Update contrib/libs/c-ares to 1.34.4

commit_hash:0ba9edead9220ea805233d858e42e63ba30c021f

12 files changed, 335 insertions, 70 deletions

diff --git a/contrib/libs/c-ares/src/lib/ares_config-linux.h b/contrib/libs/c-ares/src/lib/ares_config-linux.h
index 49e41d4f6e..778bf91eed 100644
--- a/contrib/libs/c-ares/src/lib/ares_config-linux.h
+++ b/contrib/libs/c-ares/src/lib/ares_config-linux.h
@@ -257,6 +257,9 @@
 /* Define to 1 if you have the <signal.h> header file. */
 #define HAVE_SIGNAL_H 1
 
+/* Define to 1 if you have the strnlen function. */
+#define HAVE_STRNLEN 1
+
 /* Define to 1 if your struct sockaddr_in6 has sin6_scope_id. */
 #define HAVE_STRUCT_SOCKADDR_IN6_SIN6_SCOPE_ID 1
 
diff --git a/contrib/libs/c-ares/src/lib/ares_private.h b/contrib/libs/c-ares/src/lib/ares_private.h
index ce8c3f2ddc..e6d44e8b86 100644
--- a/contrib/libs/c-ares/src/lib/ares_private.h
+++ b/contrib/libs/c-ares/src/lib/ares_private.h
@@ -388,8 +388,23 @@ ares_status_t ares_sysconfig_set_options(ares_sysconfig_t *sysconfig,
 
 ares_status_t ares_init_by_environment(ares_sysconfig_t *sysconfig);
 
+
+typedef ares_status_t (*ares_sysconfig_line_cb_t)(const ares_channel_t *channel,
+                                                  ares_sysconfig_t     *sysconfig,
+                                                  ares_buf_t           *line);
+
+ares_status_t ares_sysconfig_parse_resolv_line(const ares_channel_t *channel,
+                                               ares_sysconfig_t     *sysconfig,
+                                               ares_buf_t           *line);
+
+ares_status_t ares_sysconfig_process_buf(const ares_channel_t    *channel,
+                                         ares_sysconfig_t        *sysconfig,
+                                         ares_buf_t              *buf,
+                                         ares_sysconfig_line_cb_t cb);
+
 ares_status_t ares_init_sysconfig_files(const ares_channel_t *channel,
-                                        ares_sysconfig_t     *sysconfig);
+                                        ares_sysconfig_t     *sysconfig,
+                                        ares_bool_t process_resolvconf);
 #ifdef __APPLE__
 ares_status_t ares_init_sysconfig_macos(const ares_channel_t *channel,
                                         ares_sysconfig_t     *sysconfig);
diff --git a/contrib/libs/c-ares/src/lib/ares_set_socket_functions.c b/contrib/libs/c-ares/src/lib/ares_set_socket_functions.c
index 143c491174..7216ffa933 100644
--- a/contrib/libs/c-ares/src/lib/ares_set_socket_functions.c
+++ b/contrib/libs/c-ares/src/lib/ares_set_socket_functions.c
@@ -288,7 +288,9 @@ static int default_asetsockopt(ares_socket_t sock, ares_socket_opt_t opt,
       return setsockopt(sock, SOL_SOCKET, SO_RCVBUF, val, val_size);
 
     case ARES_SOCKET_OPT_BIND_DEVICE:
-      if (!ares_str_isprint(val, (size_t)val_size)) {
+      /* Count the number of characters before NULL terminator then
+       * validate those are all printable */
+      if (!ares_str_isprint(val, ares_strnlen(val, (size_t)val_size))) {
         SET_SOCKERRNO(EINVAL);
         return -1;
       }
diff --git a/contrib/libs/c-ares/src/lib/ares_socket.c b/contrib/libs/c-ares/src/lib/ares_socket.c
index df02fd61b6..516852a84a 100644
--- a/contrib/libs/c-ares/src/lib/ares_socket.c
+++ b/contrib/libs/c-ares/src/lib/ares_socket.c
@@ -263,7 +263,8 @@ ares_status_t ares_socket_configure(ares_channel_t *channel, int family,
      * compatibility */
     (void)channel->sock_funcs.asetsockopt(
       fd, ARES_SOCKET_OPT_BIND_DEVICE, channel->local_dev_name,
-      sizeof(channel->local_dev_name), channel->sock_func_cb_data);
+      (ares_socklen_t)ares_strlen(channel->local_dev_name),
+      channel->sock_func_cb_data);
   }
 
   /* Bind to ip address if configured */
diff --git a/contrib/libs/c-ares/src/lib/ares_sysconfig.c b/contrib/libs/c-ares/src/lib/ares_sysconfig.c
index 9f0d7e5061..286db60328 100644
--- a/contrib/libs/c-ares/src/lib/ares_sysconfig.c
+++ b/contrib/libs/c-ares/src/lib/ares_sysconfig.c
@@ -260,6 +260,94 @@ static ares_status_t ares_init_sysconfig_android(const ares_channel_t *channel,
 }
 #endif
 
+#if defined(__QNX__)
+static ares_status_t
+  ares_init_sysconfig_qnx(const ares_channel_t *channel,
+                          ares_sysconfig_t     *sysconfig)
+{
+  /* QNX:
+   *   1. use confstr(_CS_RESOLVE, ...) as primary resolv.conf data, replacing
+   *      "_" with " ".  If that is empty, then do normal /etc/resolv.conf
+   *      processing.
+   *   2. We want to process /etc/nsswitch.conf as normal.
+   *   3. if confstr(_CS_DOMAIN, ...) this is the domain name.  Use this as
+   *      preference over anything else found.
+   */
+  ares_buf_t    *buf                = ares_buf_create();
+  unsigned char *data               = NULL;
+  size_t         data_size          = 0;
+  ares_bool_t    process_resolvconf = ARES_TRUE;
+  ares_status_t  status             = ARES_SUCCESS;
+
+  /* Prefer confstr(_CS_RESOLVE, ...) */
+  buf = ares_buf_create();
+  if (buf == NULL) {
+    status = ARES_ENOMEM;
+    goto done;
+  }
+
+  data_size = 1024;
+  data      = ares_buf_append_start(buf, &data_size);
+  if (data == NULL) {
+    status = ARES_ENOMEM;
+    goto done;
+  }
+
+  data_size = confstr(_CS_RESOLVE, (char *)data, data_size);
+  if (data_size > 1) {
+    /* confstr returns byte for NULL terminator, strip */
+    data_size--;
+
+    ares_buf_append_finish(buf, data_size);
+    /* Its odd, this uses _ instead of " " between keywords, otherwise the
+     * format is the same as resolv.conf, replace. */
+    ares_buf_replace(buf, (const unsigned char *)"_", 1,
+                     (const unsigned char *)" ", 1);
+
+    status = ares_sysconfig_process_buf(channel, sysconfig, buf,
+                                        ares_sysconfig_parse_resolv_line);
+    if (status != ARES_SUCCESS) {
+      /* ENOMEM is really the only error we'll get here */
+      goto done;
+    }
+
+    /* don't read resolv.conf if we processed *any* nameservers */
+    if (ares_llist_len(sysconfig->sconfig) != 0) {
+      process_resolvconf = ARES_FALSE;
+    }
+  }
+
+  /* Process files */
+  status = ares_init_sysconfig_files(channel, sysconfig, process_resolvconf);
+  if (status != ARES_SUCCESS) {
+    goto done;
+  }
+
+  /* Read confstr(_CS_DOMAIN, ...), but if we had a search path specified with
+   * more than one domain, lets prefer that instead.  Its not exactly clear
+   * the best way to handle this. */
+  if (sysconfig->ndomains <= 1) {
+    char   domain[256];
+    size_t domain_len;
+
+    domain_len = confstr(_CS_DOMAIN, domain, sizeof(domain_len));
+    if (domain_len != 0) {
+      ares_strsplit_free(sysconfig->domains, sysconfig->ndomains);
+      sysconfig->domains = ares_strsplit(domain, ", ", &sysconfig->ndomains);
+      if (sysconfig->domains == NULL) {
+        status = ARES_ENOMEM;
+        goto done;
+      }
+    }
+  }
+
+done:
+  ares_buf_destroy(buf);
+
+  return status;
+}
+#endif
+
 #if defined(CARES_USE_LIBRESOLV)
 static ares_status_t
   ares_init_sysconfig_libresolv(const ares_channel_t *channel,
@@ -516,8 +604,10 @@ ares_status_t ares_init_by_sysconfig(ares_channel_t *channel)
   status = ares_init_sysconfig_macos(channel, &sysconfig);
 #elif defined(CARES_USE_LIBRESOLV)
   status = ares_init_sysconfig_libresolv(channel, &sysconfig);
+#elif defined(__QNX__)
+  status = ares_init_sysconfig_qnx(channel, &sysconfig);
 #else
-  status = ares_init_sysconfig_files(channel, &sysconfig);
+  status = ares_init_sysconfig_files(channel, &sysconfig, ARES_TRUE);
 #endif
 
   if (status != ARES_SUCCESS) {
diff --git a/contrib/libs/c-ares/src/lib/ares_sysconfig_files.c b/contrib/libs/c-ares/src/lib/ares_sysconfig_files.c
index 49bc330d9d..a6c2a8e62b 100644
--- a/contrib/libs/c-ares/src/lib/ares_sysconfig_files.c
+++ b/contrib/libs/c-ares/src/lib/ares_sysconfig_files.c
@@ -549,9 +549,9 @@ ares_status_t ares_init_by_environment(ares_sysconfig_t *sysconfig)
 /* This function will only return ARES_SUCCESS or ARES_ENOMEM.  Any other
  * conditions are ignored.  Users may mess up config files, but we want to
  * process anything we can. */
-static ares_status_t parse_resolvconf_line(const ares_channel_t *channel,
-                                           ares_sysconfig_t     *sysconfig,
-                                           ares_buf_t           *line)
+ares_status_t ares_sysconfig_parse_resolv_line(const ares_channel_t *channel,
+                                               ares_sysconfig_t     *sysconfig,
+                                               ares_buf_t           *line)
 {
   char          option[32];
   char          value[512];
@@ -726,9 +726,38 @@ done:
   return status;
 }
 
-typedef ares_status_t (*line_callback_t)(const ares_channel_t *channel,
-                                         ares_sysconfig_t     *sysconfig,
-                                         ares_buf_t           *line);
+
+ares_status_t ares_sysconfig_process_buf(const ares_channel_t    *channel,
+                                         ares_sysconfig_t        *sysconfig,
+                                         ares_buf_t              *buf,
+                                         ares_sysconfig_line_cb_t cb)
+{
+  ares_array_t *lines  = NULL;
+  size_t        num;
+  size_t        i;
+  ares_status_t status;
+
+  status = ares_buf_split(buf, (const unsigned char *)"\n", 1,
+                          ARES_BUF_SPLIT_TRIM, 0, &lines);
+  if (status != ARES_SUCCESS) {
+    goto done;
+  }
+
+  num = ares_array_len(lines);
+  for (i = 0; i < num; i++) {
+    ares_buf_t **bufptr = ares_array_at(lines, i);
+    ares_buf_t  *line   = *bufptr;
+
+    status = cb(channel, sysconfig, line);
+    if (status != ARES_SUCCESS) {
+      goto done;
+    }
+  }
+
+done:
+  ares_array_destroy(lines);
+  return status;
+}
 
 /* Should only return:
  *  ARES_ENOTFOUND - file not found
@@ -737,16 +766,13 @@ typedef ares_status_t (*line_callback_t)(const ares_channel_t *channel,
  *  ARES_SUCCESS   - file processed, doesn't necessarily mean it was a good
  *                   file, but we're not erroring out if we can't parse
  *                   something (or anything at all) */
-static ares_status_t process_config_lines(const ares_channel_t *channel,
-                                          const char           *filename,
-                                          ares_sysconfig_t     *sysconfig,
-                                          line_callback_t       cb)
+static ares_status_t process_config_lines(const ares_channel_t    *channel,
+                                          const char              *filename,
+                                          ares_sysconfig_t        *sysconfig,
+                                          ares_sysconfig_line_cb_t cb)
 {
   ares_status_t status = ARES_SUCCESS;
-  ares_array_t *lines  = NULL;
   ares_buf_t   *buf    = NULL;
-  size_t        num;
-  size_t        i;
 
   buf = ares_buf_create();
   if (buf == NULL) {
@@ -759,43 +785,30 @@ static ares_status_t process_config_lines(const ares_channel_t *channel,
     goto done;
   }
 
-  status = ares_buf_split(buf, (const unsigned char *)"\n", 1,
-                          ARES_BUF_SPLIT_TRIM, 0, &lines);
-  if (status != ARES_SUCCESS) {
-    goto done;
-  }
-
-  num = ares_array_len(lines);
-  for (i = 0; i < num; i++) {
-    ares_buf_t **bufptr = ares_array_at(lines, i);
-    ares_buf_t  *line   = *bufptr;
-
-    status = cb(channel, sysconfig, line);
-    if (status != ARES_SUCCESS) {
-      goto done;
-    }
-  }
+  status = ares_sysconfig_process_buf(channel, sysconfig, buf, cb);
 
 done:
   ares_buf_destroy(buf);
-  ares_array_destroy(lines);
 
   return status;
 }
 
 ares_status_t ares_init_sysconfig_files(const ares_channel_t *channel,
-                                        ares_sysconfig_t     *sysconfig)
+                                        ares_sysconfig_t     *sysconfig,
+                                        ares_bool_t process_resolvconf)
 {
   ares_status_t status = ARES_SUCCESS;
 
   /* Resolv.conf */
-  status = process_config_lines(channel,
-                                (channel->resolvconf_path != NULL)
-                                  ? channel->resolvconf_path
-                                  : PATH_RESOLV_CONF,
-                                sysconfig, parse_resolvconf_line);
-  if (status != ARES_SUCCESS && status != ARES_ENOTFOUND) {
-    goto done;
+  if (process_resolvconf) {
+    status = process_config_lines(channel,
+                                  (channel->resolvconf_path != NULL)
+                                    ? channel->resolvconf_path
+                                    : PATH_RESOLV_CONF,
+                                  sysconfig, ares_sysconfig_parse_resolv_line);
+    if (status != ARES_SUCCESS && status != ARES_ENOTFOUND) {
+      goto done;
+    }
   }
 
   /* Nsswitch.conf */
diff --git a/contrib/libs/c-ares/src/lib/event/ares_event_configchg.c b/contrib/libs/c-ares/src/lib/event/ares_event_configchg.c
index e3e665bd16..5ecc6888ab 100644
--- a/contrib/libs/c-ares/src/lib/event/ares_event_configchg.c
+++ b/contrib/libs/c-ares/src/lib/event/ares_event_configchg.c
@@ -558,14 +558,24 @@ static ares_status_t config_change_check(ares_htable_strvp_t *filestat,
                                          const char          *resolvconf_path)
 {
   size_t      i;
-  const char *configfiles[5];
+  const char *configfiles[16];
   ares_bool_t changed = ARES_FALSE;
+  size_t      cnt = 0;
 
-  configfiles[0] = resolvconf_path;
-  configfiles[1] = "/etc/nsswitch.conf";
-  configfiles[2] = "/etc/netsvc.conf";
-  configfiles[3] = "/etc/svc.conf";
-  configfiles[4] = NULL;
+  memset(configfiles, 0, sizeof(configfiles));
+
+  configfiles[cnt++] = resolvconf_path;
+  configfiles[cnt++] = "/etc/nsswitch.conf";
+#ifdef _AIX
+  configfiles[cnt++] = "/etc/netsvc.conf";
+#endif
+#ifdef __osf /* Tru64 */
+  configfiles[cnt++] = "/etc/svc.conf";
+#endif
+#ifdef __QNX__
+  configfiles[cnt++] = "/etc/net.cfg";
+#endif
+  configfiles[cnt++] = NULL;
 
   for (i = 0; configfiles[i] != NULL; i++) {
     fileinfo_t *fi = ares_htable_strvp_get_direct(filestat, configfiles[i]);
diff --git a/contrib/libs/c-ares/src/lib/include/ares_buf.h b/contrib/libs/c-ares/src/lib/include/ares_buf.h
index 7836a313e0..10d29eaf83 100644
--- a/contrib/libs/c-ares/src/lib/include/ares_buf.h
+++ b/contrib/libs/c-ares/src/lib/include/ares_buf.h
@@ -219,6 +219,26 @@ CARES_EXTERN unsigned char *ares_buf_finish_bin(ares_buf_t *buf, size_t *len);
  */
 CARES_EXTERN char          *ares_buf_finish_str(ares_buf_t *buf, size_t *len);
 
+/*! Replace the given search byte sequence with the replacement byte sequence.
+ *  This is only valid for allocated buffers, not const buffers.  Will replace
+ *  all byte sequences starting at the current offset to the end of the buffer.
+ *
+ *  \param[in]  buf       Initialized buffer object. Can not be a "const" buffer.
+ *  \param[in]  srch      Search byte sequence, must not be NULL.
+ *  \param[in]  srch_size Size of byte sequence, must not be zero.
+ *  \param[in]  rplc      Byte sequence to use as replacement.  May be NULL if
+ *                        rplc_size is zero.
+ *  \param[in]  rplc_size Size of replacement byte sequence, may be 0.
+ *  \return ARES_SUCCESS on success, otherwise on may return failure only on
+ *          memory allocation failure or misuse.  Will not return indication
+ *          if any replacements occurred
+ */
+CARES_EXTERN ares_status_t  ares_buf_replace(ares_buf_t *buf,
+                                             const unsigned char *srch,
+                                             size_t srch_size,
+                                             const unsigned char *rplc,
+                                             size_t rplc_size);
+
 /*! Tag a position to save in the buffer in case parsing needs to rollback,
  *  such as if insufficient data is available, but more data may be added in
  *  the future.  Only a single tag can be set per buffer object.  Setting a
diff --git a/contrib/libs/c-ares/src/lib/include/ares_str.h b/contrib/libs/c-ares/src/lib/include/ares_str.h
index ea75b3b3e7..4ee339510b 100644
--- a/contrib/libs/c-ares/src/lib/include/ares_str.h
+++ b/contrib/libs/c-ares/src/lib/include/ares_str.h
@@ -29,6 +29,20 @@
 
 CARES_EXTERN char  *ares_strdup(const char *s1);
 
+/*! Scan up to maxlen bytes for the first NULL character and return
+ *  its index, or maxlen if not found.  The function only returns
+ *  maxlen if the first maxlen bytes were not NULL characters; it
+ *  makes no guarantee for what \c str[maxlen] (if defined) is, and
+ *  does not access it.  It is behaving like the POSIX \c strnlen()
+ *  function, except that it returns 0 if the \p str pointer is \c
+ *  NULL.
+ *
+ *  \param[in] str    The string to scan for the NULL character
+ *  \param[in] maxlen The maximum number of bytes to scan
+ *  \return Index of first NULL byte. Between 0 and maxlen (inclusive).
+ */
+CARES_EXTERN size_t ares_strnlen(const char *str, size_t maxlen);
+
 CARES_EXTERN size_t ares_strlen(const char *str);
 
 /*! Copy string from source to destination with destination buffer size
diff --git a/contrib/libs/c-ares/src/lib/record/ares_dns_multistring.c b/contrib/libs/c-ares/src/lib/record/ares_dns_multistring.c
index 57c0d1c0a8..44fcaccd65 100644
--- a/contrib/libs/c-ares/src/lib/record/ares_dns_multistring.c
+++ b/contrib/libs/c-ares/src/lib/record/ares_dns_multistring.c
@@ -146,6 +146,18 @@ ares_status_t ares_dns_multistring_add_own(ares_dns_multistring_t *strs,
     return status;
   }
 
+  /* Issue #921, ares_dns_multistring_get() doesn't have a way to indicate
+   * success or fail on a zero-length string which is actually valid.  So we
+   * are going to allocate a 1-byte buffer to use as a placeholder in this
+   * case */
+  if (str == NULL) {
+    str = ares_malloc_zero(1);
+    if (str == NULL) {
+      ares_array_remove_last(strs->strs);
+      return ARES_ENOMEM;
+    }
+  }
+
   data->data = str;
   data->len  = len;
 
@@ -252,36 +264,38 @@ ares_status_t ares_dns_multistring_parse_buf(ares_buf_t *buf,
       break; /* LCOV_EXCL_LINE: DefensiveCoding */
     }
 
-    if (len) {
-      /* When used by the _str() parser, it really needs to be validated to
-       * be a valid printable ascii string.  Do that here */
-      if (validate_printable && ares_buf_len(buf) >= len) {
-        size_t      mylen;
-        const char *data = (const char *)ares_buf_peek(buf, &mylen);
-        if (!ares_str_isprint(data, len)) {
-          status = ARES_EBADSTR;
-          break;
-        }
+
+    /* When used by the _str() parser, it really needs to be validated to
+     * be a valid printable ascii string.  Do that here */
+    if (len && validate_printable && ares_buf_len(buf) >= len) {
+      size_t      mylen;
+      const char *data = (const char *)ares_buf_peek(buf, &mylen);
+      if (!ares_str_isprint(data, len)) {
+        status = ARES_EBADSTR;
+        break;
       }
+    }
 
-      if (strs != NULL) {
-        unsigned char *data = NULL;
+    if (strs != NULL) {
+      unsigned char *data = NULL;
+      if (len) {
         status = ares_buf_fetch_bytes_dup(buf, len, ARES_TRUE, &data);
         if (status != ARES_SUCCESS) {
           break;
         }
-        status = ares_dns_multistring_add_own(*strs, data, len);
-        if (status != ARES_SUCCESS) {
-          ares_free(data);
-          break;
-        }
-      } else {
-        status = ares_buf_consume(buf, len);
-        if (status != ARES_SUCCESS) {
-          break;
-        }
+      }
+      status = ares_dns_multistring_add_own(*strs, data, len);
+      if (status != ARES_SUCCESS) {
+        ares_free(data);
+        break;
+      }
+    } else {
+      status = ares_buf_consume(buf, len);
+      if (status != ARES_SUCCESS) {
+        break;
       }
     }
+
   }
 
   if (status != ARES_SUCCESS && strs != NULL) {
diff --git a/contrib/libs/c-ares/src/lib/str/ares_buf.c b/contrib/libs/c-ares/src/lib/str/ares_buf.c
index 69e6b38aac..63acc6cf77 100644
--- a/contrib/libs/c-ares/src/lib/str/ares_buf.c
+++ b/contrib/libs/c-ares/src/lib/str/ares_buf.c
@@ -1104,6 +1104,72 @@ const unsigned char *ares_buf_peek(const ares_buf_t *buf, size_t *len)
   return ares_buf_fetch(buf, len);
 }
 
+ares_status_t ares_buf_replace(ares_buf_t *buf, const unsigned char *srch,
+                               size_t srch_size, const unsigned char *rplc,
+                               size_t rplc_size)
+{
+  size_t        processed_len = 0;
+  ares_status_t status;
+
+  if (buf->alloc_buf == NULL || srch == NULL || srch_size == 0 ||
+      (rplc == NULL && rplc_size != 0)) {
+    return ARES_EFORMERR;
+  }
+
+  while (1) {
+    unsigned char *ptr           = buf->alloc_buf + buf->offset + processed_len;
+    size_t         remaining_len = buf->data_len - buf->offset - processed_len;
+    size_t         found_offset  = 0;
+    size_t         move_data_len;
+
+    /* Find pattern */
+    ptr = ares_memmem(ptr, remaining_len, srch, srch_size);
+    if (ptr == NULL) {
+      break;
+    }
+
+    /* Store the offset this was found because our actual pointer might be
+     * switched out from under us by the call to ensure_space() if the
+     * replacement pattern is larger than the search pattern */
+    found_offset   = (size_t)(ptr - (size_t)(buf->alloc_buf + buf->offset));
+    if (rplc_size > srch_size) {
+      status = ares_buf_ensure_space(buf, rplc_size - srch_size);
+      if (status != ARES_SUCCESS) {
+        return status;
+      }
+    }
+
+    /* Impossible, but silence clang */
+    if (buf->alloc_buf == NULL) {
+      return ARES_ENOMEM;
+    }
+
+    /* Recalculate actual pointer */
+    ptr = buf->alloc_buf + buf->offset + found_offset;
+
+    /* Move the data */
+    move_data_len = buf->data_len - buf->offset - found_offset - srch_size;
+    memmove(ptr + rplc_size,
+            ptr + srch_size,
+            move_data_len);
+
+    /* Copy in the replacement data */
+    if (rplc != NULL && rplc_size > 0) {
+      memcpy(ptr, rplc, rplc_size);
+    }
+
+    if (rplc_size > srch_size) {
+      buf->data_len += rplc_size - srch_size;
+    } else {
+      buf->data_len -= srch_size - rplc_size;
+    }
+
+    processed_len = found_offset + rplc_size;
+  }
+
+  return ARES_SUCCESS;
+}
+
 ares_status_t ares_buf_peek_byte(const ares_buf_t *buf, unsigned char *b)
 {
   size_t               remaining_len = 0;
diff --git a/contrib/libs/c-ares/src/lib/str/ares_str.c b/contrib/libs/c-ares/src/lib/str/ares_str.c
index f6bfabf11f..0eda1ab9f1 100644
--- a/contrib/libs/c-ares/src/lib/str/ares_str.c
+++ b/contrib/libs/c-ares/src/lib/str/ares_str.c
@@ -32,6 +32,23 @@
 #  include <stdint.h>
 #endif
 
+size_t ares_strnlen(const char *str, size_t maxlen) {
+  const char *p = NULL;
+  if (str == NULL) {
+    return 0;
+  }
+#ifdef HAVE_STRNLEN
+  (void)p;
+  return strnlen(str, maxlen);
+#else
+  if ((p = memchr(str, 0, maxlen)) == NULL) {
+    return maxlen;
+  } else {
+    return (size_t)(p - str);
+  }
+#endif /* HAVE_STRNLEN */
+}
+
 size_t ares_strlen(const char *str)
 {
   if (str == NULL) {