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| | // 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
*
* ip.c - IP related functions
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*/
#include <stddef.h>
#include <netinet/in.h>
#include "util.h"
#include "ip.h"
#define IPV6_NH_OPT(nh) \
((nh) == 0 || (nh) == 43 || (nh) == 44 || (nh) == 50 || \
(nh) == 51 || (nh) == 60 || (nh) == 135 || (nh) == 139 || \
(nh) == 140 || (nh) == 253 || (nh) == 254)
/**
* ipv6_l4hdr() - Find pointer to L4 header in IPv6 packet and extract protocol
* @data: IPv6 packet
* @proto: Filled with L4 protocol number
* @dlen: Data length (payload excluding header extensions), set on return
*
* Return: true if the L4 header is found and @data, @proto, @dlen are set,
* false on error. Outputs are indeterminate on failure.
*/
bool ipv6_l4hdr(struct iov_tail *data, uint8_t *proto, size_t *dlen)
{
struct ipv6_opt_hdr o_storage;
const struct ipv6_opt_hdr *o;
struct ipv6hdr ip6h_storage;
const struct ipv6hdr *ip6h;
int hdrlen;
uint8_t nh;
ip6h = IOV_REMOVE_HEADER(data, ip6h_storage);
if (!ip6h)
return false;
nh = ip6h->nexthdr;
if (!IPV6_NH_OPT(nh))
goto found;
while ((o = IOV_PEEK_HEADER(data, o_storage))) {
nh = o->nexthdr;
hdrlen = (o->hdrlen + 1) * 8;
if (IPV6_NH_OPT(nh))
iov_drop_header(data, hdrlen);
else
goto found;
}
return false;
found:
if (nh == IPPROTO_NONE)
return false;
*dlen = iov_tail_size(data);
*proto = nh;
return true;
}
/**
* ipproto_name() - Get IP protocol name from number
* @proto: IP protocol number
*
* Return: pointer to name of protocol @proto
*
* Usually this would be done with getprotobynumber(3) but that reads
* /etc/protocols and might allocate, which isn't possible for us once
* self-isolated.
*/
const char *ipproto_name(uint8_t proto)
{
switch (proto) {
case IPPROTO_ICMP:
return "ICMP";
case IPPROTO_TCP:
return "TCP";
case IPPROTO_UDP:
return "UDP";
case IPPROTO_ICMPV6:
return "ICMPv6";
default:
return "<unknown protocol>";
}
}
/**
* ip4_class_prefix_len() - Get class based prefix length for IPv4 address
* @addr: IPv4 address
*
* Return: prefix length based on address class, or 32 for other
*/
int ip4_class_prefix_len(const struct in_addr *addr)
{
in_addr_t a = ntohl(addr->s_addr);
if (IN_CLASSA(a))
return 32 - IN_CLASSA_NSHIFT;
if (IN_CLASSB(a))
return 32 - IN_CLASSB_NSHIFT;
if (IN_CLASSC(a))
return 32 - IN_CLASSC_NSHIFT;
return 32;
}
|