726 lines
22 KiB
C
726 lines
22 KiB
C
/****************************************************************************
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* net/ipforward/ipv6_forward.c
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*
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* Copyright (C) 2017 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <string.h>
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#include <assert.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/mm/iob.h>
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#include <nuttx/net/net.h>
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#include <nuttx/net/netdev.h>
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#include <nuttx/net/netstats.h>
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#include "netdev/netdev.h"
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#include "sixlowpan/sixlowpan.h"
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#include "devif/devif.h"
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#include "ipforward/ipforward.h"
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#if defined(CONFIG_NET_IPFORWARD) && defined(CONFIG_NET_IPv6)
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define PACKET_FORWARDED 0
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#define PACKET_NOT_FORWARDED 1
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: ipv6_hdrsize
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*
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* Description:
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* Return the size of the IPv6 header and the following.
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*
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* Input Parameters:
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* ipv6 - A pointer to the IPv6 header in within the IPv6 packet. This
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* is immeidately followed by the L3 header which may be TCP, UDP,
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* or ICMPv6.
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*
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* Returned Value:
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* The size of the combined L2 + L3 headers is returned on success. An
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* error is returned only if the prototype is not supported.
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*
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****************************************************************************/
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#if defined(CONFIG_NETDEV_MULTINIC) && defined(CONFIG_DEBUG_NET_WARN)
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static int ipv6_hdrsize(FAR struct ipv6_hdr_s *ipv6)
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{
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/* Size is determined by the following protocol header, */
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switch (ipv6->proto)
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{
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#ifdef CONFIG_NET_TCP
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case IP_PROTO_TCP:
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{
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FAR struct tcp_hdr_s *tcp =
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(FAR struct tcp_hdr_s *)((FAR uint8_t *)ipv6 + IPv6_HDRLEN);
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unsigned int tcpsize;
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/* The TCP header length is encoded in the top 4 bits of the
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* tcpoffset field (in units of 32-bit words).
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*/
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tcpsize = ((uint16_t)tcp->tcpoffset >> 4) << 2;
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return IPv6_HDRLEN + tcpsize;
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}
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break;
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#endif
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#ifdef CONFIG_NET_UDP
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case IP_PROTO_UDP:
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return IPv6_HDRLEN + UDP_HDRLEN;
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break;
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#endif
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#ifdef CONFIG_NET_ICMPv6
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case IP_PROTO_ICMP6:
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return IPv6_HDRLEN + ICMPv6_HDRLEN;
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break;
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#endif
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default:
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nwarn("WARNING: Unrecognized proto: %u\n", ipv6->proto);
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return -EPROTONOSUPPORT;
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}
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}
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#endif
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/****************************************************************************
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* Name: ipv6_decr_ttl
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*
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* Description:
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* Decrement the IPv6 TTL (time to live value). TTL field is set by the
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* sender of the packet and reduced by every router on the route to its
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* destination. If the TTL field reaches zero before the datagram arrives
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* at its destination, then the datagram is discarded and an ICMP error
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* packet (11 - Time Exceeded) is sent back to the sender.
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*
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* The purpose of the TTL field is to avoid a situation in which an
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* undeliverable datagram keeps circulating on an Internet system, and
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* such a system eventually becoming swamped by such "immortals".
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*
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* Input Parameters:
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* ipv6 - A pointer to the IPv6 header in within the IPv6 packet to be
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* forwarded.
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*
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* Returned Value:
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* The new TTL value is returned. A value <= 0 means the hop limit has
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* expired.
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*
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****************************************************************************/
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#if defined(CONFIG_NETDEV_MULTINIC) || defined(CONFIG_NET_6LOWPAN)
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static int ipv6_decr_ttl(FAR struct ipv6_hdr_s *ipv6)
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{
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int ttl = (int)ipv6->ttl - 1;
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if (ttl <= 0)
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{
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#ifdef CONFIG_NET_ICMPv6
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/* Return an ICMPv6 error packet back to the sender. */
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# warning Missing logic
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#endif
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/* Return zero which must cause the packet to be dropped */
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return 0;
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}
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/* Save the updated TTL value */
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ipv6->ttl = ttl;
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/* NOTE: We do not have to recalculate the IPv6 checksum because (1) the
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* IPv6 header does not include a checksum itself and (2) the TTL is not
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* included in the sum for the TCP and UDP headers.
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*/
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return ttl;
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}
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#endif
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/****************************************************************************
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* Name: ipv6_packet_conversion
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*
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* Description:
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* Generic output conversion hook. Only needed for IEEE802.15.4 for now
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* but this is a point where support for other conversions may be
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* provided.
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*
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* Returned value:
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* PACKET_FORWARDED - Packet was forwarded
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* PACKET_NOT_FORWARDED - Packet was not forwarded
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* < 0 - And error occurred (and packet not fowarded).
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*
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****************************************************************************/
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#ifdef CONFIG_NET_6LOWPAN
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static int ipv6_packet_conversion(FAR struct net_driver_s *dev,
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FAR struct net_driver_s *fwddev,
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FAR struct ipv6_hdr_s *ipv6)
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{
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int ret = PACKET_NOT_FORWARDED;
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if (dev->d_len > 0)
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{
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#ifdef CONFIG_NET_MULTILINK
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/* Handle the case where multiple link layer protocols are supported */
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if (fwddev->d_lltype == NET_LL_IEEE802154)
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{
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nwarn("WARNING: Unsupported link layer... Not forwarded\n");
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}
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else
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#endif
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#ifdef CONFIG_NET_TCP
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if (ipv6->proto == IP_PROTO_TCP)
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{
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/* Decrement the TTL in the IPv6 header. If it decrements to
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* zero, then drop the packet.
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*/
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ret = ipv6_decr_ttl(ipv6);
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if (ret < 1)
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{
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nwarn("WARNING: Hop limit exceeded... Dropping!\n");
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ret = -EMULTIHOP;
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}
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else
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{
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/* Let 6LoWPAN convert IPv6 TCP output into IEEE802.15.4
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* frames.
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*/
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sixlowpan_tcp_send(dev, fwddev, ipv6);
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/* The packet was forwarded */
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dev->d_len = 0;
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return PACKET_FORWARDED;
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}
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}
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else
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#endif
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#ifdef CONFIG_NET_UDP
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if (ipv6->proto == IP_PROTO_UDP)
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{
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/* Decrement the TTL in the IPv6 header. If it decrements to
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* zero, then drop the packet.
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*/
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ret = ipv6_decr_ttl(ipv6);
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if (ret < 1)
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{
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nwarn("WARNING: Hop limit exceeded... Dropping!\n");
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ret = -EMULTIHOP;
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}
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else
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{
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/* Let 6LoWPAN convert IPv6 UDP output into IEEE802.15.4
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* frames.
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*/
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sixlowpan_udp_send(dev, fwddev, ipv6);
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/* The packet was forwarded */
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dev->d_len = 0;
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return PACKET_FORWARDED;
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}
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}
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else
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#endif
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#ifdef CONFIG_NET_ICMPv6
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if (ipv6->proto == IP_PROTO_ICMP6)
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{
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/* Decrement the TTL in the IPv6 header. If it decrements to
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* zero, then drop the packet.
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*/
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ret = ipv6_decr_ttl(ipv6);
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if (ret < 1)
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{
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nwarn("WARNING: Hop limit exceeded... Dropping!\n");
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ret = -EMULTIHOP;
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}
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else
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{
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/* Let 6LoWPAN convert IPv6 ICMPv6 output into IEEE802.15.4
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* frames.
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*/
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sixlowpan_icmpv6_send(dev, fwddev, ipv6);
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/* The packet was forwarded */
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dev->d_len = 0;
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return PACKET_FORWARDED;
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}
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}
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else
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#endif
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{
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/* Otherwise, we cannot forward the packet */
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nwarn("WARNING: Dropping. Unsupported 6LoWPAN protocol: %d\n",
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ipv6->proto);
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}
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}
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/* The packet was not forwarded (or the HOP limit was exceeded) */
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ipv6_dropstats(ipv6);
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return ret;
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}
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#else
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# define ipv6_packet_conversion(dev, fwddev, ipv6) (PACKET_NOT_FORWARDED)
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#endif /* CONFIG_NET_6LOWPAN */
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/****************************************************************************
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* Name: ipv6_dev_forward
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*
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* Description:
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* This function is called from ipv6_forward when it is necessary to
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* forward a packet from the current device to different device. In this
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* case, the forwarding operation must be performed asynchronously when
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* the TX poll is received from the forwarding device.
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*
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* Input Parameters:
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* dev - The device on which the packet was received and which
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* contains the IPv6 packet.
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* fwdddev - The device on which the packet must be forwarded.
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* ipv6 - A pointer to the IPv6 header in within the IPv6 packet
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*
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* Returned Value:
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* Zero is returned if the packet was successfully forwarded; A negated
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* errno value is returned if the packet is not forwardable. In that
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* latter case, the caller (ipv6_input()) should drop the packet.
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*
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****************************************************************************/
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#ifdef CONFIG_NETDEV_MULTINIC
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static int ipv6_dev_forward(FAR struct net_driver_s *dev,
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FAR struct net_driver_s *fwddev,
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FAR struct ipv6_hdr_s *ipv6)
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{
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FAR struct forward_s *fwd = NULL;
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#ifdef CONFIG_DEBUG_NET_WARN
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int hdrsize;
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#endif
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int ret;
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/* Perform any necessary packet conversions. */
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ret = ipv6_packet_conversion(dev, fwddev, ipv6);
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if (ret < 0)
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{
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nwarn("WARNING: ipv6_packet_conversion failed: %d\n", ret);
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goto errout;
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}
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else if (ret == PACKET_NOT_FORWARDED)
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{
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/* Verify that the full packet will fit within the forwarding devices
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* MTU. We provide no support for fragmenting forwarded packets.
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*/
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if (NET_LL_HDRLEN(fwddev) + dev->d_len > NET_DEV_MTU(fwddev))
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{
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nwarn("WARNING: Packet > MTU... Dropping\n");
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ret = -EFBIG;
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goto errout;
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}
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/* Get a pre-allocated forwarding structure, This structure will be
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* completely zeroed when we receive it.
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*/
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fwd = ipfwd_alloc();
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if (fwd == NULL)
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{
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nwarn("WARNING: Failed to allocate forwarding structure\n");
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ret = -ENOMEM;
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goto errout;
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}
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/* Initialize the easy stuff in the forwarding structure */
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fwd->f_dev = fwddev; /* Forwarding device */
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#ifdef CONFIG_NET_IPv4
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fwd->f_domain = PF_INET6; /* IPv6 address domain */
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#endif
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#ifdef CONFIG_DEBUG_NET_WARN
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/* Get the size of the IPv6 + L3 header. */
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hdrsize = ipv6_hdrsize(ipv6);
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if (hdrsize < IPv6_HDRLEN)
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{
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nwarn("WARNING: Could not determine L2+L3 header size\n");
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ret = -EPROTONOSUPPORT;
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goto errout_with_fwd;
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}
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/* The L2/L3 headers must fit within one, contiguous IOB. */
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if (hdrsize > CONFIG_IOB_BUFSIZE)
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{
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nwarn("WARNING: Header is too big for pre-allocated structure\n");
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ret = -E2BIG;
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goto errout_with_fwd;
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}
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#endif
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/* Try to allocate the head of an IOB chain. If this fails, the
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* packet will be dropped; we are not operating in a context where
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* waiting for an IOB is a good idea
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*/
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fwd->f_iob = iob_tryalloc(false);
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if (fwd->f_iob == NULL)
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{
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nwarn("WARNING: iob_tryalloc() failed\n");
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ret = -ENOMEM;
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goto errout_with_fwd;
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}
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/* Copy the L2/L3 headers plus any following payload into an IOB
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* chain. iob_trycopin() will not wait, but will fail there are no
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* available IOBs.
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*
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* REVISIT: Consider an alternative design that does not require data
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* copying. This would require a pool of d_buf's that are managed by
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* the network rather than the network device.
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*/
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ret = iob_trycopyin(fwd->f_iob, (FAR const uint8_t *)ipv6,
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dev->d_len, 0, false);
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if (ret < 0)
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{
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nwarn("WARNING: iob_trycopyin() failed: %d\n", ret);
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goto errout_with_iobchain;
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}
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/* Decrement the TTL in the copy of the IPv6 header (retaining the
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* original TTL in the sourcee to handle the broadcast case). If the
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* TTL decrements to zero, then do not forward the packet.
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*/
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ret = ipv6_decr_ttl((FAR struct ipv6_hdr_s *)fwd->f_iob->io_data);
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if (ret < 1)
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{
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nwarn("WARNING: Hop limit exceeded... Dropping!\n");
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ret = -EMULTIHOP;
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goto errout_with_iobchain;
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}
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/* Then set up to forward the packet according to the protocol. */
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ret = ipfwd_forward(fwd);
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if (ret >= 0)
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{
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dev->d_len = 0;
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return OK;
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}
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}
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errout_with_iobchain:
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if (fwd != NULL && fwd->f_iob != NULL)
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{
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iob_free_chain(fwd->f_iob);
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}
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errout_with_fwd:
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if (fwd != NULL)
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{
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ipfwd_free(fwd);
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}
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errout:
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return ret;
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}
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#endif /* CONFIG_NETDEV_MULTINIC */
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/****************************************************************************
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* Name: ipv6_forward_callback
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*
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* Description:
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* This function is a callback from netdev_foreach. It implements the
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* the broadcase forwarding action for each network device (other than, of
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* course, the device that received the packet).
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*
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* Input Parameters:
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* dev - The device on which the packet was received and which contains
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* the IPv6 packet.
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* ipv6 - A convenience pointer to the IPv6 header in within the IPv6
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* packet
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*
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* Returned Value:
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* Typically returns zero (meaning to continue the enumeration), but will
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* return a non-zero to stop the enumeration if an error occurs.
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*
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****************************************************************************/
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#if defined(CONFIG_NET_IPFORWARD_BROADCAST) && \
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defined(CONFIG_NETDEV_MULTINIC)
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int ipv6_forward_callback(FAR struct net_driver_s *fwddev, FAR void *arg)
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{
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FAR struct net_driver_s *dev = (FAR struct net_driver_s *)arg;
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FAR struct ipv6_hdr_s *ipv6;
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int ret;
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DEBUGASSERT(fwddev != NULL && dev != NULL && dev->d_buf != NULL);
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/* Check if we are forwarding on the same device that we received the
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* packet from.
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*/
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if (fwddev != dev)
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{
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/* Recover the pointer to the IPv6 header in the receiving device's
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* d_buf.
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*/
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ipv6 = (FAR struct ipv6_hdr_s *)&dev->d_buf[NET_LL_HDRLEN(dev)];
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/* Send the packet asynchrously on the forwarding device. */
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ret = ipv6_dev_forward(dev, fwddev, ipv6);
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if (ret < 0)
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{
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nwarn("WARNING: ipv6_dev_forward failed: %d\n", ret);
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return ret;
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}
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}
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return OK;
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}
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#endif
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: ipv6_forward
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*
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* Description:
|
|
* This function is called from ipv6_input when a packet is received that
|
|
* is not destined for us. In this case, the packet may need to be
|
|
* forwarded to another device (or sent back out the same device)
|
|
* depending configuration, routing table information, and the IPv6
|
|
* networks served by various network devices.
|
|
*
|
|
* Input Parameters:
|
|
* dev - The device on which the packet was received and which contains
|
|
* the IPv6 packet.
|
|
* ipv6 - A convenience pointer to the IPv6 header in within the IPv6
|
|
* packet
|
|
*
|
|
* On input:
|
|
* - dev->d_buf holds the received packet.
|
|
* - dev->d_len holds the length of the received packet MINUS the
|
|
* size of the L1 header. That was subtracted out by ipv6_input.
|
|
* - ipv6 points to the IPv6 header with dev->d_buf.
|
|
*
|
|
* Returned Value:
|
|
* Zero is returned if the packet was successfully forward; A negated
|
|
* errno value is returned if the packet is not forwardable. In that
|
|
* latter case, the caller (ipv6_input()) should drop the packet.
|
|
*
|
|
****************************************************************************/
|
|
|
|
int ipv6_forward(FAR struct net_driver_s *dev, FAR struct ipv6_hdr_s *ipv6)
|
|
{
|
|
FAR struct net_driver_s *fwddev;
|
|
int ret;
|
|
|
|
/* Search for a device that can forward this packet. This is a trivial
|
|
* search if there is only a single network device (CONFIG_NETDEV_MULTINIC
|
|
* not defined). But netdev_findby_ipv6addr() will still assure
|
|
* routability in that case.
|
|
*/
|
|
|
|
#ifdef CONFIG_NETDEV_MULTINIC
|
|
fwddev = netdev_findby_ipv6addr(ipv6->srcipaddr, ipv6->destipaddr);
|
|
#else
|
|
fwddev = netdev_findby_ipv6addr(ipv6->destipaddr);
|
|
#endif
|
|
if (fwddev == NULL)
|
|
{
|
|
nwarn("WARNING: Not routable\n");
|
|
return (ssize_t)-ENETUNREACH;
|
|
}
|
|
|
|
#if defined(CONFIG_NETDEV_MULTINIC)
|
|
/* Check if we are forwarding on the same device that we received the
|
|
* packet from.
|
|
*/
|
|
|
|
if (fwddev != dev)
|
|
{
|
|
/* Send the packet asynchrously on the forwarding device. */
|
|
|
|
ret = ipv6_dev_forward(dev, fwddev, ipv6);
|
|
if (ret < 0)
|
|
{
|
|
nwarn("WARNING: ipv6_dev_forward failed: %d\n", ret);
|
|
goto drop;
|
|
}
|
|
}
|
|
else
|
|
#endif /* CONFIG_NETDEV_MULTINIC */
|
|
|
|
#if defined(CONFIG_NET_6LOWPAN) /* REVISIT: Currently only suport for 6LoWPAN */
|
|
{
|
|
/* Single network device. The use case here is where an endpoint acts
|
|
* as a hub in a star configuration. This is typical for a wireless star
|
|
* configuration where not all endpoints are accessible from all other
|
|
* endpoints, but seems less useful for a wired network.
|
|
*/
|
|
|
|
/* Perform any necessary packet conversions. If the packet was handled
|
|
* via a backdoor path (or dropped), then dev->d_len will be zero. If
|
|
* the packet needs to be forwarded in the normal manner then
|
|
* dev->d_len will be unchanged.
|
|
*/
|
|
|
|
ret = ipv6_packet_conversion(dev, dev, ipv6);
|
|
if (ret < 0)
|
|
{
|
|
nwarn("WARNING: ipv6_packet_conversion failed: %d\n", ret);
|
|
goto drop;
|
|
}
|
|
else if (ret == PACKET_NOT_FORWARDED)
|
|
{
|
|
#ifdef CONFIG_NET_ETHERNET
|
|
/* REVISIT: For Ethernet we may have to fix up the Ethernet header:
|
|
* - source MAC, the MAC of the current device.
|
|
* - dest MAC, the MAC associated with the destination IPv6 adress.
|
|
* This will involve ICMPv6 and Neighbor Discovery.
|
|
*/
|
|
|
|
/* Correct dev->d_buf by adding back the L1 header length */
|
|
#endif
|
|
|
|
/* Nothing other 6LoWPAN forwarding is currently handled and that
|
|
* case was dealt with in ipv6_packet_conversion().
|
|
*
|
|
* REVISIT: Is tht an issue? Do other use cases make sense?
|
|
*/
|
|
|
|
nwarn("WARNING: Packet forwarding supported only for 6LoWPAN\n");
|
|
ret = -ENOSYS;
|
|
goto drop;
|
|
}
|
|
}
|
|
|
|
#else /* CONFIG_NET_6LOWPAN */
|
|
{
|
|
nwarn("WARNING: Packet forwarding not supported in this configuration\n");
|
|
ret = -ENOSYS;
|
|
goto drop;
|
|
}
|
|
#endif /* CONFIG_NET_6LOWPAN */
|
|
|
|
/* Return success. ipv6_input will return to the network driver with
|
|
* dev->d_len set to the packet size and the network driver will perform
|
|
* the transfer.
|
|
*/
|
|
|
|
return OK;
|
|
|
|
drop:
|
|
ipv6_dropstats(ipv6);
|
|
dev->d_len = 0;
|
|
return ret;
|
|
}
|
|
|
|
/****************************************************************************
|
|
* Name: ipv6_forward_broadcast
|
|
*
|
|
* Description:
|
|
* This function is called from ipv6_input when a broadcast or multicast
|
|
* packet is received. If CONFIG_NET_IPFORWARD_BROADCAST is enabled, this
|
|
* function will forward the broadcast packet to other networks through
|
|
* other network devices.
|
|
*
|
|
* Input Parameters:
|
|
* dev - The device on which the packet was received and which contains
|
|
* the IPv6 packet.
|
|
* ipv6 - A convenience pointer to the IPv6 header in within the IPv6
|
|
* packet
|
|
*
|
|
* On input:
|
|
* - dev->d_buf holds the received packet.
|
|
* - dev->d_len holds the length of the received packet MINUS the
|
|
* size of the L1 header. That was subtracted out by ipv6_input.
|
|
* - ipv6 points to the IPv6 header with dev->d_buf.
|
|
*
|
|
* Returned Value:
|
|
* None
|
|
*
|
|
****************************************************************************/
|
|
|
|
#if defined(CONFIG_NET_IPFORWARD_BROADCAST) && \
|
|
defined(CONFIG_NETDEV_MULTINIC)
|
|
void ipv6_forward_broadcast(FAR struct net_driver_s *dev,
|
|
FAR struct ipv6_hdr_s *ipv6)
|
|
{
|
|
/* Don't bother if the TTL would expire */
|
|
|
|
if (ipv6->ttl > 1)
|
|
{
|
|
/* Forward the the broadcast/multicast packet to all devices except,
|
|
* of course, the device that received the packet.
|
|
*/
|
|
|
|
(void)netdev_foreach(ipv6_forward_callback, dev);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
#endif /* CONFIG_NET_IPFORWARD && CONFIG_NET_IPv6 */
|