POP3Svr.cpp

/*
 *  XMail by Davide Libenzi (Intranet and Internet mail server)
 *  Copyright (C) 1999,..,2010  Davide Libenzi
 *
 *  This program 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 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  Davide Libenzi <davidel@xmailserver.org>
 *
 */

#include "SysInclude.h"
#include "SysDep.h"
#include "SvrDefines.h"
#include "ShBlocks.h"
#include "SList.h"
#include "BuffSock.h"
#include "SSLBind.h"
#include "ResLocks.h"
#include "MiscUtils.h"
#include "StrUtils.h"
#include "MD5.h"
#include "SSLConfig.h"
#include "SvrUtils.h"
#include "UsrUtils.h"
#include "UsrAuth.h"
#include "POP3Svr.h"
#include "POP3Utils.h"
#include "MessQueue.h"
#include "MailDomains.h"
#include "MailConfig.h"
#include "AppDefines.h"
#include "MailSvr.h"

#define STD_POP3_TIMEOUT        30000
#define POP3_IPMAP_FILE         "pop3.ipmap.tab"
#define POP3_LOG_FILE           "pop3"

enum POP3States {
	stateInit,
	stateUser,
	stateLogged,

	stateExit
};

struct POP3Session {
	int iPOP3State;
	ThreadConfig const *pThCfg;
	POP3Config *pPOP3Cfg;
	SVRCFG_HANDLE hSvrConfig;
	int iBadLoginWait;
	SYS_INET_ADDR PeerInfo;
	char szSvrFQDN[MAX_HOST_NAME];
	char szSvrDomain[MAX_HOST_NAME];
	char szUser[MAX_ADDR_NAME];
	char szPassword[256];
	POP3_HANDLE hPOPSession;
	char szTimeStamp[256];
	int iLogPasswd;
};

static int POP3ThreadCountAdd(long lCount, SHB_HANDLE hShbPOP3,
			      POP3Config *pPOP3Cfg = NULL);
static int POP3LogEnabled(SHB_HANDLE hShbPOP3, POP3Config *pPOP3Cfg = NULL);

static POP3Config *POP3GetConfigCopy(SHB_HANDLE hShbPOP3)
{
	POP3Config *pPOP3Cfg = (POP3Config *) ShbLock(hShbPOP3);

	if (pPOP3Cfg == NULL)
		return NULL;

	POP3Config *pPOP3CfgCopy = (POP3Config *) SysAlloc(sizeof(POP3Config));

	if (pPOP3CfgCopy != NULL)
		memcpy(pPOP3CfgCopy, pPOP3Cfg, sizeof(POP3Config));

	ShbUnlock(hShbPOP3);

	return pPOP3CfgCopy;
}

static int POP3ThreadCountAdd(long lCount, SHB_HANDLE hShbPOP3, POP3Config *pPOP3Cfg)
{
	int iDoUnlock = 0;

	if (pPOP3Cfg == NULL) {
		if ((pPOP3Cfg = (POP3Config *) ShbLock(hShbPOP3)) == NULL)
			return ErrGetErrorCode();
		++iDoUnlock;
	}
	if ((pPOP3Cfg->lThreadCount + lCount) > pPOP3Cfg->lMaxThreads) {
		if (iDoUnlock)
			ShbUnlock(hShbPOP3);
		ErrSetErrorCode(ERR_SERVER_BUSY);
		return ERR_SERVER_BUSY;
	}
	pPOP3Cfg->lThreadCount += lCount;
	if (iDoUnlock)
		ShbUnlock(hShbPOP3);

	return 0;
}

static int POP3LogEnabled(SHB_HANDLE hShbPOP3, POP3Config *pPOP3Cfg)
{
	int iDoUnlock = 0;

	if (pPOP3Cfg == NULL) {
		if ((pPOP3Cfg = (POP3Config *) ShbLock(hShbPOP3)) == NULL)
			return ErrGetErrorCode();
		++iDoUnlock;
	}

	unsigned long ulFlags = pPOP3Cfg->ulFlags;

	if (iDoUnlock)
		ShbUnlock(hShbPOP3);

	return (ulFlags & POP3F_LOG_ENABLED) ? 1: 0;
}

static int POP3CheckPeerIP(SYS_SOCKET SockFD)
{
	char szIPMapFile[SYS_MAX_PATH] = "";

	CfgGetRootPath(szIPMapFile, sizeof(szIPMapFile));
	StrNCat(szIPMapFile, POP3_IPMAP_FILE, sizeof(szIPMapFile));

	if (SysExistFile(szIPMapFile)) {
		SYS_INET_ADDR PeerInfo;

		if (SysGetPeerInfo(SockFD, PeerInfo) < 0 ||
		    MscCheckAllowedIP(szIPMapFile, PeerInfo, true) < 0)
			return ErrGetErrorCode();
	}

	return 0;
}

static int POP3CheckSysResources(SVRCFG_HANDLE hSvrConfig)
{
	/* Check virtual memory */
	int iMinValue = SvrGetConfigInt("Pop3MinVirtMemSpace", -1, hSvrConfig);

	if (iMinValue > 0 && SvrCheckVirtMemSpace(1024 * (unsigned long) iMinValue) < 0)
		return ErrGetErrorCode();

	return 0;
}

static int POP3InitSession(ThreadConfig const *pThCfg, BSOCK_HANDLE hBSock,
			   POP3Session &POP3S)
{
	ZeroData(POP3S);
	POP3S.iPOP3State = stateInit;
	POP3S.pThCfg = pThCfg;
	POP3S.hSvrConfig = INVALID_SVRCFG_HANDLE;
	POP3S.pPOP3Cfg = NULL;
	POP3S.hPOPSession = INVALID_POP3_HANDLE;

	if ((POP3S.hSvrConfig = SvrGetConfigHandle()) == INVALID_SVRCFG_HANDLE)
		return ErrGetErrorCode();

	if (POP3CheckSysResources(POP3S.hSvrConfig) < 0 ||
	    SysGetPeerInfo(BSckGetAttachedSocket(hBSock), POP3S.PeerInfo) < 0) {
		SvrReleaseConfigHandle(POP3S.hSvrConfig);
		return ErrGetErrorCode();
	}
	/* Get connection socket host name */
	char szIP[128] = "???.???.???.???";

	if (MscGetSockHost(BSckGetAttachedSocket(hBSock), POP3S.szSvrFQDN,
			   sizeof(POP3S.szSvrFQDN)) < 0)
		StrSNCpy(POP3S.szSvrFQDN, SysInetNToA(POP3S.PeerInfo, szIP, sizeof(szIP)));
	else {
		/* Try to get a valid domain from the FQDN */
		if (MDomGetClientDomain(POP3S.szSvrFQDN, POP3S.szSvrDomain,
					sizeof(POP3S.szSvrDomain) - 1) < 0)
			StrSNCpy(POP3S.szSvrDomain, POP3S.szSvrFQDN);
	}

	/*
	 * If "POP3Domain" is defined, it's taken as default POP3 domain that means
	 * that users of such domain can log using only the name part of their email
	 * address.
	 */
	char *pszDefDomain = SvrGetConfigVar(POP3S.hSvrConfig, "POP3Domain");

	if (pszDefDomain != NULL) {
		StrSNCpy(POP3S.szSvrDomain, pszDefDomain);
		SysFree(pszDefDomain);
	}
	/* As a last tentative We try to get "RootDomain" to set POP3 domain */
	if (IsEmptyString(POP3S.szSvrDomain)) {
		char *pszRootDomain = SvrGetConfigVar(POP3S.hSvrConfig, "RootDomain");

		if (pszRootDomain == NULL) {
			SvrReleaseConfigHandle(POP3S.hSvrConfig);
			ErrSetErrorCode(ERR_NO_DOMAIN);
			return ERR_NO_DOMAIN;
		}
		StrSNCpy(POP3S.szSvrDomain, pszRootDomain);
		SysFree(pszRootDomain);
	}
	if ((POP3S.pPOP3Cfg = POP3GetConfigCopy(POP3S.pThCfg->hThShb)) == NULL) {
		SvrReleaseConfigHandle(POP3S.hSvrConfig);
		return ErrGetErrorCode();
	}

	POP3S.iBadLoginWait = POP3S.pPOP3Cfg->iBadLoginWait;
	POP3S.iLogPasswd = SvrGetConfigInt("Pop3LogPasswd", 0, POP3S.hSvrConfig);

	/* Create timestamp for APOP command */
	sprintf(POP3S.szTimeStamp, "<%lu.%lu@%s>",
		(unsigned long) time(NULL), SysGetCurrentThreadId(), POP3S.szSvrDomain);

	return 0;
}

static int POP3LogSession(POP3Session &POP3S, char const *pszStatus,
			  char const *pszFmt, ...)
{
	char *pszExtra = NULL;
	char szTime[256] = "";

	MscGetTimeNbrString(szTime, sizeof(szTime) - 1);
	if (pszFmt != NULL)
		StrVSprint(pszExtra, pszFmt, pszFmt);

	RLCK_HANDLE hResLock = RLckLockEX(SVR_LOGS_DIR SYS_SLASH_STR POP3_LOG_FILE);

	if (hResLock == INVALID_RLCK_HANDLE)
		return ErrGetErrorCode();

	char const *pszPassword = (POP3S.iLogPasswd == 2 || (POP3S.iLogPasswd == 1 &&
							     POP3S.iPOP3State != stateLogged)) ?
		POP3S.szPassword: "";
	char szIP[128] = "???.???.???.???";

	MscFileLog(POP3_LOG_FILE, "\"%s\""
		   "\t\"%s\""
		   "\t\"%s\""
		   "\t\"%s\""
		   "\t\"%s\""
		   "\t\"%s\""
		   "\t\"%s\""
		   "%s"
		   "\n", POP3S.szSvrFQDN, POP3S.szSvrDomain,
		   SysInetNToA(POP3S.PeerInfo, szIP, sizeof(szIP)), szTime, POP3S.szUser,
		   pszPassword, pszStatus, pszExtra != NULL ? pszExtra: "");

	RLckUnlockEX(hResLock);
	SysFree(pszExtra);

	return 0;
}

static void POP3ClearSession(POP3Session &POP3S)
{
	if (POP3S.hPOPSession != INVALID_POP3_HANDLE) {
		UPopReleaseSession(POP3S.hPOPSession, (POP3S.iPOP3State == stateExit) ? 1: 0);
		POP3S.hPOPSession = INVALID_POP3_HANDLE;
	}
	if (POP3S.hSvrConfig != INVALID_SVRCFG_HANDLE) {
		SvrReleaseConfigHandle(POP3S.hSvrConfig);
		POP3S.hSvrConfig = INVALID_SVRCFG_HANDLE;
	}
	SysFreeNullify(POP3S.pPOP3Cfg);
}

static int POP3HandleCmd_USER(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateInit) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	char **ppszTokens = StrTokenize(pszCommand, " ");

	if (ppszTokens == NULL || StrStringsCount(ppszTokens) != 2) {
		StrFreeStrings(ppszTokens);

		POP3S.iPOP3State = stateInit;

		BSckSendString(hBSock, "-ERR Invalid syntax", POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	char szAccountUser[MAX_ADDR_NAME] = "";
	char szAccountDomain[MAX_HOST_NAME] = "";

	if (StrSplitString(ppszTokens[1], POP3_USER_SPLITTERS, szAccountUser,
			   sizeof(szAccountUser), szAccountDomain,
			   sizeof(szAccountDomain)) < 0) {
		StrFreeStrings(ppszTokens);

		BSckSendString(hBSock, "-ERR Invalid username", POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}
	StrFreeStrings(ppszTokens);
	StrSNCpy(POP3S.szUser, szAccountUser);
	if (strlen(szAccountDomain) > 0)
		StrSNCpy(POP3S.szSvrDomain, szAccountDomain);

	POP3S.iPOP3State = stateUser;

	BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
			"+OK Password required for %s@%s", POP3S.szUser, POP3S.szSvrDomain);

	return 0;
}

static int POP3HandleBadLogin(BSOCK_HANDLE hBSock, POP3Session &POP3S)
{
	/* Log POP3 session */
	if (POP3LogEnabled(POP3S.pThCfg->hThShb, POP3S.pPOP3Cfg))
		POP3LogSession(POP3S, "ELOGIN", NULL);

	if (POP3S.pPOP3Cfg->ulFlags & POP3F_HANG_ON_BADLOGIN) {
		/* Exit if POP3F_HANG_ON_BADLOGIN is set */

		POP3S.iPOP3State = stateExit;

	} else {
		/* Otherwise sleep and doubles the sleeptime */
		SysSleep(POP3S.iBadLoginWait);
		POP3S.iBadLoginWait += POP3S.iBadLoginWait;

		POP3S.iPOP3State = stateInit;
	}

	BSckSendString(hBSock, "-ERR Invalid auth or access denied",
		       POP3S.pPOP3Cfg->iTimeout);

	return 0;
}

static int POP3HandleCmd_PASS(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateUser) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	char **ppszTokens = StrTokenize(pszCommand, " ");

	if (ppszTokens == NULL || StrStringsCount(ppszTokens) != 2) {
		StrFreeStrings(ppszTokens);

		POP3S.iPOP3State = stateInit;

		BSckSendString(hBSock, "-ERR Invalid syntax", POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}
	StrSNCpy(POP3S.szPassword, ppszTokens[1]);
	StrFreeStrings(ppszTokens);

	/* Check the presence of external authentication modules. If authentication
	 * succeed "pszPassword" is set to NULL that instruct "UPopBuildSession"
	 * to not make local authentication.
	 */
	char const *pszPassword = POP3S.szPassword;
	int iAuthResult = UAthAuthenticateUser(AUTH_SERVICE_POP3, POP3S.szSvrDomain,
					       POP3S.szUser, POP3S.szPassword);

	if (iAuthResult < 0) {
		if (iAuthResult != ERR_NO_EXTERNAL_AUTH_DEFINED) {
			ErrorPush();

			POP3HandleBadLogin(hBSock, POP3S);

			return ErrorPop();
		}
	} else
		pszPassword = NULL;

	/* Create POP3 session */
	if ((POP3S.hPOPSession = UPopBuildSession(POP3S.szSvrDomain, POP3S.szUser,
						  pszPassword,
						  &POP3S.PeerInfo)) == INVALID_POP3_HANDLE) {
		ErrorPush();

		POP3HandleBadLogin(hBSock, POP3S);

		return ErrorPop();
	}
	/* Save the user connection IP to use for SMTP authentication */
	UPopSaveUserIP(POP3S.hPOPSession);

	POP3S.iPOP3State = stateLogged;

	int iMsgCount = UPopGetSessionMsgCurrent(POP3S.hPOPSession);
	SYS_OFF_T llMBSize = UPopGetSessionMBSize(POP3S.hPOPSession);

	/* Log POP3 session */
	if (POP3LogEnabled(POP3S.pThCfg->hThShb, POP3S.pPOP3Cfg))
		POP3LogSession(POP3S, "LOGIN",
			       "\t\"%d\""
			       "\t\"" SYS_OFFT_FMT "\"", iMsgCount, llMBSize);

	BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
			"+OK Maildrop has %d messages (" SYS_OFFT_FMT " bytes)",
			iMsgCount, llMBSize);

	return 0;
}

static int POP3HandleCmd_APOP(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateInit) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	char **ppszTokens = StrTokenize(pszCommand, " ");

	if (ppszTokens == NULL || StrStringsCount(ppszTokens) != 3) {
		StrFreeStrings(ppszTokens);
		POP3S.iPOP3State = stateInit;

		BSckSendString(hBSock, "-ERR Invalid syntax", POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}
	/* Process parameters */
	char szAccountUser[MAX_ADDR_NAME] = "";
	char szAccountDomain[MAX_HOST_NAME] = "";

	if (StrSplitString(ppszTokens[1], POP3_USER_SPLITTERS, szAccountUser,
			   sizeof(szAccountUser), szAccountDomain,
			   sizeof(szAccountDomain)) < 0) {
		StrFreeStrings(ppszTokens);

		BSckSendString(hBSock, "-ERR Invalid username", POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}
	StrSNCpy(POP3S.szUser, szAccountUser);
	StrSNCpy(POP3S.szPassword, ppszTokens[2]);

	if (strlen(szAccountDomain) > 0)
		StrSNCpy(POP3S.szSvrDomain, szAccountDomain);

	StrFreeStrings(ppszTokens);

	/* Check the presence of external authentication modules. If authentication */
	/* succeed "pszPassword" is set to NULL that instruct "UPopBuildSession" */
	/* to not make local authentication */
	char const *pszPassword = POP3S.szPassword;
	int iAuthResult = UAthAuthenticateUser(AUTH_SERVICE_POP3,
					       POP3S.szSvrDomain, POP3S.szUser, POP3S.szPassword);

	if (iAuthResult < 0) {
		if (iAuthResult != ERR_NO_EXTERNAL_AUTH_DEFINED) {
			ErrorPush();

			POP3HandleBadLogin(hBSock, POP3S);

			return ErrorPop();
		}
	} else
		pszPassword = NULL;

	/* Do APOP authentication ( only if the external one is not performed ) */
	if (pszPassword != NULL &&
	    UPopAuthenticateAPOP(POP3S.szSvrDomain, POP3S.szUser, POP3S.szTimeStamp,
				 pszPassword) < 0) {
		ErrorPush();

		POP3HandleBadLogin(hBSock, POP3S);

		return ErrorPop();
	}
	/* Create POP3 session ( the NULL as third parameter force to not perform */
	/* user authentication that has been done before ) */
	if ((POP3S.hPOPSession = UPopBuildSession(POP3S.szSvrDomain, POP3S.szUser,
						  NULL, &POP3S.PeerInfo)) == INVALID_POP3_HANDLE)
	{
		ErrorPush();

		POP3HandleBadLogin(hBSock, POP3S);

		return ErrorPop();
	}
	/* Save the user connection IP to use for SMTP authentication */
	UPopSaveUserIP(POP3S.hPOPSession);

	POP3S.iPOP3State = stateLogged;

	int iMsgCount = UPopGetSessionMsgCurrent(POP3S.hPOPSession);
	SYS_OFF_T llMBSize = UPopGetSessionMBSize(POP3S.hPOPSession);

	/* Log POP3 session */
	if (POP3LogEnabled(POP3S.pThCfg->hThShb, POP3S.pPOP3Cfg))
		POP3LogSession(POP3S, "LOGIN",
			       "\t\"%d\""
			       "\t\"" SYS_OFFT_FMT "\"", iMsgCount, llMBSize);

	BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
			"+OK Maildrop has %d messages (" SYS_OFFT_FMT " bytes)",
			iMsgCount, llMBSize);

	return 0;
}

static int POP3HandleCmd_CAPA(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	char const *pszSTLS = "";

	if (SvrTestConfigFlag("EnablePOP3-TLS", true, POP3S.hSvrConfig) &&
	    strcmp(BSckBioName(hBSock), BSSL_BIO_NAME) != 0)
		pszSTLS = "STLS\r\n";

	BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
			"+OK Capability list follows\r\n"
			"TOP\r\n"
			"USER\r\n"
			"UIDL\r\n"
			"PIPELINING\r\n"
			"%s"
			"IMPLEMENTATION " POP3_SERVER_NAME "\r\n"
			".", pszSTLS);

	return 0;
}

static int POP3SslEnvCB(void *pPrivate, int iID, void const *pData)
{
	POP3Session *pPOP3S = (POP3Session *) pPrivate;

	/*
	 * Empty for now ...
	 */


	return 0;
}

static int POP3HandleCmd_STLS(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{

	if (POP3S.iPOP3State != stateInit) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}
	if (strcmp(BSckBioName(hBSock), BSSL_BIO_NAME) == 0) {
		/*
		 * Client is trying to run another STLS after a successful one.
		 * Not possible ...
		 */
		BSckSendString(hBSock, "-ERR Command not permitted when TLS active",
			       POP3S.pPOP3Cfg->iTimeout);

		return -1;
	}
	if (!SvrTestConfigFlag("EnablePOP3-TLS", true, POP3S.hSvrConfig)) {
		BSckSendString(hBSock, "-ERR Command disabled", POP3S.pPOP3Cfg->iTimeout);

		ErrSetErrorCode(ERR_SSL_DISABLED);
		return ERR_SSL_DISABLED;
	}

	int iError;
	SslServerBind SSLB;

	if (CSslBindSetup(&SSLB) < 0) {
		BSckSendString(hBSock, "-ERR Server TLS setup error",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	BSckSendString(hBSock, "+OK Begin TLS negotiation", POP3S.pPOP3Cfg->iTimeout);

	iError = BSslBindServer(hBSock, &SSLB, POP3SslEnvCB, &POP3S);

	CSslBindCleanup(&SSLB);
	if (iError < 0) {
		char szIP[128] = "";

		SysLogMessage(LOG_LEV_MESSAGE, "POP3 failed to STLS [%s]\n",
			      SysInetNToA(POP3S.PeerInfo, szIP, sizeof(szIP)));

		/*
		 * We have no other option than exit here ...
		 */
		POP3S.iPOP3State = stateExit;

		return iError;
	}

	return 0;
}

static int POP3HandleCmd_STAT(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateLogged) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	int iMsgCount = UPopGetSessionMsgCurrent(POP3S.hPOPSession);
	SYS_OFF_T llMBSize = UPopGetSessionMBSize(POP3S.hPOPSession);

	BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout, "+OK %d " SYS_OFFT_FMT,
			iMsgCount, llMBSize);

	return 0;
}

static int POP3HandleCmd_LIST(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateLogged) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	int iMsgIndex = -1;
	int iNumArgs = sscanf(pszCommand, "%*s %d", &iMsgIndex);

	if (iNumArgs < 1) {
		int iMsgCount = UPopGetSessionMsgCurrent(POP3S.hPOPSession);
		int iMsgTotal = UPopGetSessionMsgTotal(POP3S.hPOPSession);
		SYS_OFF_T llMBSize = UPopGetSessionMBSize(POP3S.hPOPSession);

		BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
				"+OK %d " SYS_OFFT_FMT, iMsgCount, llMBSize);

		for (int i = 0; i < iMsgTotal; i++) {
			SYS_OFF_T llMessageSize = 0;

			if (UPopGetMessageSize(POP3S.hPOPSession, i + 1,
					       llMessageSize) == 0)
				BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
						"%d " SYS_OFFT_FMT, i + 1,
						llMessageSize);
		}
		BSckSendString(hBSock, ".", POP3S.pPOP3Cfg->iTimeout);
	} else {
		SYS_OFF_T llMessageSize = 0;

		if (UPopGetMessageSize(POP3S.hPOPSession, iMsgIndex,
				       llMessageSize) < 0)
			BSckSendString(hBSock, "-ERR No such message",
				       POP3S.pPOP3Cfg->iTimeout);
		else
			BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
					"+OK %d " SYS_OFFT_FMT, iMsgIndex,
					llMessageSize);
	}

	return 0;
}

static int POP3HandleCmd_UIDL(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateLogged) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	int iMsgIndex = -1;
	int iNumArgs = sscanf(pszCommand, "%*s %d", &iMsgIndex);
	char szMessageUIDL[256];

	if (iNumArgs < 1) {
		int iMsgCount = UPopGetSessionMsgCurrent(POP3S.hPOPSession);
		int iMsgTotal = UPopGetSessionMsgTotal(POP3S.hPOPSession);

		BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout, "+OK %d", iMsgCount);

		for (int i = 0; i < iMsgTotal; i++) {
			if (UPopGetMessageUIDL(POP3S.hPOPSession, i + 1, szMessageUIDL,
					       sizeof(szMessageUIDL)) == 0)
				BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
						"%d %s", i + 1, szMessageUIDL);
		}
		BSckSendString(hBSock, ".", POP3S.pPOP3Cfg->iTimeout);
	} else {
		if (UPopGetMessageUIDL(POP3S.hPOPSession, iMsgIndex, szMessageUIDL,
				       sizeof(szMessageUIDL)) < 0)
			BSckSendString(hBSock, "-ERR No such message",
				       POP3S.pPOP3Cfg->iTimeout);
		else
			BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
					"+OK %d %s", iMsgIndex, szMessageUIDL);
	}

	return 0;
}

static int POP3HandleCmd_QUIT(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	POP3S.iPOP3State = stateExit;

	BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
			"+OK %s closing session", POP3_SERVER_NAME);

	return 0;
}

static int POP3HandleCmd_RETR(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateLogged) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	int iMsgIndex = -1;

	if (sscanf(pszCommand, "%*s %d", &iMsgIndex) < 1) {
		BSckSendString(hBSock, "-ERR Invalid syntax",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	return UPopSessionSendMsg(POP3S.hPOPSession, iMsgIndex, hBSock);
}

static int POP3HandleCmd_TOP(char const *pszCommand, BSOCK_HANDLE hBSock,
			     POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateLogged) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	int iMsgIndex = -1, iNumLines = 0;

	if (sscanf(pszCommand, "%*s %d %d", &iMsgIndex, &iNumLines) < 2) {
		BSckSendString(hBSock, "-ERR Invalid syntax",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	return UPopSessionTopMsg(POP3S.hPOPSession, iMsgIndex, iNumLines, hBSock);
}

static int POP3HandleCmd_DELE(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateLogged) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	int iMsgIndex = -1;

	if (sscanf(pszCommand, "%*s %d", &iMsgIndex) < 1) {
		BSckSendString(hBSock, "-ERR Invalid syntax",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	if (UPopDeleteMessage(POP3S.hPOPSession, iMsgIndex) < 0) {
		UPopSendErrorResponse(hBSock, ErrGetErrorCode(),
				      POP3S.pPOP3Cfg->iTimeout);

		return ErrGetErrorCode();
	}

	BSckSendString(hBSock, "+OK Message deleted", POP3S.pPOP3Cfg->iTimeout);

	return 0;
}

static int POP3HandleCmd_NOOP(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateLogged) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	int iMsgCount = UPopGetSessionMsgCurrent(POP3S.hPOPSession);
	SYS_OFF_T llMBSize = UPopGetSessionMBSize(POP3S.hPOPSession);

	BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
			"+OK Maildrop has %d messages (" SYS_OFFT_FMT " bytes)",
			iMsgCount, llMBSize);

	return 0;
}

static int POP3HandleCmd_LAST(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateLogged) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	int iMsgLast = UPopGetSessionLastAccessed(POP3S.hPOPSession);

	BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout, "+OK %d", iMsgLast);

	return 0;
}

static int POP3HandleCmd_RSET(char const *pszCommand, BSOCK_HANDLE hBSock,
			      POP3Session &POP3S)
{
	if (POP3S.iPOP3State != stateLogged) {
		BSckSendString(hBSock, "-ERR Command not valid here",
			       POP3S.pPOP3Cfg->iTimeout);
		return -1;
	}

	UPopResetSession(POP3S.hPOPSession);

	int iMsgCount = UPopGetSessionMsgCurrent(POP3S.hPOPSession);
	SYS_OFF_T llMBSize = UPopGetSessionMBSize(POP3S.hPOPSession);

	BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
			"+OK Maildrop has %d messages (" SYS_OFFT_FMT " bytes)",
			iMsgCount, llMBSize);

	return 0;
}

static int POP3HandleCommand(char const *pszCommand, BSOCK_HANDLE hBSock,
			     POP3Session &POP3S)
{
	int iCmdResult = -1;

	if (StrCmdMatch(pszCommand, "USER"))
		iCmdResult = POP3HandleCmd_USER(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "PASS"))
		iCmdResult = POP3HandleCmd_PASS(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "APOP"))
		iCmdResult = POP3HandleCmd_APOP(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "CAPA"))
		iCmdResult = POP3HandleCmd_CAPA(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "STLS"))
		iCmdResult = POP3HandleCmd_STLS(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "STAT"))
		iCmdResult = POP3HandleCmd_STAT(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "LIST"))
		iCmdResult = POP3HandleCmd_LIST(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "UIDL"))
		iCmdResult = POP3HandleCmd_UIDL(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "QUIT"))
		iCmdResult = POP3HandleCmd_QUIT(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "RETR"))
		iCmdResult = POP3HandleCmd_RETR(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "TOP"))
		iCmdResult = POP3HandleCmd_TOP(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "DELE"))
		iCmdResult = POP3HandleCmd_DELE(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "NOOP"))
		iCmdResult = POP3HandleCmd_NOOP(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "LAST"))
		iCmdResult = POP3HandleCmd_LAST(pszCommand, hBSock, POP3S);
	else if (StrCmdMatch(pszCommand, "RSET"))
		iCmdResult = POP3HandleCmd_RSET(pszCommand, hBSock, POP3S);
	else
		BSckSendString(hBSock, "-ERR Invalid command", POP3S.pPOP3Cfg->iTimeout);

	return iCmdResult;
}

static int POP3HandleSession(ThreadConfig const *pThCfg, BSOCK_HANDLE hBSock)
{
	/* Session structure declaration and init */
	POP3Session POP3S;

	if (POP3InitSession(pThCfg, hBSock, POP3S) < 0) {
		ErrorPush();

		UPopSendErrorResponse(hBSock, ErrGetErrorCode(), STD_POP3_TIMEOUT);

		return ErrorPop();
	}

	char szIP[128] = "???.???.???.???";

	SysLogMessage(LOG_LEV_MESSAGE, "POP3 client connection from [%s]\n",
		      SysInetNToA(POP3S.PeerInfo, szIP, sizeof(szIP)));

	/* Send welcome message */
	char szTime[256] = "";

	MscGetTimeStr(szTime, sizeof(szTime) - 1);
	if (BSckVSendString(hBSock, POP3S.pPOP3Cfg->iTimeout,
			    "+OK %s %s service ready; %s", POP3S.szTimeStamp,
			    POP3_SERVER_NAME, szTime) < 0) {
		POP3ClearSession(POP3S);
		return ErrGetErrorCode();
	}
	/* Command loop */
	char szCommand[1024] = "";

	while (!SvrInShutdown() && POP3S.iPOP3State != stateExit &&
	       BSckGetString(hBSock, szCommand, sizeof(szCommand) - 1,
			     POP3S.pPOP3Cfg->iSessionTimeout) != NULL &&
	       MscCmdStringCheck(szCommand) == 0) {
		if (pThCfg->ulFlags & THCF_SHUTDOWN)
			break;

		/* Handle coomand */
		POP3HandleCommand(szCommand, hBSock, POP3S);
	}

	SysLogMessage(LOG_LEV_MESSAGE, "POP3 client exit [%s]\n",
		      SysInetNToA(POP3S.PeerInfo, szIP, sizeof(szIP)));

	POP3ClearSession(POP3S);

	return 0;
}

unsigned int POP3ClientThread(void *pThreadData)
{
	ThreadCreateCtx *pThCtx = (ThreadCreateCtx *) pThreadData;

	/* Link socket to the bufferer */
	BSOCK_HANDLE hBSock = BSckAttach(pThCtx->SockFD);

	if (hBSock == INVALID_BSOCK_HANDLE) {
		ErrorPush();
		SysCloseSocket(pThCtx->SockFD);
		SysFree(pThCtx);
		return ErrorPop();
	}

	/*
	 * Do we need to switch to TLS?
	 */
	if (pThCtx->pThCfg->ulFlags & THCF_USE_SSL) {
		int iError;
		SslServerBind SSLB;
		SslBindEnv SslE;

		if (CSslBindSetup(&SSLB) < 0) {
			ErrorPush();
			BSckDetach(hBSock, 1);
			SysFree(pThCtx);
			return ErrorPop();
		}
		ZeroData(SslE);

		iError = BSslBindServer(hBSock, &SSLB, MscSslEnvCB, &SslE);

		CSslBindCleanup(&SSLB);
		if (iError < 0) {
			ErrorPush();
			BSckDetach(hBSock, 1);
			SysFree(pThCtx);
			return ErrorPop();
		}
		/*
		 * We may want to add verify code here ...
		 */

		SysFree(SslE.pszIssuer);
		SysFree(SslE.pszSubject);
	}

	/* Check IP permission */
	if (POP3CheckPeerIP(pThCtx->SockFD) < 0) {
		ErrorPush();

		UPopSendErrorResponse(hBSock, ErrGetErrorCode(), STD_POP3_TIMEOUT);

		BSckDetach(hBSock, 1);
		SysFree(pThCtx);
		return ErrorPop();
	}

	/* Increase threads count */
	if (POP3ThreadCountAdd(+1, pThCtx->pThCfg->hThShb) < 0) {
		ErrorPush();
		SysLogMessage(LOG_LEV_ERROR, "%s (POP3 thread count)\n",
			      ErrGetErrorString(ErrorFetch()));
		UPopSendErrorResponse(hBSock, ErrGetErrorCode(), STD_POP3_TIMEOUT);

		BSckDetach(hBSock, 1);
		SysFree(pThCtx);
		return ErrorPop();
	}

	/* Handle client session */
	POP3HandleSession(pThCtx->pThCfg, hBSock);

	/* Decrease threads count */
	POP3ThreadCountAdd(-1, pThCtx->pThCfg->hThShb);

	/* Unlink socket from the bufferer and close it */
	BSckDetach(hBSock, 1);
	SysFree(pThCtx);

	return 0;
}