samples/bpf: bpf_tail_call example for networking
Usage:
$ sudo ./sockex3
IP src.port -> dst.port bytes packets
127.0.0.1.42010 -> 127.0.0.1.12865 1568 8
127.0.0.1.59526 -> 127.0.0.1.33778 11422636 173070
127.0.0.1.33778 -> 127.0.0.1.59526 11260224828 341974
127.0.0.1.12865 -> 127.0.0.1.42010 1832 12
IP src.port -> dst.port bytes packets
127.0.0.1.42010 -> 127.0.0.1.12865 1568 8
127.0.0.1.59526 -> 127.0.0.1.33778 23198092 351486
127.0.0.1.33778 -> 127.0.0.1.59526 22972698518 698616
127.0.0.1.12865 -> 127.0.0.1.42010 1832 12
this example is similar to sockex2 in a way that it accumulates per-flow
statistics, but it does packet parsing differently.
sockex2 inlines full packet parser routine into single bpf program.
This sockex3 example have 4 independent programs that parse vlan, mpls, ip, ipv6
and one main program that starts the process.
bpf_tail_call() mechanism allows each program to be small and be called
on demand potentially multiple times, so that many vlan, mpls, ip in ip,
gre encapsulations can be parsed. These and other protocol parsers can
be added or removed at runtime. TLVs can be parsed in similar manner.
Note, tail_call_cnt dynamic check limits the number of tail calls to 32.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
4 files changed