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1/* Copyright (c) 2017 Facebook2 *3 * This program is free software; you can redistribute it and/or4 * modify it under the terms of version 2 of the GNU General Public5 * License as published by the Free Software Foundation.6 *7 * BPF program to set initial receive window to 40 packets and send8 * and receive buffers to 1.5MB. This would usually be done after9 * doing appropriate checks that indicate the hosts are far enough10 * away (i.e. large RTT).11 *12 * Use "bpftool cgroup attach $cg sock_ops $prog" 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/bpf_helpers.h>21#include <bpf/bpf_endian.h>22 23#define DEBUG 124 25SEC("sockops")26int bpf_bufs(struct bpf_sock_ops *skops)27{28 int bufsize = 1500000;29 int rwnd_init = 40;30 int rv = 0;31 int op;32 33 /* For testing purposes, only execute rest of BPF program34 * if neither port numberis 5560135 */36 if (bpf_ntohl(skops->remote_port) != 55601 &&37 skops->local_port != 55601) {38 skops->reply = -1;39 return 1;40 }41 42 op = (int) skops->op;43 44#ifdef DEBUG45 bpf_printk("Returning %d\n", rv);46#endif47 48 /* Usually there would be a check to insure the hosts are far49 * from each other so it makes sense to increase buffer sizes50 */51 switch (op) {52 case BPF_SOCK_OPS_RWND_INIT:53 rv = rwnd_init;54 break;55 case BPF_SOCK_OPS_TCP_CONNECT_CB:56 /* Set sndbuf and rcvbuf of active connections */57 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,58 sizeof(bufsize));59 rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,60 &bufsize, sizeof(bufsize));61 break;62 case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:63 /* Nothing to do */64 break;65 case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:66 /* Set sndbuf and rcvbuf of passive connections */67 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,68 sizeof(bufsize));69 rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,70 &bufsize, sizeof(bufsize));71 break;72 default:73 rv = -1;74 }75#ifdef DEBUG76 bpf_printk("Returning %d\n", rv);77#endif78 skops->reply = rv;79 return 1;80}81char _license[] SEC("license") = "GPL";82