Real Name

ixwebsocket/IXSocketConnect.cpp

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+/*
+ *  IXSocketConnect.cpp
+ *  Author: Benjamin Sergeant
+ *  Copyright (c) 2018 Machine Zone, Inc. All rights reserved.
+ */
+
+#include "IXSocketConnect.h"
+
+#include "IXDNSLookup.h"
+#include "IXNetSystem.h"
+#include "IXSelectInterrupt.h"
+#include "IXSocket.h"
+#include "IXUniquePtr.h"
+#include <fcntl.h>
+#include <string.h>
+#include <sys/types.h>
+
+// Android needs extra headers for TCP_NODELAY and IPPROTO_TCP
+#ifdef ANDROID
+#include <linux/in.h>
+#include <linux/tcp.h>
+#endif
+
+namespace ix
+{
+//
+// This function can be cancelled every 50 ms
+// This is important so that we don't block the main UI thread when shutting
+// down a connection which is already trying to reconnect, and can be blocked
+// waiting for
+// ::connect to respond.
+//
+int SocketConnect::connectToAddress(
+    const struct addrinfo *address,
+    std::string &errMsg,
+    const CancellationRequest &isCancellationRequested)
+{
+    errMsg = "no error";
+
+    socket_t fd =
+        socket(address->ai_family, address->ai_socktype, address->ai_protocol);
+    if (fd < 0) {
+        errMsg = "Cannot create a socket";
+        return -1;
+    }
+
+    // Set the socket to non blocking mode, so that slow responses cannot
+    // block us for too long
+    SocketConnect::configure(fd);
+
+    int res = ::connect(fd, address->ai_addr, address->ai_addrlen);
+
+    if (res == -1 && !Socket::isWaitNeeded()) {
+        errMsg = strerror(Socket::getErrno());
+        Socket::closeSocket(fd);
+        return -1;
+    }
+
+    for (;;) {
+        if (isCancellationRequested &&
+            isCancellationRequested()) // Must handle timeout as well
+        {
+            Socket::closeSocket(fd);
+            errMsg = "Cancelled";
+            return -1;
+        }
+
+        int timeoutMs = 10;
+        bool readyToRead = false;
+        auto selectInterrupt = ix::make_unique<SelectInterrupt>();
+        PollResultType pollResult =
+            Socket::poll(readyToRead, timeoutMs, fd, selectInterrupt);
+
+        if (pollResult == PollResultType::Timeout) {
+            continue;
+        } else if (pollResult == PollResultType::Error) {
+            Socket::closeSocket(fd);
+            errMsg =
+                std::string("Connect error: ") + strerror(Socket::getErrno());
+            return -1;
+        } else if (pollResult == PollResultType::ReadyForWrite) {
+            return fd;
+        } else {
+            Socket::closeSocket(fd);
+            errMsg =
+                std::string("Connect error: ") + strerror(Socket::getErrno());
+            return -1;
+        }
+    }
+
+    Socket::closeSocket(fd);
+    errMsg = "connect timed out after 60 seconds";
+    return -1;
+}
+
+int SocketConnect::connect(const std::string &hostname,
+                           int port,
+                           std::string &errMsg,
+                           const CancellationRequest &isCancellationRequested)
+{
+    //
+    // First do DNS resolution
+    //
+    auto dnsLookup = std::make_shared<DNSLookup>(hostname, port);
+    struct addrinfo *res = dnsLookup->resolve(errMsg, isCancellationRequested);
+    if (res == nullptr) {
+        return -1;
+    }
+
+    int sockfd = -1;
+
+    // iterate through the records to find a working peer
+    struct addrinfo *address;
+    for (address = res; address != nullptr; address = address->ai_next) {
+        //
+        // Second try to connect to the remote host
+        //
+        sockfd = connectToAddress(address, errMsg, isCancellationRequested);
+        if (sockfd != -1) {
+            break;
+        }
+    }
+
+    freeaddrinfo(res);
+    return sockfd;
+}
+
+// FIXME: configure is a terrible name
+void SocketConnect::configure(int sockfd)
+{
+    // 1. disable Nagle's algorithm
+    int flag = 1;
+    setsockopt(sockfd, IPPROTO_TCP, TCP_NODELAY, (char *)&flag, sizeof(flag));
+
+    // 2. make socket non blocking
+#ifdef _WIN32
+    unsigned long nonblocking = 1;
+    ioctlsocket(sockfd, FIONBIO, &nonblocking);
+#else
+    fcntl(sockfd, F_SETFL, O_NONBLOCK); // make socket non blocking
+#endif
+
+    // 3. (apple) prevent SIGPIPE from being emitted when the remote end
+    // disconnect
+#ifdef SO_NOSIGPIPE
+    int value = 1;
+    setsockopt(sockfd, SOL_SOCKET, SO_NOSIGPIPE, (void *)&value, sizeof(value));
+#endif
+}
+} // namespace ix