/* This source code was modified by Martin Hedenfalk <mhe@stacken.kth.se> for
 * use in Curl. His latest changes were done 2000-09-18.
 *
 * It has since been patched away like a madman by Daniel Stenberg
 * <daniel@haxx.se> to make it better applied to curl conditions, and to make
 * it not use globals, pollute name space and more. This source code awaits a
 * rewrite to work around the paragraph 2 in the BSD licenses as explained
 * below.
 *
 * Copyright (c) 1995, 1996, 1997, 1998, 1999 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.  */

#include "setup.h"

#ifndef CURL_DISABLE_FTP
#ifdef HAVE_KRB4

#include "security.h"
#include "base64.h"
#include <stdlib.h>
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#include <string.h>
#include <krb.h>
#include <des.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h> /* for getpid() */
#endif

#include "ftp.h"
#include "sendf.h"
#include "krb4.h"
#include "memory.h"

#if defined( HAVE_INET_NTOA_R ) && !defined( HAVE_INET_NTOA_R_DECL )
#include "inet_ntoa_r.h"
#endif

/* The last #include file should be: */
#include "memdebug.h"

#define LOCAL_ADDR ( &conn->local_addr )
#define REMOTE_ADDR conn->ip_addr->ai_addr
#define myctladdr LOCAL_ADDR
#define hisctladdr REMOTE_ADDR

struct krb4_data {
	des_cblock key;
	des_key_schedule schedule;
	char name[ANAME_SZ];
	char instance[INST_SZ];
	char realm[REALM_SZ];
};

#ifndef HAVE_STRLCPY
/* if it ever goes non-static, make it Curl_ prefixed! */
static size_t
strlcpy( char *dst, const char *src, size_t dst_sz ) {
	size_t n;
	char *p;

	for ( p = dst, n = 0;
		  n + 1 < dst_sz && *src != '\0';
		  ++p, ++src, ++n )
		*p = *src;
	*p = '\0';
	if ( *src == '\0' ) {
		return n;
	} else {
		return n + strlen( src );
	}
}
#else
size_t strlcpy( char *dst, const char *src, size_t dst_sz );
#endif

static int
krb4_check_prot( void *app_data, int level ) {
	app_data = NULL; /* prevent compiler warning */
	if ( level == prot_confidential ) {
		return -1;
	}
	return 0;
}

static int
krb4_decode( void *app_data, void *buf, int len, int level,
			 struct connectdata *conn ) {
	MSG_DAT m;
	int e;
	struct krb4_data *d = app_data;

	if ( level == prot_safe ) {
		e = krb_rd_safe( buf, len, &d->key,
						 (struct sockaddr_in *)REMOTE_ADDR,
						 (struct sockaddr_in *)LOCAL_ADDR, &m );
	} else {
		e = krb_rd_priv( buf, len, d->schedule, &d->key,
						 (struct sockaddr_in *)REMOTE_ADDR,
						 (struct sockaddr_in *)LOCAL_ADDR, &m );
	}
	if ( e ) {
		struct SessionHandle *data = conn->data;
		infof( data, "krb4_decode: %s\n", krb_get_err_text( e ) );
		return -1;
	}
	memmove( buf, m.app_data, m.app_length );
	return m.app_length;
}

static int
krb4_overhead( void *app_data, int level, int len ) {
	/* no arguments are used, just init them to prevent compiler warnings */
	app_data = NULL;
	level = 0;
	len = 0;
	return 31;
}

static int
krb4_encode( void *app_data, void *from, int length, int level, void **to,
			 struct connectdata *conn ) {
	struct krb4_data *d = app_data;
	*to = malloc( length + 31 );
	if ( level == prot_safe ) {
		return krb_mk_safe( from, *to, length, &d->key,
							(struct sockaddr_in *)LOCAL_ADDR,
							(struct sockaddr_in *)REMOTE_ADDR );
	} else if ( level == prot_private )   {
		return krb_mk_priv( from, *to, length, d->schedule, &d->key,
							(struct sockaddr_in *)LOCAL_ADDR,
							(struct sockaddr_in *)REMOTE_ADDR );
	} else {
		return -1;
	}
}

static int
mk_auth( struct krb4_data *d, KTEXT adat,
		 const char *service, char *host, int checksum ) {
	int ret;
	CREDENTIALS cred;
	char sname[SNAME_SZ], inst[INST_SZ], realm[REALM_SZ];

	strlcpy( sname, service, sizeof( sname ) );
	strlcpy( inst, krb_get_phost( host ), sizeof( inst ) );
	strlcpy( realm, krb_realmofhost( host ), sizeof( realm ) );
	ret = krb_mk_req( adat, sname, inst, realm, checksum );
	if ( ret ) {
		return ret;
	}
	strlcpy( sname, service, sizeof( sname ) );
	strlcpy( inst, krb_get_phost( host ), sizeof( inst ) );
	strlcpy( realm, krb_realmofhost( host ), sizeof( realm ) );
	ret = krb_get_cred( sname, inst, realm, &cred );
	memmove( &d->key, &cred.session, sizeof( des_cblock ) );
	des_key_sched( &d->key, d->schedule );
	memset( &cred, 0, sizeof( cred ) );
	return ret;
}

#ifdef HAVE_KRB_GET_OUR_IP_FOR_REALM
int krb_get_our_ip_for_realm( char *, struct in_addr * );
#endif

static int
krb4_auth( void *app_data, struct connectdata *conn ) {
	int ret;
	char *p;
	int len;
	KTEXT_ST adat;
	MSG_DAT msg_data;
	int checksum;
	u_int32_t cs;
	struct krb4_data *d = app_data;
	char *host = conn->host.name;
	ssize_t nread;
	int l = sizeof( conn->local_addr );
	struct SessionHandle *data = conn->data;
	CURLcode result;

	if ( getsockname( conn->sock[FIRSTSOCKET],
					  (struct sockaddr *)LOCAL_ADDR, &l ) < 0 ) {
		perror( "getsockname()" );
	}

	checksum = getpid();
	ret = mk_auth( d, &adat, "ftp", host, checksum );
	if ( ret == KDC_PR_UNKNOWN ) {
		ret = mk_auth( d, &adat, "rcmd", host, checksum );
	}
	if ( ret ) {
		Curl_infof( data, "%s\n", krb_get_err_text( ret ) );
		return AUTH_CONTINUE;
	}

#ifdef HAVE_KRB_GET_OUR_IP_FOR_REALM
	if ( krb_get_config_bool( "nat_in_use" ) ) {
		struct sockaddr_in *localaddr  = (struct sockaddr_in *)LOCAL_ADDR;
		struct in_addr natAddr;

		if ( krb_get_our_ip_for_realm( krb_realmofhost( host ),
									   &natAddr ) != KSUCCESS
			 && krb_get_our_ip_for_realm( NULL, &natAddr ) != KSUCCESS ) {
			Curl_infof( data, "Can't get address for realm %s\n",
						krb_realmofhost( host ) );
		} else {
			if ( natAddr.s_addr != localaddr->sin_addr.s_addr ) {
#ifdef HAVE_INET_NTOA_R
				char ntoa_buf[64];
				char *ip = (char *)inet_ntoa_r( natAddr, ntoa_buf, sizeof( ntoa_buf ) );
#else
				char *ip = (char *)inet_ntoa( natAddr );
#endif
				Curl_infof( data, "Using NAT IP address (%s) for kerberos 4\n", ip );
				localaddr->sin_addr = natAddr;
			}
		}
	}
#endif

	if ( Curl_base64_encode( (char *)adat.dat, adat.length, &p ) < 1 ) {
		Curl_failf( data, "Out of memory base64-encoding" );
		return AUTH_CONTINUE;
	}

	result = Curl_ftpsendf( conn, "ADAT %s", p );

	free( p );

	if ( result ) {
		return -2;
	}

	if ( Curl_GetFTPResponse( &nread, conn, NULL ) ) {
		return -1;
	}

	if ( data->state.buffer[0] != '2' ) {
		Curl_failf( data, "Server didn't accept auth data" );
		return AUTH_ERROR;
	}

	p = strstr( data->state.buffer, "ADAT=" );
	if ( !p ) {
		Curl_failf( data, "Remote host didn't send adat reply" );
		return AUTH_ERROR;
	}
	p += 5;
	len = Curl_base64_decode( p, (char *)adat.dat );
	if ( len < 0 ) {
		Curl_failf( data, "Failed to decode base64 from server" );
		return AUTH_ERROR;
	}
	adat.length = len;
	ret = krb_rd_safe( adat.dat, adat.length, &d->key,
					   (struct sockaddr_in *)hisctladdr,
					   (struct sockaddr_in *)myctladdr, &msg_data );
	if ( ret ) {
		Curl_failf( data, "Error reading reply from server: %s",
					krb_get_err_text( ret ) );
		return AUTH_ERROR;
	}
	krb_get_int( msg_data.app_data, &cs, 4, 0 );
	if ( cs - checksum != 1 ) {
		Curl_failf( data, "Bad checksum returned from server" );
		return AUTH_ERROR;
	}
	return AUTH_OK;
}

struct Curl_sec_client_mech Curl_krb4_client_mech = {
	"KERBEROS_V4",
	sizeof( struct krb4_data ),
	NULL, /* init */
	krb4_auth,
	NULL, /* end */
	krb4_check_prot,
	krb4_overhead,
	krb4_encode,
	krb4_decode
};

CURLcode Curl_krb_kauth( struct connectdata *conn ) {
	des_cblock key;
	des_key_schedule schedule;
	KTEXT_ST tkt, tktcopy;
	char *name;
	char *p;
	char passwd[100];
	int tmp;
	ssize_t nread;
	int save;
	CURLcode result;

	save = Curl_set_command_prot( conn, prot_private );

	result = Curl_ftpsendf( conn, "SITE KAUTH %s", conn->user );

	if ( result ) {
		return result;
	}

	result = Curl_GetFTPResponse( &nread, conn, NULL );
	if ( result ) {
		return result;
	}

	if ( conn->data->state.buffer[0] != '3' ) {
		Curl_set_command_prot( conn, save );
		return CURLE_FTP_WEIRD_SERVER_REPLY;
	}

	p = strstr( conn->data->state.buffer, "T=" );
	if ( !p ) {
		Curl_failf( conn->data, "Bad reply from server" );
		Curl_set_command_prot( conn, save );
		return CURLE_FTP_WEIRD_SERVER_REPLY;
	}

	p += 2;
	tmp = Curl_base64_decode( p, (char *)tkt.dat );
	if ( tmp < 0 ) {
		Curl_failf( conn->data, "Failed to decode base64 in reply.\n" );
		Curl_set_command_prot( conn, save );
		return CURLE_FTP_WEIRD_SERVER_REPLY;
	}
	tkt.length = tmp;
	tktcopy.length = tkt.length;

	p = strstr( conn->data->state.buffer, "P=" );
	if ( !p ) {
		Curl_failf( conn->data, "Bad reply from server" );
		Curl_set_command_prot( conn, save );
		return CURLE_FTP_WEIRD_SERVER_REPLY;
	}
	name = p + 2;
	for (; *p && *p != ' ' && *p != '\r' && *p != '\n'; p++ ) ;
	*p = 0;

	des_string_to_key( conn->passwd, &key );
	des_key_sched( &key, schedule );

	des_pcbc_encrypt( (void *)tkt.dat, (void *)tktcopy.dat,
					  tkt.length,
					  schedule, &key, DES_DECRYPT );
	if ( strcmp( (char*)tktcopy.dat + 8,
				 KRB_TICKET_GRANTING_TICKET ) != 0 ) {
		afs_string_to_key( passwd,
						   krb_realmofhost( conn->host.name ),
						   &key );
		des_key_sched( &key, schedule );
		des_pcbc_encrypt( (void *)tkt.dat, (void *)tktcopy.dat,
						  tkt.length,
						  schedule, &key, DES_DECRYPT );
	}
	memset( key, 0, sizeof( key ) );
	memset( schedule, 0, sizeof( schedule ) );
	memset( passwd, 0, sizeof( passwd ) );
	if ( Curl_base64_encode( (char *)tktcopy.dat, tktcopy.length, &p ) < 1 ) {
		failf( conn->data, "Out of memory base64-encoding." );
		Curl_set_command_prot( conn, save );
		return CURLE_OUT_OF_MEMORY;
	}
	memset( tktcopy.dat, 0, tktcopy.length );

	result = Curl_ftpsendf( conn, "SITE KAUTH %s %s", name, p );
	free( p );
	if ( result ) {
		return result;
	}

	result = Curl_GetFTPResponse( &nread, conn, NULL );
	if ( result ) {
		return result;
	}
	Curl_set_command_prot( conn, save );

	return CURLE_OK;
}

#endif /* HAVE_KRB4 */
#endif /* CURL_DISABLE_FTP */