/*
 * tcp.c	TCP-specific functions.
 *
 * Version:	$Id: 59a923cb14ee9306cda78111d5b98485e7841991 $
 *
 *   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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 *
 * Copyright (C) 2009 Dante http://dante.net
 */

RCSID("$Id: 59a923cb14ee9306cda78111d5b98485e7841991 $")

#include	<freeradius-devel/libradius.h>

#ifdef WITH_TCP

/* FIXME: into common RADIUS header? */
#define MAX_PACKET_LEN 4096

/*
 *	Open a socket on the given IP and port.
 */
int fr_tcp_socket(fr_ipaddr_t *ipaddr, int port)
{
	int sockfd;
	int on = 1;
	struct sockaddr_storage salocal;
	socklen_t	salen;

	if ((port < 0) || (port > 65535)) {
		fr_strerror_printf("Port %d is out of allowed bounds", port);
		return -1;
	}

	sockfd = socket(ipaddr->af, SOCK_STREAM, 0);
	if (sockfd < 0) {
		return sockfd;
	}

	if (fr_nonblock(sockfd) < 0) {
		close(sockfd);
		return -1;
	}

	if (!fr_ipaddr2sockaddr(ipaddr, port, &salocal, &salen)) {
		close(sockfd);
		return -1;
	}

#ifdef HAVE_STRUCT_SOCKADDR_IN6
	if (ipaddr->af == AF_INET6) {
		/*
		 *	Listening on '::' does NOT get you IPv4 to
		 *	IPv6 mapping.  You've got to listen on an IPv4
		 *	address, too.  This makes the rest of the server
		 *	design a little simpler.
		 */
#ifdef IPV6_V6ONLY

		if (IN6_IS_ADDR_UNSPECIFIED(&ipaddr->ipaddr.ip6addr)) {
			if (setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
				       (char *)&on, sizeof(on)) < 0) {
				fr_strerror_printf("Failed in setsockopt(): %s",
						   fr_syserror(errno));
				close(sockfd);
				return -1;
			}
		}
#endif /* IPV6_V6ONLY */
	}
#endif /* HAVE_STRUCT_SOCKADDR_IN6 */

	if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0) {
		fr_strerror_printf("Failed in setsockopt(): %s", fr_syserror(errno));
		close(sockfd);
		return -1;
	}

	if (bind(sockfd, (struct sockaddr *) &salocal, salen) < 0) {
		fr_strerror_printf("Failed in bind(): %s", fr_syserror(errno));
		close(sockfd);
		return -1;
	}

	if (listen(sockfd, 8) < 0) {
		fr_strerror_printf("Failed in listen(): %s", fr_syserror(errno));
		close(sockfd);
		return -1;
	}

	return sockfd;
}


/*
 *	Open a socket TO the given IP and port.
 */
int fr_tcp_client_socket(fr_ipaddr_t *src_ipaddr,
			 fr_ipaddr_t *dst_ipaddr, int dst_port)
{
	int sockfd;
	struct sockaddr_storage salocal;
	socklen_t	salen;

	if ((dst_port < 0) || (dst_port > 65535)) {
		fr_strerror_printf("Port %d is out of allowed bounds",
				   dst_port);
		return -1;
	}

	if (!dst_ipaddr) return -1;

	sockfd = socket(dst_ipaddr->af, SOCK_STREAM, 0);
	if (sockfd < 0) {
		return sockfd;
	}

#if 0
#ifdef O_NONBLOCK
	{
		int flags;

		if ((flags = fcntl(sockfd, F_GETFL, NULL)) < 0)  {
			fr_strerror_printf("Failure getting socket flags: %s",
				   fr_syserror(errno));
			close(sockfd);
			return -1;
		}

		flags |= O_NONBLOCK;
		if( fcntl(sockfd, F_SETFL, flags) < 0) {
			fr_strerror_printf("Failure setting socket flags: %s",
				   fr_syserror(errno));
			close(sockfd);
			return -1;
		}
	}
#endif
#endif
	/*
	 *	Allow the caller to bind us to a specific source IP.
	 */
	if (src_ipaddr && (src_ipaddr->af != AF_UNSPEC)) {
		if (!fr_ipaddr2sockaddr(src_ipaddr, 0, &salocal, &salen)) {
			close(sockfd);
			return -1;
		}

		if (bind(sockfd, (struct sockaddr *) &salocal, salen) < 0) {
			fr_strerror_printf("Failure binding to IP: %s",
					   fr_syserror(errno));
			close(sockfd);
			return -1;
		}
	}

	if (!fr_ipaddr2sockaddr(dst_ipaddr, dst_port, &salocal, &salen)) {
			close(sockfd);
		return -1;
	}

	/*
	 *	FIXME: If EINPROGRESS, then tell the caller that
	 *	somehow.  The caller can then call connect() when the
	 *	socket is ready...
	 */
	if (connect(sockfd, (struct sockaddr *) &salocal, salen) < 0) {
		fr_strerror_printf("Failed in connect(): %s", fr_syserror(errno));
		close(sockfd);
		return -1;
	}

	return sockfd;
}


RADIUS_PACKET *fr_tcp_recv(int sockfd, int flags)
{
	RADIUS_PACKET *packet = rad_alloc(NULL, 0);

	if (!packet) return NULL;

	packet->sockfd = sockfd;

	if (fr_tcp_read_packet(packet, flags) != 1) {
		rad_free(&packet);
		return NULL;
	}

	return packet;
}


/*
 *	Receives a packet, assuming that the RADIUS_PACKET structure
 *	has been filled out already.
 *
 *	This ASSUMES that the packet is allocated && fields
 *	initialized.
 *
 *	This ASSUMES that the socket is marked as O_NONBLOCK, which
 *	the function above does set, if your system supports it.
 *
 *	Calling this function MAY change sockfd,
 *	if src_ipaddr.af == AF_UNSPEC.
 */
int fr_tcp_read_packet(RADIUS_PACKET *packet, int flags)
{
	ssize_t len;

	/*
	 *	No data allocated.  Read the 4-byte header into
	 *	a temporary buffer.
	 */
	if (!packet->data) {
		int packet_len;

		len = recv(packet->sockfd, packet->vector + packet->data_len,
			   4 - packet->data_len, 0);
		if (len == 0) return -2; /* clean close */

#ifdef ECONNRESET
		if ((len < 0) && (errno == ECONNRESET)) { /* forced */
			return -2;
		}
#endif

		if (len < 0) {
			fr_strerror_printf("Error receiving packet: %s",
				   fr_syserror(errno));
			return -1;
		}

		packet->data_len += len;
		if (packet->data_len < 4) { /* want more data */
			return 0;
		}

		packet_len = (packet->vector[2] << 8) | packet->vector[3];

		if (packet_len < AUTH_HDR_LEN) {
			fr_strerror_printf("Discarding packet: Smaller than RFC minimum of 20 bytes.");
			return -1;
		}

		/*
		 *	If the packet is too big, then the socket is bad.
		 */
		if (packet_len > MAX_PACKET_LEN) {
			fr_strerror_printf("Discarding packet: Larger than RFC limitation of 4096 bytes.");
			return -1;
		}

		packet->data = talloc_array(packet, uint8_t, packet_len);
		if (!packet->data) {
			fr_strerror_printf("Out of memory");
			return -1;
		}

		packet->data_len = packet_len;
		packet->partial = 4;
		memcpy(packet->data, packet->vector, 4);
	}

	/*
	 *	Try to read more data.
	 */
	len = recv(packet->sockfd, packet->data + packet->partial,
		   packet->data_len - packet->partial, 0);
	if (len == 0) return -2; /* clean close */

#ifdef ECONNRESET
	if ((len < 0) && (errno == ECONNRESET)) { /* forced */
		return -2;
	}
#endif

	if (len < 0) {
		fr_strerror_printf("Error receiving packet: %s", fr_syserror(errno));
		return -1;
	}

	packet->partial += len;

	if (packet->partial < packet->data_len) {
		return 0;
	}

	/*
	 *	See if it's a well-formed RADIUS packet.
	 */
	if (!rad_packet_ok(packet, flags)) {
		return -1;
	}

	/*
	 *	Explicitly set the VP list to empty.
	 */
	packet->vps = NULL;

	if (fr_debug_flag) {
		char ip_buf[128], buffer[256];

		if (packet->src_ipaddr.af != AF_UNSPEC) {
			inet_ntop(packet->src_ipaddr.af,
				  &packet->src_ipaddr.ipaddr,
				  ip_buf, sizeof(ip_buf));
			snprintf(buffer, sizeof(buffer), "host %s port %d",
				 ip_buf, packet->src_port);
		} else {
			snprintf(buffer, sizeof(buffer), "socket %d",
				 packet->sockfd);
		}


		if ((packet->code > 0) && (packet->code < FR_MAX_PACKET_CODE)) {
			DEBUG("rad_recv: %s packet from %s",
			      fr_packet_codes[packet->code], buffer);
		} else {
			DEBUG("rad_recv: Packet from %s code=%d",
			      buffer, packet->code);
		}
		DEBUG(", id=%d, length=%zu\n", packet->id, packet->data_len);
	}

	return 1;		/* done reading the packet */
}

RADIUS_PACKET *fr_tcp_accept(int sockfd)
{
	int newfd;
	socklen_t salen;
	RADIUS_PACKET *packet;
	struct sockaddr_storage src;

	salen = sizeof(src);

	newfd = accept(sockfd, (struct sockaddr *) &src, &salen);
	if (newfd < 0) {
		/*
		 *	Non-blocking sockets must handle this.
		 */
#ifdef EWOULDBLOCK
		if (errno == EWOULDBLOCK) {
			packet = rad_alloc(NULL, 0);
			if (!packet) return NULL;

			packet->sockfd = sockfd;
			packet->src_ipaddr.af = AF_UNSPEC;
			return packet;
		}
#endif

		return NULL;
	}

	packet = rad_alloc(NULL, 0);
	if (!packet) {
		close(newfd);
		return NULL;
	}

	if (src.ss_family == AF_INET) {
		struct sockaddr_in	s4;

		memcpy(&s4, &src, sizeof(s4));
		packet->src_ipaddr.af = AF_INET;
		packet->src_ipaddr.ipaddr.ip4addr = s4.sin_addr;
		packet->src_port = ntohs(s4.sin_port);

#ifdef HAVE_STRUCT_SOCKADDR_IN6
	} else if (src.ss_family == AF_INET6) {
		struct sockaddr_in6	s6;

		memcpy(&s6, &src, sizeof(s6));
		packet->src_ipaddr.af = AF_INET6;
		packet->src_ipaddr.ipaddr.ip6addr = s6.sin6_addr;
		packet->src_port = ntohs(s6.sin6_port);

#endif
	} else {
		rad_free(&packet);
		close(newfd);
		return NULL;
	}

	packet->sockfd = newfd;

	/*
	 *	Note: Caller has to set dst_ipaddr && dst_port.
	 */
	return packet;
}


/*
 *	Writes a packet, assuming it's already been encoded.
 *
 *	It returns the number of bytes written, which MAY be less than
 *	the packet size (data_len).  It is the caller's responsibility
 *	to check the return code, and to schedule writes again.
 */
ssize_t fr_tcp_write_packet(RADIUS_PACKET *packet)
{
	ssize_t rcode;

	if (!packet || !packet->data) return 0;

	if (packet->partial >= packet->data_len) return packet->data_len;

	rcode = write(packet->sockfd, packet->data + packet->partial,
		      packet->data_len - packet->partial);
	if (rcode < 0) return packet->partial; /* ignore most errors */

	packet->partial += rcode;

	return packet->partial;
}
#endif /* WITH_TCP */
