sys/src/cmd/ip/snoopy/tcp.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   sport[2];
  11         uchar   dport[2];
  12         uchar   seq[4];
  13         uchar   ack[4];
  14         uchar   flag[2];
  15         uchar   win[2];
  16         uchar   cksum[2];
  17         uchar   urg[2];
  18         uchar   opt[1];
  19 };
  20
  21 typedef struct PseudoHdr{
  22         uchar   src[4];
  23         uchar   dst[4];
  24         uchar   zero;
  25         uchar   proto;
  26         uchar   length[2];
  27         uchar   hdrdata[1580];
  28 } PseudoHdr;
  29
  30 enum
  31 {
  32         TCPLEN= 20,
  33 };
  34
  35 enum
  36 {
  37         Os,
  38         Od,
  39         Osd,
  40 };
  41
  42 static Field p_fields[] =
  43 {
  44         {"s",           Fnum,   Os,     "source port",  } ,
  45         {"d",           Fnum,   Od,     "dest port",    } ,
  46         {"a",           Fnum,   Osd,    "source/dest port",     } ,
  47         {"sd",          Fnum,   Osd,    "source/dest port",     } ,
  48         {0}
  49 };
  50
  51 static Mux p_mux[] =
  52 {
  53         {"dns",         53, },
  54         {"ninep",       17007, },       /* exportfs */
  55         {"ninep",       564, },         /* 9fs */
  56         {"ninep",       17005, },       /* ocpu */
  57         {"ninep",       17010, },       /* ncpu */
  58         {"ninep",       17013, },       /* cpu */
  59         {0},
  60 };
  61
  62 enum
  63 {
  64         EOLOPT          = 0,
  65         NOOPOPT         = 1,
  66         MSSOPT          = 2,
  67         MSS_LENGTH      = 4,            /* Mean segment size */
  68         WSOPT           = 3,
  69         WS_LENGTH       = 3,            /* Bits to scale window size by */
  70 };
  71
  72 static void
  73 p_compile(Filter *f)
  74 {
  75         Mux *m;
  76
  77         if(f->op == '='){
  78                 compile_cmp(tcp.name, f, p_fields);
  79                 return;
  80         }
  81         for(m = p_mux; m->name != nil; m++)
  82                 if(strcmp(f->s, m->name) == 0){
  83                         f->pr = m->pr;
  84                         f->ulv = m->val;
  85                         f->subop = Osd;
  86                         return;
  87                 }
  88         sysfatal("unknown tcp field or protocol: %s", f->s);
  89 }
  90
  91 static int
  92 p_filter(Filter *f, Msg *m)
  93 {
  94         Hdr *h;
  95
  96         if(m->pe - m->ps < TCPLEN)
  97                 return 0;
  98
  99         h = (Hdr*)m->ps;
 100         m->ps += (NetS(h->flag)>>10) & 0x3f;
 101
 102         switch(f->subop){
 103         case Os:
 104                 return NetS(h->sport) == f->ulv;
 105         case Od:
 106                 return NetS(h->dport) == f->ulv;
 107         case Osd:
 108                 return NetS(h->sport) == f->ulv || NetS(h->dport) == f->ulv;
 109         }
 110         return 0;
 111 }
 112
 113 enum
 114 {
 115         URG             = 0x20,         /* Data marked urgent */
 116         ACK             = 0x10,         /* Aknowledge is valid */
 117         PSH             = 0x08,         /* Whole data pipe is pushed */
 118         RST             = 0x04,         /* Reset connection */
 119         SYN             = 0x02,         /* Pkt. is synchronise */
 120         FIN             = 0x01,         /* Start close down */
 121 };
 122
 123 static char*
 124 flags(int f)
 125 {
 126         static char fl[20];
 127         char *p;
 128
 129         p = fl;
 130         if(f & URG)
 131                 *p++ = 'U';
 132         if(f & ACK)
 133                 *p++ = 'A';
 134         if(f & PSH)
 135                 *p++ = 'P';
 136         if(f & RST)
 137                 *p++ = 'R';
 138         if(f & SYN)
 139                 *p++ = 'S';
 140         if(f & FIN)
 141                 *p++ = 'F';
 142         *p = 0;
 143         return fl;
 144 }
 145
 146
 147 static int
 148 p_seprint(Msg *m)
 149 {
 150         int dport, sport, len, flag, optlen;
 151         uchar *optr;
 152         Hdr *h;
 153
 154         if(m->pe - m->ps < TCPLEN)
 155                 return -1;
 156         h = (Hdr*)m->ps;
 157
 158         /* get tcp header length */
 159         flag = NetS(h->flag);
 160         len = (flag>>10) & ~3;
 161         flag &= 0x3ff;
 162         m->ps += len;
 163
 164         /* next protocol */
 165         dport = NetS(h->dport);
 166         sport = NetS(h->sport);
 167         demux(p_mux, sport, dport, m, &dump);
 168
 169         m->p = seprint(m->p, m->e, "s=%d d=%d seq=%lud ack=%lud fl=%s win=%d ck=%4.4ux",
 170                         NetS(h->sport), dport,
 171                         (ulong)NetL(h->seq), (ulong)NetL(h->ack),
 172                         flags(flag), NetS(h->win),
 173                         NetS(h->cksum));
 174
 175         /* tcp options */
 176         len -= TCPLEN;
 177         optr = h->opt;
 178         while(len > 0) {
 179                 if(*optr == EOLOPT){
 180                         m->p = seprint(m->p, m->e, " opt=EOL");
 181                         break;
 182                 }
 183                 if(*optr == NOOPOPT) {
 184                         m->p = seprint(m->p, m->e, " opt=NOOP");
 185                         len--;
 186                         optr++;
 187                         continue;
 188                 }
 189                 optlen = optr[1];
 190                 if(optlen < 2 || optlen > len)
 191                         break;
 192                 switch(*optr) {
 193                 case MSSOPT:
 194                         m->p = seprint(m->p, m->e, " opt%d=(mss %ud)",
 195                                 optlen, nhgets(optr+2));
 196                         break;
 197                 case WSOPT:
 198                         m->p = seprint(m->p, m->e, " opt%d=(wscale %ud)",
 199                                 optlen, *(optr+2));
 200                         break;
 201                 default:
 202                         m->p = seprint(m->p, m->e, " opt%d=(%ud %.*H)",
 203                                 optlen, *optr, optlen-2, optr+2);
 204                 }
 205                 len -= optlen;
 206                 optr += optlen;
 207         }
 208         return 0;
 209 }
 210
 211 Proto tcp =
 212 {
 213         "tcp",
 214         p_compile,
 215         p_filter,
 216         p_seprint,
 217         p_mux,
 218         "%lud",
 219         p_fields,
 220         defaultframer,
 221 };