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 2012 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"

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

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 SPAM_HASH_SUBJECT_MIN_LEN	10	/* characters */

#define STATUS_WFC	"Listening"

static mail_startup_t* startup=NULL;
static scfg_t	scfg;
static SOCKET	server_socket=INVALID_SOCKET;
static SOCKET	submission_socket=INVALID_SOCKET;
static SOCKET	pop3_socket=INVALID_SOCKET;
static protected_int32_t active_clients;
static protected_int32_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;
	SOCKADDR_IN		client_addr;
} smtp_t,pop3_t;

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) {
		errorlog(&scfg,startup==NULL ? NULL:startup->host_name,sbuf), stats.errors++;
		if(startup!=NULL && startup->errormsg!=NULL)
			startup->errormsg(startup->cbdata,level,sbuf);
	}

	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