// SPDX-License-Identifier: GPL-2.0-or-later

  /* RxRPC remote transport endpoint record management

   *

   * Copyright (C) 2007, 2016 Red Hat, Inc. All Rights Reserved.

   * Written by David Howells (dhowells@redhat.com)

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #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/slab.h>

  #include <linux/hashtable.h>

  #include <net/sock.h>
  #include <net/af_rxrpc.h>
  #include <net/ip.h>

  #include <net/route.h>

  #include <net/ip6_route.h>

  #include "ar-internal.h"

  /*
   * Hash a peer key.
   */
  static unsigned long rxrpc_peer_hash_key(struct rxrpc_local *local,
  					 const struct sockaddr_rxrpc *srx)
  {
  	const u16 *p;
  	unsigned int i, size;
  	unsigned long hash_key;
  
  	_enter("");
  
  	hash_key = (unsigned long)local / __alignof__(*local);
  	hash_key += srx->transport_type;
  	hash_key += srx->transport_len;
  	hash_key += srx->transport.family;
  
  	switch (srx->transport.family) {
  	case AF_INET:
  		hash_key += (u16 __force)srx->transport.sin.sin_port;
  		size = sizeof(srx->transport.sin.sin_addr);
  		p = (u16 *)&srx->transport.sin.sin_addr;
  		break;

  #ifdef CONFIG_AF_RXRPC_IPV6

  	case AF_INET6:
  		hash_key += (u16 __force)srx->transport.sin.sin_port;
  		size = sizeof(srx->transport.sin6.sin6_addr);
  		p = (u16 *)&srx->transport.sin6.sin6_addr;
  		break;

  #endif

  	default:
  		WARN(1, "AF_RXRPC: Unsupported transport address family
  ");
  		return 0;

  	}
  
  	/* Step through the peer address in 16-bit portions for speed */
  	for (i = 0; i < size; i += sizeof(*p), p++)
  		hash_key += *p;
  
  	_leave(" 0x%lx", hash_key);
  	return hash_key;
  }
  
  /*
   * Compare a peer to a key.  Return -ve, 0 or +ve to indicate less than, same
   * or greater than.
   *
   * Unfortunately, the primitives in linux/hashtable.h don't allow for sorted
   * buckets and mid-bucket insertion, so we don't make full use of this
   * information at this point.
   */
  static long rxrpc_peer_cmp_key(const struct rxrpc_peer *peer,
  			       struct rxrpc_local *local,
  			       const struct sockaddr_rxrpc *srx,
  			       unsigned long hash_key)
  {
  	long diff;
  
  	diff = ((peer->hash_key - hash_key) ?:
  		((unsigned long)peer->local - (unsigned long)local) ?:
  		(peer->srx.transport_type - srx->transport_type) ?:
  		(peer->srx.transport_len - srx->transport_len) ?:
  		(peer->srx.transport.family - srx->transport.family));
  	if (diff != 0)
  		return diff;
  
  	switch (srx->transport.family) {
  	case AF_INET:
  		return ((u16 __force)peer->srx.transport.sin.sin_port -
  			(u16 __force)srx->transport.sin.sin_port) ?:
  			memcmp(&peer->srx.transport.sin.sin_addr,
  			       &srx->transport.sin.sin_addr,
  			       sizeof(struct in_addr));

  #ifdef CONFIG_AF_RXRPC_IPV6

  	case AF_INET6:
  		return ((u16 __force)peer->srx.transport.sin6.sin6_port -
  			(u16 __force)srx->transport.sin6.sin6_port) ?:
  			memcmp(&peer->srx.transport.sin6.sin6_addr,
  			       &srx->transport.sin6.sin6_addr,
  			       sizeof(struct in6_addr));

  #endif

  	default:
  		BUG();
  	}
  }
  
  /*
   * Look up a remote transport endpoint for the specified address using RCU.
   */
  static struct rxrpc_peer *__rxrpc_lookup_peer_rcu(
  	struct rxrpc_local *local,
  	const struct sockaddr_rxrpc *srx,
  	unsigned long hash_key)
  {
  	struct rxrpc_peer *peer;

  	struct rxrpc_net *rxnet = local->rxnet;

  	hash_for_each_possible_rcu(rxnet->peer_hash, peer, hash_link, hash_key) {

  		if (rxrpc_peer_cmp_key(peer, local, srx, hash_key) == 0 &&
  		    atomic_read(&peer->usage) > 0)

  			return peer;

  	}
  
  	return NULL;
  }
  
  /*
   * Look up a remote transport endpoint for the specified address using RCU.
   */
  struct rxrpc_peer *rxrpc_lookup_peer_rcu(struct rxrpc_local *local,
  					 const struct sockaddr_rxrpc *srx)
  {
  	struct rxrpc_peer *peer;
  	unsigned long hash_key = rxrpc_peer_hash_key(local, srx);
  
  	peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
  	if (peer) {

  		_net("PEER %d {%pISp}", peer->debug_id, &peer->srx.transport);

  		_leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));
  	}
  	return peer;
  }

  
  /*

   * assess the MTU size for the network interface through which this peer is
   * reached
   */

  static void rxrpc_assess_MTU_size(struct rxrpc_sock *rx,
  				  struct rxrpc_peer *peer)

  {

  	struct net *net = sock_net(&rx->sk);

  	struct dst_entry *dst;

  	struct rtable *rt;

  	struct flowi fl;
  	struct flowi4 *fl4 = &fl.u.ip4;

  #ifdef CONFIG_AF_RXRPC_IPV6

  	struct flowi6 *fl6 = &fl.u.ip6;

  #endif

  
  	peer->if_mtu = 1500;

  	memset(&fl, 0, sizeof(fl));
  	switch (peer->srx.transport.family) {
  	case AF_INET:
  		rt = ip_route_output_ports(

  			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;
  		}
  		dst = &rt->dst;
  		break;

  #ifdef CONFIG_AF_RXRPC_IPV6

  	case AF_INET6:
  		fl6->flowi6_iif = LOOPBACK_IFINDEX;
  		fl6->flowi6_scope = RT_SCOPE_UNIVERSE;
  		fl6->flowi6_proto = IPPROTO_UDP;
  		memcpy(&fl6->daddr, &peer->srx.transport.sin6.sin6_addr,
  		       sizeof(struct in6_addr));
  		fl6->fl6_dport = htons(7001);
  		fl6->fl6_sport = htons(7000);

  		dst = ip6_route_output(net, NULL, fl6);

  		if (dst->error) {
  			_leave(" [route err %d]", dst->error);

  			return;
  		}
  		break;

  #endif

  
  	default:
  		BUG();

  	}

  	peer->if_mtu = dst_mtu(dst);
  	dst_release(dst);

  	_leave(" [if_mtu %u]", peer->if_mtu);

  }
  
  /*

   * Allocate a peer.

   */

  struct rxrpc_peer *rxrpc_alloc_peer(struct rxrpc_local *local, gfp_t gfp)

  {

  	const void *here = __builtin_return_address(0);

  	struct rxrpc_peer *peer;
  
  	_enter("");
  
  	peer = kzalloc(sizeof(struct rxrpc_peer), gfp);
  	if (peer) {

  		atomic_set(&peer->usage, 1);

  		peer->local = rxrpc_get_local(local);

  		INIT_HLIST_HEAD(&peer->error_targets);

  		peer->service_conns = RB_ROOT;

  		seqlock_init(&peer->service_conn_lock);

  		spin_lock_init(&peer->lock);

  		spin_lock_init(&peer->rtt_input_lock);

  		peer->debug_id = atomic_inc_return(&rxrpc_debug_id);

  		rxrpc_peer_init_rtt(peer);

  		if (RXRPC_TX_SMSS > 2190)
  			peer->cong_cwnd = 2;
  		else if (RXRPC_TX_SMSS > 1095)
  			peer->cong_cwnd = 3;
  		else
  			peer->cong_cwnd = 4;

  		trace_rxrpc_peer(peer->debug_id, rxrpc_peer_new, 1, here);

  	}
  
  	_leave(" = %p", peer);
  	return peer;
  }
  
  /*

   * Initialise peer record.
   */

  static void rxrpc_init_peer(struct rxrpc_sock *rx, struct rxrpc_peer *peer,
  			    unsigned long hash_key)

  {

  	peer->hash_key = hash_key;

  	rxrpc_assess_MTU_size(rx, peer);

  	peer->mtu = peer->if_mtu;

  	peer->rtt_last_req = ktime_get_real();

  	switch (peer->srx.transport.family) {
  	case AF_INET:

  		peer->hdrsize = sizeof(struct iphdr);

  		break;

  #ifdef CONFIG_AF_RXRPC_IPV6

  	case AF_INET6:
  		peer->hdrsize = sizeof(struct ipv6hdr);
  		break;

  #endif

  	default:
  		BUG();
  	}
  
  	switch (peer->srx.transport_type) {
  	case SOCK_DGRAM:
  		peer->hdrsize += sizeof(struct udphdr);
  		break;
  	default:

  		BUG();
  	}
  
  	peer->hdrsize += sizeof(struct rxrpc_wire_header);
  	peer->maxdata = peer->mtu - peer->hdrsize;
  }
  
  /*

   * Set up a new peer.
   */

  static struct rxrpc_peer *rxrpc_create_peer(struct rxrpc_sock *rx,
  					    struct rxrpc_local *local,

  					    struct sockaddr_rxrpc *srx,
  					    unsigned long hash_key,
  					    gfp_t gfp)
  {
  	struct rxrpc_peer *peer;
  
  	_enter("");
  
  	peer = rxrpc_alloc_peer(local, gfp);
  	if (peer) {

  		memcpy(&peer->srx, srx, sizeof(*srx));

  		rxrpc_init_peer(rx, peer, hash_key);

  	}

  	_leave(" = %p", peer);
  	return peer;
  }

  /*

   * Set up a new incoming peer.  There shouldn't be any other matching peers
   * since we've already done a search in the list from the non-reentrant context
   * (the data_ready handler) that is the only place we can add new peers.

   */

  void rxrpc_new_incoming_peer(struct rxrpc_sock *rx, struct rxrpc_local *local,
  			     struct rxrpc_peer *peer)

  {

  	struct rxrpc_net *rxnet = local->rxnet;

  	unsigned long hash_key;

  	hash_key = rxrpc_peer_hash_key(local, &peer->srx);

  	rxrpc_init_peer(rx, peer, hash_key);

  	spin_lock(&rxnet->peer_hash_lock);

  	hash_add_rcu(rxnet->peer_hash, &peer->hash_link, hash_key);
  	list_add_tail(&peer->keepalive_link, &rxnet->peer_keepalive_new);

  	spin_unlock(&rxnet->peer_hash_lock);

  }
  
  /*
   * obtain a remote transport endpoint for the specified address
   */

  struct rxrpc_peer *rxrpc_lookup_peer(struct rxrpc_sock *rx,
  				     struct rxrpc_local *local,

  				     struct sockaddr_rxrpc *srx, gfp_t gfp)

  {
  	struct rxrpc_peer *peer, *candidate;

  	struct rxrpc_net *rxnet = local->rxnet;

  	unsigned long hash_key = rxrpc_peer_hash_key(local, srx);

  	_enter("{%pISp}", &srx->transport);

  
  	/* search the peer list first */

  	rcu_read_lock();
  	peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
  	if (peer && !rxrpc_get_peer_maybe(peer))
  		peer = NULL;
  	rcu_read_unlock();
  
  	if (!peer) {
  		/* The peer is not yet present in hash - create a candidate
  		 * for a new record and then redo the search.
  		 */

  		candidate = rxrpc_create_peer(rx, local, srx, hash_key, gfp);

  		if (!candidate) {
  			_leave(" = NULL [nomem]");
  			return NULL;
  		}

  		spin_lock_bh(&rxnet->peer_hash_lock);

  		/* Need to check that we aren't racing with someone else */
  		peer = __rxrpc_lookup_peer_rcu(local, srx, hash_key);
  		if (peer && !rxrpc_get_peer_maybe(peer))
  			peer = NULL;

  		if (!peer) {

  			hash_add_rcu(rxnet->peer_hash,

  				     &candidate->hash_link, hash_key);

  			list_add_tail(&candidate->keepalive_link,
  				      &rxnet->peer_keepalive_new);

  		}

  		spin_unlock_bh(&rxnet->peer_hash_lock);

  		if (peer)
  			kfree(candidate);
  		else
  			peer = candidate;
  	}

  	_net("PEER %d {%pISp}", peer->debug_id, &peer->srx.transport);

  	_leave(" = %p {u=%d}", peer, atomic_read(&peer->usage));

  	return peer;

  }
  
  /*

   * Get a ref on a peer record.

   */

  struct rxrpc_peer *rxrpc_get_peer(struct rxrpc_peer *peer)
  {
  	const void *here = __builtin_return_address(0);
  	int n;
  
  	n = atomic_inc_return(&peer->usage);

  	trace_rxrpc_peer(peer->debug_id, rxrpc_peer_got, n, here);

  	return peer;
  }
  
  /*
   * Get a ref on a peer record unless its usage has already reached 0.
   */
  struct rxrpc_peer *rxrpc_get_peer_maybe(struct rxrpc_peer *peer)
  {
  	const void *here = __builtin_return_address(0);
  
  	if (peer) {

  		int n = atomic_fetch_add_unless(&peer->usage, 1, 0);

  		if (n > 0)

  			trace_rxrpc_peer(peer->debug_id, rxrpc_peer_got, n + 1, here);

  		else
  			peer = NULL;
  	}
  	return peer;
  }
  
  /*

   * Discard a peer record.
   */
  static void __rxrpc_put_peer(struct rxrpc_peer *peer)

  {

  	struct rxrpc_net *rxnet = peer->local->rxnet;

  	ASSERT(hlist_empty(&peer->error_targets));

  	spin_lock_bh(&rxnet->peer_hash_lock);

  	hash_del_rcu(&peer->hash_link);

  	list_del_init(&peer->keepalive_link);

  	spin_unlock_bh(&rxnet->peer_hash_lock);

  	rxrpc_put_local(peer->local);

  	kfree_rcu(peer, rcu);

  }

  /*
   * Drop a ref on a peer record.
   */
  void rxrpc_put_peer(struct rxrpc_peer *peer)
  {
  	const void *here = __builtin_return_address(0);

  	unsigned int debug_id;

  	int n;
  
  	if (peer) {

  		debug_id = peer->debug_id;

  		n = atomic_dec_return(&peer->usage);

  		trace_rxrpc_peer(debug_id, rxrpc_peer_put, n, here);

  		if (n == 0)
  			__rxrpc_put_peer(peer);
  	}
  }

  /*

   * Drop a ref on a peer record where the caller already holds the
   * peer_hash_lock.
   */
  void rxrpc_put_peer_locked(struct rxrpc_peer *peer)
  {
  	const void *here = __builtin_return_address(0);

  	unsigned int debug_id = peer->debug_id;

  	int n;
  
  	n = atomic_dec_return(&peer->usage);

  	trace_rxrpc_peer(debug_id, rxrpc_peer_put, n, here);

  	if (n == 0) {
  		hash_del_rcu(&peer->hash_link);
  		list_del_init(&peer->keepalive_link);

  		rxrpc_put_local(peer->local);

  		kfree_rcu(peer, rcu);
  	}
  }
  
  /*

   * Make sure all peer records have been discarded.
   */
  void rxrpc_destroy_all_peers(struct rxrpc_net *rxnet)
  {
  	struct rxrpc_peer *peer;
  	int i;
  
  	for (i = 0; i < HASH_SIZE(rxnet->peer_hash); i++) {
  		if (hlist_empty(&rxnet->peer_hash[i]))
  			continue;
  
  		hlist_for_each_entry(peer, &rxnet->peer_hash[i], hash_link) {
  			pr_err("Leaked peer %u {%u} %pISp
  ",
  			       peer->debug_id,
  			       atomic_read(&peer->usage),
  			       &peer->srx.transport);
  		}
  	}
  }

  /**
   * rxrpc_kernel_get_peer - Get the peer address of a call
   * @sock: The socket on which the call is in progress.
   * @call: The call to query
   * @_srx: Where to place the result
   *
   * Get the address of the remote peer in a call.
   */
  void rxrpc_kernel_get_peer(struct socket *sock, struct rxrpc_call *call,
  			   struct sockaddr_rxrpc *_srx)
  {
  	*_srx = call->peer->srx;
  }
  EXPORT_SYMBOL(rxrpc_kernel_get_peer);

  
  /**

   * rxrpc_kernel_get_srtt - Get a call's peer smoothed RTT

   * @sock: The socket on which the call is in progress.
   * @call: The call to query

   * @_srtt: Where to store the SRTT value.

   *

   * Get the call's peer smoothed RTT in uS.

   */

  bool rxrpc_kernel_get_srtt(struct socket *sock, struct rxrpc_call *call,
  			   u32 *_srtt)

  {

  	struct rxrpc_peer *peer = call->peer;
  
  	if (peer->rtt_count == 0) {
  		*_srtt = 1000000; /* 1S */
  		return false;
  	}
  
  	*_srtt = call->peer->srtt_us >> 3;
  	return true;

  }

  EXPORT_SYMBOL(rxrpc_kernel_get_srtt);