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// SPDX-License-Identifier: GPL-2.0
/*
* Test functionality of BPF filters with SO_REUSEPORT. This program creates
* an SO_REUSEPORT receiver group containing one socket per CPU core. It then
* creates a BPF program that will select a socket from this group based
* on the core id that receives the packet. The sending code artificially
* moves itself to run on different core ids and sends one message from
* each core. Since these packets are delivered over loopback, they should
* arrive on the same core that sent them. The receiving code then ensures
* that the packet was received on the socket for the corresponding core id.
* This entire process is done for several different core id permutations
* and for each IPv4/IPv6 and TCP/UDP combination.
*/
#define _GNU_SOURCE
#include <arpa/inet.h>
#include <errno.h>
#include <error.h>
#include <linux/filter.h>
#include <linux/in.h>
#include <linux/unistd.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
static const int PORT = 8888;
static void build_rcv_group(int *rcv_fd, size_t len, int family, int proto)
{
struct sockaddr_storage addr;
struct sockaddr_in *addr4;
struct sockaddr_in6 *addr6;
size_t i;
int opt;
switch (family) {
case AF_INET:
addr4 = (struct sockaddr_in *)&addr;
addr4->sin_family = AF_INET;
addr4->sin_addr.s_addr = htonl(INADDR_ANY);
addr4->sin_port = htons(PORT);
break;
case AF_INET6:
addr6 = (struct sockaddr_in6 *)&addr;
addr6->sin6_family = AF_INET6;
addr6->sin6_addr = in6addr_any;
addr6->sin6_port = htons(PORT);
break;
default:
error(1, 0, "Unsupported family %d", family);
}
for (i = 0; i < len; ++i) {
rcv_fd[i] = socket(family, proto, 0);
if (rcv_fd[i] < 0)
error(1, errno, "failed to create receive socket");
opt = 1;
if (setsockopt(rcv_fd[i], SOL_SOCKET, SO_REUSEPORT, &opt,
sizeof(opt)))
error(1, errno, "failed to set SO_REUSEPORT");
if (bind(rcv_fd[i], (struct sockaddr *)&addr, sizeof(addr)))
error(1, errno, "failed to bind receive socket");
if (proto == SOCK_STREAM && listen(rcv_fd[i], len * 10))
error(1, errno, "failed to listen on receive port");
}
}
static void attach_bpf(int fd)
{
struct sock_filter code[] = {
/* A = raw_smp_processor_id() */
{ BPF_LD | BPF_W | BPF_ABS, 0, 0, SKF_AD_OFF + SKF_AD_CPU },
/* return A */
{ BPF_RET | BPF_A, 0, 0, 0 },
};
struct sock_fprog p = {
.len = 2,
.filter = code,
};
if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_REUSEPORT_CBPF, &p, sizeof(p)))
error(1, errno, "failed to set SO_ATTACH_REUSEPORT_CBPF");
}
static void send_from_cpu(int cpu_id, int family, int proto)
{
struct sockaddr_storage saddr, daddr;
struct sockaddr_in *saddr4, *daddr4;
struct sockaddr_in6 *saddr6, *daddr6;
cpu_set_t cpu_set;
int fd;
switch (family) {
case AF_INET:
saddr4 = (struct sockaddr_in *)&saddr;
saddr4->sin_family = AF_INET;
saddr4->sin_addr.s_addr = htonl(INADDR_ANY);
saddr4->sin_port = 0;
daddr4 = (struct sockaddr_in *)&daddr;
daddr4->sin_family = AF_INET;
daddr4->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
daddr4->sin_port = htons(PORT);
break;
case AF_INET6:
saddr6 = (struct sockaddr_in6 *)&saddr;
saddr6->sin6_family = AF_INET6;
saddr6->sin6_addr = in6addr_any;
saddr6->sin6_port = 0;
daddr6 = (struct sockaddr_in6 *)&daddr;
daddr6->sin6_family = AF_INET6;
daddr6->sin6_addr = in6addr_loopback;
daddr6->sin6_port = htons(PORT);
break;
default:
error(1, 0, "Unsupported family %d", family);
}
memset(&cpu_set, 0, sizeof(cpu_set));
CPU_SET(cpu_id, &cpu_set);
if (sched_setaffinity(0, sizeof(cpu_set), &cpu_set) < 0)
error(1, errno, "failed to pin to cpu");
fd = socket(family, proto, 0);
if (fd < 0)
error(1, errno, "failed to create send socket");
if (bind(fd, (struct sockaddr *)&saddr, sizeof(saddr)))
error(1, errno, "failed to bind send socket");
if (connect(fd, (struct sockaddr *)&daddr, sizeof(daddr)))
error(1, errno, "failed to connect send socket");
if (send(fd, "a", 1, 0) < 0)
error(1, errno, "failed to send message");
close(fd);
}
static
void receive_on_cpu(int *rcv_fd, int len, int epfd, int cpu_id, int proto)
{
struct epoll_event ev;
int i, fd;
char buf[8];
i = epoll_wait(epfd, &ev, 1, -1);
if (i < 0)
error(1, errno, "epoll_wait failed");
if (proto == SOCK_STREAM) {
fd = accept(ev.data.fd, NULL, NULL);
if (fd < 0)
error(1, errno, "failed to accept");
i = recv(fd, buf, sizeof(buf), 0);
close(fd);
} else {
i = recv(ev.data.fd, buf, sizeof(buf), 0);
}
if (i < 0)
error(1, errno, "failed to recv");
for (i = 0; i < len; ++i)
if (ev.data.fd == rcv_fd[i])
break;
if (i == len)
error(1, 0, "failed to find socket");
fprintf(stderr, "send cpu %d, receive socket %d\n", cpu_id, i);
if (cpu_id != i)
error(1, 0, "cpu id/receive socket mismatch");
}
static void test(int *rcv_fd, int len, int family, int proto)
{
struct epoll_event ev;
int epfd, cpu;
build_rcv_group(rcv_fd, len, family, proto);
attach_bpf(rcv_fd[0]);
epfd = epoll_create(1);
if (epfd < 0)
error(1, errno, "failed to create epoll");
for (cpu = 0; cpu < len; ++cpu) {
ev.events = EPOLLIN;
ev.data.fd = rcv_fd[cpu];
if (epoll_ctl(epfd, EPOLL_CTL_ADD, rcv_fd[cpu], &ev))
error(1, errno, "failed to register sock epoll");
}
/* Forward iterate */
for (cpu = 0; cpu < len; ++cpu) {
send_from_cpu(cpu, family, proto);
receive_on_cpu(rcv_fd, len, epfd, cpu, proto);
}
/* Reverse iterate */
for (cpu = len - 1; cpu >= 0; --cpu) {
send_from_cpu(cpu, family, proto);
receive_on_cpu(rcv_fd, len, epfd, cpu, proto);
}
/* Even cores */
for (cpu = 0; cpu < len; cpu += 2) {
send_from_cpu(cpu, family, proto);
receive_on_cpu(rcv_fd, len, epfd, cpu, proto);
}
/* Odd cores */
for (cpu = 1; cpu < len; cpu += 2) {
send_from_cpu(cpu, family, proto);
receive_on_cpu(rcv_fd, len, epfd, cpu, proto);
}
close(epfd);
for (cpu = 0; cpu < len; ++cpu)
close(rcv_fd[cpu]);
}
int main(void)
{
int *rcv_fd, cpus;
cpus = sysconf(_SC_NPROCESSORS_ONLN);
if (cpus <= 0)
error(1, errno, "failed counting cpus");
rcv_fd = calloc(cpus, sizeof(int));
if (!rcv_fd)
error(1, 0, "failed to allocate array");
fprintf(stderr, "---- IPv4 UDP ----\n");
test(rcv_fd, cpus, AF_INET, SOCK_DGRAM);
fprintf(stderr, "---- IPv6 UDP ----\n");
test(rcv_fd, cpus, AF_INET6, SOCK_DGRAM);
fprintf(stderr, "---- IPv4 TCP ----\n");
test(rcv_fd, cpus, AF_INET, SOCK_STREAM);
fprintf(stderr, "---- IPv6 TCP ----\n");
test(rcv_fd, cpus, AF_INET6, SOCK_STREAM);
free(rcv_fd);
fprintf(stderr, "SUCCESS\n");
return 0;
}
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