/***
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*
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* ipv4/ip_input.c - process incoming IP packets
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*
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* Copyright (C) 2002 Ulrich Marx <marx@kammer.uni-hannover.de>
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* 2003-2005 Jan Kiszka <jan.kiszka@web.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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#include <net/checksum.h>
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#include <net/ip.h>
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#include <rtskb.h>
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#include <rtnet_socket.h>
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#include <stack_mgr.h>
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#include <ipv4/ip_fragment.h>
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#include <ipv4/protocol.h>
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#include <ipv4/route.h>
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#if IS_ENABLED(CONFIG_XENO_DRIVERS_NET_ADDON_PROXY)
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#include <ipv4/ip_input.h>
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rt_ip_fallback_handler_t rt_ip_fallback_handler = NULL;
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EXPORT_SYMBOL_GPL(rt_ip_fallback_handler);
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#endif /* CONFIG_XENO_DRIVERS_NET_ADDON_PROXY */
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/***
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* rt_ip_local_deliver
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*/
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static inline void rt_ip_local_deliver(struct rtskb *skb)
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{
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struct iphdr *iph = skb->nh.iph;
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unsigned short protocol = iph->protocol;
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struct rtinet_protocol *ipprot;
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struct rtsocket *sock;
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int err;
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ipprot = rt_inet_protocols[rt_inet_hashkey(protocol)];
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/* Check if we are supporting the protocol */
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if ((ipprot != NULL) && (ipprot->protocol == protocol)) {
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__rtskb_pull(skb, iph->ihl * 4);
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/* Point into the IP datagram, just past the header. */
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skb->h.raw = skb->data;
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/* Reassemble IP fragments */
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if (iph->frag_off & htons(IP_MF | IP_OFFSET)) {
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skb = rt_ip_defrag(skb, ipprot);
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if (!skb)
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return;
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sock = skb->sk;
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} else {
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/* Get the destination socket */
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if ((sock = ipprot->dest_socket(skb)) == NULL) {
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#if IS_ENABLED(CONFIG_XENO_DRIVERS_NET_ADDON_PROXY)
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if (rt_ip_fallback_handler) {
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__rtskb_push(skb, iph->ihl * 4);
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rt_ip_fallback_handler(skb);
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return;
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}
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#endif
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kfree_rtskb(skb);
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return;
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}
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/* Acquire the rtskb, to unlock the device skb pool */
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err = rtskb_acquire(skb, &sock->skb_pool);
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if (err) {
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kfree_rtskb(skb);
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rt_socket_dereference(sock);
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return;
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}
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}
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/* Deliver the packet to the next layer */
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ipprot->rcv_handler(skb);
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/* Packet is queued, socket can be released */
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rt_socket_dereference(sock);
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#if IS_ENABLED(CONFIG_XENO_DRIVERS_NET_ADDON_PROXY)
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} else if (rt_ip_fallback_handler) {
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/* If a fallback handler for IP protocol has been installed,
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* call it. */
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rt_ip_fallback_handler(skb);
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#endif /* CONFIG_XENO_DRIVERS_NET_ADDON_PROXY */
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} else {
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if (IS_ENABLED(CONFIG_XENO_DRIVERS_NET_RTIPV4_DEBUG))
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rtdm_printk("RTnet: no protocol found\n");
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kfree_rtskb(skb);
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}
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}
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/***
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* rt_ip_rcv
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*/
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int rt_ip_rcv(struct rtskb *skb, struct rtpacket_type *pt)
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{
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struct iphdr *iph;
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__u32 len;
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/* When the interface is in promisc. mode, drop all the crap
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* that it receives, do not try to analyse it.
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*/
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if (skb->pkt_type == PACKET_OTHERHOST)
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goto drop;
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iph = skb->nh.iph;
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/*
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* RFC1122: 3.1.2.2 MUST silently discard any IP frame that fails the checksum.
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*
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* Is the datagram acceptable?
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*
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* 1. Length at least the size of an ip header
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* 2. Version of 4
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* 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
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* 4. Doesn't have a bogus length
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*/
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if (iph->ihl < 5 || iph->version != 4)
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goto drop;
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if (ip_fast_csum((u8 *)iph, iph->ihl) != 0)
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goto drop;
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len = ntohs(iph->tot_len);
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if ((skb->len < len) || (len < ((__u32)iph->ihl << 2)))
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goto drop;
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rtskb_trim(skb, len);
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#ifdef CONFIG_XENO_DRIVERS_NET_RTIPV4_ROUTER
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if (rt_ip_route_forward(skb, iph->daddr))
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return 0;
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#endif /* CONFIG_XENO_DRIVERS_NET_RTIPV4_ROUTER */
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rt_ip_local_deliver(skb);
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return 0;
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drop:
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kfree_rtskb(skb);
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return 0;
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}
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