/*

    kbs - Simple, easily fooled, POP3 spam filter

    Copyright (C) 2003  Ian Cowburn (ianc@noddybox.demon.co.uk)

    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

    -------------------------------------------------------------------------

    Config

*/
static const char id[]="$Id$";

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <ctype.h>

#include "global.h"
#include "config.h"
#include "dstring.h"
#include "dbase.h"
#include "rexp.h"
#include "util.h"


/* ---------------------------------------- TYPES
*/
typedef enum {	
		TOK_Expression,
		TOK_Set,
		TOK_OpenBracket,
		TOK_CloseBracket,
		TOK_Domain,
		TOK_TrustedUsers,
		TOK_TrustedDomains,
		TOK_Default,
		TOK_BlockUser,
		TOK_AllowSubject,
		TOK_BlockSubject,
		TOK_SubjectMacro,
		TOK_Blacklist,
		TOK_VarHostname,
		TOK_VarPort,
		TOK_VarUsername,
		TOK_VarPassword,
		TOK_VarLog,
		TOK_VarTimeout,
		TOK_VarCasesense,
		TOK_VarDejunk,
		TOK_VarTestmode,
		TOK_VarBlockHTML,
		TOK_VarVerbose,
		TOK_ConstOn,
		TOK_ConstOff,
		TOK_ConstBlock,
		TOK_ConstAllow,
		TOK_EOF
	     } Token;

typedef struct Command
    {
    const char	*cmd;
    Token	token;
    } Command;

typedef struct
    {
    char	*macro;
    char	*expansion;
    } Macro;


/* ---------------------------------------- GLOBALS
*/
static DString	error;

static char	*hostname=NULL;
static char	*username=NULL;
static char	*password=NULL;
static char	*log=NULL;
static int	port=110;
static int	timeout=60;
static int	casesense=FALSE;
static int	dejunk=FALSE;
static int	testmode=FALSE;
static int	blockhtml=FALSE;
static int	verbose=TRUE;

static int	no_macro=0;
static Macro	*macro=NULL;


/* ---------------------------------------- COMMAND TABLE
*/
static const Command cmd_table[]=
	{
	    /* Commands and main tokens
	    */
	    {"set",		TOK_Set},
	    {"trusted_users",	TOK_TrustedUsers},
	    {"trusted_domains",	TOK_TrustedDomains},
	    {"{",		TOK_OpenBracket},
	    {"}",		TOK_CloseBracket},
	    {"domain",		TOK_Domain},
	    {"default",		TOK_Default},
	    {"block_user",	TOK_BlockUser},
	    {"allow_subject",	TOK_AllowSubject},
	    {"block_subject",	TOK_BlockSubject},
	    {"subject_macro",	TOK_SubjectMacro},
	    {"blacklist",	TOK_Blacklist},

	    /* Variables
	    */
	    {"hostname",	TOK_VarHostname},
	    {"port",		TOK_VarPort},
	    {"username",	TOK_VarUsername},
	    {"password",	TOK_VarPassword},
	    {"log",		TOK_VarLog},
	    {"timeout",		TOK_VarTimeout},
	    {"casesense",	TOK_VarCasesense},
	    {"dejunk",		TOK_VarDejunk},
	    {"testmode",	TOK_VarTestmode},
	    {"blockhtml",	TOK_VarBlockHTML},
	    {"verbose",		TOK_VarVerbose},

	    /* Constants
	    */
	    {"on",		TOK_ConstOn},
	    {"off",		TOK_ConstOff},
	    {"block",		TOK_ConstBlock},
	    {"allow",		TOK_ConstAllow},

	    /* End of table
	    */
	    {NULL,		TOK_EOF}
	};


/* ---------------------------------------- REQUIRED PROTOS
*/
static Token	GetToken(FILE *fp, DString *ret);


/* ---------------------------------------- COMMAND HANDLER UTILS
*/
static DString	ExpandRE(DString re)
{
    DString new;
    Macro *m;
    char *p;
    int f;

    new=DSInit();

    p=re->text;

    while(*p)
    {
	m=NULL;

    	for(f=0;f<no_macro && !m;f++)
	{
	    if (strncmp(p,macro[f].macro,strlen(macro[f].macro))==0)
	    {
	    	m=macro+f;
	    }
	}

	if (!m)
	{
	    DSAddChar(new,*p);
	    p++;
	}
	else
	{
	    DSAddCP(new,m->expansion);
	    p+=strlen(m->macro);
	}
    }

    DSFree(re);
    return new;
}


/* ---------------------------------------- COMMAND HANDLERS
*/
static int DoSet(FILE *fp)
{
#   define TYPE_STR	0
#   define TYPE_INT	1
#   define TYPE_ONOFF	2

    static const struct VarTable
    	{
	Token	token;
	int	type;
	void	*ptr;
	} var_table[]=
	    {
		{TOK_VarHostname,	TYPE_STR,	(void *)&hostname},
		{TOK_VarPort,		TYPE_INT,	(void *)&port},
		{TOK_VarUsername,	TYPE_STR,	(void *)&username},
		{TOK_VarPassword,	TYPE_STR,	(void *)&password},
		{TOK_VarLog,		TYPE_STR,	(void *)&log},
		{TOK_VarTimeout,	TYPE_INT,	(void *)&timeout},
		{TOK_VarCasesense,	TYPE_ONOFF,	(void *)&casesense},
		{TOK_VarDejunk,		TYPE_ONOFF,	(void *)&dejunk},
		{TOK_VarTestmode,	TYPE_ONOFF,	(void *)&testmode},
		{TOK_VarBlockHTML,	TYPE_ONOFF,	(void *)&blockhtml},
		{TOK_VarVerbose,	TYPE_ONOFF,	(void *)&verbose},
		{TOK_EOF,0,NULL}
	    };

    const struct VarTable *vt=NULL;
    DString ds;
    Token tok;
    int status=TRUE;
    int f;

    ds=DSInit();

    tok=GetToken(fp,&ds);

    for(f=0;var_table[f].token!=TOK_EOF && !vt;f++)
    	if (var_table[f].token==tok)
	    vt=var_table+f;

    if (vt)
    {
	char **cp;
	int *ip;

    	switch(vt->type)
	{
	    case TYPE_STR:
	    	cp=vt->ptr;
		tok=GetToken(fp,&ds);

		if (*cp)
		    free(*cp);

		*cp=CopyStr(ds->text);
	    	break;

	    case TYPE_INT:
	    	ip=vt->ptr;
		tok=GetToken(fp,&ds);
		*ip=atoi(ds->text);
	    	break;

	    case TYPE_ONOFF:
	    	ip=vt->ptr;
		tok=GetToken(fp,&ds);

		switch(tok)
		{
		    case TOK_ConstOn:
		    	*ip=TRUE;
			break;

		    case TOK_ConstOff:
		    	*ip=FALSE;
			break;

		    default:
			status=FALSE;
			DSAddCP(error,"Expected on/off.  Got: ");
			DSAddDS(error,ds);
		}
	    	break;
	}
    }
    else
    {
	status=FALSE;
	DSAddCP(error,"Unrecognised variable: ");
	DSAddDS(error,ds);
    }

    DSFree(ds);

#   undef TYPE_STR
#   undef TYPE_INT
#   undef TYPE_ONOFF

    return status;
}


static int DoDomain(FILE *fp)
{
    DString ds;
    Token tok;
    Domain *domain;
    RE_Expression re;

    ds=DSInit();

    tok=GetToken(fp,&ds);

    if (tok!=TOK_Expression)
    {
	DSAddCP(error,"Domain must be followed by expression.  Got: ");
	DSAddDS(error,ds);
	DSFree(ds);
	return FALSE;
    }

    if (!(re=RECompile(ds->text)))
    {
	DSAddCP(error,"Bad regular expression: ");
	DSAddDS(error,ds);
	DSFree(ds);
	return FALSE;
    }

    domain=DBNewDomain(re);

    tok=GetToken(fp,&ds);

    if (tok!=TOK_OpenBracket)
    {
	DSAddCP(error,"Missing opening bracket in domain");
	DSFree(ds);
	return FALSE;
    }

    while((tok=GetToken(fp,&ds))!=TOK_CloseBracket)
    {
    	if (tok==TOK_EOF)
	{
	    DSAddCP(error,"Missing close bracket in domain");
	    DSFree(ds);
	    return FALSE;
	}

	switch(tok)
	{
	    case TOK_Default:
		switch(GetToken(fp,&ds))
		{
		    case TOK_ConstAllow:
		    	DBDefault(domain,FALSE);
			break;

		    case TOK_ConstBlock:
		    	DBDefault(domain,TRUE);
			break;

		    default:
			DSAddCP(error,"Unexpected value in default command: ");
			DSAddDS(error,ds);
			DSFree(ds);
			return FALSE;
		    	break;
		}

	    	break;

	    case TOK_BlockUser:
		GetToken(fp,&ds);
		DBBlockUser(domain,ds->text);
	    	break;

	    case TOK_AllowSubject:
		GetToken(fp,&ds);

		ds=ExpandRE(ds);

		if (!(re=RECompile(ds->text)))
		{
		    DSAddCP(error,"Bad regular expression: ");
		    DSAddDS(error,ds);
		    DSFree(ds);
		    return FALSE;
		}

		DBAllowSubject(domain,re);
	    	break;

	    case TOK_BlockSubject:
		GetToken(fp,&ds);

		ds=ExpandRE(ds);

		if (!(re=RECompile(ds->text)))
		{
		    DSAddCP(error,"Bad regular expression: ");
		    DSAddDS(error,ds);
		    DSFree(ds);
		    return FALSE;
		}

		DBBlockSubject(domain,re);
	    	break;

	    default:
		DSAddCP(error,"Unexpected string in domain command: ");
		DSAddDS(error,ds);
		DSFree(ds);
		return FALSE;
		break;
	}
    }

    DSFree(ds);

    return TRUE;
}


static int DoTrustedUsers(FILE *fp)
{
    DString ds;
    Token tok;

    ds=DSInit();

    tok=GetToken(fp,&ds);

    if (tok!=TOK_OpenBracket)
    {
	DSAddCP(error,"Missing opening bracket in trusted_users");
	DSFree(ds);
	return FALSE;
    }

    while((tok=GetToken(fp,&ds))!=TOK_CloseBracket)
    {
    	if (tok==TOK_EOF)
	{
	    DSAddCP(error,"Missing close bracket in trusted_users");
	    DSFree(ds);
	    return FALSE;
	}

	DBTrustedUser(ds->text);
    }

    DSFree(ds);

    return TRUE;
}


static int DoTrustedDomains(FILE *fp)
{
    DString ds;
    Token tok;

    ds=DSInit();

    tok=GetToken(fp,&ds);

    if (tok!=TOK_OpenBracket)
    {
	DSAddCP(error,"Missing opening bracket in trusted_domains");
	return FALSE;
    }

    while((tok=GetToken(fp,&ds))!=TOK_CloseBracket)
    {
    	if (tok==TOK_EOF)
	{
	    DSAddCP(error,"Missing close bracket in trusted_domains");
	    return FALSE;
	}

	DBTrustedDomain(ds->text);
    }

    return TRUE;
}


static int DoSubjectMacro(FILE *fp)
{
    DString arg[2];
    int f;

    for(f=0;f<2;f++)
    {
    	arg[f]=DSInit();

	if (GetToken(fp,&arg[f])==TOK_EOF)
	{
	    DSAddCP(error,"Unexpected EOF in subject_macro");
	    return FALSE;
	}
    }

    if (arg[0]->len==0 || arg[1]->len==0)
    {
	DSAddCP(error,"Can't use zero length strings in subject_macro");
	return FALSE;
    }

    no_macro++;

    macro=Realloc(macro,sizeof *macro * no_macro);

    macro[no_macro-1].macro=CopyStr(arg[0]->text);
    macro[no_macro-1].expansion=CopyStr(arg[1]->text);

    for(f=0;f<2;f++)
    	DSFree(arg[f]);

    return TRUE;
}


static int DoBlacklist(FILE *fp)
{
    DString ds;
    Token tok;

    ds=DSInit();

    tok=GetToken(fp,&ds);

    if (tok!=TOK_OpenBracket)
    {
	DSAddCP(error,"Missing opening bracket in blacklist");
	DSFree(ds);
	return FALSE;
    }

    while((tok=GetToken(fp,&ds))!=TOK_CloseBracket)
    {
	RE_Expression re;

    	if (tok==TOK_EOF)
	{
	    DSAddCP(error,"Missing close bracket in blacklist");
	    DSFree(ds);
	    return FALSE;
	}

	if (!(re=RECompile(ds->text)))
	{
	    DSAddCP(error,"Bad regular expression: ");
	    DSAddDS(error,ds);
	    DSFree(ds);
	    return FALSE;
	}

	DBBlacklist(re);
    }

    DSFree(ds);

    return TRUE;
}


/* ---------------------------------------- PRVIVATE FUNCTIONS
*/
static int Getc(FILE *fp)
{
    int ch;

    ch=fgetc(fp);

    if (ch=='#')
    {
    	ch=fgetc(fp);

	while(ch!=EOF && ch!='\n')
	    ch=fgetc(fp);
    }

    return ch;
}


static int SkipWS(FILE *fp)
{
    int ch;

    ch=Getc(fp);

    while(isspace(ch))
	ch=Getc(fp);

    if (ch==EOF)
    	return FALSE;
    else
    	{
	ungetc(ch,fp);
	return TRUE;
	}
}


static Token FindToken(const char *p)
{
    int f;

    for(f=0;cmd_table[f].cmd;f++)
    	if (strcmp(cmd_table[f].cmd,p)==0)
	    return cmd_table[f].token;

    return TOK_Expression;
}


static int IsTerm(int ch)
{
    return isspace(ch) || ch=='#';
}


static Token GetToken(FILE *fp, DString *ret)
{
    int ch;
    int done=FALSE;
    int quote=0;
    Token tok;

    *ret=DSReset(*ret);

    if (feof(fp))
	{
	DSAddCP(*ret,"EOF");
    	return TOK_EOF;
	}

    if (!SkipWS(fp))
	{
	DSAddCP(*ret,"EOF");
    	return TOK_EOF;
	}

    while(!done)
    {
    	ch=fgetc(fp);

	if (quote)
	{
	    if (ch==EOF)
	    {
		done=TRUE;

		DSAddCP(error,"Unexpected EOF in string");
		tok=TOK_EOF;
	    }
	    else if (ch==quote)
	    {
		done=TRUE;
	    	tok=FindToken((*ret)->text);
	    }
	    else
	    {
	    	DSAddChar(*ret,ch);
	    }
	}
	else
	{
	    if (ch==EOF)
	    {
	    	done=TRUE;

		if ((*ret)->len)
		    tok=FindToken((*ret)->text);
		else
		    tok=TOK_EOF;
	    }
	    else if (IsTerm(ch))
	    {
		ungetc(ch,fp);
		done=TRUE;
		tok=FindToken((*ret)->text);
	    }
	    else if (ch=='\'' || ch=='"')
	    {
	    	quote=ch;
	    }
	    else
	    {
	    	DSAddChar(*ret,ch);
	    }
	}
    }

    return tok;
}


static int Parse(FILE *fp)
{
    DString txt;
    Token tok;

    txt=DSInit();

    while((tok=GetToken(fp,&txt))!=TOK_EOF)
    {
	int ok=TRUE;

    	switch(tok)
	{
	    case TOK_Set:
		if (!DoSet(fp))
		    ok=FALSE;
		break;

	    case TOK_Domain:
		if (!DoDomain(fp))
		    ok=FALSE;
		break;

	    case TOK_TrustedUsers:
		if (!DoTrustedUsers(fp))
		    ok=FALSE;
		break;

	    case TOK_TrustedDomains:
		if (!DoTrustedDomains(fp))
		    ok=FALSE;
		break;

	    case TOK_SubjectMacro:
		if (!DoSubjectMacro(fp))
		    ok=FALSE;
		break;

	    case TOK_Blacklist:
		if (!DoBlacklist(fp))
		    ok=FALSE;
		break;

	    case TOK_Expression:
		DSAddCP(error,"Unknown command in config file: ");
		DSAddDS(error,txt);
		ok=FALSE;
		break;

	    default:
		DSAddCP(error,"Unexpected token in config file: ");
		DSAddDS(error,txt);
		ok=FALSE;
		break;
	}

	if (!ok)
	    break;

	txt=DSReset(txt);
    }

    DSFree(txt);

    return error->len==0;
}


/* ---------------------------------------- INTERFACES
*/

int ConfigLoad(void)
{
    DString ds;
    FILE *fp;
    int ret;

    error=DSInit();

    hostname=CopyStr("localhost");
    username=CopyStr("nobody");
    password=CopyStr("");
    log=CopyStr("");

    if (!getenv("HOME"))
    	return FALSE;

    ds=DSInit();

    DSAddCP(ds,getenv("HOME"));
    DSAddChar(ds,'/');
    DSAddCP(ds,".kbsrc");

    if ((fp=fopen(ds->text,"r")))
    	ret=Parse(fp);
    else
    	ret=FALSE;

    DSFree(ds);

    return ret;
}


const char *ConfigError(void)
{
    if (strlen(error->text))
    	return error->text;
    else
    	return strerror(errno);
}


const char *ConfigString(ConfigStringVar var)
{
    switch(var)
    {
	case CONFIG_HOSTNAME:
	    return hostname;

	case CONFIG_USERNAME:
	    return username;

	case CONFIG_PASSWORD:
	    return password;

	case CONFIG_LOG:
	    return log;

	default:
	    return "";
    }
}


int ConfigInt(ConfigIntVar var)
{
    switch(var)
    {
	case CONFIG_PORT:
	    return port;

	case CONFIG_TIMEOUT:
	    return timeout;

	case CONFIG_CASESENSE:
	    return casesense;

	case CONFIG_DEJUNK:
	    return dejunk;

	case CONFIG_TESTMODE:
	    return testmode;

	case CONFIG_BLOCKHTML:
	    return blockhtml;

	case CONFIG_VERBOSE:
	    return verbose;

	default:
	    return 0;
    }
}


void ConfigClose(void)
{
    int f;

    for(f=0;f<no_macro;f++)
    {
    	free(macro[f].macro);
    	free(macro[f].expansion);
    }
    
    free(macro);

    DSFree(error);
    free(hostname);
    free(username);
    free(password);
    free(log);
}


/* END OF FILE */