/* Copyright (c) 2010-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"

#include "dns-util.h"

/**

  return first position from b->a of c or a if not found

 */

static inline

const char *strchr_ba(const char *a, const char *b, char c)

{

  for(;b>a && *b != c; b--);

  return b;

}

int dns_ncompare(const char *a, const char *b, size_t n)

{

  if (a == NULL && b == NULL) return 0;

  if (a == NULL && b != NULL) return 1;

  if (a != NULL && b == NULL) return -1;

  for(size_t i = 0; i < n &&

        *a != '\0' &&

        *b != '\0' &&

        dns_tolower(*a) == dns_tolower(*b);

      i++, a++, b++);

  return dns_tolower(*a) - dns_tolower(*b);

}

int dns_compare(const char *a, const char *b)

{

  return dns_ncompare(a, b, SIZE_MAX);

}

int dns_compare_labels(const char *a, const char *b)

{

  if (a == NULL && b == NULL) return 0;

  if (a == NULL && b != NULL) return 1;

  if (a != NULL && b == NULL) return -1;

  const char *ptr_a = a + strlen(a);

  const char *ptr_b = b + strlen(b);

  const char *label_a = ptr_a, *label_b = ptr_b;

  int comp = 0;

  while(comp == 0 && ptr_a > a && ptr_b > b) {

    /* look for start of label, including dot */

    label_a = strchr_ba(a, ptr_a, '.');

    label_b = strchr_ba(b, ptr_b, '.');

    if (ptr_a - label_a != ptr_b - label_b)

      /* compare labels up to minimum length

         but include \0 to make sure that we

         don't consider alpha and alphabet

         equal */

      return dns_ncompare(label_a, label_b,

             I_MIN(ptr_a - label_a,

             ptr_b - label_b)+1);

    comp = dns_ncompare(label_a, label_b, ptr_a -label_a);

    ptr_a = label_a - 1;

    ptr_b = label_b - 1;

  }

  return dns_tolower(*label_a) - dns_tolower(*label_b);

}

int dns_match_wildcard(const char *name, const char *mask)

{

  i_assert(name != NULL && mask != NULL);

  for(;*name != '\0' && *mask != '\0'; name++, mask++) {

    switch(*mask) {

    case '*':

      name = strchr(name, '.');

      if (name == NULL || mask[1] != '.') return -1;

      mask++;

      break;

    case '?':

      break;

    default:

      if (dns_tolower(*name) != dns_tolower(*mask)) return -1;

    }

  }

  if (*mask == '*') mask++;

  return dns_tolower(*name) == dns_tolower(*mask) ? 0 : -1;

}