sys/src/cmd/ip/snoopy/arp.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <ip.h>
   4 #include "dat.h"
   5 #include "protos.h"
   6
   7 typedef struct Hdr      Hdr;
   8 struct Hdr
   9 {
  10         uchar   hrd[2];
  11         uchar   pro[2];
  12         uchar   hln;
  13         uchar   pln;
  14         uchar   op[2];
  15         uchar   sha[6];
  16         uchar   spa[4];
  17         uchar   tha[6];
  18         uchar   tpa[4];
  19 };
  20
  21 enum
  22 {
  23         ARPLEN= 28,
  24 };
  25
  26 enum
  27 {
  28         Ospa,
  29         Otpa,
  30         Ostpa,
  31         Osha,
  32         Otha,
  33         Ostha,
  34         Opa,
  35 };
  36
  37 static Field p_fields[] =
  38 {
  39         {"spa",         Fv4ip,  Ospa,   "protocol source",      } ,
  40         {"tpa",         Fv4ip,  Otpa,   "protocol target",      } ,
  41         {"a",           Fv4ip,  Ostpa,  "protocol source/target",       } ,
  42         {"sha",         Fba,    Osha,   "hardware source",      } ,
  43         {"tha",         Fba,    Otha,   "hardware target",      } ,
  44         {"ah",          Fba,    Ostha,  "hardware source/target",       } ,
  45         {0}
  46 };
  47
  48 static void
  49 p_compile(Filter *f)
  50 {
  51         if(f->op == '='){
  52                 compile_cmp(arp.name, f, p_fields);
  53                 return;
  54         }
  55         sysfatal("unknown arp field: %s", f->s);
  56 }
  57
  58 static int
  59 p_filter(Filter *f, Msg *m)
  60 {
  61         Hdr *h;
  62
  63         if(m->pe - m->ps < ARPLEN)
  64                 return 0;
  65
  66         h = (Hdr*)m->ps;
  67         m->ps += ARPLEN;
  68
  69         switch(f->subop){
  70         case Ospa:
  71                 return h->pln == 4 && NetL(h->spa) == f->ulv;
  72         case Otpa:
  73                 return h->pln == 4 && NetL(h->tpa) == f->ulv;
  74         case Ostpa:
  75                 return h->pln == 4 && (NetL(h->tpa) == f->ulv ||
  76                         NetL(h->spa) == f->ulv);
  77         case Osha:
  78                 return memcmp(h->sha, f->a, h->hln) == 0;
  79         case Otha:
  80                 return memcmp(h->tha, f->a, h->hln) == 0;
  81         case Ostha:
  82                 return memcmp(h->sha, f->a, h->hln)==0
  83                         ||memcmp(h->tha, f->a, h->hln)==0;
  84         }
  85         return 0;
  86 }
  87
  88 static int
  89 p_seprint(Msg *m)
  90 {
  91         Hdr *h;
  92
  93         if(m->pe - m->ps < ARPLEN)
  94                 return -1;
  95
  96         h = (Hdr*)m->ps;
  97         m->ps += ARPLEN;
  98
  99         /* no next protocol */
 100         m->pr = nil;
 101
 102         m->p = seprint(m->p, m->e, "op=%1d len=%1d/%1d spa=%V sha=%E tpa=%V tha=%E",
 103                         NetS(h->op), h->pln, h->hln,
 104                         h->spa, h->sha, h->tpa, h->tha);
 105         return 0;
 106 }
 107
 108 Proto arp =
 109 {
 110         "arp",
 111         p_compile,
 112         p_filter,
 113         p_seprint,
 114         nil,
 115         nil,
 116         p_fields,
 117         defaultframer,
 118 };
 119
 120 Proto rarp =
 121 {
 122         "rarp",
 123         p_compile,
 124         p_filter,
 125         p_seprint,
 126         nil,
 127         nil,
 128         p_fields,
 129         defaultframer,
 130 };