LXR linux/samples/bpf/tcp_bufs

   1/* Copyright (c) 2017 Facebook
   2 *
   3 * This program is free software; you can redistribute it and/or
   4 * modify it under the terms of version 2 of the GNU General Public
   5 * License as published by the Free Software Foundation.
   6 *
   7 * BPF program to set initial receive window to 40 packets and send
   8 * and receive buffers to 1.5MB. This would usually be done after
   9 * doing appropriate checks that indicate the hosts are far enough
  10 * away (i.e. large RTT).
  11 *
  12 * Use load_sock_ops to load this BPF program.
  13 */
  14
  15#include <uapi/linux/bpf.h>
  16#include <uapi/linux/if_ether.h>
  17#include <uapi/linux/if_packet.h>
  18#include <uapi/linux/ip.h>
  19#include <linux/socket.h>
  20#include "bpf_helpers.h"
  21#include "bpf_endian.h"
  22
  23#define DEBUG 1
  24
  25#define bpf_printk(fmt, ...)                                    \
  26({                                                              \
  27               char ____fmt[] = fmt;                            \
  28               bpf_trace_printk(____fmt, sizeof(____fmt),       \
  29                                ##__VA_ARGS__);                 \
  30})
  31
  32SEC("sockops")
  33int bpf_bufs(struct bpf_sock_ops *skops)
  34{
  35        int bufsize = 1500000;
  36        int rwnd_init = 40;
  37        int rv = 0;
  38        int op;
  39
  40        /* For testing purposes, only execute rest of BPF program
  41         * if neither port numberis 55601
  42         */
  43        if (bpf_ntohl(skops->remote_port) != 55601 &&
  44            skops->local_port != 55601)
  45                return -1;
  46
  47        op = (int) skops->op;
  48
  49#ifdef DEBUG
  50        bpf_printk("Returning %d\n", rv);
  51#endif
  52
  53        /* Usually there would be a check to insure the hosts are far
  54         * from each other so it makes sense to increase buffer sizes
  55         */
  56        switch (op) {
  57        case BPF_SOCK_OPS_RWND_INIT:
  58                rv = rwnd_init;
  59                break;
  60        case BPF_SOCK_OPS_TCP_CONNECT_CB:
  61                /* Set sndbuf and rcvbuf of active connections */
  62                rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
  63                                    sizeof(bufsize));
  64                rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
  65                                             &bufsize, sizeof(bufsize));
  66                break;
  67        case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
  68                /* Nothing to do */
  69                break;
  70        case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
  71                /* Set sndbuf and rcvbuf of passive connections */
  72                rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
  73                                    sizeof(bufsize));
  74                rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
  75                                             &bufsize, sizeof(bufsize));
  76                break;
  77        default:
  78                rv = -1;
  79        }
  80#ifdef DEBUG
  81        bpf_printk("Returning %d\n", rv);
  82#endif
  83        skops->reply = rv;
  84        return 1;
  85}
  86char _license[] SEC("license") = "GPL";
  87