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// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
*
* util.c - Convenience helpers
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*
*/
#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
#include <unistd.h>
#include <linux/ipv6.h>
#include <arpa/inet.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <sys/epoll.h>
#include "passt.h"
/**
* csum_fold() - Fold long sum for IP and TCP checksum
* @sum: Original long sum
*
* Return: 16-bit folded sum
*/
uint16_t csum_fold(uint32_t sum)
{
while (sum >> 16)
sum = (sum & 0xffff) + (sum >> 16);
return sum;
}
/**
* csum_ipv4() - Calculate IPv4 checksum
* @buf: Packet buffer, L3 headers
* @len: Total L3 packet length
*
* Return: 16-bit IPv4-style checksum
*/
uint16_t csum_ip4(void *buf, size_t len)
{
uint32_t sum = 0;
uint16_t *p = buf;
size_t len1 = len / 2;
size_t off;
for (off = 0; off < len1; off++, p++)
sum += *p;
if (len % 2)
sum += *p & 0xff;
return ~csum_fold(sum);
}
/**
* csum_ipv4() - Calculate TCP checksum for IPv4 and set in place
* @iph: Packet buffer, IP header
*/
void csum_tcp4(struct iphdr *iph)
{
struct tcphdr *th = (struct tcphdr *)((char *)iph + iph->ihl * 4);
uint16_t tlen = ntohs(iph->tot_len) - iph->ihl * 4, *p = (uint16_t *)th;
uint32_t sum = 0;
sum += (iph->saddr >> 16) & 0xffff;
sum += iph->saddr & 0xffff;
sum += (iph->daddr >> 16) & 0xffff;
sum += iph->daddr & 0xffff;
sum += htons(IPPROTO_TCP);
sum += htons(tlen);
th->check = 0;
while (tlen > 1) {
sum += *p++;
tlen -= 2;
}
if (tlen > 0) {
sum += *p & htons(0xff00);
}
th->check = (uint16_t)~csum_fold(sum);
}
/**
* ipv6_l4hdr() - Find pointer to L4 header in IPv6 packet and extract protocol
* @ip6h: IPv6 header
* @proto: Filled with L4 protocol number
*
* Return: pointer to L4 header, NULL if not found
*/
char *ipv6_l4hdr(struct ipv6hdr *ip6h, uint8_t *proto)
{
int offset, len, hdrlen;
struct ipv6_opt_hdr *o;
uint8_t nh;
len = ntohs(ip6h->payload_len);
offset = 0;
while (offset < len) {
if (!offset) {
nh = ip6h->nexthdr;
hdrlen = sizeof(struct ipv6hdr);
} else {
nh = o->nexthdr;
hdrlen = (o->hdrlen + 1) * 8;
}
if (nh == 59)
return NULL;
if (nh == 0 || nh == 43 || nh == 44 || nh == 50 ||
nh == 51 || nh == 60 || nh == 135 || nh == 139 ||
nh == 140 || nh == 253 || nh == 254) {
offset += hdrlen;
o = (struct ipv6_opt_hdr *)(unsigned char *)ip6h +
offset;
} else {
*proto = nh;
return (char *)(ip6h + 1) + offset;
}
}
return NULL;
}
/**
* sock_l4_add() - Create and bind socket for given L4, add to epoll list
* @c: Execution context
* @v: IP protocol, 4 or 6
* @proto: Protocol number, network order
* @port: Port, network order
*
* Return: newly created socket, -1 on error
*/
int sock_l4_add(struct ctx *c, int v, uint16_t proto, uint16_t port)
{
struct sockaddr_in addr4 = {
.sin_family = AF_INET,
.sin_port = port,
.sin_addr = { .s_addr = INADDR_ANY },
};
struct sockaddr_in6 addr6 = {
.sin6_family = AF_INET6,
.sin6_port = port,
.sin6_addr = IN6ADDR_ANY_INIT,
};
struct epoll_event ev = { 0 };
const struct sockaddr *sa;
int fd, sl;
if (proto != IPPROTO_TCP && proto != IPPROTO_UDP)
return -1; /* Not implemented. */
fd = socket(v == 4 ? AF_INET : AF_INET6,
proto == IPPROTO_TCP ? SOCK_STREAM : SOCK_DGRAM, proto);
if (fd < 0) {
perror("L4 socket");
return -1;
}
if (v == 4) {
sa = (const struct sockaddr *)&addr4;
sl = sizeof(addr4);
} else {
sa = (const struct sockaddr *)&addr6;
sl = sizeof(addr6);
}
if (bind(fd, sa, sl) < 0) {
/* We'll fail to bind to low ports if we don't have enough
* capabilities, and we'll fail to bind on already bound ports,
* this is fine.
*/
close(fd);
return 0;
}
if (proto == IPPROTO_TCP && listen(fd, 128) < 0) {
perror("TCP socket listen");
close(fd);
return -1;
}
ev.events = EPOLLIN;
ev.data.fd = fd;
if (epoll_ctl(c->epollfd, EPOLL_CTL_ADD, fd, &ev) == -1) {
perror("L4 epoll_ctl");
return -1;
}
return fd;
}
/**
* timespec_diff_ms() - Report difference in milliseconds between two timestamps
* @a: Minuend timestamp
* @b: Subtrahend timestamp
*
* Return: difference in milliseconds
*/
int timespec_diff_ms(struct timespec *a, struct timespec *b)
{
if (a->tv_nsec < b->tv_nsec) {
return (b->tv_nsec - a->tv_nsec) / 1000 +
(a->tv_sec - b->tv_sec - 1) * 1000;
}
return (a->tv_nsec - b->tv_nsec) / 1000 +
(a->tv_sec - b->tv_sec) * 1000;
}
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