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// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* ndp.c - NDP support for PASST
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*
*/
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <linux/if_ether.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/icmpv6.h>
#include <linux/udp.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <arpa/inet.h>
#include "passt.h"
#include "util.h"
#include "tap.h"
#define RS 133
#define RA 134
#define NS 135
#define NA 136
/**
* ndp() - Check for NDP solicitations, reply as needed
* @c: Execution context
* @len: Total L2 packet length
* @eh: Packet buffer, Ethernet header
*
* Return: 0 if not handled here, 1 if handled, -1 on failure
*/
int ndp(struct ctx *c, struct ethhdr *eh, size_t len)
{
struct ethhdr *ehr;
struct ipv6hdr *ip6h = (struct ipv6hdr *)(eh + 1), *ip6hr;
struct icmp6hdr *ih, *ihr;
char buf[BUFSIZ] = { 0 };
uint8_t proto, *p;
ih = (struct icmp6hdr *)ipv6_l4hdr(ip6h, &proto);
if (!ih)
return -1;
if (proto != IPPROTO_ICMPV6 ||
ih->icmp6_type < RS || ih->icmp6_type > NA)
return 0;
ehr = (struct ethhdr *)buf;
ip6hr = (struct ipv6hdr *)(ehr + 1);
ihr = (struct icmp6hdr *)(ip6hr + 1);
if (ih->icmp6_type == NS) {
fprintf(stderr, "NDP: received NS, sending NA\n");
ihr->icmp6_type = NA;
ihr->icmp6_code = 0;
ihr->icmp6_router = 1;
ihr->icmp6_solicited = 1;
ihr->icmp6_override = 1;
p = (unsigned char *)(ihr + 1);
memcpy(p, &c->gw6, sizeof(c->gw6)); /* target address */
p += 16;
*p++ = 2; /* target ll */
*p++ = 1; /* length */
memcpy(p, c->mac, ETH_ALEN);
p += 6;
} else if (ih->icmp6_type == RS) {
fprintf(stderr, "NDP: received RS, sending RA\n");
ihr->icmp6_type = RA;
ihr->icmp6_code = 0;
ihr->icmp6_rt_lifetime = htons(3600);
p = (unsigned char *)(ihr + 1);
p += 8; /* reachable, retrans time */
*p++ = 3; /* prefix */
*p++ = 4; /* length */
*p++ = 64; /* prefix length */
*p++ = 0xc0; /* flags: L, A */
*(uint32_t *)p = htonl(3600); /* lifetime */
p += 4;
*(uint32_t *)p = htonl(3600); /* preferred lifetime */
p += 8;
memcpy(p, &c->addr6, 8); /* prefix */
p += 16;
*p++ = 25; /* RDNS */
*p++ = 3; /* length */
p += 2;
*(uint32_t *)p = htonl(60); /* lifetime */
p += 4;
memcpy(p, &c->dns6, 16); /* address */
p += 16;
*p++ = 1; /* source ll */
*p++ = 1; /* length */
memcpy(p, c->mac, ETH_ALEN);
p += 6;
} else {
return 1;
}
len = (uintptr_t)p - (uintptr_t)ihr - sizeof(*ihr);
ip6hr->daddr = ip6h->saddr;
ip6hr->saddr = c->gw6;
ip6hr->payload_len = htons(sizeof(*ihr) + len);
ip6hr->hop_limit = IPPROTO_ICMPV6;
ihr->icmp6_cksum = 0;
ihr->icmp6_cksum = csum_ip4(ip6hr, sizeof(*ip6hr) +
sizeof(*ihr) + len);
ip6hr->version = 6;
ip6hr->nexthdr = IPPROTO_ICMPV6;
ip6hr->hop_limit = 255;
len += sizeof(*ehr) + sizeof(*ip6hr) + sizeof(*ihr);
memcpy(ehr->h_dest, eh->h_source, ETH_ALEN);
memcpy(ehr->h_source, c->mac, ETH_ALEN);
ehr->h_proto = htons(ETH_P_IPV6);
if (tap_send(c->fd_unix, ehr, len, 0) < 0)
perror("NDP: send");
return 1;
}
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