/*
 * Copyright (C) 2003-2005 Pawel Foremski <pjf@asn.pl>
 *
 * 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.
 *
 */

#include <stdlib.h>
#include <stdio.h>
#include "spf.h"

void block(peer_info_t *peer_info)
{
	char *explain;
	explain = SPF_get_explain(peer_info);

	if (explain) {
		printf("E550 %s (#5.7.1)\n", explain);
		fprintf(stderr, "spf: blocked with: %s\n", explain);
		free(explain);
	} else {
		printf("E550 Blocked with SPF (#5.7.1)\n", explain);
		fprintf(stderr, "spf: WARNING: no explanation for blocked mail!\n");
	}
}

int main()
{
	int spf;
	char *me, *remote, *helo, *sender, *spf_env, *header;
	peer_info_t *peer_info;

	/**
	 * env variables
	 **/
	if (getenv("RELAYCLIENT") ||              /* known user */
	    !(spf_env = getenv("SPF"))) return 0; /* plugin disabled */

	spf = atoi(spf_env);
	if (spf < 1 || spf > 6) {
		if (spf > 6)
			fprintf(stderr, "spf: ERROR: invalid value (%d) of SPF variable\n", spf);
		return 0;
	}

	remote  = getenv("TCPREMOTEIP"); 
	me      = getenv("TCPLOCALHOST");
	if (!me) me = getenv("TCPLOCALIP");
	if (!remote || !me) { /* should never happen */
		fprintf(stderr, "spf: ERROR: can't get tcpserver variables\n");
		if(!remote) fprintf(stderr, "spf: can't read TCPREMOTEIP\n");
		else fprintf(stderr, "spf: can't read TCPLOCALHOST nor TCPLOCALIP\n");
		return 0;
	}

	sender = getenv("SMTPMAILFROM");
	if (!sender) { /* should never happen */
		fprintf(stderr, "spf: ERROR: can't get envelope sender address\n");
		fprintf(stderr, "spf: can't read SMTPMAILFROM\n");
		return 0;
	}
	if (!*sender) return 0; /* null sender mail */

	helo = getenv("SMTPHELOHOST");

	/**
	 * SPF
	 **/
	peer_info = SPF_init(me, remote, SPF_EXPLAIN, NULL, NULL, 0, 0);
	if (!peer_info) { /* init failed */
		fprintf(stderr, "spf: ERROR: can't initialize SPF library\n");
		return 0;
	}

	if (helo) SPF_smtp_helo(peer_info, helo);
	SPF_smtp_from(peer_info, sender);
	peer_info->RES = SPF_policy_main(peer_info); /* rock takes place here */

	/* check whether mail needn`t to be blocked */
	switch (peer_info->RES) {
		case SPF_PASS:    break;
		case SPF_H_FAIL:  if (spf > 0) { block(peer_info); return 0; } break;
		case SPF_S_FAIL:  if (spf > 1) { block(peer_info); return 0; } break;
		case SPF_NEUTRAL: if (spf > 2) { block(peer_info); return 0; } break;
		case SPF_NONE:    if (spf > 3) { block(peer_info); return 0; } break;
		case SPF_ERROR:   if (spf > 4) { block(peer_info); return 0; } break;
		case SPF_UNKNOWN: if (spf > 5) { block(peer_info); return 0; } break;
		case SPF_UNMECH:  break;
	}

	/* add header */
	header = SPF_build_header(peer_info);
	printf("H");
	if (header[0] != 'R') printf("Received-SPF: "); /* hack for old libspf ver. */
	printf("%s\n", header);
	free(header);

	SPF_close(peer_info);

	return 0;
}