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linux/net/rxrpc/ar-error.c
David Howells 224711df5c [AF_RXRPC]: Sort out MTU handling. 
Sort out the MTU determination and handling in AF_RXRPC:

 (1) If it's present, parse the additional information supplied by the peer at
     the end of the ACK packet (struct ackinfo) to determine the MTU sizes
     that peer is willing to support.

 (2) Initialise the MTU size to that peer from the kernel's routing records.

 (3) Send ACKs rather than ACKALLs as the former carry the additional info,
     and the latter do not.

 (4) Declare the interface MTU size in outgoing ACKs as a maximum amount of
     data that can be stuffed into an RxRPC packet without it having to be
     fragmented to come in this computer's NIC.

 (5) If sendmsg() is given MSG_MORE then it should allocate an skb of the
     maximum size rather than one just big enough for the data it's got left
     to process on the theory that there is more data to come that it can
     append to that packet.

     This means, for example, that if AFS does a large StoreData op, all the
     packets barring the last will be filled to the maximum unfragmented size.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-05-04 12:41:11 -07:00

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/* 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 "NIPQUAD_FMT":%hu",
NIPQUAD(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 local, 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:
local = 0;
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);
local = 1;
break;
case SO_EE_ORIGIN_NONE:
case SO_EE_ORIGIN_ICMP6:
default:
_proto("Rx Received error report { orig=%u }",
ee->ee_origin);
local = 0;
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("");
}
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