/* nsd_ptcp.c
 *
 * An implementation of the nsd interface for plain tcp sockets.
 * 
 * Copyright 2007, 2008 Rainer Gerhards and Adiscon GmbH.
 *
 * This file is part of the rsyslog runtime library.
 *
 * The rsyslog runtime library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * The rsyslog runtime library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the rsyslog runtime library.  If not, see <http://www.gnu.org/licenses/>.
 *
 * A copy of the GPL can be found in the file "COPYING" in this distribution.
 * A copy of the LGPL can be found in the file "COPYING.LESSER" in this distribution.
 */
#include "config.h"

#include "rsyslog.h"
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <signal.h>
#include <ctype.h>
#include <netdb.h>
#include <fnmatch.h>
#include <fcntl.h>
#include <unistd.h>

#include "syslogd-types.h"
#include "module-template.h"
#include "parse.h"
#include "srUtils.h"
#include "obj.h"
#include "errmsg.h"
#include "net.h"
#include "nsd_ptcp.h"

MODULE_TYPE_LIB

/* static data */
DEFobjStaticHelpers
DEFobjCurrIf(errmsg)
DEFobjCurrIf(glbl)
DEFobjCurrIf(net)


/* a few deinit helpers */

/* close socket if open (may always be called) */
static void
sockClose(int *pSock)
{
	if(*pSock >= 0) {
		close(*pSock);
		*pSock = -1;
	}
}

/* Standard-Constructor
 */
BEGINobjConstruct(nsd_ptcp) /* be sure to specify the object type also in END macro! */
	pThis->sock = -1;
ENDobjConstruct(nsd_ptcp)


/* destructor for the nsd_ptcp object */
BEGINobjDestruct(nsd_ptcp) /* be sure to specify the object type also in END and CODESTART macros! */
CODESTARTobjDestruct(nsd_ptcp)
	sockClose(&pThis->sock);
	if(pThis->pRemHostIP != NULL)
		free(pThis->pRemHostIP);
	if(pThis->pRemHostName != NULL)
		free(pThis->pRemHostName);
ENDobjDestruct(nsd_ptcp)


/* abort a connection. This is meant to be called immediately
 * before the Destruct call. -- rgerhards, 2008-03-24
 */
static rsRetVal
Abort(nsd_t *pNsd)
{
	struct linger ling;
	nsd_ptcp_t *pThis = (nsd_ptcp_t*) pNsd;

	DEFiRet;
	ISOBJ_TYPE_assert((pThis), nsd_ptcp);

	if((pThis)->sock != -1) {
		ling.l_onoff = 1;
		ling.l_linger = 0;
       		if(setsockopt((pThis)->sock, SOL_SOCKET, SO_LINGER, &ling, sizeof(ling)) < 0 ) {
			dbgprintf("could not set SO_LINGER, errno %d\n", errno);
		}
	}

	RETiRet;
}


/* Set pRemHost based on the address provided. This is to be called upon accept()ing
 * a connection request. It must be provided by the socket we received the
 * message on as well as a NI_MAXHOST size large character buffer for the FQDN.
 * Please see http://www.hmug.org/man/3/getnameinfo.php (under Caveats)
 * for some explanation of the code found below. If we detect a malicious
 * hostname, we return RS_RET_MALICIOUS_HNAME and let the caller decide
 * on how to deal with that.
 * rgerhards, 2008-03-31
 */
static rsRetVal
FillRemHost(nsd_ptcp_t *pThis, struct sockaddr *pAddr)
{
	int error;
	uchar szIP[NI_MAXHOST] = "";
	uchar szHname[NI_MAXHOST] = "";
	struct addrinfo hints, *res;
	size_t len;
	
	DEFiRet;
	ISOBJ_TYPE_assert(pThis, nsd_ptcp);
	assert(pAddr != NULL);

        error = getnameinfo(pAddr, SALEN(pAddr), (char*)szIP, sizeof(szIP), NULL, 0, NI_NUMERICHOST);

        if(error) {
                dbgprintf("Malformed from address %s\n", gai_strerror(error));
		strcpy((char*)szHname, "???");
		strcpy((char*)szIP, "???");
		ABORT_FINALIZE(RS_RET_INVALID_HNAME);
	}

	if(!glbl.GetDisableDNS()) {
		error = getnameinfo(pAddr, SALEN(pAddr), (char*)szHname, NI_MAXHOST, NULL, 0, NI_NAMEREQD);
		if(error == 0) {
			memset (&hints, 0, sizeof (struct addrinfo));
			hints.ai_flags = AI_NUMERICHOST;
			hints.ai_socktype = SOCK_STREAM;
			/* we now do a lookup once again. This one should fail,
			 * because we should not have obtained a non-numeric address. If
			 * we got a numeric one, someone messed with DNS!
			 */
			if(getaddrinfo((char*)szHname, NULL, &hints, &res) == 0) {
				freeaddrinfo (res);
				/* OK, we know we have evil, so let's indicate this to our caller */
				snprintf((char*)szHname, NI_MAXHOST, "[MALICIOUS:IP=%s]", szIP);
				dbgprintf("Malicious PTR record, IP = \"%s\" HOST = \"%s\"", szIP, szHname);
				iRet = RS_RET_MALICIOUS_HNAME;
			}
		} else {
			strcpy((char*)szHname, (char*)szIP);
		}
	} else {
		strcpy((char*)szHname, (char*)szIP);
	}

	/* We now have the names, so now let's allocate memory and store them permanently.
	 * (side note: we may hold on to these values for quite a while, thus we trim their
	 * memory consumption)
	 */
	len = strlen((char*)szIP) + 1; /* +1 for \0 byte */
	if((pThis->pRemHostIP = malloc(len)) == NULL)
		ABORT_FINALIZE(RS_RET_OUT_OF_MEMORY);
	memcpy(pThis->pRemHostIP, szIP, len);

	len = strlen((char*)szHname) + 1; /* +1 for \0 byte */
	if((pThis->pRemHostName = malloc(len)) == NULL) {
		free(pThis->pRemHostIP); /* prevent leak */
		pThis->pRemHostIP = NULL;
		ABORT_FINALIZE(RS_RET_OUT_OF_MEMORY);
	}
	memcpy(pThis->pRemHostName, szHname, len);

finalize_it:
	RETiRet;
}



/* accept an incoming connection request
 * rgerhards, 2008-04-22
 */
static rsRetVal
AcceptConnReq(nsd_t *pNsd, nsd_t **ppNew)
{
	int sockflags;
	nsd_ptcp_t *pThis = (nsd_ptcp_t*) pNsd;
	struct sockaddr_storage addr;
	socklen_t addrlen = sizeof(addr);
	nsd_ptcp_t *pNew = NULL;
	int iNewSock = -1;

	DEFiRet;
	assert(ppNew != NULL);
	ISOBJ_TYPE_assert(pThis, nsd_ptcp_t);

	iNewSock = accept(pThis->sock, (struct sockaddr*) &addr, &addrlen);
	if(iNewSock < 0) {
		ABORT_FINALIZE(RS_RET_ACCEPT_ERR);
	}

	/* construct our object so that we can use it... */
	CHKiRet(nsd_ptcpConstruct(&pNew));

	CHKiRet(FillRemHost(pNew, (struct sockaddr*) &addr));

	/* set the new socket to non-blocking IO -TODO:do we really need to do this here? Do we always want it? */
	if((sockflags = fcntl(iNewSock, F_GETFL)) != -1) {
		sockflags |= O_NONBLOCK;
		/* SETFL could fail too, so get it caught by the subsequent
		 * error check.
		 */
		sockflags = fcntl(iNewSock, F_SETFL, sockflags);
	}
	if(sockflags == -1) {
		dbgprintf("error %d setting fcntl(O_NONBLOCK) on tcp socket %d", errno, iNewSock);
		ABORT_FINALIZE(RS_RET_IO_ERROR);
	}

	pNew->sock = iNewSock;
	*ppNew = (nsd_t*) pNew;

finalize_it:
	if(iRet != RS_RET_OK) {
		if(pNew != NULL)
			nsd_ptcpDestruct(&pNew);
		/* the close may be redundant, but that doesn't hurt... */
		sockClose(&iNewSock);
	}

	RETiRet;
}


/* initialize tcp sockets for a listner. This function returns an array of nds_t
 * objects. The size of this array is returend in pLstnArrSize.
 * pLstnPort must point to a port name or number. NULL is NOT permitted. pLstnIP
 * points to the port to listen to (NULL means "all"), iMaxSess has the maximum
 * number of sessions permitted.
 * rgerhards, 2008-04-22
 */
static rsRetVal
LstnInit(nsd_t ***parrLstnNsd, int *pLstnArrSize, uchar *pLstnPort, uchar *pLstnIP, int iSessMax)
{
	DEFiRet;
        struct addrinfo hints, *res = NULL, *r;
	nsd_ptcp_t **arrLstn = NULL;
        int error, maxs, on = 1;
	int sock;
	int sockflags;

	assert(parrLstnNsd != NULL);
	assert(pLstnPort != NULL);
	assert(iSessMax >= 0);

	dbgprintf("creating tcp listen socket on port %s\n", pLstnPort);

        memset(&hints, 0, sizeof(hints));
        hints.ai_flags = AI_PASSIVE;
        hints.ai_family = glbl.GetDefPFFamily();
        hints.ai_socktype = SOCK_STREAM;

        error = getaddrinfo((char*)pLstnIP, (char*) pLstnPort, &hints, &res);
        if(error) {
		dbgprintf("error %d querying port '%s'\n", error, pLstnPort);
		ABORT_FINALIZE(RS_RET_INVALID_PORT);
	}

        /* Count max number of sockets we may open */
        for(maxs = 0, r = res; r != NULL ; r = r->ai_next, maxs++)
		/* EMPTY */;
        CHKmalloc(arrLstn = (nsd_ptcp_t**) malloc((maxs+1) * sizeof(nsd_ptcp_t*)));

        *pLstnArrSize = 0;   /* num of sockets counter at start of array */
	for(r = res; r != NULL ; r = r->ai_next) {
               sock = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
        	if(sock < 0) {
			if(!(r->ai_family == PF_INET6 && errno == EAFNOSUPPORT))
				dbgprintf("error %d creating tcp listen socket", errno);
				/* 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(sock, IPPROTO_IPV6, IPV6_V6ONLY,
			      (char *)&iOn, sizeof (iOn)) < 0) {
				close(sock);
				continue;
                	}
                }
#endif
       		if(setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (char *) &on, sizeof(on)) < 0 ) {
			dbgprintf("error %d setting tcp socket option\n", errno);
                        close(sock);
			continue;
		}

		/* We use non-blocking IO! */
		if((sockflags = fcntl(sock, F_GETFL)) != -1) {
			sockflags |= O_NONBLOCK;
			/* SETFL could fail too, so get it caught by the subsequent
			 * error check.
			 */
			sockflags = fcntl(sock, F_SETFL, sockflags);
		}
		if(sockflags == -1) {
			dbgprintf("error %d setting fcntl(O_NONBLOCK) on tcp socket", errno);
                        close(sock);
			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(net.should_use_so_bsdcompat()) {
			if (setsockopt(sock, SOL_SOCKET, SO_BSDCOMPAT,
					(char *) &on, sizeof(on)) < 0) {
				errmsg.LogError(NO_ERRCODE, "TCP setsockopt(BSDCOMPAT)");
                                close(sock);
				continue;
			}
		}
#endif

	        if( (bind(sock, r->ai_addr, r->ai_addrlen) < 0)
#ifndef IPV6_V6ONLY
		     && (errno != EADDRINUSE)
#endif
	           ) {
			/* TODO: check if *we* bound the socket - else we *have* an error! */
                        dbgprintf("error %d while binding tcp socket", errno);
                	close(sock);
                        continue;
                }

		if(listen(sock, iSessMax / 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.
			 */
			dbgprintf("listen with a backlog of %d failed - retrying with default of 32.",
				   iSessMax / 10 + 5);
			if(listen(sock, 32) < 0) {
				dbgprintf("tcp listen error %d, suspending\n", errno);
	                	close(sock);
               		        continue;
			}
		}

		/* if we reach this point, we were able to obtain a valid socket, which we
		 * now can save to the array of listen sockets. -- rgerhards, 2008-04-22
		 */
		CHKiRet(nsd_ptcpConstruct(arrLstn+*pLstnArrSize));
        	arrLstn[*pLstnArrSize]->sock = sock;
		++(*pLstnArrSize);
	}

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

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

        if(*pLstnArrSize == 0) {
		dbgprintf("No TCP listen sockets could successfully be initialized, "
			  "message reception disabled.\n");
		ABORT_FINALIZE(RS_RET_COULD_NOT_BIND);
	}

	*parrLstnNsd = (nsd_t**) arrLstn;
	arrLstn = NULL; /* prevent from being freed in error handler */

finalize_it:
	if(iRet != RS_RET_OK) {
		if(res != NULL)
			freeaddrinfo(res);
		if(arrLstn != NULL) {
			for(maxs = 0 ; maxs < *pLstnArrSize ;  ++maxs)
				nsd_ptcpDestruct(arrLstn+*pLstnArrSize);
		}
	}

	RETiRet;
}


/* receive data from a tcp socket
 * The lenBuf parameter must contain the max buffer size on entry and contains
 * the number of octets read (or -1 in case of error) on exit. This function
 * never blocks, not even when called on a blocking socket. That is important
 * for client sockets, which are set to block during send, but should not
 * block when trying to read data. If *pLenBuf is -1, an error occured and
 * errno holds the exact error cause.
 * rgerhards, 2008-03-17
 */
static rsRetVal
Rcv(nsd_t *pNsd, uchar *pRcvBuf, ssize_t *pLenBuf)
{
	DEFiRet;
	nsd_ptcp_t *pThis = (nsd_ptcp_t*) pNsd;
	ISOBJ_TYPE_assert(pThis, nsd_ptcp);

	*pLenBuf = recv(pThis->sock, pRcvBuf, *pLenBuf, MSG_DONTWAIT);

	RETiRet;
}


/* send a buffer. On entry, pLenBuf contains the number of octets to
 * write. On exit, it contains the number of octets actually written.
 * If this number is lower than on entry, only a partial buffer has
 * been written.
 * rgerhards, 2008-03-19
 */
static rsRetVal
Send(nsd_t *pNsd, uchar *pBuf, ssize_t *pLenBuf)
{
	nsd_ptcp_t *pThis = (nsd_ptcp_t*) pNsd;
	ssize_t written;
	DEFiRet;
	ISOBJ_TYPE_assert(pThis, nsd_ptcp);

	written = send(pThis->sock, pBuf, *pLenBuf, 0);

	if(written == -1) {
		switch(errno) {
			case EAGAIN:
			case EINTR:
				/* this is fine, just retry... */
				written = 0;
				break;
			default:
				ABORT_FINALIZE(RS_RET_IO_ERROR);
				break;
		}
	}

	*pLenBuf = written;
finalize_it:
	RETiRet;
}


/* open a connection to a remote host (server).
 * rgerhards, 2008-03-19
 */
static rsRetVal
Connect(nsd_t *pNsd, int family, uchar *port, uchar *host)
{
	nsd_ptcp_t *pThis = (nsd_ptcp_t*) pNsd;
	struct addrinfo *res = NULL;
	struct addrinfo hints;

	DEFiRet;
	ISOBJ_TYPE_assert(pThis, nsd_ptcp);
	assert(port != NULL);
	assert(host != NULL);
	assert(pThis->sock == -1);

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = family;
	hints.ai_socktype = SOCK_STREAM;
	if(getaddrinfo((char*)host, (char*)port, &hints, &res) != 0) {
		dbgprintf("error %d in getaddrinfo\n", errno);
		ABORT_FINALIZE(RS_RET_IO_ERROR);
	}
	
	if((pThis->sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol)) == -1) {
		ABORT_FINALIZE(RS_RET_IO_ERROR);
	}

	if(connect(pThis->sock, res->ai_addr, res->ai_addrlen) != 0) {
		ABORT_FINALIZE(RS_RET_IO_ERROR);
	}

finalize_it:
	if(res != NULL)
               freeaddrinfo(res);
		
	if(iRet != RS_RET_OK) {
		sockClose(&pThis->sock);
	}

	RETiRet;
}


/* queryInterface function */
BEGINobjQueryInterface(nsd_ptcp)
CODESTARTobjQueryInterface(nsd_ptcp)
	if(pIf->ifVersion != nsdCURR_IF_VERSION) {/* check for current version, increment on each change */
		ABORT_FINALIZE(RS_RET_INTERFACE_NOT_SUPPORTED);
	}

	/* ok, we have the right interface, so let's fill it
	 * Please note that we may also do some backwards-compatibility
	 * work here (if we can support an older interface version - that,
	 * of course, also affects the "if" above).
	 */
	pIf->Construct = (rsRetVal(*)(nsd_t**)) nsd_ptcpConstruct;
	pIf->Destruct = (rsRetVal(*)(nsd_t**)) nsd_ptcpDestruct;
	pIf->Abort = Abort;
	pIf->Rcv = Rcv;
	pIf->Send = Send;
	pIf->LstnInit = LstnInit;
	pIf->AcceptConnReq = AcceptConnReq;
	pIf->Connect = Connect;
finalize_it:
ENDobjQueryInterface(nsd_ptcp)


/* exit our class
 */
BEGINObjClassExit(nsd_ptcp, OBJ_IS_LOADABLE_MODULE) /* CHANGE class also in END MACRO! */
CODESTARTObjClassExit(nsd_ptcp)
	/* release objects we no longer need */
	objRelease(net, CORE_COMPONENT);
	objRelease(glbl, CORE_COMPONENT);
	objRelease(errmsg, CORE_COMPONENT);
ENDObjClassExit(nsd_ptcp)


/* Initialize the nsd_ptcp class. Must be called as the very first method
 * before anything else is called inside this class.
 * rgerhards, 2008-02-19
 */
BEGINObjClassInit(nsd_ptcp, 1, OBJ_IS_LOADABLE_MODULE) /* class, version */
	/* request objects we use */
	CHKiRet(objUse(errmsg, CORE_COMPONENT));
	CHKiRet(objUse(glbl, CORE_COMPONENT));
	CHKiRet(objUse(net, CORE_COMPONENT));

	/* set our own handlers */
ENDObjClassInit(nsd_ptcp)


/* --------------- here now comes the plumbing that makes as a library module --------------- */


BEGINmodExit
CODESTARTmodExit
	nsd_ptcpClassExit();
ENDmodExit


BEGINqueryEtryPt
CODESTARTqueryEtryPt
CODEqueryEtryPt_STD_LIB_QUERIES
ENDqueryEtryPt


BEGINmodInit()
CODESTARTmodInit
	*ipIFVersProvided = CURR_MOD_IF_VERSION; /* we only support the current interface specification */

	/* Initialize all classes that are in our module - this includes ourselfs */
	CHKiRet(nsd_ptcpClassInit(pModInfo)); /* must be done after tcps_sess, as we use it */
ENDmodInit
/* vi:set ai:
 */