]>
Commit | Line | Data |
---|---|---|
c400296b LB |
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 when using IPv6 | |
8 | * and the first 5.5 bytes of the IPv6 addresses are not the same (in this | |
9 | * example that means both hosts are not the same datacenter). | |
10 | * | |
ea9b6362 | 11 | * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program. |
c400296b LB |
12 | */ |
13 | ||
14 | #include <uapi/linux/bpf.h> | |
15 | #include <uapi/linux/if_ether.h> | |
16 | #include <uapi/linux/if_packet.h> | |
17 | #include <uapi/linux/ip.h> | |
18 | #include <linux/socket.h> | |
7cf245a3 THJ |
19 | #include <bpf/bpf_helpers.h> |
20 | #include <bpf/bpf_endian.h> | |
c400296b LB |
21 | |
22 | #define DEBUG 1 | |
23 | ||
c400296b LB |
24 | SEC("sockops") |
25 | int bpf_rwnd(struct bpf_sock_ops *skops) | |
26 | { | |
27 | int rv = -1; | |
28 | int op; | |
29 | ||
30 | /* For testing purposes, only execute rest of BPF program | |
31 | * if neither port numberis 55601 | |
32 | */ | |
33 | if (bpf_ntohl(skops->remote_port) != | |
016e661b LB |
34 | 55601 && skops->local_port != 55601) { |
35 | skops->reply = -1; | |
36 | return 1; | |
37 | } | |
c400296b LB |
38 | |
39 | op = (int) skops->op; | |
40 | ||
41 | #ifdef DEBUG | |
42 | bpf_printk("BPF command: %d\n", op); | |
43 | #endif | |
44 | ||
45 | /* Check for RWND_INIT operation and IPv6 addresses */ | |
46 | if (op == BPF_SOCK_OPS_RWND_INIT && | |
47 | skops->family == AF_INET6) { | |
48 | ||
49 | /* If the first 5.5 bytes of the IPv6 address are not the same | |
50 | * then both hosts are not in the same datacenter | |
51 | * so use a larger initial advertized window (40 packets) | |
52 | */ | |
53 | if (skops->local_ip6[0] != skops->remote_ip6[0] || | |
54 | (bpf_ntohl(skops->local_ip6[1]) & 0xfffff000) != | |
55 | (bpf_ntohl(skops->remote_ip6[1]) & 0xfffff000)) | |
56 | rv = 40; | |
57 | } | |
58 | #ifdef DEBUG | |
59 | bpf_printk("Returning %d\n", rv); | |
60 | #endif | |
61 | skops->reply = rv; | |
62 | return 1; | |
63 | } | |
64 | char _license[] SEC("license") = "GPL"; |