inspector: bind to random port with --inspect=0

Allow binding to a randomly assigned port number with `--inspect=0`
or `--inspect-brk=0`.
PR-URL: #5025
Refs: #4419
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>

Author: bnoordhuis

src/inspector_io.cc

@@ -175,7 +175,7 @@ InspectorIo::InspectorIo(Environment* env, v8::Platform* platform,
  io_thread_req_(), platform_(platform),
  dispatching_messages_(false), session_id_(0),
  script_name_(path),
- wait_for_connect_(wait_for_connect) {
+ wait_for_connect_(wait_for_connect), port_(-1) {
  main_thread_req_ = newAsyncAndAgent({uv_async_t(), env->inspector_agent()});
 CHECK_EQ(0, uv_async_init(env->event_loop(), &main_thread_req_->first,
  InspectorIo::MainThreadAsyncCb));
@@ -298,6 +298,7 @@ void InspectorIo::WorkerRunIO() {
 uv_sem_post(&start_sem_);
 return;
  }
+ port_ = server.port(); // Safe, main thread is waiting on semaphore.
 if (!wait_for_connect_) {
 uv_sem_post(&start_sem_);
  }

src/inspector_io.h

@@ -68,6 +68,8 @@ class InspectorIo {
 uv_close(reinterpret_cast<uv_handle_t*>(&io_thread_req_), nullptr);
  }
 
+intport() const { return port_; }
+
 private:
 template <typename Action>
 using MessageQueue =
@@ -129,6 +131,7 @@ class InspectorIo {
  std::string script_path_;
 const std::string id_;
 constbool wait_for_connect_;
+int port_;
 
 friendclassDispatchMessagesTask;
 friendclassIoSessionDelegate;

src/node.cc

@@ -40,6 +40,10 @@
 #include"node_i18n.h"
 #endif
 
+#if HAVE_INSPECTOR
+#include"inspector_io.h"
+#endif
+
 #if defined HAVE_DTRACE || defined HAVE_ETW
 #include"node_dtrace.h"
 #endif
@@ -3048,7 +3052,15 @@ static Local<Object> GetFeatures(Environment* env) {
 
 staticvoidDebugPortGetter(Local<Name> property,
 const PropertyCallbackInfo<Value>& info) {
- info.GetReturnValue().Set(debug_options.port());
+int port = debug_options.port();
+#if HAVE_INSPECTOR
+if (port == 0) {
+ Environment* env = Environment::GetCurrent(info);
+if (env->inspector_agent()->IsStarted())
+ port = env->inspector_agent()->io()->port();
+ }
+#endif// HAVE_INSPECTOR
+ info.GetReturnValue().Set(port);
 }
 
 

src/node_debug_options.cc

@@ -21,8 +21,9 @@ int parse_and_validate_port(const std::string& port) {
 char* endptr;
  errno = 0;
 constlong result = strtol(port.c_str(), &endptr, 10); // NOLINT(runtime/int)
-if (errno != 0 || *endptr != '\0'|| result < 1024 || result > 65535) {
-fprintf(stderr, "Debug port must be in range 1024 to 65535.\n");
+if (errno != 0 || *endptr != '\0'||
+ (result != 0 && result < 1024) || result > 65535) {
+fprintf(stderr, "Debug port must be 0 or in range 1024 to 65535.\n");
 exit(12);
  }
 returnstatic_cast<int>(result);

test/inspector/test-inspector-port-zero-cluster.js

@@ -0,0 +1,32 @@
+// Flags: --inspect=0
+'use strict';
+
+constcommon=require('../common');
+constassert=require('assert');
+constcluster=require('cluster');
+
+if(cluster.isMaster){
+constports=[];
+for(constworkerof[cluster.fork(),
+cluster.fork(),
+cluster.fork()]){
+worker.on('message',common.mustCall((message)=>{
+ports.push(message.debugPort);
+worker.kill();
+}));
+worker.send('debugPort');
+}
+process.on('exit',()=>{
+ports.sort();
+assert.strictEqual(ports.length,3);
+assert(ports.every((port)=>port>0));
+assert(ports.every((port)=>port<65536));
+assert.strictEqual(ports[0]+1,ports[1]);// Ports should be consecutive.
+assert.strictEqual(ports[1]+1,ports[2]);
+});
+}else{
+process.on('message',(message)=>{
+if(message==='debugPort')
+process.send({debugPort: process.debugPort});
+});
+}

test/inspector/test-inspector-port-zero.js

@@ -0,0 +1,46 @@
+'use strict';
+
+const{ mustCall }=require('../common');
+constassert=require('assert');
+const{URL}=require('url');
+const{ spawn }=require('child_process');
+
+functiontest(arg){
+constargs=[arg,'-p','process.debugPort'];
+constproc=spawn(process.execPath,args);
+proc.stdout.setEncoding('utf8');
+proc.stderr.setEncoding('utf8');
+letstdout='';
+letstderr='';
+proc.stdout.on('data',(data)=>stdout+=data);
+proc.stderr.on('data',(data)=>stderr+=data);
+proc.stdout.on('close',assert.ifError);
+proc.stderr.on('close',assert.ifError);
+letport='';
+proc.stderr.on('data',()=>{
+if(!stderr.includes('\n'))return;
+assert(/Debuggerlisteningon(.+)/.test(stderr));
+port=newURL(RegExp.$1).port;
+assert(+port>0);
+});
+if(/inspect-brk/.test(arg)){
+proc.stderr.on('data',()=>{
+if(stderr.includes('\n')&&!proc.killed)proc.kill();
+});
+}else{
+letonclose=()=>{
+onclose=()=>assert.strictEqual(port,stdout.trim());
+};
+proc.stdout.on('close',mustCall(()=>onclose()));
+proc.stderr.on('close',mustCall(()=>onclose()));
+proc.on('exit',mustCall((exitCode)=>assert.strictEqual(exitCode,0)));
+}
+}
+
+test('--inspect=0');
+test('--inspect=127.0.0.1:0');
+test('--inspect=localhost:0');
+
+test('--inspect-brk=0');
+test('--inspect-brk=127.0.0.1:0');
+test('--inspect-brk=localhost:0');