84 lines
2.0 KiB
C
84 lines
2.0 KiB
C
/* 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 congestion control to dctcp when both hosts are
|
|
* in the same datacenter (as deteremined by IPv6 prefix).
|
|
*
|
|
* Use load_sock_ops to load this BPF program.
|
|
*/
|
|
|
|
#include <uapi/linux/bpf.h>
|
|
#include <uapi/linux/tcp.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
|
|
|
|
#define bpf_printk(fmt, ...) \
|
|
({ \
|
|
char ____fmt[] = fmt; \
|
|
bpf_trace_printk(____fmt, sizeof(____fmt), \
|
|
##__VA_ARGS__); \
|
|
})
|
|
|
|
SEC("sockops")
|
|
int bpf_cong(struct bpf_sock_ops *skops)
|
|
{
|
|
char cong[] = "dctcp";
|
|
int rv = 0;
|
|
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)
|
|
return -1;
|
|
|
|
op = (int) skops->op;
|
|
|
|
#ifdef DEBUG
|
|
bpf_printk("BPF command: %d\n", op);
|
|
#endif
|
|
|
|
/* Check if both hosts are in the same datacenter. For this
|
|
* example they are if the 1st 5.5 bytes in the IPv6 address
|
|
* are the same.
|
|
*/
|
|
if (skops->family == AF_INET6 &&
|
|
skops->local_ip6[0] == skops->remote_ip6[0] &&
|
|
(bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) ==
|
|
(bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) {
|
|
switch (op) {
|
|
case BPF_SOCK_OPS_NEEDS_ECN:
|
|
rv = 1;
|
|
break;
|
|
case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
|
|
rv = bpf_setsockopt(skops, SOL_TCP, TCP_CONGESTION,
|
|
cong, sizeof(cong));
|
|
break;
|
|
case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
|
|
rv = bpf_setsockopt(skops, SOL_TCP, TCP_CONGESTION,
|
|
cong, sizeof(cong));
|
|
break;
|
|
default:
|
|
rv = -1;
|
|
}
|
|
} else {
|
|
rv = -1;
|
|
}
|
|
#ifdef DEBUG
|
|
bpf_printk("Returning %d\n", rv);
|
|
#endif
|
|
skops->reply = rv;
|
|
return 1;
|
|
}
|
|
char _license[] SEC("license") = "GPL";
|