sys/src/cmd/ndb/dnsquery.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <bio.h>
   4 #include <ctype.h>
   5 #include <ndb.h>
   6 #include "dns.h"
   7 #include "ip.h"
   8
   9 static void
  10 querydns(int fd, char *line, int n)
  11 {
  12         char buf[8192+1];
  13
  14         seek(fd, 0, 0);
  15         if(write(fd, line, n) != n) {
  16                 print("!%r\n");
  17                 return;
  18         }
  19         seek(fd, 0, 0);
  20         while((n = read(fd, buf, sizeof(buf)-1)) > 0){
  21                 buf[n++] = '\n';
  22                 write(1, buf, n);
  23         }
  24 }
  25
  26 /*
  27  *  convert address into a reverse lookup address
  28  */
  29 static void
  30 mkptrname(char *ip, char *rip, int rlen)
  31 {
  32         uchar a[IPaddrlen];
  33         char *p, *e;
  34         int i;
  35
  36         if(cistrstr(ip, "in-addr.arpa") || cistrstr(ip, "ip6.arpa") || parseip(a, ip) == -1)
  37                 snprint(rip, rlen, "%s", ip);
  38         else if(isv4(a))
  39                 snprint(rip, rlen, "%ud.%ud.%ud.%ud.in-addr.arpa",
  40                         a[15], a[14], a[13], a[12]);
  41         else{
  42                 p = rip;
  43                 e = rip + rlen;
  44                 for(i = 15; i >= 0; i--){
  45                         p = seprint(p, e, "%ux.", a[i]&0xf);
  46                         p = seprint(p, e, "%ux.", a[i]>>4);
  47                 }
  48                 seprint(p, e, "ip6.arpa");
  49         }
  50 }
  51
  52 static void
  53 query(int fd)
  54 {
  55         int n;
  56         char *lp;
  57         char buf[1024], line[1024];
  58         Biobuf in;
  59
  60         Binit(&in, 0, OREAD);
  61         for(print("> "); lp = Brdline(&in, '\n'); print("> ")){
  62                 n = Blinelen(&in) -1;
  63                 while(isspace(lp[n]))
  64                         lp[n--] = 0;
  65                 n++;
  66                 while(isspace(*lp)){
  67                         lp++;
  68                         n--;
  69                 }
  70                 if(!*lp)
  71                         continue;
  72                 strcpy(line, lp);
  73
  74                 /* default to an "ip" request if alpha, "ptr" if numeric */
  75                 if(strchr(line, ' ') == nil)
  76                         if(strcmp(ipattr(line), "ip") == 0) {
  77                                 strcat(line, " ptr");
  78                                 n += 4;
  79                         } else {
  80                                 strcat(line, " ip");
  81                                 n += 3;
  82                         }
  83
  84                 if(n > 4 && strcmp(" ptr", &line[n-4]) == 0){
  85                         line[n-4] = 0;
  86                         mkptrname(line, buf, sizeof buf);
  87                         n = snprint(line, sizeof line, "%s ptr", buf);
  88                 }
  89
  90                 querydns(fd, line, n);
  91         }
  92         Bterm(&in);
  93 }
  94
  95 void
  96 main(int argc, char *argv[])
  97 {
  98         char *dns  = "/net/dns";
  99         int fd;
 100
 101         ARGBEGIN {
 102         case 'x':
 103                 dns = "/net.alt/dns";
 104                 break;
 105         default:
 106                 fprint(2, "usage: %s [-x] [/net/dns]\n", argv0);
 107                 exits("usage");
 108         } ARGEND;
 109
 110         if(argc > 0)
 111                 dns = argv[0];
 112
 113         fd = open(dns, ORDWR);
 114         if(fd < 0)
 115                 sysfatal("can't open %s: %r", dns);
 116
 117         query(fd);
 118         exits(0);
 119 }