1 files changed, 303 insertions, 0 deletions

diff --git a/net/rxrpc/ar-peer.c b/net/rxrpc/ar-peer.c
new file mode 100644
index 00000000..2754f098
--- /dev/null
+++ b/net/rxrpc/ar-peer.c
@@ -0,0 +1,303 @@
+/* RxRPC remote transport endpoint management
+ *
+ * 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/udp.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/icmp.h>
+#include <linux/slab.h>
+#include <net/sock.h>
+#include <net/af_rxrpc.h>
+#include <net/ip.h>
+#include <net/route.h>
+#include "ar-internal.h"
+
+static LIST_HEAD(rxrpc_peers);
+static DEFINE_RWLOCK(rxrpc_peer_lock);
+static DECLARE_WAIT_QUEUE_HEAD(rxrpc_peer_wq);
+
+static void rxrpc_destroy_peer(struct work_struct *work);
+
+/*
+ * assess the MTU size for the network interface through which this peer is
+ * reached
+ */
+static void rxrpc_assess_MTU_size(struct rxrpc_peer *peer)
+{
+	struct rtable *rt;
+	struct flowi4 fl4;
+
+	peer->if_mtu = 1500;
+
+	rt = ip_route_output_ports(&init_net, &fl4, NULL,
+				   peer->srx.transport.sin.sin_addr.s_addr, 0,
+				   htons(7000), htons(7001),
+				   IPPROTO_UDP, 0, 0);
+	if (IS_ERR(rt)) {
+		_leave(" [route err %ld]", PTR_ERR(rt));
+		return;
+	}
+
+	peer->if_mtu = dst_mtu(&rt->dst);
+	dst_release(&rt->dst);
+
+	_leave(" [if_mtu %u]", peer->if_mtu);
+}
+
+/*
+ * allocate a new peer
+ */
+static struct rxrpc_peer *rxrpc_alloc_peer(struct sockaddr_rxrpc *srx,
+					   gfp_t gfp)
+{
+	struct rxrpc_peer *peer;
+
+	_enter("");
+
+	peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
+	if (peer) {
+		INIT_WORK(&peer->destroyer, &rxrpc_destroy_peer);
+		INIT_LIST_HEAD(&peer->link);
+		INIT_LIST_HEAD(&peer->error_targets);
+		spin_lock_init(&peer->lock);
+		atomic_set(&peer->usage, 1);
+		peer->debug_id = atomic_inc_return(&rxrpc_debug_id);
+		memcpy(&peer->srx, srx, sizeof(*srx));
+
+		rxrpc_assess_MTU_size(peer);
+		peer->mtu = peer->if_mtu;
+
+		if (srx->transport.family == AF_INET) {
+			peer->hdrsize = sizeof(struct iphdr);
+			switch (srx->transport_type) {
+			case SOCK_DGRAM:
+				peer->hdrsize += sizeof(struct udphdr);
+				break;
+			default:
+				BUG();
+				break;
+			}
+		} else {
+			BUG();
+		}
+
+		peer->hdrsize += sizeof(struct rxrpc_header);
+		peer->maxdata = peer->mtu - peer->hdrsize;
+	}
+
+	_leave(" = %p", peer);
+	return peer;
+}
+
+/*
+ * obtain a remote transport endpoint for the specified address
+ */
+struct rxrpc_peer *rxrpc_get_peer(struct sockaddr_rxrpc *srx, gfp_t gfp)
+{
+	struct rxrpc_peer *peer, *candidate;
+	const char *new = "old";
+	int usage;
+
+	_enter("{%d,%d,%pI4+%hu}",
+	       srx->transport_type,
+	       srx->transport_len,
+	       &srx->transport.sin.sin_addr,
+	       ntohs(srx->transport.sin.sin_port));
+
+	/* search the peer list first */
+	read_lock_bh(&rxrpc_peer_lock);
+	list_for_each_entry(peer, &rxrpc_peers, link) {
+		_debug("check PEER %d { u=%d t=%d l=%d }",
+		       peer->debug_id,
+		       atomic_read(&peer->usage),
+		       peer->srx.transport_type,
+		       peer->srx.transport_len);
+
+		if (atomic_read(&peer->usage) > 0 &&
+		    peer->srx.transport_type == srx->transport_type &&
+		    peer->srx.transport_len == srx->transport_len &&
+		    memcmp(&peer->srx.transport,
+			   &srx->transport,
+			   srx->transport_len) == 0)
+			goto found_extant_peer;
+	}
+	read_unlock_bh(&rxrpc_peer_lock);
+
+	/* not yet present - create a candidate for a new record and then
+	 * redo the search */
+	candidate = rxrpc_alloc_peer(srx, gfp);
+	if (!candidate) {
+		_leave(" = -ENOMEM");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	write_lock_bh(&rxrpc_peer_lock);
+
+	list_for_each_entry(peer, &rxrpc_peers, link) {
+		if (atomic_read(&peer->usage) > 0 &&
+		    peer->srx.transport_type == srx->transport_type &&
+		    peer->srx.transport_len == srx->transport_len &&
+		    memcmp(&peer->srx.transport,
+			   &srx->transport,
+			   srx->transport_len) == 0)
+			goto found_extant_second;
+	}
+
+	/* we can now add the new candidate to the list */
+	peer = candidate;
+	candidate = NULL;
+	usage = atomic_read(&peer->usage);
+
+	list_add_tail(&peer->link, &rxrpc_peers);
+	write_unlock_bh(&rxrpc_peer_lock);
+	new = "new";
+
+success:
+	_net("PEER %s %d {%d,%u,%pI4+%hu}",
+	     new,
+	     peer->debug_id,
+	     peer->srx.transport_type,
+	     peer->srx.transport.family,
+	     &peer->srx.transport.sin.sin_addr,
+	     ntohs(peer->srx.transport.sin.sin_port));
+
+	_leave(" = %p {u=%d}", peer, usage);
+	return peer;
+
+	/* we found the peer in the list immediately */
+found_extant_peer:
+	usage = atomic_inc_return(&peer->usage);
+	read_unlock_bh(&rxrpc_peer_lock);
+	goto success;
+
+	/* we found the peer on the second time through the list */
+found_extant_second:
+	usage = atomic_inc_return(&peer->usage);
+	write_unlock_bh(&rxrpc_peer_lock);
+	kfree(candidate);
+	goto success;
+}
+
+/*
+ * find the peer associated with a packet
+ */
+struct rxrpc_peer *rxrpc_find_peer(struct rxrpc_local *local,
+				   __be32 addr, __be16 port)
+{
+	struct rxrpc_peer *peer;
+
+	_enter("");
+
+	/* search the peer list */
+	read_lock_bh(&rxrpc_peer_lock);
+
+	if (local->srx.transport.family == AF_INET &&
+	    local->srx.transport_type == SOCK_DGRAM
+	    ) {
+		list_for_each_entry(peer, &rxrpc_peers, link) {
+			if (atomic_read(&peer->usage) > 0 &&
+			    peer->srx.transport_type == SOCK_DGRAM &&
+			    peer->srx.transport.family == AF_INET &&
+			    peer->srx.transport.sin.sin_port == port &&
+			    peer->srx.transport.sin.sin_addr.s_addr == addr)
+				goto found_UDP_peer;
+		}
+
+		goto new_UDP_peer;
+	}
+
+	read_unlock_bh(&rxrpc_peer_lock);
+	_leave(" = -EAFNOSUPPORT");
+	return ERR_PTR(-EAFNOSUPPORT);
+
+found_UDP_peer:
+	_net("Rx UDP DGRAM from peer %d", peer->debug_id);
+	atomic_inc(&peer->usage);
+	read_unlock_bh(&rxrpc_peer_lock);
+	_leave(" = %p", peer);
+	return peer;
+
+new_UDP_peer:
+	_net("Rx UDP DGRAM from NEW peer %d", peer->debug_id);
+	read_unlock_bh(&rxrpc_peer_lock);
+	_leave(" = -EBUSY [new]");
+	return ERR_PTR(-EBUSY);
+}
+
+/*
+ * release a remote transport endpoint
+ */
+void rxrpc_put_peer(struct rxrpc_peer *peer)
+{
+	_enter("%p{u=%d}", peer, atomic_read(&peer->usage));
+
+	ASSERTCMP(atomic_read(&peer->usage), >, 0);
+
+	if (likely(!atomic_dec_and_test(&peer->usage))) {
+		_leave(" [in use]");
+		return;
+	}
+
+	rxrpc_queue_work(&peer->destroyer);
+	_leave("");
+}
+
+/*
+ * destroy a remote transport endpoint
+ */
+static void rxrpc_destroy_peer(struct work_struct *work)
+{
+	struct rxrpc_peer *peer =
+		container_of(work, struct rxrpc_peer, destroyer);
+
+	_enter("%p{%d}", peer, atomic_read(&peer->usage));
+
+	write_lock_bh(&rxrpc_peer_lock);
+	list_del(&peer->link);
+	write_unlock_bh(&rxrpc_peer_lock);
+
+	_net("DESTROY PEER %d", peer->debug_id);
+	kfree(peer);
+
+	if (list_empty(&rxrpc_peers))
+		wake_up_all(&rxrpc_peer_wq);
+	_leave("");
+}
+
+/*
+ * preemptively destroy all the peer records from a transport endpoint rather
+ * than waiting for them to time out
+ */
+void __exit rxrpc_destroy_all_peers(void)
+{
+	DECLARE_WAITQUEUE(myself,current);
+
+	_enter("");
+
+	/* we simply have to wait for them to go away */
+	if (!list_empty(&rxrpc_peers)) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		add_wait_queue(&rxrpc_peer_wq, &myself);
+
+		while (!list_empty(&rxrpc_peers)) {
+			schedule();
+			set_current_state(TASK_UNINTERRUPTIBLE);
+		}
+
+		remove_wait_queue(&rxrpc_peer_wq, &myself);
+		set_current_state(TASK_RUNNING);
+	}
+
+	_leave("");
+}