mirror of
https://passt.top/passt
synced 2024-12-22 05:35:23 +00:00
f9d677bff6
This fixes a number of harmless but slightly ugly warts in the ARP resolution code: * Use in4addr_any to represent 0.0.0.0 rather than hand constructing an example. * When comparing am->sip against 0.0.0.0 use sizeof(am->sip) instead of sizeof(am->tip) (same value, but makes more logical sense) * Described the guest's assigned address as such, rather than as "our address" - that's not usually what we mean by "our address" these days * Remove "we might have the same IP address" comment which I can't make sense of in context (possibly it's relating to the statement below, which already has its own comment?) Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
87 lines
2.1 KiB
C
87 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
|
|
/* PASST - Plug A Simple Socket Transport
|
|
* for qemu/UNIX domain socket mode
|
|
*
|
|
* PASTA - Pack A Subtle Tap Abstraction
|
|
* for network namespace/tap device mode
|
|
*
|
|
* arp.c - ARP implementation
|
|
*
|
|
* Copyright (c) 2020-2021 Red Hat GmbH
|
|
* Author: Stefano Brivio <sbrivio@redhat.com>
|
|
*/
|
|
|
|
#include <arpa/inet.h>
|
|
#include <limits.h>
|
|
#include <net/if.h>
|
|
#include <net/if_arp.h>
|
|
#include <netinet/if_ether.h>
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
#include <stdio.h>
|
|
#include <unistd.h>
|
|
#include <string.h>
|
|
|
|
#include "util.h"
|
|
#include "log.h"
|
|
#include "arp.h"
|
|
#include "dhcp.h"
|
|
#include "passt.h"
|
|
#include "tap.h"
|
|
|
|
/**
|
|
* arp() - Check if this is a supported ARP message, reply as needed
|
|
* @c: Execution context
|
|
* @p: Packet pool, single packet with Ethernet buffer
|
|
*
|
|
* Return: 1 if handled, -1 on failure
|
|
*/
|
|
int arp(const struct ctx *c, const struct pool *p)
|
|
{
|
|
unsigned char swap[4];
|
|
struct ethhdr *eh;
|
|
struct arphdr *ah;
|
|
struct arpmsg *am;
|
|
size_t l2len;
|
|
|
|
eh = packet_get(p, 0, 0, sizeof(*eh), NULL);
|
|
ah = packet_get(p, 0, sizeof(*eh), sizeof(*ah), NULL);
|
|
am = packet_get(p, 0, sizeof(*eh) + sizeof(*ah), sizeof(*am), NULL);
|
|
|
|
if (!eh || !ah || !am)
|
|
return -1;
|
|
|
|
if (ah->ar_hrd != htons(ARPHRD_ETHER) ||
|
|
ah->ar_pro != htons(ETH_P_IP) ||
|
|
ah->ar_hln != ETH_ALEN ||
|
|
ah->ar_pln != 4 ||
|
|
ah->ar_op != htons(ARPOP_REQUEST))
|
|
return 1;
|
|
|
|
/* Discard announcements, but not 0.0.0.0 "probes" */
|
|
if (memcmp(am->sip, &in4addr_any, sizeof(am->sip)) &&
|
|
!memcmp(am->sip, am->tip, sizeof(am->sip)))
|
|
return 1;
|
|
|
|
/* Don't resolve the guest's assigned address, either. */
|
|
if (!memcmp(am->tip, &c->ip4.addr, sizeof(am->tip)))
|
|
return 1;
|
|
|
|
ah->ar_op = htons(ARPOP_REPLY);
|
|
memcpy(am->tha, am->sha, sizeof(am->tha));
|
|
memcpy(am->sha, c->our_tap_mac, sizeof(am->sha));
|
|
|
|
memcpy(swap, am->tip, sizeof(am->tip));
|
|
memcpy(am->tip, am->sip, sizeof(am->tip));
|
|
memcpy(am->sip, swap, sizeof(am->sip));
|
|
|
|
l2len = sizeof(*eh) + sizeof(*ah) + sizeof(*am);
|
|
memcpy(eh->h_dest, eh->h_source, sizeof(eh->h_dest));
|
|
memcpy(eh->h_source, c->our_tap_mac, sizeof(eh->h_source));
|
|
|
|
tap_send_single(c, eh, l2len);
|
|
|
|
return 1;
|
|
}
|