dns: add "tries" option to Resolve options

PR-URL: #39610 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Michaël Zasso <targos@protonmail.com>
nodejs · Aug 16, 2021 · c7e918b · c7e918b
1 parent 760cafa
commit c7e918b
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Showing 5 changed files with 34 additions and 8 deletions.
diff --git a/doc/api/dns.md b/doc/api/dns.md
@@ -108,6 +108,8 @@ Create a new resolver.
 * `options` {Object}
   * `timeout` {integer} Query timeout in milliseconds, or `-1` to use the
     default timeout.
+  * `tries` {integer} The number of tries the resolver will try contacting
+    each name server before giving up, `4` by default.
 
 ### `resolver.cancel()`
 <!-- YAML

diff --git a/lib/internal/dns/promises.js b/lib/internal/dns/promises.js
@@ -12,6 +12,7 @@ const {
   Resolver: CallbackResolver,
   validateHints,
   validateTimeout,
+  validateTries,
   emitInvalidHostnameWarning,
   getDefaultVerbatim,
 } = require('internal/dns/utils');
@@ -216,7 +217,8 @@ const resolveMap = ObjectCreate(null);
 class Resolver {
   constructor(options = undefined) {
     const timeout = validateTimeout(options);
-    this._handle = new ChannelWrap(timeout);
+    const tries = validateTries(options);
+    this._handle = new ChannelWrap(timeout, tries);
   }
 }
 

diff --git a/lib/internal/dns/utils.js b/lib/internal/dns/utils.js
@@ -43,11 +43,18 @@ function validateTimeout(options) {
   return timeout;
 }
 
+function validateTries(options) {
+  const { tries = 4 } = { ...options };
+  validateInt32(tries, 'options.tries', 1, 2 ** 31 - 1);
+  return tries;
+}
+
 // Resolver instances correspond 1:1 to c-ares channels.
 class Resolver {
   constructor(options = undefined) {
     const timeout = validateTimeout(options);
-    this._handle = new ChannelWrap(timeout);
+    const tries = validateTries(options);
+    this._handle = new ChannelWrap(timeout, tries);
   }
 
   cancel() {
@@ -209,6 +216,7 @@ module.exports = {
   setDefaultResolver,
   validateHints,
   validateTimeout,
+  validateTries,
   Resolver,
   emitInvalidHostnameWarning,
   getDefaultVerbatim,

diff --git a/src/cares_wrap.cc b/src/cares_wrap.cc
@@ -631,9 +631,14 @@ int ParseSoaReply(
 }
 }  // anonymous namespace
 
-ChannelWrap::ChannelWrap(Environment* env, Local<Object> object, int timeout)
+ChannelWrap::ChannelWrap(
+      Environment* env,
+      Local<Object> object,
+      int timeout,
+      int tries)
     : AsyncWrap(env, object, PROVIDER_DNSCHANNEL),
-      timeout_(timeout) {
+      timeout_(timeout),
+      tries_(tries) {
   MakeWeak();
 
   Setup();
@@ -647,11 +652,13 @@ void ChannelWrap::MemoryInfo(MemoryTracker* tracker) const {
 
 void ChannelWrap::New(const FunctionCallbackInfo<Value>& args) {
   CHECK(args.IsConstructCall());
-  CHECK_EQ(args.Length(), 1);
+  CHECK_EQ(args.Length(), 2);
   CHECK(args[0]->IsInt32());
+  CHECK(args[1]->IsInt32());
   const int timeout = args[0].As<Int32>()->Value();
+  const int tries = args[1].As<Int32>()->Value();
   Environment* env = Environment::GetCurrent(args);
-  new ChannelWrap(env, args.This(), timeout);
+  new ChannelWrap(env, args.This(), timeout, tries);
 }
 
 GetAddrInfoReqWrap::GetAddrInfoReqWrap(
@@ -704,6 +711,7 @@ void ChannelWrap::Setup() {
   options.sock_state_cb = ares_sockstate_cb;
   options.sock_state_cb_data = this;
   options.timeout = timeout_;
+  options.tries = tries_;
 
   int r;
   if (!library_inited_) {
@@ -717,7 +725,8 @@ void ChannelWrap::Setup() {
 
   /* We do the call to ares_init_option for caller. */
   const int optmask =
-      ARES_OPT_FLAGS | ARES_OPT_TIMEOUTMS | ARES_OPT_SOCK_STATE_CB;
+      ARES_OPT_FLAGS | ARES_OPT_TIMEOUTMS |
+      ARES_OPT_SOCK_STATE_CB | ARES_OPT_TRIES;
   r = ares_init_options(&channel_, &options, optmask);
 
   if (r != ARES_SUCCESS) {

diff --git a/src/cares_wrap.h b/src/cares_wrap.h
@@ -147,7 +147,11 @@ struct NodeAresTask final : public MemoryRetainer {
 
 class ChannelWrap final : public AsyncWrap {
  public:
-  ChannelWrap(Environment* env, v8::Local<v8::Object> object, int timeout);
+  ChannelWrap(
+    Environment* env,
+    v8::Local<v8::Object> object,
+    int timeout,
+    int tries);
   ~ChannelWrap() override;
 
   static void New(const v8::FunctionCallbackInfo<v8::Value>& args);
@@ -181,6 +185,7 @@ class ChannelWrap final : public AsyncWrap {
   bool is_servers_default_ = true;
   bool library_inited_ = false;
   int timeout_;
+  int tries_;
   int active_query_count_ = 0;
   NodeAresTask::List task_list_;
 };