mailsrvr.c

/* mailsrvr.c */

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

/* $Id$ */

/****************************************************************************
 * @format.tab-size 4		(Plain Text/Source Code File Header)			*
 * @format.use-tabs true	(see http://www.synchro.net/ptsc_hdr.html)		*
 *																			*
 * Copyright 2000 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.	*
 ****************************************************************************/

/* Platform-specific headers */
#ifdef _WIN32

	#include <io.h>			/* open/close */
	#include <share.h>		/* share open flags */
	#include <process.h>	/* _beginthread */
	#include <windows.h>	/* required for mmsystem.h */
	#include <mmsystem.h>	/* SND_ASYNC */

#elif defined(__unix__)

	#include <signal.h>		/* signal/SIGPIPE */

#endif


/* ANSI C Library headers */
#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 */
#include "sbbs.h"
#include "mailsrvr.h"
#include "mime.h"
#include "crc32.h"

/* Constants */
#define MAIL_VERSION "1.11"

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

#define SMTP_OK		"250 OK"
#define SMTP_BADSEQ	"503 Bad sequence of commands"

#define TIMEOUT_THREAD_WAIT		30		/* Seconds */

#define MAX_RECIPIENTS			1000	/* 0xffff = abs max */

#define LINES_PER_YIELD			100		/* Yield every this many lines of text */

#define STATUS_WFC	"Listening"

static const char *wday[]={"Sun","Mon","Tue","Wed","Thu","Fri","Sat"};
static const char *mon[]={"Jan","Feb","Mar","Apr","May","Jun"
            ,"Jul","Aug","Sep","Oct","Nov","Dec"};

static mail_startup_t* startup=NULL;
static scfg_t	scfg;
static SOCKET	server_socket=INVALID_SOCKET;
static SOCKET	pop3_socket=INVALID_SOCKET;
static DWORD	active_clients=0;
static int		active_sendmail=0;
static DWORD	thread_count=0;
static BOOL		sendmail_running=FALSE;
static DWORD	sockets=0;

typedef struct {
	SOCKET			socket;
	SOCKADDR_IN		client_addr;
} smtp_t,pop3_t;

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

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

#if defined(_WIN32) && defined(_DEBUG)
	if(IsBadCodePtr((FARPROC)startup->lputs)) {
		DebugBreak();
		return(0);
	}
#endif

	va_start(argptr,fmt);
    vsprintf(sbuf,fmt,argptr);
    va_end(argptr);
    return(startup->lputs(sbuf));
}

#ifdef _WINSOCKAPI_

static WSADATA WSAData;
static BOOL WSAInitialized=FALSE;

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

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

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

#else /* No WINSOCK */

#define winsock_startup()	(TRUE)

#endif

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

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

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

static void thread_up(void)
{
	thread_count++;
	if(startup!=NULL && startup->thread_up!=NULL)
		startup->thread_up(TRUE);
}

static void thread_down(void)
{
	if(thread_count>0)
		thread_count--;
	if(startup!=NULL && startup->thread_up!=NULL)
		startup->thread_up(FALSE);
}

SOCKET mail_open_socket(int type)
{
	SOCKET sock;

	sock=socket(AF_INET, type, IPPROTO_IP);
	if(sock!=INVALID_SOCKET && startup!=NULL && startup->socket_open!=NULL) 
		startup->socket_open(TRUE);
	if(sock!=INVALID_SOCKET) {
		sockets++;
#if 0 /*def _DEBUG */
		lprintf("%04d Socket opened (%d sockets in use)",sock,sockets);
#endif
	}
	return(sock);
}

int mail_close_socket(SOCKET sock)