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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 * Sample BPF program to set send and receive buffers to 150KB, sndcwnd clamp8 * to 100 packets and SYN and SYN_ACK RTOs to 10ms when both hosts are within9 * the same datacenter. For his example, we assume they are within the same10 * datacenter when the first 5.5 bytes of their IPv6 addresses are the same.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_clamp(struct bpf_sock_ops *skops)27{28 int bufsize = 150000;29 int to_init = 10;30 int clamp = 100;31 int rv = 0;32 int op;33 34 /* For testing purposes, only execute rest of BPF program35 * if neither port numberis 5560136 */37 if (bpf_ntohl(skops->remote_port) != 55601 && skops->local_port != 55601) {38 skops->reply = -1;39 return 0;40 }41 42 op = (int) skops->op;43 44#ifdef DEBUG45 bpf_printk("BPF command: %d\n", op);46#endif47 48 /* Check that both hosts are within same datacenter. For this example49 * it is the case when the first 5.5 bytes of their IPv6 addresses are50 * the same.51 */52 if (skops->family == AF_INET6 &&53 skops->local_ip6[0] == skops->remote_ip6[0] &&54 (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) ==55 (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) {56 switch (op) {57 case BPF_SOCK_OPS_TIMEOUT_INIT:58 rv = to_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,63 &bufsize, sizeof(bufsize));64 rv += bpf_setsockopt(skops, SOL_SOCKET,65 SO_RCVBUF, &bufsize,66 sizeof(bufsize));67 break;68 case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:69 rv = bpf_setsockopt(skops, SOL_TCP,70 TCP_BPF_SNDCWND_CLAMP,71 &clamp, sizeof(clamp));72 break;73 case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:74 /* Set sndbuf and rcvbuf of passive connections */75 rv = bpf_setsockopt(skops, SOL_TCP,76 TCP_BPF_SNDCWND_CLAMP,77 &clamp, sizeof(clamp));78 rv += bpf_setsockopt(skops, SOL_SOCKET,79 SO_SNDBUF, &bufsize,80 sizeof(bufsize));81 rv += bpf_setsockopt(skops, SOL_SOCKET,82 SO_RCVBUF, &bufsize,83 sizeof(bufsize));84 break;85 default:86 rv = -1;87 }88 } else {89 rv = -1;90 }91#ifdef DEBUG92 bpf_printk("Returning %d\n", rv);93#endif94 skops->reply = rv;95 return 1;96}97char _license[] SEC("license") = "GPL";98