/* Copyright (c) 2017 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* BPF program to set initial receive window to 40 packets and send
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* and receive buffers to 1.5MB. This would usually be done after
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* doing appropriate checks that indicate the hosts are far enough
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* away (i.e. large RTT).
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*
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* Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program.
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*/
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#include <uapi/linux/bpf.h>
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#include <uapi/linux/if_ether.h>
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#include <uapi/linux/if_packet.h>
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#include <uapi/linux/ip.h>
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#include <linux/socket.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_endian.h>
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#define DEBUG 1
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SEC("sockops")
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int bpf_bufs(struct bpf_sock_ops *skops)
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{
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int bufsize = 1500000;
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int rwnd_init = 40;
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int rv = 0;
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int op;
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/* For testing purposes, only execute rest of BPF program
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* if neither port numberis 55601
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*/
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if (bpf_ntohl(skops->remote_port) != 55601 &&
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skops->local_port != 55601) {
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skops->reply = -1;
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return 1;
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}
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op = (int) skops->op;
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#ifdef DEBUG
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bpf_printk("Returning %d\n", rv);
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#endif
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/* Usually there would be a check to insure the hosts are far
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* from each other so it makes sense to increase buffer sizes
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*/
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switch (op) {
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case BPF_SOCK_OPS_RWND_INIT:
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rv = rwnd_init;
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break;
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case BPF_SOCK_OPS_TCP_CONNECT_CB:
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/* Set sndbuf and rcvbuf of active connections */
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rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
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sizeof(bufsize));
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rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
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&bufsize, sizeof(bufsize));
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break;
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case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
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/* Nothing to do */
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break;
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case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
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/* Set sndbuf and rcvbuf of passive connections */
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rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
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sizeof(bufsize));
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rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
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&bufsize, sizeof(bufsize));
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break;
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default:
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rv = -1;
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}
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#ifdef DEBUG
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bpf_printk("Returning %d\n", rv);
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#endif
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skops->reply = rv;
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return 1;
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}
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char _license[] SEC("license") = "GPL";
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