| /* 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. |
| * |
| * BPF program to set SYN and SYN-ACK RTOs to 10ms when using IPv6 addresses |
| * and the first 5.5 bytes of the IPv6 addresses are the same (in this example |
| * that means both hosts are in the same datacenter). |
| * |
| * 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 |
| |
| SEC("sockops") |
| int bpf_synrto(struct bpf_sock_ops *skops) |
| { |
| int rv = -1; |
| 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 1; |
| } |
| |
| op = (int) skops->op; |
| |
| #ifdef DEBUG |
| bpf_printk("BPF command: %d\n", op); |
| #endif |
| |
| /* Check for TIMEOUT_INIT operation and IPv6 addresses */ |
| if (op == BPF_SOCK_OPS_TIMEOUT_INIT && |
| skops->family == AF_INET6) { |
| |
| /* If the first 5.5 bytes of the IPv6 address are the same |
| * then both hosts are in the same datacenter |
| * so use an RTO of 10ms |
| */ |
| if (skops->local_ip6[0] == skops->remote_ip6[0] && |
| (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) == |
| (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) |
| rv = 10; |
| } |
| #ifdef DEBUG |
| bpf_printk("Returning %d\n", rv); |
| #endif |
| skops->reply = rv; |
| return 1; |
| } |
| char _license[] SEC("license") = "GPL"; |