ceph/src/spdk/dpdk/test/bpf/t1.c

   1 /* SPDX-License-Identifier: BSD-3-Clause
   2  * Copyright(c) 2018 Intel Corporation
   3  */
   4
   5 /*
   6  * eBPF program sample.
   7  * Accepts pointer to first segment packet data as an input parameter.
   8  * analog of tcpdump -s 1 -d 'dst 1.2.3.4 && udp && dst port 5000'
   9  * (000) ldh      [12]
  10  * (001) jeq      #0x800           jt 2    jf 12
  11  * (002) ld       [30]
  12  * (003) jeq      #0x1020304       jt 4    jf 12
  13  * (004) ldb      [23]
  14  * (005) jeq      #0x11            jt 6    jf 12
  15  * (006) ldh      [20]
  16  * (007) jset     #0x1fff          jt 12   jf 8
  17  * (008) ldxb     4*([14]&0xf)
  18  * (009) ldh      [x + 16]
  19  * (010) jeq      #0x1388          jt 11   jf 12
  20  * (011) ret      #1
  21  * (012) ret      #0
  22  *
  23  * To compile:
  24  * clang -O2 -target bpf -c t1.c
  25  */
  26
  27 #include <stdint.h>
  28 #include <net/ethernet.h>
  29 #include <netinet/ip.h>
  30 #include <netinet/udp.h>
  31
  32 uint64_t
  33 entry(void *pkt)
  34 {
  35         struct ether_header *ether_header = (void *)pkt;
  36
  37         if (ether_header->ether_type != __builtin_bswap16(0x0800))
  38                 return 0;
  39
  40         struct iphdr *iphdr = (void *)(ether_header + 1);
  41         if (iphdr->protocol != 17 || (iphdr->frag_off & 0x1ffff) != 0 ||
  42                         iphdr->daddr != __builtin_bswap32(0x1020304))
  43                 return 0;
  44
  45         int hlen = iphdr->ihl * 4;
  46         struct udphdr *udphdr = (void *)iphdr + hlen;
  47
  48         if (udphdr->dest !=  __builtin_bswap16(5000))
  49                 return 0;
  50
  51         return 1;
  52 }