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/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		The User Datagram Protocol (UDP).
 *
 * Authors:	Ross Biro
 *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
 *		Alan Cox, <alan@lxorguk.ukuu.org.uk>
 *		Hirokazu Takahashi, <taka@valinux.co.jp>
 *
 * Fixes:
 *		Alan Cox	:	verify_area() calls
 *		Alan Cox	: 	stopped close while in use off icmp
 *					messages. Not a fix but a botch that
 *					for udp at least is 'valid'.
 *		Alan Cox	:	Fixed icmp handling properly
 *		Alan Cox	: 	Correct error for oversized datagrams
 *		Alan Cox	:	Tidied select() semantics.
 *		Alan Cox	:	udp_err() fixed properly, also now
 *					select and read wake correctly on errors
 *		Alan Cox	:	udp_send verify_area moved to avoid mem leak
 *		Alan Cox	:	UDP can count its memory
 *		Alan Cox	:	send to an unknown connection causes
 *					an ECONNREFUSED off the icmp, but
 *					does NOT close.
 *		Alan Cox	:	Switched to new sk_buff handlers. No more backlog!
 *		Alan Cox	:	Using generic datagram code. Even smaller and the PEEK
 *					bug no longer crashes it.
 *		Fred Van Kempen	: 	Net2e support for sk->broadcast.
 *		Alan Cox	:	Uses skb_free_datagram
 *		Alan Cox	:	Added get/set sockopt support.
 *		Alan Cox	:	Broadcasting without option set returns EACCES.
 *		Alan Cox	:	No wakeup calls. Instead we now use the callbacks.
 *		Alan Cox	:	Use ip_tos and ip_ttl
 *		Alan Cox	:	SNMP Mibs
 *		Alan Cox	:	MSG_DONTROUTE, and 0.0.0.0 support.
 *		Matt Dillon	:	UDP length checks.
 *		Alan Cox	:	Smarter af_inet used properly.
 *		Alan Cox	:	Use new kernel side addressing.
 *		Alan Cox	:	Incorrect return on truncated datagram receive.
 *	Arnt Gulbrandsen 	:	New udp_send and stuff
 *		Alan Cox	:	Cache last socket
 *		Alan Cox	:	Route cache
 *		Jon Peatfield	:	Minor efficiency fix to sendto().
 *		Mike Shaver	:	RFC1122 checks.
 *		Alan Cox	:	Nonblocking error fix.
 *	Willy Konynenberg	:	Transparent proxying support.
 *		Mike McLagan	:	Routing by source
 *		David S. Miller	:	New socket lookup architecture.
 *					Last socket cache retained as it
 *					does have a high hit rate.
 *		Olaf Kirch	:	Don't linearise iovec on sendmsg.
 *		Andi Kleen	:	Some cleanups, cache destination entry
 *					for connect.
 *	Vitaly E. Lavrov	:	Transparent proxy revived after year coma.
 *		Melvin Smith	:	Check msg_name not msg_namelen in sendto(),
 *					return ENOTCONN for unconnected sockets (POSIX)
 *		Janos Farkas	:	don't deliver multi/broadcasts to a different
 *					bound-to-device socket
 *	Hirokazu Takahashi	:	HW checksumming for outgoing UDP
 *					datagrams.
 *	Hirokazu Takahashi	:	sendfile() on UDP works now.
 *		Arnaldo C. Melo :	convert /proc/net/udp to seq_file
 *	YOSHIFUJI Hideaki @USAGI and:	Support IPV6_V6ONLY socket option, which
 *	Alexey Kuznetsov:		allow both IPv4 and IPv6 sockets to bind
 *					a single port at the same time.
 *	Derek Atkins <derek@ihtfp.com>: Add Encapulation Support
 *	James Chapman		:	Add L2TP encapsulation type.
 *
 *
 *		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.
 */

#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/ioctls.h>
#include <linux/bootmem.h>
#include <linux/highmem.h>
#include <linux/swap.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/module.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/igmp.h>
#include <linux/in.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <net/tcp_states.h>
#include <linux/skbuff.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <net/net_namespace.h>
#include <net/icmp.h>
#include <net/route.h>
#include <net/checksum.h>
#include <net/xfrm.h>
#include "udp_impl.h"

struct udp_table udp_table;
EXPORT_SYMBOL(udp_table);

int sysctl_udp_mem[3] __read_mostly;
EXPORT_SYMBOL(sysctl_udp_mem);

int sysctl_udp_rmem_min __read_mostly;
EXPORT_SYMBOL(sysctl_udp_rmem_min);

int sysctl_udp_wmem_min __read_mostly;
EXPORT_SYMBOL(sysctl_udp_wmem_min);

atomic_t udp_memory_allocated;
EXPORT_SYMBOL(udp_memory_allocated);

#define PORTS_PER_CHAIN (65536 / UDP_HTABLE_SIZE)

static int udp_lib_lport_inuse(struct net *net, __u16 num,
			       const struct udp_hslot *hslot,
			       unsigned long *bitmap,
			       struct sock *sk,
			       int (*saddr_comp)(const struct sock *sk1,
						 const struct sock *sk2))
{
	struct sock *sk2;
	struct hlist_nulls_node *node;

	sk_nulls_for_each(sk2, node, &hslot->head)
		if (net_eq(sock_net(sk2), net)			&&
		    sk2 != sk					&&
		    (bitmap || sk2->sk_hash == num)		&&
		    (!sk2->sk_reuse || !sk->sk_reuse)		&&
		    (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if
			|| sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
		    (*saddr_comp)(sk, sk2)) {
			if (bitmap)
				__set_bit(sk2->sk_hash / UDP_HTABLE_SIZE,
					  bitmap);
			else
				return 1;
		}
	return 0;
}

/**
 *  udp_lib_get_port  -  UDP/-Lite port lookup for IPv4 and IPv6
 *
 *  @sk:          socket struct in question
 *  @snum:        port number to look up
 *  @saddr_comp:  AF-dependent comparison of bound local IP addresses
 */
int udp_lib_get_port(struct sock *sk, unsigned short snum,
		       int (*saddr_comp)(const struct sock *sk1,
					 const struct sock *sk2))
{
	struct udp_hslot *hslot;
	struct udp_table *udptable = sk->sk_prot->h.udp_table;
	int    error = 1;
	struct net *net = sock_net(sk);

	if (!snum) {
		int low, high, remaining;
		unsigned rand;
		unsigned short first, last;
		DECLARE_BITMAP(bitmap, PORTS_PER_CHAIN);

		inet_get_local_port_range(&low, &high);
		remaining = (high - low) + 1;

		rand = net_random();
		first = (((u64)rand * remaining) >> 32) + low;
		/*
		 * force rand to be an odd multiple of UDP_HTABLE_SIZE
		 */
		rand = (rand | 1) * UDP_HTABLE_SIZE;
		for (last = first + UDP_HTABLE_SIZE; first != last; first++) {
			hslot = &udptable->hash[udp_hashfn(net, first)];
			bitmap_zero(bitmap, PORTS_PER_CHAIN);
			spin_lock_bh(&hslot->lock);
			udp_lib_lport_inuse(net, snum, hslot, bitmap, sk,
					    saddr_comp);

			snum = first;
			/*
			 * Iterate on all possible values of snum for this hash.
			 * Using steps of an odd multiple of UDP_HTABLE_SIZE
			 * give us randomization and full range coverage.
			 */
			do {
				if (low <= snum && snum <= high &&
				    !test_bit(snum / UDP_HTABLE_SIZE, bitmap))
					goto found;
				snum += rand;
			} while (snum != first);
			spin_unlock_bh(&hslot->lock);
		}
		goto fail;
	} else {
		hslot = &udptable->hash[udp_hashfn(net, snum)];
		spin_lock_bh(&hslot->lock);
		if (udp_lib_lport_inuse(net, snum, hslot, NULL, sk, saddr_comp))
			goto fail_unlock;
	}
found:
	inet_sk(sk)->num = snum;
	sk->sk_hash = snum;
	if (sk_unhashed(sk)) {
		sk_nulls_add_node_rcu(sk, &hslot->head);
		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
	}
	error = 0;
fail_unlock:
	spin_unlock_bh(&hslot->lock);
fail:
	return error;
}
EXPORT_SYMBOL(udp_lib_get_port);

static int ipv4_rcv_saddr_equal(const struct sock *sk1, const struct sock *sk2)
{