src/dnsstub/dns_dtda.c


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#include "dnsresolv.h"
#include "stralloc.h"

/**
  @file dns_dtda.c
  @author djb
  @source ucspi-tcp
  @brief domain to dot append
*/

int dns_domain_todot_cat(stralloc *out, const char *d)
{
  char ch;
  char ch2;
  unsigned char ch3;
  char buf[4];

  if (!*d) return stralloc_append(out, ".");

  for (;;) {
    ch = *d++;
    while (ch--) {
      ch2 = *d++;
      if ((ch2 >= 'A') && (ch2 <= 'Z')) ch2 += 32;  // FQDN -> lowercase
      if (((ch2 >= 'a') && (ch2 <= 'z')) || ((ch2 >= '0') && (ch2 <= '9')) || (ch2 == '-')
          || (ch2 == '_'))
      {
        if (!stralloc_append(out, &ch2)) return DNS_MEM;
      } else {  // decimal -> octal
        ch3 = ch2;
        buf[3] = '0' + (ch3 & 7);
        ch3 >>= 3;
        buf[2] = '0' + (ch3 & 7);
        ch3 >>= 3;
        buf[1] = '0' + (ch3 & 7);
        buf[0] = '\\';
        if (!stralloc_catb(out, buf, 4)) return DNS_MEM;
      }
    }
    if (!*d) return 1;
    if (!stralloc_append(out, ".")) return DNS_MEM;
  }
}