Refactor endpoint verification prior to connection

Summary:
^

There's a similar issue/request for Android. So, this change moves the code out from the FlipperKit into Flipper as to be able to reuse it.

Reviewed By: aigoncharov

Differential Revision: D35961745

fbshipit-source-id: aa255db582a7852dc06c2feaba389d1dac3b0f67

iOS/FlipperKit/FlipperPlatformWebSocket.mm

@@ -8,12 +8,9 @@
 #ifdef FB_SONARKIT_ENABLED
 
 #import "FlipperPlatformWebSocket.h"
+#import <Flipper/FlipperConnectionEndpointVerifier.h>
 #import <Flipper/Log.h>
 #import <SocketRocket/SocketRocket.h>
-#include <netdb.h>
-#include <stdio.h>
-#include <sys/socket.h>
-#include <unistd.h>
 
 static constexpr int connectionKeepaliveSeconds = 10;
 
@@ -152,52 +149,8 @@ static constexpr int connectionKeepaliveSeconds = 10;
     // there is a process listening at the specified port.
     // CFNetwork seems to be quite verbose when the host cannot be reached
     // causing unnecessary and annoying logs to be printed to the console.
-    struct addrinfo hints;
-
-    memset(&hints, 0, sizeof(hints));
-    hints.ai_family = AF_UNSPEC;
-    hints.ai_socktype = SOCK_STREAM;
-    hints.ai_flags = AI_PASSIVE;
-    struct addrinfo* address;
-    getaddrinfo(
-        strongSelf->_url.host.UTF8String,
-        strongSelf->_url.port.stringValue.UTF8String,
-        &hints,
-        &address);
-
-    int sfd =
-        socket(address->ai_family, address->ai_socktype, address->ai_protocol);
-
-    fcntl(sfd, F_SETFL, O_NONBLOCK);
-    connect(sfd, address->ai_addr, address->ai_addrlen);
-
-    fd_set fdset;
-    struct timeval tv;
-
-    FD_ZERO(&fdset);
-    FD_SET(sfd, &fdset);
-    // Set a timeout of 3 seconds.
-    tv.tv_sec = 3;
-    tv.tv_usec = 0;
-
-    bool listening = false;
-    if (select(sfd + 1, NULL, &fdset, NULL, &tv) == 1) {
-      int so_error;
-      socklen_t len = sizeof so_error;
-
-      getsockopt(sfd, SOL_SOCKET, SO_ERROR, &so_error, &len);
-
-      if (so_error == 0) {
-        listening = true;
-      }
-      // If there's an error, most likely there is no process
-      // listening at the specified host/port (ECONNREFUSED).
-    }
-
-    freeaddrinfo(address);
-    close(sfd);
-
-    if (!listening) {
+    if (!facebook::flipper::ConnectionEndpointVerifier::verify(
+            strongSelf->_url.host.UTF8String, strongSelf->_url.port.intValue)) {
       strongSelf->_eventHandler(facebook::flipper::SocketEvent::ERROR);
       return;
     }

xplat/Flipper/FlipperConnectionEndpointVerifier.cpp

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include "FlipperConnectionEndpointVerifier.h"
+#include <netdb.h>
+#include <stdio.h>
+#include <sys/fcntl.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include <cstring>
+
+namespace facebook {
+namespace flipper {
+
+bool ConnectionEndpointVerifier::verify(const std::string& host, int port) {
+  auto sport = std::to_string(port);
+
+  struct addrinfo hints;
+
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = AF_UNSPEC;
+  hints.ai_socktype = SOCK_STREAM;
+  hints.ai_flags = AI_PASSIVE;
+  struct addrinfo* address;
+  getaddrinfo(host.c_str(), sport.c_str(), &hints, &address);
+
+  int sfd =
+      socket(address->ai_family, address->ai_socktype, address->ai_protocol);
+
+  fcntl(sfd, F_SETFL, O_NONBLOCK);
+  connect(sfd, address->ai_addr, address->ai_addrlen);
+
+  fd_set fdset;
+  struct timeval tv;
+
+  FD_ZERO(&fdset);
+  FD_SET(sfd, &fdset);
+  // Set a timeout of 3 seconds.
+  tv.tv_sec = 3;
+  tv.tv_usec = 0;
+
+  bool listening = false;
+  if (select(sfd + 1, NULL, &fdset, NULL, &tv) == 1) {
+    int so_error;
+    socklen_t len = sizeof so_error;
+
+    getsockopt(sfd, SOL_SOCKET, SO_ERROR, &so_error, &len);
+
+    if (so_error == 0) {
+      listening = true;
+    }
+    // If there's an error, most likely there is no process
+    // listening at the specified host/port (ECONNREFUSED).
+  }
+
+  freeaddrinfo(address);
+  close(sfd);
+
+  return listening;
+}
+
+} // namespace flipper
+} // namespace facebook

xplat/Flipper/FlipperConnectionEndpointVerifier.h

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <string>
+
+namespace facebook {
+namespace flipper {
+struct ConnectionEndpointVerifier {
+  /** Verifies whether the given endpoint is listening
+   for incoming connections. */
+  static bool verify(const std::string& host, int port);
+};
+} // namespace flipper
+} // namespace facebook