/*
   * 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.
   *
   *		"Ping" sockets
   *
   *		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.
   *
   * Based on ipv4/udp.c code.
   *
   * Authors:	Vasiliy Kulikov / Openwall (for Linux 2.6),
   *		Pavel Kankovsky (for Linux 2.4.32)
   *
   * Pavel gave all rights to bugs to Vasiliy,
   * none of the bugs are Pavel's now.
   *
   */

  #include <linux/uaccess.h>

  #include <linux/types.h>
  #include <linux/fcntl.h>
  #include <linux/socket.h>
  #include <linux/sockios.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/snmp.h>
  #include <net/ip.h>
  #include <net/ipv6.h>
  #include <net/icmp.h>
  #include <net/protocol.h>
  #include <linux/skbuff.h>
  #include <linux/proc_fs.h>

  #include <linux/export.h>

  #include <net/sock.h>
  #include <net/ping.h>

  #include <net/udp.h>
  #include <net/route.h>
  #include <net/inet_common.h>
  #include <net/checksum.h>

  static struct ping_table ping_table;

  static u16 ping_port_rover;

  static inline int ping_hashfn(struct net *net, unsigned int num, unsigned int mask)

  {
  	int res = (num + net_hash_mix(net)) & mask;

  	pr_debug("hash(%d) = %d
  ", num, res);
  	return res;
  }
  
  static inline struct hlist_nulls_head *ping_hashslot(struct ping_table *table,

  					     struct net *net, unsigned int num)

  {
  	return &table->hash[ping_hashfn(net, num, PING_HTABLE_MASK)];
  }
  
  static int ping_v4_get_port(struct sock *sk, unsigned short ident)
  {
  	struct hlist_nulls_node *node;
  	struct hlist_nulls_head *hlist;
  	struct inet_sock *isk, *isk2;
  	struct sock *sk2 = NULL;
  
  	isk = inet_sk(sk);
  	write_lock_bh(&ping_table.lock);
  	if (ident == 0) {
  		u32 i;
  		u16 result = ping_port_rover + 1;
  
  		for (i = 0; i < (1L << 16); i++, result++) {
  			if (!result)
  				result++; /* avoid zero */
  			hlist = ping_hashslot(&ping_table, sock_net(sk),
  					    result);
  			ping_portaddr_for_each_entry(sk2, node, hlist) {
  				isk2 = inet_sk(sk2);
  
  				if (isk2->inet_num == result)
  					goto next_port;
  			}
  
  			/* found */
  			ping_port_rover = ident = result;
  			break;
  next_port:
  			;
  		}
  		if (i >= (1L << 16))
  			goto fail;
  	} else {
  		hlist = ping_hashslot(&ping_table, sock_net(sk), ident);
  		ping_portaddr_for_each_entry(sk2, node, hlist) {
  			isk2 = inet_sk(sk2);
  
  			if ((isk2->inet_num == ident) &&
  			    (sk2 != sk) &&
  			    (!sk2->sk_reuse || !sk->sk_reuse))
  				goto fail;
  		}
  	}
  
  	pr_debug("found port/ident = %d
  ", ident);
  	isk->inet_num = ident;
  	if (sk_unhashed(sk)) {
  		pr_debug("was not hashed
  ");
  		sock_hold(sk);
  		hlist_nulls_add_head(&sk->sk_nulls_node, hlist);
  		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
  	}
  	write_unlock_bh(&ping_table.lock);
  	return 0;
  
  fail:
  	write_unlock_bh(&ping_table.lock);
  	return 1;
  }
  
  static void ping_v4_hash(struct sock *sk)
  {
  	pr_debug("ping_v4_hash(sk->port=%u)
  ", inet_sk(sk)->inet_num);
  	BUG(); /* "Please do not press this button again." */
  }
  
  static void ping_v4_unhash(struct sock *sk)
  {
  	struct inet_sock *isk = inet_sk(sk);
  	pr_debug("ping_v4_unhash(isk=%p,isk->num=%u)
  ", isk, isk->inet_num);
  	if (sk_hashed(sk)) {

  		write_lock_bh(&ping_table.lock);
  		hlist_nulls_del(&sk->sk_nulls_node);
  		sock_put(sk);

  		isk->inet_num = 0;
  		isk->inet_sport = 0;

  		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
  		write_unlock_bh(&ping_table.lock);
  	}
  }

  static struct sock *ping_v4_lookup(struct net *net, __be32 saddr, __be32 daddr,

  				   u16 ident, int dif)

  {
  	struct hlist_nulls_head *hslot = ping_hashslot(&ping_table, net, ident);
  	struct sock *sk = NULL;
  	struct inet_sock *isk;
  	struct hlist_nulls_node *hnode;

  	pr_debug("try to find: num = %d, daddr = %pI4, dif = %d
  ",

  		 (int)ident, &daddr, dif);

  	read_lock_bh(&ping_table.lock);
  
  	ping_portaddr_for_each_entry(sk, hnode, hslot) {
  		isk = inet_sk(sk);

  		pr_debug("found: %p: num = %d, daddr = %pI4, dif = %d
  ", sk,
  			 (int)isk->inet_num, &isk->inet_rcv_saddr,

  			 sk->sk_bound_dev_if);
  
  		pr_debug("iterate
  ");
  		if (isk->inet_num != ident)
  			continue;
  		if (isk->inet_rcv_saddr && isk->inet_rcv_saddr != daddr)
  			continue;
  		if (sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif)
  			continue;
  
  		sock_hold(sk);
  		goto exit;
  	}
  
  	sk = NULL;
  exit:
  	read_unlock_bh(&ping_table.lock);
  
  	return sk;
  }

  static void inet_get_ping_group_range_net(struct net *net, gid_t *low,
  					  gid_t *high)

  {
  	gid_t *data = net->ipv4.sysctl_ping_group_range;

  	unsigned int seq;

  	do {
  		seq = read_seqbegin(&sysctl_local_ports.lock);
  
  		*low = data[0];
  		*high = data[1];
  	} while (read_seqretry(&sysctl_local_ports.lock, seq));
  }

  static int ping_init_sock(struct sock *sk)
  {
  	struct net *net = sock_net(sk);
  	gid_t group = current_egid();
  	gid_t range[2];
  	struct group_info *group_info = get_current_groups();
  	int i, j, count = group_info->ngroups;

  	kgid_t low, high;

  
  	inet_get_ping_group_range_net(net, range, range+1);

  	low = make_kgid(&init_user_ns, range[0]);
  	high = make_kgid(&init_user_ns, range[1]);
  	if (!gid_valid(low) || !gid_valid(high) || gid_lt(high, low))
  		return -EACCES;

  	if (range[0] <= group && group <= range[1])
  		return 0;
  
  	for (i = 0; i < group_info->nblocks; i++) {
  		int cp_count = min_t(int, NGROUPS_PER_BLOCK, count);

  		for (j = 0; j < cp_count; j++) {

  			kgid_t gid = group_info->blocks[i][j];
  			if (gid_lte(low, gid) && gid_lte(gid, high))

  				return 0;
  		}
  
  		count -= cp_count;
  	}
  
  	return -EACCES;
  }
  
  static void ping_close(struct sock *sk, long timeout)
  {
  	pr_debug("ping_close(sk=%p,sk->num=%u)
  ",

  		 inet_sk(sk), inet_sk(sk)->inet_num);

  	pr_debug("isk->refcnt = %d
  ", sk->sk_refcnt.counter);
  
  	sk_common_release(sk);
  }
  
  /*
   * We need our own bind because there are no privileged id's == local ports.
   * Moreover, we don't allow binding to multi- and broadcast addresses.
   */
  
  static int ping_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  {
  	struct sockaddr_in *addr = (struct sockaddr_in *)uaddr;
  	struct inet_sock *isk = inet_sk(sk);
  	unsigned short snum;
  	int chk_addr_ret;
  	int err;
  
  	if (addr_len < sizeof(struct sockaddr_in))
  		return -EINVAL;
  
  	pr_debug("ping_v4_bind(sk=%p,sa_addr=%08x,sa_port=%d)
  ",

  		 sk, addr->sin_addr.s_addr, ntohs(addr->sin_port));

  
  	chk_addr_ret = inet_addr_type(sock_net(sk), addr->sin_addr.s_addr);

  	if (addr->sin_addr.s_addr == htonl(INADDR_ANY))

  		chk_addr_ret = RTN_LOCAL;
  
  	if ((sysctl_ip_nonlocal_bind == 0 &&
  	    isk->freebind == 0 && isk->transparent == 0 &&
  	     chk_addr_ret != RTN_LOCAL) ||
  	    chk_addr_ret == RTN_MULTICAST ||
  	    chk_addr_ret == RTN_BROADCAST)
  		return -EADDRNOTAVAIL;
  
  	lock_sock(sk);
  
  	err = -EINVAL;
  	if (isk->inet_num != 0)
  		goto out;
  
  	err = -EADDRINUSE;
  	isk->inet_rcv_saddr = isk->inet_saddr = addr->sin_addr.s_addr;
  	snum = ntohs(addr->sin_port);
  	if (ping_v4_get_port(sk, snum) != 0) {
  		isk->inet_saddr = isk->inet_rcv_saddr = 0;
  		goto out;
  	}

  	pr_debug("after bind(): num = %d, daddr = %pI4, dif = %d
  ",

  		 (int)isk->inet_num,
  		 &isk->inet_rcv_saddr,
  		 (int)sk->sk_bound_dev_if);

  
  	err = 0;
  	if (isk->inet_rcv_saddr)
  		sk->sk_userlocks |= SOCK_BINDADDR_LOCK;
  	if (snum)
  		sk->sk_userlocks |= SOCK_BINDPORT_LOCK;
  	isk->inet_sport = htons(isk->inet_num);
  	isk->inet_daddr = 0;
  	isk->inet_dport = 0;
  	sk_dst_reset(sk);
  out:
  	release_sock(sk);
  	pr_debug("ping_v4_bind -> %d
  ", err);
  	return err;
  }
  
  /*
   * Is this a supported type of ICMP message?
   */
  
  static inline int ping_supported(int type, int code)
  {
  	if (type == ICMP_ECHO && code == 0)
  		return 1;
  	return 0;
  }
  
  /*
   * This routine is called by the ICMP module when it gets some
   * sort of error condition.
   */
  
  static int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
  
  void ping_err(struct sk_buff *skb, u32 info)
  {
  	struct iphdr *iph = (struct iphdr *)skb->data;
  	struct icmphdr *icmph = (struct icmphdr *)(skb->data+(iph->ihl<<2));
  	struct inet_sock *inet_sock;
  	int type = icmph->type;
  	int code = icmph->code;
  	struct net *net = dev_net(skb->dev);
  	struct sock *sk;
  	int harderr;
  	int err;
  
  	/* We assume the packet has already been checked by icmp_unreach */
  
  	if (!ping_supported(icmph->type, icmph->code))
  		return;
  
  	pr_debug("ping_err(type=%04x,code=%04x,id=%04x,seq=%04x)
  ", type,

  		 code, ntohs(icmph->un.echo.id), ntohs(icmph->un.echo.sequence));

  
  	sk = ping_v4_lookup(net, iph->daddr, iph->saddr,
  			    ntohs(icmph->un.echo.id), skb->dev->ifindex);
  	if (sk == NULL) {

  		pr_debug("no socket, dropping
  ");
  		return;	/* No socket for error */
  	}
  	pr_debug("err on socket %p
  ", sk);
  
  	err = 0;
  	harderr = 0;
  	inet_sock = inet_sk(sk);
  
  	switch (type) {
  	default:
  	case ICMP_TIME_EXCEEDED:
  		err = EHOSTUNREACH;
  		break;
  	case ICMP_SOURCE_QUENCH:
  		/* This is not a real error but ping wants to see it.
  		 * Report it with some fake errno. */
  		err = EREMOTEIO;
  		break;
  	case ICMP_PARAMETERPROB:
  		err = EPROTO;
  		harderr = 1;
  		break;
  	case ICMP_DEST_UNREACH:
  		if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */

  			ipv4_sk_update_pmtu(skb, sk, info);

  			if (inet_sock->pmtudisc != IP_PMTUDISC_DONT) {
  				err = EMSGSIZE;
  				harderr = 1;
  				break;
  			}
  			goto out;
  		}
  		err = EHOSTUNREACH;
  		if (code <= NR_ICMP_UNREACH) {
  			harderr = icmp_err_convert[code].fatal;
  			err = icmp_err_convert[code].errno;
  		}
  		break;
  	case ICMP_REDIRECT:
  		/* See ICMP_SOURCE_QUENCH */

  		ipv4_sk_redirect(skb, sk);

  		err = EREMOTEIO;
  		break;
  	}
  
  	/*
  	 *      RFC1122: OK.  Passes ICMP errors back to application, as per
  	 *	4.1.3.3.
  	 */
  	if (!inet_sock->recverr) {
  		if (!harderr || sk->sk_state != TCP_ESTABLISHED)
  			goto out;
  	} else {
  		ip_icmp_error(sk, skb, err, 0 /* no remote port */,
  			 info, (u8 *)icmph);
  	}
  	sk->sk_err = err;
  	sk->sk_error_report(sk);
  out:
  	sock_put(sk);
  }
  
  /*
   *	Copy and checksum an ICMP Echo packet from user space into a buffer.
   */
  
  struct pingfakehdr {
  	struct icmphdr icmph;
  	struct iovec *iov;

  	__wsum wcheck;

  };

  static int ping_getfrag(void *from, char *to,

  			int offset, int fraglen, int odd, struct sk_buff *skb)
  {
  	struct pingfakehdr *pfh = (struct pingfakehdr *)from;
  
  	if (offset == 0) {
  		if (fraglen < sizeof(struct icmphdr))
  			BUG();
  		if (csum_partial_copy_fromiovecend(to + sizeof(struct icmphdr),
  			    pfh->iov, 0, fraglen - sizeof(struct icmphdr),
  			    &pfh->wcheck))
  			return -EFAULT;
  
  		return 0;
  	}
  	if (offset < sizeof(struct icmphdr))
  		BUG();
  	if (csum_partial_copy_fromiovecend
  			(to, pfh->iov, offset - sizeof(struct icmphdr),
  			 fraglen, &pfh->wcheck))
  		return -EFAULT;
  	return 0;
  }

  static int ping_push_pending_frames(struct sock *sk, struct pingfakehdr *pfh,
  				    struct flowi4 *fl4)

  {
  	struct sk_buff *skb = skb_peek(&sk->sk_write_queue);
  
  	pfh->wcheck = csum_partial((char *)&pfh->icmph,
  		sizeof(struct icmphdr), pfh->wcheck);
  	pfh->icmph.checksum = csum_fold(pfh->wcheck);
  	memcpy(icmp_hdr(skb), &pfh->icmph, sizeof(struct icmphdr));
  	skb->ip_summed = CHECKSUM_NONE;
  	return ip_push_pending_frames(sk, fl4);
  }

  static int ping_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
  			size_t len)

  {
  	struct net *net = sock_net(sk);
  	struct flowi4 fl4;
  	struct inet_sock *inet = inet_sk(sk);
  	struct ipcm_cookie ipc;
  	struct icmphdr user_icmph;
  	struct pingfakehdr pfh;
  	struct rtable *rt = NULL;
  	struct ip_options_data opt_copy;
  	int free = 0;

  	__be32 saddr, daddr, faddr;

  	u8  tos;
  	int err;
  
  	pr_debug("ping_sendmsg(sk=%p,sk->num=%u)
  ", inet, inet->inet_num);
  
  
  	if (len > 0xFFFF)
  		return -EMSGSIZE;
  
  	/*
  	 *	Check the flags.
  	 */
  
  	/* Mirror BSD error message compatibility */
  	if (msg->msg_flags & MSG_OOB)
  		return -EOPNOTSUPP;
  
  	/*
  	 *	Fetch the ICMP header provided by the userland.
  	 *	iovec is modified!
  	 */
  
  	if (memcpy_fromiovec((u8 *)&user_icmph, msg->msg_iov,
  			     sizeof(struct icmphdr)))
  		return -EFAULT;
  	if (!ping_supported(user_icmph.type, user_icmph.code))
  		return -EINVAL;
  
  	/*
  	 *	Get and verify the address.
  	 */
  
  	if (msg->msg_name) {
  		struct sockaddr_in *usin = (struct sockaddr_in *)msg->msg_name;
  		if (msg->msg_namelen < sizeof(*usin))
  			return -EINVAL;
  		if (usin->sin_family != AF_INET)
  			return -EINVAL;
  		daddr = usin->sin_addr.s_addr;
  		/* no remote port */
  	} else {
  		if (sk->sk_state != TCP_ESTABLISHED)
  			return -EDESTADDRREQ;
  		daddr = inet->inet_daddr;
  		/* no remote port */
  	}
  
  	ipc.addr = inet->inet_saddr;
  	ipc.opt = NULL;
  	ipc.oif = sk->sk_bound_dev_if;
  	ipc.tx_flags = 0;
  	err = sock_tx_timestamp(sk, &ipc.tx_flags);
  	if (err)
  		return err;
  
  	if (msg->msg_controllen) {
  		err = ip_cmsg_send(sock_net(sk), msg, &ipc);
  		if (err)
  			return err;
  		if (ipc.opt)
  			free = 1;
  	}
  	if (!ipc.opt) {
  		struct ip_options_rcu *inet_opt;
  
  		rcu_read_lock();
  		inet_opt = rcu_dereference(inet->inet_opt);
  		if (inet_opt) {
  			memcpy(&opt_copy, inet_opt,
  			       sizeof(*inet_opt) + inet_opt->opt.optlen);
  			ipc.opt = &opt_copy.opt;
  		}
  		rcu_read_unlock();
  	}
  
  	saddr = ipc.addr;
  	ipc.addr = faddr = daddr;
  
  	if (ipc.opt && ipc.opt->opt.srr) {
  		if (!daddr)
  			return -EINVAL;
  		faddr = ipc.opt->opt.faddr;
  	}
  	tos = RT_TOS(inet->tos);
  	if (sock_flag(sk, SOCK_LOCALROUTE) ||
  	    (msg->msg_flags & MSG_DONTROUTE) ||
  	    (ipc.opt && ipc.opt->opt.is_strictroute)) {
  		tos |= RTO_ONLINK;
  	}
  
  	if (ipv4_is_multicast(daddr)) {
  		if (!ipc.oif)
  			ipc.oif = inet->mc_index;
  		if (!saddr)
  			saddr = inet->mc_addr;

  	} else if (!ipc.oif)
  		ipc.oif = inet->uc_index;

  
  	flowi4_init_output(&fl4, ipc.oif, sk->sk_mark, tos,
  			   RT_SCOPE_UNIVERSE, sk->sk_protocol,
  			   inet_sk_flowi_flags(sk), faddr, saddr, 0, 0);
  
  	security_sk_classify_flow(sk, flowi4_to_flowi(&fl4));
  	rt = ip_route_output_flow(net, &fl4, sk);
  	if (IS_ERR(rt)) {
  		err = PTR_ERR(rt);
  		rt = NULL;
  		if (err == -ENETUNREACH)
  			IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
  		goto out;
  	}
  
  	err = -EACCES;
  	if ((rt->rt_flags & RTCF_BROADCAST) &&
  	    !sock_flag(sk, SOCK_BROADCAST))
  		goto out;
  
  	if (msg->msg_flags & MSG_CONFIRM)
  		goto do_confirm;
  back_from_confirm:
  
  	if (!ipc.addr)
  		ipc.addr = fl4.daddr;
  
  	lock_sock(sk);
  
  	pfh.icmph.type = user_icmph.type; /* already checked */
  	pfh.icmph.code = user_icmph.code; /* ditto */
  	pfh.icmph.checksum = 0;
  	pfh.icmph.un.echo.id = inet->inet_sport;
  	pfh.icmph.un.echo.sequence = user_icmph.un.echo.sequence;
  	pfh.iov = msg->msg_iov;
  	pfh.wcheck = 0;
  
  	err = ip_append_data(sk, &fl4, ping_getfrag, &pfh, len,
  			0, &ipc, &rt, msg->msg_flags);
  	if (err)
  		ip_flush_pending_frames(sk);
  	else
  		err = ping_push_pending_frames(sk, &pfh, &fl4);
  	release_sock(sk);
  
  out:
  	ip_rt_put(rt);
  	if (free)
  		kfree(ipc.opt);
  	if (!err) {
  		icmp_out_count(sock_net(sk), user_icmph.type);
  		return len;
  	}
  	return err;
  
  do_confirm:
  	dst_confirm(&rt->dst);
  	if (!(msg->msg_flags & MSG_PROBE) || len)
  		goto back_from_confirm;
  	err = 0;
  	goto out;
  }

  static int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
  			size_t len, int noblock, int flags, int *addr_len)

  {
  	struct inet_sock *isk = inet_sk(sk);
  	struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
  	struct sk_buff *skb;
  	int copied, err;
  
  	pr_debug("ping_recvmsg(sk=%p,sk->num=%u)
  ", isk, isk->inet_num);

  	err = -EOPNOTSUPP;

  	if (flags & MSG_OOB)
  		goto out;
  
  	if (addr_len)
  		*addr_len = sizeof(*sin);
  
  	if (flags & MSG_ERRQUEUE)
  		return ip_recv_error(sk, msg, len);
  
  	skb = skb_recv_datagram(sk, flags, noblock, &err);
  	if (!skb)
  		goto out;
  
  	copied = skb->len;
  	if (copied > len) {
  		msg->msg_flags |= MSG_TRUNC;
  		copied = len;
  	}
  
  	/* Don't bother checking the checksum */
  	err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
  	if (err)
  		goto done;
  
  	sock_recv_timestamp(msg, sk, skb);
  
  	/* Copy the address. */
  	if (sin) {
  		sin->sin_family = AF_INET;
  		sin->sin_port = 0 /* skb->h.uh->source */;
  		sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
  		memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
  	}
  	if (isk->cmsg_flags)
  		ip_cmsg_recv(msg, skb);
  	err = copied;
  
  done:
  	skb_free_datagram(sk, skb);
  out:
  	pr_debug("ping_recvmsg -> %d
  ", err);
  	return err;
  }
  
  static int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
  {
  	pr_debug("ping_queue_rcv_skb(sk=%p,sk->num=%d,skb=%p)
  ",

  		 inet_sk(sk), inet_sk(sk)->inet_num, skb);

  	if (sock_queue_rcv_skb(sk, skb) < 0) {

  		kfree_skb(skb);
  		pr_debug("ping_queue_rcv_skb -> failed
  ");
  		return -1;
  	}
  	return 0;
  }
  
  
  /*
   *	All we need to do is get the socket.
   */
  
  void ping_rcv(struct sk_buff *skb)
  {
  	struct sock *sk;
  	struct net *net = dev_net(skb->dev);
  	struct iphdr *iph = ip_hdr(skb);
  	struct icmphdr *icmph = icmp_hdr(skb);

  	__be32 saddr = iph->saddr;
  	__be32 daddr = iph->daddr;

  
  	/* We assume the packet has already been checked by icmp_rcv */
  
  	pr_debug("ping_rcv(skb=%p,id=%04x,seq=%04x)
  ",

  		 skb, ntohs(icmph->un.echo.id), ntohs(icmph->un.echo.sequence));

  
  	/* Push ICMP header back */
  	skb_push(skb, skb->data - (u8 *)icmph);
  
  	sk = ping_v4_lookup(net, saddr, daddr, ntohs(icmph->un.echo.id),
  			    skb->dev->ifindex);
  	if (sk != NULL) {
  		pr_debug("rcv on socket %p
  ", sk);
  		ping_queue_rcv_skb(sk, skb_get(skb));
  		sock_put(sk);
  		return;
  	}
  	pr_debug("no socket, dropping
  ");
  
  	/* We're called from icmp_rcv(). kfree_skb() is done there. */
  }
  
  struct proto ping_prot = {
  	.name =		"PING",
  	.owner =	THIS_MODULE,
  	.init =		ping_init_sock,
  	.close =	ping_close,
  	.connect =	ip4_datagram_connect,
  	.disconnect =	udp_disconnect,

  	.setsockopt =	ip_setsockopt,
  	.getsockopt =	ip_getsockopt,
  	.sendmsg =	ping_sendmsg,
  	.recvmsg =	ping_recvmsg,
  	.bind =		ping_bind,
  	.backlog_rcv =	ping_queue_rcv_skb,
  	.hash =		ping_v4_hash,
  	.unhash =	ping_v4_unhash,
  	.get_port =	ping_v4_get_port,
  	.obj_size =	sizeof(struct inet_sock),
  };
  EXPORT_SYMBOL(ping_prot);
  
  #ifdef CONFIG_PROC_FS
  
  static struct sock *ping_get_first(struct seq_file *seq, int start)
  {
  	struct sock *sk;
  	struct ping_iter_state *state = seq->private;
  	struct net *net = seq_file_net(seq);
  
  	for (state->bucket = start; state->bucket < PING_HTABLE_SIZE;
  	     ++state->bucket) {
  		struct hlist_nulls_node *node;

  		struct hlist_nulls_head *hslot;
  
  		hslot = &ping_table.hash[state->bucket];

  
  		if (hlist_nulls_empty(hslot))
  			continue;
  
  		sk_nulls_for_each(sk, node, hslot) {
  			if (net_eq(sock_net(sk), net))
  				goto found;
  		}
  	}
  	sk = NULL;
  found:
  	return sk;
  }
  
  static struct sock *ping_get_next(struct seq_file *seq, struct sock *sk)
  {
  	struct ping_iter_state *state = seq->private;
  	struct net *net = seq_file_net(seq);
  
  	do {
  		sk = sk_nulls_next(sk);
  	} while (sk && (!net_eq(sock_net(sk), net)));
  
  	if (!sk)
  		return ping_get_first(seq, state->bucket + 1);
  	return sk;
  }
  
  static struct sock *ping_get_idx(struct seq_file *seq, loff_t pos)
  {
  	struct sock *sk = ping_get_first(seq, 0);
  
  	if (sk)
  		while (pos && (sk = ping_get_next(seq, sk)) != NULL)
  			--pos;
  	return pos ? NULL : sk;
  }
  
  static void *ping_seq_start(struct seq_file *seq, loff_t *pos)
  {
  	struct ping_iter_state *state = seq->private;
  	state->bucket = 0;
  
  	read_lock_bh(&ping_table.lock);
  
  	return *pos ? ping_get_idx(seq, *pos-1) : SEQ_START_TOKEN;
  }
  
  static void *ping_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {
  	struct sock *sk;
  
  	if (v == SEQ_START_TOKEN)
  		sk = ping_get_idx(seq, 0);
  	else
  		sk = ping_get_next(seq, v);
  
  	++*pos;
  	return sk;
  }
  
  static void ping_seq_stop(struct seq_file *seq, void *v)
  {
  	read_unlock_bh(&ping_table.lock);
  }
  
  static void ping_format_sock(struct sock *sp, struct seq_file *f,
  		int bucket, int *len)
  {
  	struct inet_sock *inet = inet_sk(sp);
  	__be32 dest = inet->inet_daddr;
  	__be32 src = inet->inet_rcv_saddr;
  	__u16 destp = ntohs(inet->inet_dport);
  	__u16 srcp = ntohs(inet->inet_sport);
  
  	seq_printf(f, "%5d: %08X:%04X %08X:%04X"
  		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %pK %d%n",
  		bucket, src, srcp, dest, destp, sp->sk_state,
  		sk_wmem_alloc_get(sp),
  		sk_rmem_alloc_get(sp),
  		0, 0L, 0, sock_i_uid(sp), 0, sock_i_ino(sp),
  		atomic_read(&sp->sk_refcnt), sp,
  		atomic_read(&sp->sk_drops), len);
  }
  
  static int ping_seq_show(struct seq_file *seq, void *v)
  {
  	if (v == SEQ_START_TOKEN)
  		seq_printf(seq, "%-127s
  ",
  			   "  sl  local_address rem_address   st tx_queue "
  			   "rx_queue tr tm->when retrnsmt   uid  timeout "
  			   "inode ref pointer drops");
  	else {
  		struct ping_iter_state *state = seq->private;
  		int len;
  
  		ping_format_sock(v, seq, state->bucket, &len);
  		seq_printf(seq, "%*s
  ", 127 - len, "");
  	}
  	return 0;
  }
  
  static const struct seq_operations ping_seq_ops = {
  	.show		= ping_seq_show,
  	.start		= ping_seq_start,
  	.next		= ping_seq_next,
  	.stop		= ping_seq_stop,
  };
  
  static int ping_seq_open(struct inode *inode, struct file *file)
  {
  	return seq_open_net(inode, file, &ping_seq_ops,
  			   sizeof(struct ping_iter_state));
  }
  
  static const struct file_operations ping_seq_fops = {
  	.open		= ping_seq_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= seq_release_net,
  };
  
  static int ping_proc_register(struct net *net)
  {
  	struct proc_dir_entry *p;
  	int rc = 0;
  
  	p = proc_net_fops_create(net, "icmp", S_IRUGO, &ping_seq_fops);
  	if (!p)
  		rc = -ENOMEM;
  	return rc;
  }
  
  static void ping_proc_unregister(struct net *net)
  {
  	proc_net_remove(net, "icmp");
  }
  
  
  static int __net_init ping_proc_init_net(struct net *net)
  {
  	return ping_proc_register(net);
  }
  
  static void __net_exit ping_proc_exit_net(struct net *net)
  {
  	ping_proc_unregister(net);
  }
  
  static struct pernet_operations ping_net_ops = {
  	.init = ping_proc_init_net,
  	.exit = ping_proc_exit_net,
  };
  
  int __init ping_proc_init(void)
  {
  	return register_pernet_subsys(&ping_net_ops);
  }
  
  void ping_proc_exit(void)
  {
  	unregister_pernet_subsys(&ping_net_ops);
  }
  
  #endif
  
  void __init ping_init(void)
  {
  	int i;
  
  	for (i = 0; i < PING_HTABLE_SIZE; i++)
  		INIT_HLIST_NULLS_HEAD(&ping_table.hash[i], i);
  	rwlock_init(&ping_table.lock);
  }