tudp.c - plan9port - [fork] Plan 9 from user space
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       ---
       tudp.c (2009B)
       ---
            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];        /* Source port */
           11         uchar        dport[2];        /* Destination port */
           12         uchar        len[2];                /* data length */
           13         uchar        cksum[2];        /* Checksum */
           14 };
           15 
           16 enum
           17 {
           18         UDPLEN=        8
           19 };
           20 
           21 enum
           22 {
           23         Os,
           24         Od,
           25         Osd,
           26         Osetport
           27 };
           28 
           29 static Field p_fields[] =
           30 {
           31         {"s",                Fnum,        Os,        "source port",        } ,
           32         {"d",                Fnum,        Od,        "dest port",        } ,
           33         {"a",                Fnum,        Osd,        "source/dest port",        } ,
           34         {"sd",                Fnum,        Osd,        "source/dest port",        } ,
           35         {0}
           36 };
           37 
           38 #define ANYPORT ~0UL
           39 
           40 static Mux p_mux[] =
           41 {
           42         {"bootp",        67, },
           43         {"ninep",        6346, },        /* tvs */
           44         {"dns", 53 },
           45         {"rtp",                ANYPORT, },
           46         {"rtcp",        ANYPORT, },
           47         {0}
           48 };
           49 
           50 /* default next protocol, can be changed by p_filter, reset by p_compile */
           51 static Proto        *defproto = &dump;
           52 
           53 static void
           54 p_compile(Filter *f)
           55 {
           56         Mux *m;
           57 
           58         if(f->op == '='){
           59                 compile_cmp(udp.name, f, p_fields);
           60                 return;
           61         }
           62         for(m = p_mux; m->name != nil; m++)
           63                 if(strcmp(f->s, m->name) == 0){
           64                         f->pr = m->pr;
           65                         f->ulv = m->val;
           66                         f->subop = Osd;
           67                         return;
           68                 }
           69 
           70         sysfatal("unknown udp field or protocol: %s", f->s);
           71 }
           72 
           73 static int
           74 p_filter(Filter *f, Msg *m)
           75 {
           76         Hdr *h;
           77 
           78         if(m->pe - m->ps < UDPLEN)
           79                 return 0;
           80 
           81         h = (Hdr*)m->ps;
           82         m->ps += UDPLEN;
           83 
           84         switch(f->subop){
           85         case Os:
           86                 return NetS(h->sport) == f->ulv;
           87         case Od:
           88                 return NetS(h->dport) == f->ulv;
           89         case Osd:
           90                 if(f->ulv == ANYPORT){
           91                         defproto = f->pr;
           92                         return 1;
           93                 }
           94                 return NetS(h->sport) == f->ulv || NetS(h->dport) == f->ulv;
           95         }
           96         return 0;
           97 }
           98 
           99 static int
          100 p_seprint(Msg *m)
          101 {
          102         Hdr *h;
          103         int dport, sport;
          104 
          105 
          106         if(m->pe - m->ps < UDPLEN)
          107                 return -1;
          108         h = (Hdr*)m->ps;
          109         m->ps += UDPLEN;
          110 
          111         /* next protocol */
          112         sport = NetS(h->sport);
          113         dport = NetS(h->dport);
          114         demux(p_mux, sport, dport, m, defproto);
          115         defproto = &dump;
          116 
          117         m->p = seprint(m->p, m->e, "s=%d d=%d ck=%4.4ux ln=%4d",
          118                         NetS(h->sport), dport,
          119                         NetS(h->cksum), NetS(h->len));
          120         return 0;
          121 }
          122 
          123 Proto udp =
          124 {
          125         "udp",
          126         p_compile,
          127         p_filter,
          128         p_seprint,
          129         p_mux,
          130         "%lud",
          131         p_fields,
          132         defaultframer
          133 };