name : tc_neighbor_sharing.c // Copyright (c) PLUMgrid, Inc. // Licensed under the Apache License, Version 2.0 (the "License") #include <bcc/proto.h> struct ipkey { u32 client_ip; }; BPF_HASH(learned_ips, struct ipkey, int, 1024); // trivial action int pass(struct __sk_buff *skb) { return 1; } // Process each wan packet, and determine if the packet is in the IP // table or not. Learned IPs are rate-limited and unclassified are not. // returns: > 0 when an IP is known // = 0 when an IP is not known, or non-IP traffic int classify_wan(struct __sk_buff *skb) { u8 *cursor = 0; ethernet: { struct ethernet_t *ethernet = cursor_advance(cursor, sizeof(*ethernet)); switch (ethernet->type) { case ETH_P_IP: goto ip; default: goto EOP; } } ip: { struct ip_t *ip = cursor_advance(cursor, sizeof(*ip)); u32 dip = ip->dst; struct ipkey key = {.client_ip=dip}; int *val = learned_ips.lookup(&key); if (val) return *val; goto EOP; } EOP: return 0; } // Process each neighbor packet, and store the source IP in the learned table. // Mark the inserted entry with a non-zero value to be used by the classify_wan // lookup. int classify_neighbor(struct __sk_buff *skb) { u8 *cursor = 0; ethernet: { struct ethernet_t *ethernet = cursor_advance(cursor, sizeof(*ethernet)); switch (ethernet->type) { case ETH_P_IP: goto ip; default: goto EOP; } } ip: { struct ip_t *ip = cursor_advance(cursor, sizeof(*ip)); u32 sip = ip->src; struct ipkey key = {.client_ip=sip}; int val = 1; learned_ips.insert(&key, &val); goto EOP; } EOP: return 1; }