1 /* Copyright (c) 2017 Facebook
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.
7 * BPF program to set initial congestion window and initial receive
8 * window to 40 packets and send and receive buffers to 1.5MB. This
9 * would usually be done after doing appropriate checks that indicate
10 * the hosts are far enough away (i.e. large RTT).
12 * Use load_sock_ops to load this BPF program.
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"
25 #define bpf_printk(fmt, ...) \
27 char ____fmt[] = fmt; \
28 bpf_trace_printk(____fmt, sizeof(____fmt), \
33 int bpf_iw(struct bpf_sock_ops *skops)
35 int bufsize = 1500000;
41 /* For testing purposes, only execute rest of BPF program
42 * if neither port numberis 55601
44 if (bpf_ntohl(skops->remote_port) != 55601 &&
45 skops->local_port != 55601)
51 bpf_printk("BPF command: %d\n", op);
54 /* Usually there would be a check to insure the hosts are far
55 * from each other so it makes sense to increase buffer sizes
58 case BPF_SOCK_OPS_RWND_INIT:
61 case BPF_SOCK_OPS_TCP_CONNECT_CB:
62 /* Set sndbuf and rcvbuf of active connections */
63 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
65 rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
66 &bufsize, sizeof(bufsize));
68 case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
69 rv = bpf_setsockopt(skops, SOL_TCP, TCP_BPF_IW, &iw,
72 case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
73 /* Set sndbuf and rcvbuf of passive connections */
74 rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
76 rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
77 &bufsize, sizeof(bufsize));
83 bpf_printk("Returning %d\n", rv);
88 char _license[] SEC("license") = "GPL";