mailsrvr.c

/* Synchronet Mail (SMTP/POP3) server and sendmail threads */

/* $Id$ */
// vi: tabstop=4

/****************************************************************************
 * @format.tab-size 4		(Plain Text/Source Code File Header)			*
 * @format.use-tabs true	(see http://www.synchro.net/ptsc_hdr.html)		*
 *																			*
 * Copyright Rob Swindell - http://www.synchro.net/copyright.html			*
 *																			*
 * 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.					*
 * See the GNU General Public License for more details: gpl.txt or			*
 * http://www.fsf.org/copyleft/gpl.html										*
 *																			*
 * Anonymous FTP access to the most recent released source is available at	*
 * ftp://vert.synchro.net, ftp://cvs.synchro.net and ftp://ftp.synchro.net	*
 *																			*
 * Anonymous CVS access to the development source and modification history	*
 * is available at cvs.synchro.net:/cvsroot/sbbs, example:					*
 * cvs -d :pserver:anonymous@cvs.synchro.net:/cvsroot/sbbs login			*
 *     (just hit return, no password is necessary)							*
 * cvs -d :pserver:anonymous@cvs.synchro.net:/cvsroot/sbbs checkout src		*
 *																			*
 * For Synchronet coding style and modification guidelines, see				*
 * http://www.synchro.net/source.html										*
 *																			*
 * You are encouraged to submit any modifications (preferably in Unix diff	*
 * format) via e-mail to mods@synchro.net									*
 *																			*
 * Note: If this box doesn't appear square, then you need to fix your tabs.	*
 ****************************************************************************/

/* ANSI C Library headers */
#include <limits.h>			/* UINT_MAX */
#include <stdio.h>
#include <stdlib.h>			/* ltoa in GNU C lib */
#include <stdarg.h>			/* va_list */
#include <string.h>			/* strrchr */
#include <ctype.h>			/* isdigit */
#include <fcntl.h>			/* Open flags */
#include <errno.h>			/* errno */

/* Synchronet-specific headers */
#undef SBBS	/* this shouldn't be defined unless building sbbs.dll/libsbbs.so */
#include "sbbs.h"
#include "mailsrvr.h"
#include "mime.h"
#include "md5.h"
#include "crc32.h"
#include "base64.h"
#include "ini_file.h"
#include "netwrap.h"	/* getNameServerList() */
#include "xpendian.h"
#include "js_rtpool.h"
#include "js_request.h"
#include "multisock.h"
#include "ssl.h"
#include "cryptlib.h"

/* Constants */
static const char*	server_name="Synchronet Mail Server";
#define FORWARD			"forward:"
#define NO_FORWARD		"local:"
#define NO_SPAM			"#nospam"

int dns_getmx(char* name, char* mx, char* mx2
			  ,DWORD intf, DWORD ip_addr, BOOL use_tcp, int timeout);

static char* pop_err	=	"-ERR";
static char* ok_rsp		=	"250 OK";
static char* auth_ok	=	"235 User Authenticated";
static char* sys_error	=	"421 System error";
static char* sys_unavail=	"421 System unavailable, try again later";
static char* insuf_stor =	"452 Insufficient system storage";
static char* badarg_rsp =	"501 Bad argument";
static char* badseq_rsp	=	"503 Bad sequence of commands";
static char* badauth_rsp=	"535 Authentication failure";
static char* badrsp_err	=	"%s replied with:\r\n\"%s\"\r\n"
							"instead of the expected reply:\r\n\"%s ...\"";

#define TIMEOUT_THREAD_WAIT		60		/* Seconds */
#define DNSBL_THROTTLE_VALUE	1000	/* Milliseconds */

#define STATUS_WFC	"Listening"

static mail_startup_t* startup=NULL;
static scfg_t	scfg;
static struct xpms_set	*mail_set=NULL;
static BOOL terminated=FALSE;
static protected_uint32_t active_clients;
static protected_uint32_t thread_count;
static volatile int		active_sendmail=0;
static volatile BOOL	sendmail_running=FALSE;
static volatile BOOL	terminate_server=FALSE;
static volatile BOOL	terminate_sendmail=FALSE;
static sem_t	sendmail_wakeup_sem;
static char		revision[16];
static volatile time_t	uptime;
static str_list_t recycle_semfiles;
static str_list_t shutdown_semfiles;
static int		mailproc_count;
static js_server_props_t js_server_props;

struct {
	volatile ulong	sockets;
	volatile ulong	errors;
	volatile ulong	crit_errors;
	volatile ulong	connections_ignored;
	volatile ulong	connections_refused;
	volatile ulong	connections_served;
	volatile ulong	pop3_served;
	volatile ulong	smtp_served;
	/* SMTP: */
	volatile ulong	sessions_refused;
	volatile ulong	msgs_ignored;
	volatile ulong	msgs_refused;
	volatile ulong	msgs_received;
} stats;

struct mailproc {
	char		name[INI_MAX_VALUE_LEN];
	char		cmdline[INI_MAX_VALUE_LEN];
	char		eval[INI_MAX_VALUE_LEN];
	str_list_t	to;
	str_list_t	from;
	BOOL		passthru;
	BOOL		native;
	BOOL		ignore_on_error;	/* Ignore mail message if cmdline fails */
	BOOL		disabled;
	BOOL		process_spam;
	BOOL		process_dnsbl;
	uint8_t*	ar;
	ulong		handled;			/* counter (for stats display) */
} *mailproc_list;

typedef struct {
	SOCKET			socket;
	union xp_sockaddr	client_addr;
	socklen_t		client_addr_len;
	BOOL			tls_port;
} smtp_t,pop3_t;

#define GCES(status, server, sock, sess, action) do {                             \
	char *GCES_estr;                                                               \
	int GCES_level;                                                                 \
	get_crypt_error_string(status, sess, &GCES_estr, action, &GCES_level);  \
	if (GCES_estr) {                                                                  \
		lprintf(GCES_level, "%04d %s/TLS %s", sock, server, GCES_estr);                     \
		free_crypt_attrstr(GCES_estr);                                                  \
	}                                                                                    \
} while(0)

#define GCESH(status, server, sock, host, sess, action) do {                      \
	char *GCES_estr;                                                               \
	int GCES_level;                                                                 \
	get_crypt_error_string(status, sess, &GCES_estr, action, &GCES_level);  \
	if (GCES_estr) {                                                                  \
		lprintf(GCES_level, "%04d %s/TLS [%s] %s", sock, server, host, GCES_estr);         \
		free_crypt_attrstr(GCES_estr);                                                  \
	}                                                                                    \
} while(0)

static int lprintf(int level, const char *fmt, ...)
{
	va_list argptr;
	char sbuf[1024];

	va_start(argptr,fmt);
    vsnprintf(sbuf,sizeof(sbuf),fmt,argptr);
	sbuf[sizeof(sbuf)-1]=0;
    va_end(argptr);

	if(level <= LOG_ERR) {
		char errmsg[sizeof(sbuf)+16];
		SAFEPRINTF(errmsg, "mail %s", sbuf);
		errorlog(&scfg,startup==NULL ? NULL:startup->host_name,errmsg), stats.errors++;
		if(startup!=NULL && startup->errormsg!=NULL)
			startup->errormsg(startup->cbdata,level,errmsg);
	}

	if(level <= LOG_CRIT)
		stats.crit_errors++;

    if(startup==NULL || startup->lputs==NULL || level > startup->log_level)
		return(0);

#if defined(_WIN32)
	if(IsBadCodePtr((FARPROC)startup->lputs))
		return(0);
#endif

    return(startup->lputs(startup->cbdata,level,sbuf));
}

#ifdef _WINSOCKAPI_

static WSADATA WSAData;
#define SOCKLIB_DESC WSAData.szDescription
static BOOL WSAInitialized=FALSE;

static BOOL winsock_startup(void)
{
	int		status;             /* Status Code */

    if((status = WSAStartup(MAKEWORD(1,1), &WSAData))==0) {
		lprintf(LOG_DEBUG,"%s %s",WSAData.szDescription, WSAData.szSystemStatus);
		WSAInitialized=TRUE;
		return (TRUE);
	}

    lprintf(LOG_CRIT,"!WinSock startup ERROR %d", status);
	return (FALSE);
}

#else /* No WINSOCK */

#define winsock_startup()	(TRUE)
#define SOCKLIB_DESC NULL

#endif

static void update_clients(void)
{
	if(startup!=NULL && startup->clients!=NULL)
		startup->clients(startup->cbdata,protected_uint32_value(active_clients)+active_sendmail);
}

static void client_on(SOCKET sock, client_t* client, BOOL update)
{
	if(startup!=NULL && startup->client_on!=NULL)
		startup->client_on(startup->cbdata,TRUE,sock,client,update);
}

static void client_off(SOCKET sock)
{
	if(startup!=NULL && startup->client_on!=NULL)
		startup->client_on(startup->cbdata,FALSE,sock,NULL,FALSE);
}

static void thread_up(BOOL setuid)
{
	if(startup!=NULL && startup->thread_up!=NULL)
		startup->thread_up(startup->cbdata,TRUE,setuid);
}

static int32_t thread_down(void)
{
	int32_t count = protected_uint32_adjust(&thread_count,-1);
	if(startup!=NULL && startup->thread_up!=NULL)
		startup->thread_up(startup->cbdata,FALSE,FALSE);
	return count;
}

void mail_open_socket(SOCKET sock, void* cb_protocol)
{
	char	*protocol=(char *)cb_protocol;
	char	error[256];
	char	section[128];

	if(startup!=NULL && startup->socket_open!=NULL)
		startup->socket_open(startup->cbdata,TRUE);
	SAFEPRINTF(section,"mail|%s",protocol);
	if(set_socket_options(&scfg, sock, section, error, sizeof(error)))
		lprintf(LOG_ERR,"%04d !ERROR %s",sock,error);

	stats.sockets++;
}

void mail_close_socket_cb(SOCKET sock, void* cb_protocol)
{
	if(startup!=NULL && startup->socket_open!=NULL)
		startup->socket_open(startup->cbdata,FALSE);
	stats.sockets--;
}

int mail_close_socket(SOCKET sock)
{
	int		result;

	if(sock==INVALID_SOCKET)
		return(-1);

	shutdown(sock,SHUT_RDWR);	/* required on Unix */
	result=closesocket(sock);
	if(startup!=NULL && startup->socket_open!=NULL)
		startup->socket_open(startup->cbdata,FALSE);
	stats.sockets--;
	if(result!=0) {
		if(ERROR_VALUE!=ENOTSOCK)
			lprintf(LOG_WARNING,"%04d !ERROR %d closing socket",sock, ERROR_VALUE);
	}
#if 0 /*def _DEBUG */
	else 
		lprintf(LOG_DEBUG,"%04d Socket closed (%d sockets in use)",sock,stats.sockets);
#endif

	return(result);
}

static void status(char* str)
{
	if(startup!=NULL && startup->status!=NULL)
	    startup->status(startup->cbdata,str);
}

int sockprintf(SOCKET sock, CRYPT_SESSION sess, char *fmt, ...)
{
	int		len;
	int		maxlen;
	int		result;
	va_list argptr;
	char	sbuf[1024];
	fd_set	socket_set;
	struct timeval tv;

    va_start(argptr,fmt);
    len=vsnprintf(sbuf,maxlen=sizeof(sbuf)-2,fmt,argptr);
    va_end(argptr);

	if(len<0 || len > maxlen) /* format error or output truncated */
		len=maxlen;
	if(startup->options&MAIL_OPT_DEBUG_TX)
		lprintf(LOG_DEBUG,"%04d TX%s: %.*s", sock, sess != -1 ? "S" : "", len, sbuf);
	memcpy(sbuf+len,"\r\n",2);
	len+=2;

	if(sock==INVALID_SOCKET) {
		lprintf(LOG_WARNING,"!INVALID SOCKET in call to sockprintf");
		return(0);
	}

	/* Check socket for writability (using select) */
	tv.tv_sec=300;
	tv.tv_usec=0;

	FD_ZERO(&socket_set);
	FD_SET(sock,&socket_set);

	if((result=select(sock+1,NULL,&socket_set,NULL,&tv))<1) {
		if(result==0)
			lprintf(LOG_NOTICE,"%04d !TIMEOUT selecting socket for send"
				,sock);
		else
			lprintf(LOG_NOTICE,"%04d !ERROR %d selecting socket for send"
				,sock, ERROR_VALUE);
		return(0);
	}

	if (sess != -1) {
		int tls_sent;
		int sent = 0;
		while (sent < len) {
			result = cryptPushData(sess, sbuf+sent, len-sent, &tls_sent);
			if (result == CRYPT_OK)
				sent += tls_sent;
			else {
				GCES(result, "", sock, sess, "pushing data");
				return 0;
			}
		}
		if ((result = cryptFlushData(sess)) != CRYPT_OK) {
			GCES(result, "", sock, sess, "flushing data");
			return 0;
		}
	}
	else {
		// It looks like this could stutter on partial sends -- Deuce
		while((result=sendsocket(sock,sbuf,len))!=len) {
			if(result==SOCKET_ERROR) {
				if(ERROR_VALUE==EWOULDBLOCK) {
					YIELD();
					continue;
				}
				if(ERROR_VALUE==ECONNRESET) 
					lprintf(LOG_NOTICE,"%04d Connection reset by peer on send",sock);
				else if(ERROR_VALUE==ECONNABORTED) 
					lprintf(LOG_NOTICE,"%04d Connection aborted by peer on send",sock);
				else
					lprintf(LOG_NOTICE,"%04d !ERROR %d sending on socket",sock,ERROR_VALUE);
				return(0);
			}
			lprintf(LOG_WARNING,"%04d !ERROR: short send on socket: %d instead of %d",sock,result,len);
		}
	}
	return(len);
}

static void sockerror(SOCKET socket, int rd, const char* action)
{
	if(rd==0) 
		lprintf(LOG_NOTICE,"%04d Socket closed by peer on %s"
			,socket, action);
	else if(rd==SOCKET_ERROR) {
		if(ERROR_VALUE==ECONNRESET) 
			lprintf(LOG_NOTICE,"%04d Connection reset by peer on %s"
				,socket, action);
		else if(ERROR_VALUE==ECONNABORTED) 
			lprintf(LOG_NOTICE,"%04d Connection aborted by peer on %s"
				,socket, action);
		else
			lprintf(LOG_NOTICE,"%04d !SOCKET ERROR %d on %s"
				,socket, ERROR_VALUE, action);
	} else
		lprintf(LOG_WARNING,"%04d !SOCKET ERROR: unexpected return value %d from %s"
			,socket, rd, action);
}

static int sock_recvbyte(SOCKET sock, CRYPT_SESSION sess, char *buf, time_t start)
{
	int len=0;
	fd_set	socket_set;
	struct	timeval	tv;
	int ret;
	int i;

	if (sess > -1) {
		while (1) {
			ret = cryptPopData(sess, buf, 1, &len);
			GCES(ret, "", sock, sess, "popping data");
			switch(ret) {
				case CRYPT_OK:
					break;
				case CRYPT_ERROR_TIMEOUT:
					return -1;
				case CRYPT_ERROR_COMPLETE:
					return 0;
				default:
					if (ret < -1)
						return ret;
					return -2;
			}
			if (len)
				return len;
			if(startup->max_inactivity && (time(NULL)-start)>startup->max_inactivity) {
				lprintf(LOG_WARNING,"%04d !TIMEOUT in sock_recvbyte (%u seconds):  INACTIVE SOCKET"
					,sock, startup->max_inactivity);
				return(-1);
			}
		}
	}
	else {
		tv.tv_sec=startup->max_inactivity;
		tv.tv_usec=0;

		FD_ZERO(&socket_set);
		FD_SET(sock,&socket_set);

		i=select(sock+1,&socket_set,NULL,NULL,&tv);

		if(i<1) {
			if(i==0) {
				if(startup->max_inactivity && (time(NULL)-start)>startup->max_inactivity) {
					lprintf(LOG_WARNING,"%04d !TIMEOUT in sock_recvbyte (%u seconds):  INACTIVE SOCKET"
						,sock, startup->max_inactivity);
					return(-1);
				}
				return 0;
			}
			sockerror(sock,i,"select");
			return 0;
		}
		i=recv(sock, buf, 1, 0);
		if(i<1)
			sockerror(sock,i,"receive");
		return i;
	}
}

static int sockreadline(SOCKET socket, CRYPT_SESSION sess, char* buf, int len)
{
	char	ch;
	int		i,rd=0;
	time_t	start;

	buf[0]=0;

	start=time(NULL);

	if(socket==INVALID_SOCKET) {
		lprintf(LOG_WARNING,"!INVALID SOCKET in call to sockreadline");
		return(-1);
	}
	
	while(rd<len-1) {

		if(terminated || terminate_server) {
			lprintf(LOG_WARNING,"%04d !ABORTING sockreadline",socket);
			return(-1);
		}

		i = sock_recvbyte(socket, sess, &ch, start);

		if(i<1)
			return(-1);

		if(ch=='\n' /* && rd>=1 */ ) { /* Mar-9-2003: terminate on sole LF */
			break;
		}
		buf[rd++]=ch;
	}
	if(rd>0 && buf[rd-1]=='\r')
		rd--;
	buf[rd]=0;
	
	return(rd);
}

static BOOL sockgetrsp(SOCKET socket, CRYPT_SESSION sess, char* rsp, char *buf, int len)
{
	int rd;

	while(1) {
		rd = sockreadline(socket, sess, buf, len);
		if(rd<1) {
			if(rd==0 && rsp != NULL)
				lprintf(LOG_WARNING,"%04d !RECEIVED BLANK RESPONSE, Expected '%s'", socket, rsp);
			return(FALSE);
		}
		if(buf[3]=='-')	{ /* Multi-line response */
			if(startup->options&MAIL_OPT_DEBUG_RX_RSP) 
				lprintf(LOG_DEBUG,"%04d RX%s: %s",socket, sess != -1 ? "S" : "", buf);
			continue;
		}
		if(rsp!=NULL && strnicmp(buf,rsp,strlen(rsp))) {
			lprintf(LOG_WARNING,"%04d !INVALID RESPONSE: '%s' Expected: '%s'", socket, buf, rsp);
			return(FALSE);
		}
		break;
	}
	if(startup->options&MAIL_OPT_DEBUG_RX_RSP) 
		lprintf(LOG_DEBUG,"%04d RX%s: %s",socket,sess != -1 ? "S" : "", buf);
	return(TRUE);
}

static int sockgetrsp_opt(SOCKET socket, CRYPT_SESSION sess, char* rsp, char *opt, char *buf, int len)
{
	int rd;
	int ret = 0;
	size_t moptlen;
	char *mopt;

	moptlen = strlen(rsp)+strlen(opt) + 1;
	mopt = malloc(moptlen+1);
	if (mopt == NULL)
		return -1;
	sprintf(mopt, "%s-%s", rsp, opt);
	while(1) {
		rd = sockreadline(socket, sess, buf, len);
		if(rd<1) {
			if(rd==0)
				lprintf(LOG_WARNING,"%04d !RECEIVED BLANK RESPONSE, Expected '%s'", socket, rsp);
			free(mopt);
			return(-1);
		}
		if(buf[3]=='-')	{ /* Multi-line response */
			if (strncmp(buf, mopt, moptlen) == 0)
				ret = 1;
			if(startup->options&MAIL_OPT_DEBUG_RX_RSP) 
				lprintf(LOG_DEBUG,"%04d RX%s: %s",socket, sess != -1 ? "S" : "", buf);
			continue;
		}
		if(rsp!=NULL && strnicmp(buf,rsp,strlen(rsp))) {
			lprintf(LOG_WARNING,"%04d !INVALID RESPONSE: '%s' Expected: '%s'", socket, buf, rsp);
			free(mopt);
			return(-1);
		}
		break;
	}
	mopt[strlen(rsp)] = ' ';
	if (strncmp(buf, mopt, moptlen) == 0)
		ret = 1;
	free(mopt);
	if(startup->options&MAIL_OPT_DEBUG_RX_RSP)
		lprintf(LOG_DEBUG,"%04d RX%s: %s",socket,sess != -1 ? "S" : "", buf);
	return(ret);
}

/* non-standard, but documented (mostly) in draft-newman-msgheader-originfo-05 */
void originator_info(SOCKET socket, CRYPT_SESSION sess, smbmsg_t* msg)
{
	char* user		= msg->from_ext;
	char* login		= smb_get_hfield(msg,SENDERUSERID,NULL);
	char* server	= smb_get_hfield(msg,SENDERSERVER,NULL);
	char* client	= smb_get_hfield(msg,SENDERHOSTNAME,NULL);
	char* addr		= smb_get_hfield(msg,SENDERIPADDR,NULL);
	char* prot		= smb_get_hfield(msg,SENDERPROTOCOL,NULL);
	char* port		= smb_get_hfield(msg,SENDERPORT,NULL);
	char* time		= smb_get_hfield(msg,SENDERTIME,NULL);

	if(user || login || server || client || addr || prot || port || time)
		sockprintf(socket, sess
			,"X-Originator-Info: account=%s; login-id=%s; server=%s; client=%s; addr=%s; prot=%s; port=%s; time=%s"
			,user
			,login
			,server
			,client
			,addr
			,prot
			,port
			,time
			);
}

/* RFC822: The maximum total length of a text line including the
   <CRLF> is 1000 characters (but not counting the leading
   dot duplicated for transparency). 

   POP3 (RFC1939) actually calls for a 512 byte line length limit!
*/
#define MAX_LINE_LEN	998		

static ulong sockmimetext(SOCKET socket, CRYPT_SESSION sess, smbmsg_t* msg, char* msgtxt, ulong maxlines
						  ,str_list_t file_list, char* mime_boundary)
{
	char		toaddr[256]="";
	char		fromaddr[256]="";
	char		fromhost[256];
	char		msgid[256];
	char		date[64];
	uchar*		p;
	char*		np;
	char*		content_type=NULL;
	int			i;
	int			s;
	ulong		lines;
	int			len,tlen;

	/* HEADERS (in recommended order per RFC822 4.1) */

	if(msg->reverse_path!=NULL)
		if(!sockprintf(socket,sess,"Return-Path: %s", msg->reverse_path))
			return(0);

	for(i=0;i<msg->total_hfields;i++)
		if(msg->hfield[i].type == SMTPRECEIVED && msg->hfield_dat[i]!=NULL) 
			if(!sockprintf(socket,sess,"Received: %s", msg->hfield_dat[i]))
				return(0);

	if(!sockprintf(socket,sess,"Date: %s",msgdate(msg->hdr.when_written,date)))
		return(0);

	if((p=smb_get_hfield(msg,RFC822FROM,NULL))!=NULL)
		s=sockprintf(socket,sess,"From: %s",p);	/* use original RFC822 header field */
	else {
		char fromname[256];
		SAFEPRINTF(fromname, "\"%s\"", msg->from);
		if(msg->from_net.type==NET_QWK && msg->from_net.addr!=NULL)
			SAFEPRINTF2(fromaddr,"%s!%s"
				,(char*)msg->from_net.addr
				,usermailaddr(&scfg,fromhost,msg->from));
		else if(msg->from_net.type==NET_FIDO && msg->from_net.addr!=NULL) {
			faddr_t* faddr = (faddr_t *)msg->from_net.addr;
			char faddrstr[128];
			SAFEPRINTF2(fromname,"\"%s\" (%s)", msg->from, smb_faddrtoa(faddr, NULL));
			if(faddr->point)
				SAFEPRINTF4(faddrstr,"p%hu.f%hu.n%hu.z%hu"FIDO_TLD
					,faddr->point, faddr->node, faddr->net, faddr->zone);
			else
				SAFEPRINTF3(faddrstr,"f%hu.n%hu.z%hu"FIDO_TLD
					,faddr->node, faddr->net, faddr->zone);
			SAFEPRINTF2(fromaddr,"%s@%s", usermailaddr(NULL,fromhost,msg->from), faddrstr);
		} else if(msg->from_net.type!=NET_NONE && msg->from_net.addr!=NULL)
			SAFECOPY(fromaddr,(char*)msg->from_net.addr);
		else 
			usermailaddr(&scfg,fromaddr,msg->from);
		if(fromaddr[0]=='<')
			s=sockprintf(socket,sess,"From: %s %s",fromname,fromaddr);
		else
			s=sockprintf(socket,sess,"From: %s <%s>",fromname,fromaddr);
	}
	if(!s)
		return(0);

	if(msg->from_org!=NULL || msg->from_net.type==NET_NONE)
		if(!sockprintf(socket,sess,"Organization: %s"
			,msg->from_org==NULL ? scfg.sys_name : msg->from_org))
			return(0);

	if(!sockprintf(socket,sess,"Subject: %s",msg->subj))
		return(0);

	if((p=smb_get_hfield(msg,RFC822TO,NULL))!=NULL)
		s=sockprintf(socket,sess,"To: %s",p);	/* use original RFC822 header field */
	else {
		if(strchr(msg->to,'@')!=NULL || msg->to_net.addr==NULL)
			s=sockprintf(socket,sess,"To: %s",msg->to);	/* Avoid double-@ */
		else if(msg->to_net.type==NET_INTERNET || msg->to_net.type==NET_QWK) {
			if(strchr((char*)msg->to_net.addr,'<')!=NULL)
				s=sockprintf(socket,sess,"To: %s",(char*)msg->to_net.addr);
			else
				s=sockprintf(socket,sess,"To: \"%s\" <%s>",msg->to,(char*)msg->to_net.addr);
		} else if(msg->to_net.type==NET_FIDO) {
			s=sockprintf(socket,sess,"To: \"%s\" (%s)",msg->to, smb_faddrtoa((fidoaddr_t*)msg->to_net.addr, NULL));
		} else {
			usermailaddr(&scfg,toaddr,msg->to);
			s=sockprintf(socket,sess,"To: \"%s\" <%s>",msg->to,toaddr);
		}
	}
	if(!s)
		return(0);
	if((p=smb_get_hfield(msg,SMB_CARBONCOPY,NULL))!=NULL)
		if(!sockprintf(socket,sess,"CC: %s",p))
			return(0);
	np=NULL;
	if((p=smb_get_hfield(msg,RFC822REPLYTO,NULL))==NULL) {
		np=msg->replyto;
		if(msg->replyto_net.type==NET_INTERNET)
			p=msg->replyto_net.addr;
	}
	if(p!=NULL) {
		if(np!=NULL)
			s=sockprintf(socket,sess,"Reply-To: \"%s\" <%s>",np,p);
		else 
			s=sockprintf(socket,sess,"Reply-To: %s",p);
	}
	if(!s)
		return(0);
	if(!sockprintf(socket,sess,"Message-ID: %s",get_msgid(&scfg,INVALID_SUB,msg,msgid,sizeof(msgid))))
		return(0);
	if(msg->reply_id!=NULL)
		if(!sockprintf(socket,sess,"In-Reply-To: %s",msg->reply_id))
			return(0);

	originator_info(socket, sess, msg);

	/* Include all possible FidoNet header fields here */
	for(i=0;i<msg->total_hfields;i++) {
		switch(msg->hfield[i].type) {
			case FIDOCTRL:
			case FIDOAREA:	
			case FIDOSEENBY:
			case FIDOPATH:
			case FIDOMSGID:
			case FIDOREPLYID:
			case FIDOPID:
			case FIDOFLAGS:
			case FIDOTID:
				if(!sockprintf(socket,sess, "%s: %s", smb_hfieldtype(msg->hfield[i].type), (char*)msg->hfield_dat[i]))
					return(0);
				break;
		}
	}
	for(i=0;i<msg->total_hfields;i++) { 
		if(msg->hfield[i].type==RFC822HEADER) { 
			if(strnicmp((char*)msg->hfield_dat[i],"Content-Type:",13)==0)
				content_type=msg->hfield_dat[i];
			if(!sockprintf(socket,sess,"%s",(char*)msg->hfield_dat[i]))
				return(0);
        }
    }
	/* Default MIME Content-Type for non-Internet messages */
	if(msg->from_net.type!=NET_INTERNET && content_type==NULL && startup->default_charset[0]) {
		/* No content-type specified, so assume IBM code-page 437 (full ex-ASCII) */
		sockprintf(socket,sess,"Content-Type: text/plain; charset=%s", startup->default_charset);
		sockprintf(socket,sess,"Content-Transfer-Encoding: 8bit");
	}

	if(strListCount(file_list)) {	/* File attachments */
        mimeheaders(socket,sess,mime_boundary);
        sockprintf(socket,sess,"");
        mimeblurb(socket,sess,mime_boundary);
        sockprintf(socket,sess,"");
        mimetextpartheader(socket, sess,mime_boundary, startup->default_charset);
	}
	if(!sockprintf(socket,sess,""))	/* Header Terminator */
		return(0);

	/* MESSAGE BODY */
	lines=0;
	np=msgtxt;
	while(*np && lines<maxlines) {
		len=0;
		while(len<MAX_LINE_LEN && *(np+len)!=0 && *(np+len)!='\n')
			len++;

		tlen=len;
		while(tlen && *(np+(tlen-1))<=' ') /* Takes care of '\r' or spaces */
			tlen--;

		if(!sockprintf(socket,sess, "%s%.*s", *np=='.' ? ".":"", tlen, np))
			break;
		lines++;
		if(*(np+len)=='\r')
			len++;
		if(*(np+len)=='\n')
			len++;
		np+=len;
		/* release time-slices every x lines */
		if(startup->lines_per_yield
			&& !(lines%startup->lines_per_yield))	
			YIELD();
	}
	if(file_list!=NULL) {
		for(i=0;file_list[i];i++) { 
			sockprintf(socket,sess,"");
			lprintf(LOG_INFO,"%04u MIME Encoding and sending %s",socket,file_list[i]);
			if(!mimeattach(socket,sess,mime_boundary,file_list[i]))
				lprintf(LOG_ERR,"%04u !ERROR opening/encoding/sending %s",socket,file_list[i]);
			else {
				endmime(socket,sess,mime_boundary);
				if(msg->hdr.auxattr&MSG_KILLFILE)
					if(remove(file_list[i])!=0)
						lprintf(LOG_WARNING,"%04u !ERROR %d removing %s",socket,errno,file_list[i]);
			}
		}
	}
    sockprintf(socket,sess,".");	/* End of text */
	return(lines);
}

static ulong sockmsgtxt(SOCKET socket, CRYPT_SESSION sess, smbmsg_t* msg, char* msgtxt, ulong maxlines)
{
	char		filepath[MAX_PATH+1];
	ulong		retval;
	char*		boundary=NULL;
	unsigned	i;
	str_list_t	file_list=NULL;
	str_list_t	split;

	if(msg->hdr.auxattr&MSG_FILEATTACH) {

		boundary = mimegetboundary();
		file_list = strListInit();

		/* Parse header fields */
		for(i=0;i<msg->total_hfields;i++)
	        if(msg->hfield[i].type==FILEATTACH) 
				strListPush(&file_list,(char*)msg->hfield_dat[i]);

		/* Parse subject (if necessary) */
		if(!strListCount(file_list)) {	/* filename(s) stored in subject */
			split=strListSplitCopy(NULL,msg->subj," ");
			if(split!=NULL) {
				for(i=0;split[i];i++) {
					if(msg->idx.to!=0)
						SAFEPRINTF3(filepath,"%sfile/%04u.in/%s"
							,scfg.data_dir,msg->idx.to,getfname(truncsp(split[i])));
					else
						SAFEPRINTF3(filepath,"%sfile/%04u.out/%s"
							,scfg.data_dir,msg->idx.from,getfname(truncsp(split[i])));
					strListPush(&file_list,filepath);
				}
				strListFree(&split);
			}
		}
    }

	retval = sockmimetext(socket,sess,msg,msgtxt,maxlines,file_list,boundary);

	strListFree(&file_list);

	if(boundary!=NULL)
		free(boundary);

	return(retval);
}

static u_long resolve_ip(const char *inaddr)
{
	char*		p;
	char*		addr;
	char		buf[128];
	HOSTENT*	host;

	SAFECOPY(buf,inaddr);
	addr=buf;
	if(*addr=='[' && *(p=lastchar(addr))==']') { /* Support [ip_address] notation */
		addr++;
		*p=0;
	}

	if(*addr==0)
		return((u_long)INADDR_NONE);

	for(p=addr;*p;p++)
		if(*p!='.' && !isdigit((uchar)*p))
			break;
	if(!(*p))
		return(inet_addr(addr));

	if((host=gethostbyname(inaddr))==NULL)
		return((u_long)INADDR_NONE);

	return(*((ulong*)host->h_addr_list[0]));
}

/****************************************************************************/
/* Consecutive failed login (possible password hack) attempt tracking		*/
/****************************************************************************/
/* Counter is global so it is tracked between multiple connections.			*/
/* Failed consecutive login attempts > 10 will generate a hacklog entry	and	*/
/* immediately disconnect (after the usual failed-login delay).				*/
/* A failed login from a different host resets the counter.					*/
/* A successful login from the same host resets the counter.				*/
/****************************************************************************/

static void badlogin(SOCKET sock, CRYPT_SESSION sess, const char* prot, const char* resp, char* user, char* passwd, char* host, union xp_sockaddr* addr)
{
	char	reason[128];
	char	ip[INET6_ADDRSTRLEN];
	ulong	count;
	
	if(user == NULL)
		user = "<unspecified>";

	if(addr!=NULL) {
		SAFEPRINTF(reason,"%s LOGIN", prot);
		count=loginFailure(startup->login_attempt_list, addr, prot, user, passwd);
		if(startup->login_attempt.hack_threshold && count>=startup->login_attempt.hack_threshold)
			hacklog(&scfg, reason, user, passwd, host, addr);
		inet_addrtop(addr, ip, sizeof(ip));
		if(startup->login_attempt.filter_threshold && count>=startup->login_attempt.filter_threshold)
			filter_ip(&scfg, (char*)prot, "- TOO MANY CONSECUTIVE FAILED LOGIN ATTEMPTS"
				,host, ip, user, /* fname: */NULL);
	}

	mswait(startup->login_attempt.delay);
	sockprintf(sock,sess,(char*)resp);
}

static void pop3_thread(void* arg)
{
	char*		p;
	char		str[128];
	char		buf[512];
	char		host_name[128];
	char		host_ip[INET6_ADDRSTRLEN];
	char		username[128];
	char		password[128];
	char		challenge[256];
	uchar		digest[MD5_DIGEST_SIZE];
	char*		response="";
	char*		msgtxt;
	int			i;
	int			rd;
	BOOL		activity=TRUE;
	BOOL		apop=FALSE;
	uint32_t	l;
	long		lm_mode = 0;
	ulong		lines;
	ulong		lines_sent;
	ulong		login_attempts;
	uint32_t	msgs;
	uint32_t	msgnum;
	ulong		bytes;
	SOCKET		socket;
	smb_t		smb;
	smbmsg_t	msg;
	user_t		user;
	client_t	client;
	mail_t*		mail;
	pop3_t		pop3=*(pop3_t*)arg;
	login_attempt_t attempted;
	CRYPT_SESSION	session = -1;
	BOOL nodelay=TRUE;
	ulong nb = 0;
	char *estr;
	int level;
	int stat;

	SetThreadName("sbbs/pop3");
	thread_up(TRUE /* setuid */);

	free(arg);

	socket=pop3.socket;

	if(startup->options&MAIL_OPT_DEBUG_POP3)
		lprintf(LOG_DEBUG,"%04d POP3 session thread started", socket);

#ifdef _WIN32
	if(startup->pop3_sound[0] && !(startup->options&MAIL_OPT_MUTE)) 
		PlaySound(startup->pop3_sound, NULL, SND_ASYNC|SND_FILENAME);
#endif

	inet_addrtop(&pop3.client_addr, host_ip, sizeof(host_ip));

	if(startup->options&MAIL_OPT_DEBUG_POP3)
		lprintf(LOG_INFO,"%04d POP3 connection accepted from: %s port %u"
			,socket, host_ip, inet_addrport(&pop3.client_addr));

	if(getnameinfo(&pop3.client_addr.addr, pop3.client_addr_len, host_name, sizeof(host_name), NULL, 0, (startup->options&MAIL_OPT_NO_HOST_LOOKUP)?NI_NUMERICHOST:0)!=0)
		SAFECOPY(host_name, "<no name>");

	if(!(startup->options&MAIL_OPT_NO_HOST_LOOKUP) && (startup->options&MAIL_OPT_DEBUG_POP3))
		lprintf(LOG_INFO,"%04d POP3 Hostname: %s", socket, host_name);

	if (pop3.tls_port) {
		if (get_ssl_cert(&scfg, &estr, &level) == -1) {
			if (estr) {
				lprintf(level, "%04d !POP3 [%s] %s", socket, host_ip);
				free_crypt_attrstr(estr);
			}
			mail_close_socket(socket);
			thread_down();
			return;