %d will be closed, error ignored\n", iSess);
				TCPSessClose(iSess);
				return -1;
			}

			if (ret < 4) {
				dbgprintf("GSS-API Reverting to plain TCP\n");
				pTCPSessions[iSess].allowedMethods = ALLOWEDMETHOD_TCP;
				return 0;
			} else if (ret == 4) {
				/* The client might has been interupted after sending
				 * the data length (4B), give him another chance.
				 */
				sleep(1);
				do {
					ret = recv(fdSess, buf, sizeof (buf), MSG_PEEK);
				} while (ret < 0 && errno == EINTR);
				if (ret <= 0) {
					if (ret == 0)
						dbgprintf("GSS-API Connection closed by peer\n");
					else
						logerrorInt("TCP session %d will be closed, error ignored\n", iSess);
					TCPSessClose(iSess);
					return -1;
				}
			}

			len = ntohl((buf[0] << 24)
				    | (buf[1] << 16)
				    | (buf[2] << 8)
				    | buf[3]);
			if ((ret - 4) < len || len == 0) {
				dbgprintf("GSS-API Reverting to plain TCP\n");
				pTCPSessions[iSess].allowedMethods = ALLOWEDMETHOD_TCP;
				return 0;
			}
		}

		context = &pTCPSessions[iSess].gss_context;
		*context = GSS_C_NO_CONTEXT;
		sess_flags = &pTCPSessions[iSess].gss_flags;
		do {
			if (recv_token(fdSess, &recv_tok) <= 0) {
				logerrorInt("TCP session %d will be closed, error ignored\n", iSess);
				TCPSessClose(iSess);
				return -1;
			}
			maj_stat = gss_accept_sec_context(&acc_sec_min_stat, context, gss_server_creds,
							  &recv_tok, GSS_C_NO_CHANNEL_BINDINGS, &client,
							  NULL, &send_tok, sess_flags, NULL, NULL);
			if (recv_tok.value) {
				free(recv_tok.value);
				recv_tok.value = NULL;
			}
			if (maj_stat != GSS_S_COMPLETE
			    && maj_stat != GSS_S_CONTINUE_NEEDED) {
				gss_release_buffer(&min_stat, &send_tok);
				if (*context != GSS_C_NO_CONTEXT)
					gss_delete_sec_context(&min_stat, context, GSS_C_NO_BUFFER);
				if ((allowedMethods & ALLOWEDMETHOD_TCP) && 
				    (GSS_ROUTINE_ERROR(maj_stat) == GSS_S_DEFECTIVE_TOKEN)) {
					dbgprintf("GSS-API Reverting to plain TCP\n");
					dbgprintf("tcp session socket with new data: #%d\n", fdSess);
					if(TCPSessDataRcvd(iSess, buf, ret) == 0) {
						logerrorInt("Tearing down TCP Session %d - see "
							    "previous messages for reason(s)\n",
							    iSess);
						TCPSessClose(iSess);
						return -1;
					}
					pTCPSessions[iSess].allowedMethods = ALLOWEDMETHOD_TCP;
					return 0;
				}
				display_status("accepting context", maj_stat,
					       acc_sec_min_stat);
				TCPSessClose(iSess);
				return -1;
			}
			if (send_tok.length != 0) {
				if (send_token(fdSess, &send_tok) < 0) {
					gss_release_buffer(&min_stat, &send_tok);
					logerrorInt("TCP session %d will be closed, error ignored\n", iSess);
					if (*context != GSS_C_NO_CONTEXT)
						gss_delete_sec_context(&min_stat, context, GSS_C_NO_BUFFER);
					TCPSessClose(iSess);
					return -1;
				}
				gss_release_buffer(&min_stat, &send_tok);
			}
		} while (maj_stat == GSS_S_CONTINUE_NEEDED);

		maj_stat = gss_display_name(&min_stat, client, &recv_tok, NULL);
		if (maj_stat != GSS_S_COMPLETE)
			display_status("displaying name", maj_stat, min_stat);
		else
			dbgprintf("GSS-API Accepted connection from: %s\n", (char*) recv_tok.value);
		gss_release_name(&min_stat, &client);
		gss_release_buffer(&min_stat, &recv_tok);

		dbgprintf("GSS-API Provided context flags:\n");
		display_ctx_flags(*sess_flags);
		pTCPSessions[iSess].allowedMethods = ALLOWEDMETHOD_GSS;
	}

	return 0;
}


/* returns: ? */
int TCPSessGSSRecv(int iSess, void *buf, size_t buf_len)
{
	gss_buffer_desc xmit_buf, msg_buf;
	gss_ctx_id_t *context;
	OM_uint32 maj_stat, min_stat;
	int fdSess;
	int     conf_state;
	int state, len;

	fdSess = pTCPSessions[iSess].sock;
	if ((state = recv_token(fdSess, &xmit_buf)) <= 0)
		return state;

	context = &pTCPSessions[iSess].gss_context;
	maj_stat = gss_unwrap(&min_stat, *context, &xmit_buf, &msg_buf,
			      &conf_state, (gss_qop_t *) NULL);
	if (maj_stat != GSS_S_COMPLETE) {
		display_status("unsealing message", maj_stat, min_stat);
		if (xmit_buf.value) {
			free(xmit_buf.value);
			xmit_buf.value = 0;
		}
		return (-1);
	}
	if (xmit_buf.value) {
		free(xmit_buf.value);
		xmit_buf.value = 0;
	}

	len = msg_buf.length < buf_len ? msg_buf.length : buf_len;
	memcpy(buf, msg_buf.value, len);
	gss_release_buffer(&min_stat, &msg_buf);

	return len;
}


void TCPSessGSSClose(int iSess) {
	OM_uint32 maj_stat, min_stat;
	gss_ctx_id_t *context;

	if(iSess < 0 || iSess > iTCPSessMax) {
		errno = 0;
		logerror("internal error, trying to close an invalid TCP session!");
		return;
	}

	context = &pTCPSessions[iSess].gss_context;
	maj_stat = gss_delete_sec_context(&min_stat, context, GSS_C_NO_BUFFER);
	if (maj_stat != GSS_S_COMPLETE)
		display_status("deleting context", maj_stat, min_stat);
	*context = GSS_C_NO_CONTEXT;
	pTCPSessions[iSess].gss_flags = 0;
	pTCPSessions[iSess].allowedMethods = 0;

	TCPSessClose(iSess);
}


void TCPSessGSSDeinit(void) {
	OM_uint32 maj_stat, min_stat;

	maj_stat = gss_release_cred(&min_stat, &gss_server_creds);
	if (maj_stat != GSS_S_COMPLETE)
		display_status("releasing credentials", maj_stat, min_stat);
}
#endif /* #ifdef USE_GSSAPI */


/* This function is called to gather input.
 */
BEGINrunInput
	int maxfds;
	int nfds;
	int i;
	int iTCPSess;
	fd_set readfds;
CODESTARTrunInput
	/* this is an endless loop - it is terminated when the thread is
	 * signalled to do so. This, however, is handled by the framework,
	 * right into the sleep below.
	 */
	while(1) {
		/* Add the Unix Domain Sockets to the list of read
		 * descriptors.
		 * rgerhards 2005-08-01: we must now check if there are
		 * any local sockets to listen to at all. If the -o option
		 * is given without -a, we do not need to listen at all..
		 */
	        maxfds = 0;
	        FD_ZERO (&readfds);

		/* Add the TCP listen sockets to the list of read descriptors.
	    	 */
		if(sockTCPLstn != NULL && *sockTCPLstn) {
			for (i = 0; i < *sockTCPLstn; i++) {
				/* The if() below is theoretically not needed, but I leave it in
				 * so that a socket may become unsuable during execution. That
				 * feature is not yet supported by the current code base.
				 */
				if (sockTCPLstn[i+1] != -1) {
					if(Debug)
						debugListenInfo(sockTCPLstn[i+1], "TCP");
					FD_SET(sockTCPLstn[i+1], &readfds);
					if(sockTCPLstn[i+1]>maxfds) maxfds=sockTCPLstn[i+1];
				}
			}
			/* do the sessions */
			iTCPSess = TCPSessGetNxtSess(-1);
			while(iTCPSess != -1) {
				int fdSess;
				fdSess = pTCPSessions[iTCPSess].sock;
				dbgprintf("Adding TCP Session %d\n", fdSess);
				FD_SET(fdSess, &readfds);
				if (fdSess>maxfds) maxfds=fdSess;
				/* now get next... */
				iTCPSess = TCPSessGetNxtSess(iTCPSess);
			}
		}

		if(Debug) {
			dbgprintf("--------imTCP calling select, active file descriptors (max %d): ", maxfds);
			for (nfds = 0; nfds <= maxfds; ++nfds)
				if ( FD_ISSET(nfds, &readfds) )
					dbgprintf("%d ", nfds);
			dbgprintf("\n");
		}

		/* wait for io to become ready */
		nfds = select(maxfds+1, (fd_set *) &readfds, NULL, NULL, NULL);

		for (i = 0; i < *sockTCPLstn; i++) {
			if (FD_ISSET(sockTCPLstn[i+1], &readfds)) {
				dbgprintf("New connect on TCP inetd socket: #%d\n", sockTCPLstn[i+1]);
#				ifdef USE_GSSAPI
				if(bEnableTCP & ALLOWEDMETHOD_GSS)
					TCPSessGSSAccept(sockTCPLstn[i+1]);
				else
#				endif
					TCPSessAccept(sockTCPLstn[i+1]);
				--nfds; /* indicate we have processed one */
			}
		}

		/* now check the sessions */
		iTCPSess = TCPSessGetNxtSess(-1);
		while(nfds && iTCPSess != -1) {
			int fdSess;
			int state;
			fdSess = pTCPSessions[iTCPSess].sock;
			if(FD_ISSET(fdSess, &readfds)) {
				char buf[MAXLINE];
				dbgprintf("tcp session socket with new data: #%d\n", fdSess);

				/* Receive message */
#				ifdef USE_GSSAPI
				int allowedMethods = pTCPSessions[iTCPSess].allowedMethods;
				if(allowedMethods & ALLOWEDMETHOD_GSS)
					state = TCPSessGSSRecv(iTCPSess, buf, sizeof(buf));
				else
#				endif
					state = recv(fdSess, buf, sizeof(buf), 0);
				if(state == 0) {
#					ifdef USE_GSSAPI
					if(allowedMethods & ALLOWEDMETHOD_GSS)
						TCPSessGSSClose(iTCPSess);
					else {
#					endif
						/* process any incomplete frames left over */
						TCPSessPrepareClose(iTCPSess);
						/* Session closed */
						TCPSessClose(iTCPSess);
#					ifdef USE_GSSAPI
					}
#					endif
				} else if(state == -1) {
					logerrorInt("TCP session %d will be closed, error ignored\n",
						    fdSess);
#					ifdef USE_GSSAPI
					if(allowedMethods & ALLOWEDMETHOD_GSS)
						TCPSessGSSClose(iTCPSess);
					else
#					endif
						TCPSessClose(iTCPSess);
				} else {
					/* valid data received, process it! */
					if(TCPSessDataRcvd(iTCPSess, buf, state) == 0) {
						/* in this case, something went awfully wrong.
						 * We are instructed to terminate the session.
						 */
						logerrorInt("Tearing down TCP Session %d - see "
							    "previous messages for reason(s)\n",
							    iTCPSess);
#						ifdef USE_GSSAPI
						if(allowedMethods & ALLOWEDMETHOD_GSS)
							TCPSessGSSClose(iTCPSess);
						else
#						endif
							TCPSessClose(iTCPSess);
					}
				}
				--nfds; /* indicate we have processed one */
			}
			iTCPSess = TCPSessGetNxtSess(iTCPSess);
		}
	}

	return iRet;
ENDrunInput


/* initialize and return if will run or not */
BEGINwillRun
CODESTARTwillRun
	/* first apply some config settings */
dbgprintf("imtcp: bEnableTCP %d\n", bEnableTCP);
	PrintAllowedSenders(2); /* TCP */
#ifdef USE_GSSAPI
	PrintAllowedSenders(3); /* GSS */
#endif
	if (bEnableTCP) {
		if(sockTCPLstn == NULL) {
#			ifdef USE_GSSAPI
			if(bEnableTCP & ALLOWEDMETHOD_GSS) {
				if(TCPSessGSSInit()) {
					logerror("GSS-API initialization failed\n");
					bEnableTCP &= ~(ALLOWEDMETHOD_GSS);
				}
			}
			if(bEnableTCP)
#			endif
				if((sockTCPLstn = create_tcp_socket()) != NULL) {
					dbgprintf("Opened %d syslog TCP port(s).\n", *sockTCPLstn);
				}
		}
	}
ENDwillRun


BEGINafterRun
CODESTARTafterRun
	/* do cleanup here */
	if (pAllowedSenders_TCP != NULL) {
		clearAllowedSenders (pAllowedSenders_TCP);
		pAllowedSenders_TCP = NULL;
	}
#ifdef USE_GSSAPI
	if (pAllowedSenders_GSS != NULL) {
		clearAllowedSenders (pAllowedSenders_GSS);
		pAllowedSenders_GSS = NULL;
	}
#endif
ENDafterRun


BEGINfreeInstance
CODESTARTfreeInstance
ENDfreeInstance


BEGINdbgPrintInstInfo
CODESTARTdbgPrintInstInfo
ENDdbgPrintInstInfo


BEGINmodExit
CODESTARTmodExit
	/* Close the TCP inet socket. */
	if(sockTCPLstn != NULL && *sockTCPLstn) {
		deinit_tcp_listener();
	}
#ifdef USE_GSSAPI
	if(bEnableTCP & ALLOWEDMETHOD_GSS)
		TCPSessGSSDeinit();
#endif
ENDmodExit


BEGINqueryEtryPt
CODESTARTqueryEtryPt
CODEqueryEtryPt_STD_IMOD_QUERIES
ENDqueryEtryPt

static rsRetVal resetConfigVariables(uchar __attribute__((unused)) *pp, void __attribute__((unused)) *pVal)
{
#if defined(USE_GSSAPI)
	if (gss_listen_service_name != NULL) {
		free(gss_listen_service_name);
		gss_listen_service_name = NULL;
	}
#endif
	return RS_RET_OK;
}


BEGINmodInit()
CODESTARTmodInit
	*ipIFVersProvided = 1; /* so far, we only support the initial definition */
CODEmodInit_QueryRegCFSLineHdlr
	/* register config file handlers */
	CHKiRet(omsdRegCFSLineHdlr((uchar *)"inputtcpserverrun", 0, eCmdHdlrGetWord,
				   addTCPListener, NULL, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr((uchar *)"inputtcpmaxsessions", 0, eCmdHdlrInt,
				   NULL, &iTCPSessMax, STD_LOADABLE_MODULE_ID));
#if defined(USE_GSSAPI)
	CHKiRet(omsdRegCFSLineHdlr((uchar *)"inputgssserverrun", 0, eCmdHdlrGetWord,
				   addGSSListener, NULL, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr((uchar *)"inputgssserverservicename", 0, eCmdHdlrGetWord,
				   NULL, &gss_listen_service_name, STD_LOADABLE_MODULE_ID));
#endif
	CHKiRet(omsdRegCFSLineHdlr((uchar *)"resetconfigvariables", 1, eCmdHdlrCustomHandler,
		resetConfigVariables, NULL, STD_LOADABLE_MODULE_ID));
ENDmodInit
/*
 * vi:set ai:
 */