/* Error message handling (ICMP)
   *
   * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * 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 <linux/module.h>
  #include <linux/net.h>
  #include <linux/skbuff.h>
  #include <linux/errqueue.h>
  #include <linux/udp.h>
  #include <linux/in.h>
  #include <linux/in6.h>
  #include <linux/icmp.h>
  #include <net/sock.h>
  #include <net/af_rxrpc.h>
  #include <net/ip.h>
  #include "ar-internal.h"
  
  /*
   * handle an error received on the local endpoint
   */
  void rxrpc_UDP_error_report(struct sock *sk)
  {
  	struct sock_exterr_skb *serr;
  	struct rxrpc_transport *trans;
  	struct rxrpc_local *local = sk->sk_user_data;
  	struct rxrpc_peer *peer;
  	struct sk_buff *skb;
  	__be32 addr;
  	__be16 port;
  
  	_enter("%p{%d}", sk, local->debug_id);
  
  	skb = skb_dequeue(&sk->sk_error_queue);
  	if (!skb) {
  		_leave("UDP socket errqueue empty");
  		return;
  	}
  
  	rxrpc_new_skb(skb);
  
  	serr = SKB_EXT_ERR(skb);
  	addr = *(__be32 *)(skb_network_header(skb) + serr->addr_offset);
  	port = serr->port;

  	_net("Rx UDP Error from %pI4:%hu", &addr, ntohs(port));

  	_debug("Msg l:%d d:%d", skb->len, skb->data_len);
  
  	peer = rxrpc_find_peer(local, addr, port);
  	if (IS_ERR(peer)) {
  		rxrpc_free_skb(skb);
  		_leave(" [no peer]");
  		return;
  	}
  
  	trans = rxrpc_find_transport(local, peer);
  	if (!trans) {
  		rxrpc_put_peer(peer);
  		rxrpc_free_skb(skb);
  		_leave(" [no trans]");
  		return;
  	}
  
  	if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP &&
  	    serr->ee.ee_type == ICMP_DEST_UNREACH &&
  	    serr->ee.ee_code == ICMP_FRAG_NEEDED
  	    ) {
  		u32 mtu = serr->ee.ee_info;
  
  		_net("Rx Received ICMP Fragmentation Needed (%d)", mtu);
  
  		/* wind down the local interface MTU */
  		if (mtu > 0 && peer->if_mtu == 65535 && mtu < peer->if_mtu) {
  			peer->if_mtu = mtu;
  			_net("I/F MTU %u", mtu);
  		}
  
  		/* ip_rt_frag_needed() may have eaten the info */
  		if (mtu == 0)
  			mtu = ntohs(icmp_hdr(skb)->un.frag.mtu);
  
  		if (mtu == 0) {
  			/* they didn't give us a size, estimate one */
  			if (mtu > 1500) {
  				mtu >>= 1;
  				if (mtu < 1500)
  					mtu = 1500;
  			} else {
  				mtu -= 100;
  				if (mtu < peer->hdrsize)
  					mtu = peer->hdrsize + 4;
  			}
  		}
  
  		if (mtu < peer->mtu) {

  			spin_lock_bh(&peer->lock);

  			peer->mtu = mtu;
  			peer->maxdata = peer->mtu - peer->hdrsize;

  			spin_unlock_bh(&peer->lock);

  			_net("Net MTU %u (maxdata %u)",
  			     peer->mtu, peer->maxdata);
  		}
  	}
  
  	rxrpc_put_peer(peer);
  
  	/* pass the transport ref to error_handler to release */
  	skb_queue_tail(&trans->error_queue, skb);

  	rxrpc_queue_work(&trans->error_handler);

  
  	/* reset and regenerate socket error */
  	spin_lock_bh(&sk->sk_error_queue.lock);
  	sk->sk_err = 0;
  	skb = skb_peek(&sk->sk_error_queue);
  	if (skb) {
  		sk->sk_err = SKB_EXT_ERR(skb)->ee.ee_errno;
  		spin_unlock_bh(&sk->sk_error_queue.lock);
  		sk->sk_error_report(sk);
  	} else {
  		spin_unlock_bh(&sk->sk_error_queue.lock);
  	}
  
  	_leave("");
  }
  
  /*
   * deal with UDP error messages
   */
  void rxrpc_UDP_error_handler(struct work_struct *work)
  {
  	struct sock_extended_err *ee;
  	struct sock_exterr_skb *serr;
  	struct rxrpc_transport *trans =
  		container_of(work, struct rxrpc_transport, error_handler);
  	struct sk_buff *skb;

  	int err;

  
  	_enter("");
  
  	skb = skb_dequeue(&trans->error_queue);
  	if (!skb)
  		return;
  
  	serr = SKB_EXT_ERR(skb);
  	ee = &serr->ee;
  
  	_net("Rx Error o=%d t=%d c=%d e=%d",
  	     ee->ee_origin, ee->ee_type, ee->ee_code, ee->ee_errno);
  
  	err = ee->ee_errno;
  
  	switch (ee->ee_origin) {
  	case SO_EE_ORIGIN_ICMP:

  		switch (ee->ee_type) {
  		case ICMP_DEST_UNREACH:
  			switch (ee->ee_code) {
  			case ICMP_NET_UNREACH:
  				_net("Rx Received ICMP Network Unreachable");
  				err = ENETUNREACH;
  				break;
  			case ICMP_HOST_UNREACH:
  				_net("Rx Received ICMP Host Unreachable");
  				err = EHOSTUNREACH;
  				break;
  			case ICMP_PORT_UNREACH:
  				_net("Rx Received ICMP Port Unreachable");
  				err = ECONNREFUSED;
  				break;
  			case ICMP_FRAG_NEEDED:
  				_net("Rx Received ICMP Fragmentation Needed (%d)",
  				     ee->ee_info);
  				err = 0; /* dealt with elsewhere */
  				break;
  			case ICMP_NET_UNKNOWN:
  				_net("Rx Received ICMP Unknown Network");
  				err = ENETUNREACH;
  				break;
  			case ICMP_HOST_UNKNOWN:
  				_net("Rx Received ICMP Unknown Host");
  				err = EHOSTUNREACH;
  				break;
  			default:
  				_net("Rx Received ICMP DestUnreach code=%u",
  				     ee->ee_code);
  				break;
  			}
  			break;
  
  		case ICMP_TIME_EXCEEDED:
  			_net("Rx Received ICMP TTL Exceeded");
  			break;
  
  		default:
  			_proto("Rx Received ICMP error { type=%u code=%u }",
  			       ee->ee_type, ee->ee_code);
  			break;
  		}
  		break;
  
  	case SO_EE_ORIGIN_LOCAL:
  		_proto("Rx Received local error { error=%d }",
  		       ee->ee_errno);

  		break;
  
  	case SO_EE_ORIGIN_NONE:
  	case SO_EE_ORIGIN_ICMP6:
  	default:
  		_proto("Rx Received error report { orig=%u }",
  		       ee->ee_origin);

  		break;
  	}
  
  	/* terminate all the affected calls if there's an unrecoverable
  	 * error */
  	if (err) {
  		struct rxrpc_call *call, *_n;
  
  		_debug("ISSUE ERROR %d", err);
  
  		spin_lock_bh(&trans->peer->lock);
  		trans->peer->net_error = err;
  
  		list_for_each_entry_safe(call, _n, &trans->peer->error_targets,
  					 error_link) {
  			write_lock(&call->state_lock);
  			if (call->state != RXRPC_CALL_COMPLETE &&
  			    call->state < RXRPC_CALL_NETWORK_ERROR) {
  				call->state = RXRPC_CALL_NETWORK_ERROR;
  				set_bit(RXRPC_CALL_RCVD_ERROR, &call->events);

  				rxrpc_queue_call(call);

  			}
  			write_unlock(&call->state_lock);
  			list_del_init(&call->error_link);
  		}
  
  		spin_unlock_bh(&trans->peer->lock);
  	}
  
  	if (!skb_queue_empty(&trans->error_queue))

  		rxrpc_queue_work(&trans->error_handler);

  
  	rxrpc_free_skb(skb);
  	rxrpc_put_transport(trans);
  	_leave("");
  }