linux-imx

/* Copyright (c) 2017 Facebook

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of version 2 of the GNU General Public

 * License as published by the Free Software Foundation.

 *

 * Sample BPF program to set send and receive buffers to 150KB, sndcwnd clamp

 * to 100 packets and SYN and SYN_ACK RTOs to 10ms when both hosts are within

 * the same datacenter. For his example, we assume they are within the same

 * datacenter when the first 5.5 bytes of their IPv6 addresses are the same.

 *

 * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program.

 */

​

#include <uapi/linux/bpf.h>

#include <uapi/linux/if_ether.h>

#include <uapi/linux/if_packet.h>

#include <uapi/linux/ip.h>

#include <linux/socket.h>

#include "bpf_helpers.h"

#include "bpf_endian.h"

​

#define DEBUG 1

​

#define bpf_printk(fmt, ...)                    \

({                              \

           char ____fmt[] = fmt;                \

           bpf_trace_printk(____fmt, sizeof(____fmt),   \

                ##__VA_ARGS__);         \

})

​

SEC("sockops")

int bpf_clamp(struct bpf_sock_ops *skops)

{

    int bufsize = 150000;

    int to_init = 10;

    int clamp = 100;

    int rv = 0;

    int op;

​

    /* For testing purposes, only execute rest of BPF program

     * if neither port numberis 55601

     */

    if (bpf_ntohl(skops->remote_port) != 55601 && skops->local_port != 55601) {

        skops->reply = -1;

        return 0;

    }

​

    op = (int) skops->op;

​

#ifdef DEBUG

    bpf_printk("BPF command: %d\n", op);

#endif

​

    /* Check that both hosts are within same datacenter. For this example

     * it is the case when the first 5.5 bytes of their IPv6 addresses are

     * the same.

     */

    if (skops->family == AF_INET6 &&

        skops->local_ip6[0] == skops->remote_ip6[0] &&

        (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) ==

        (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) {

        switch (op) {