From 103fa130f74244b29abe07e752bf22c67bfe84fc Mon Sep 17 00:00:00 2001
From: Michael van der Werve <mvdwerve@outlook.com>
Date: Tue, 29 Sep 2020 13:51:54 +0200
Subject: [PATCH] {auto} implement timeout on initial connection instead of
 being subjected to kernel

---
 src/linux_tcp/tcpconnection.cpp |  2 +-
 src/linux_tcp/tcpresolver.h     | 68 ++++++++++++++++++++++++++-------
 2 files changed, 55 insertions(+), 15 deletions(-)

diff --git a/src/linux_tcp/tcpconnection.cpp b/src/linux_tcp/tcpconnection.cpp
index d7aaf30d..7d9e8cce 100644
--- a/src/linux_tcp/tcpconnection.cpp
+++ b/src/linux_tcp/tcpconnection.cpp
@@ -26,7 +26,7 @@ namespace AMQP {
  */
 TcpConnection::TcpConnection(TcpHandler *handler, const Address &address) :
     _handler(handler),
-    _state(new TcpResolver(this, address.hostname(), address.port(), address.secure())),
+    _state(new TcpResolver(this, address.hostname(), address.port(), address.secure(), address.option("connectTimeout", 5))),
     _connection(this, address.login(), address.vhost()) 
 {
     // tell the handler
diff --git a/src/linux_tcp/tcpresolver.h b/src/linux_tcp/tcpresolver.h
index 0d3bb618..6ad9f9a8 100644
--- a/src/linux_tcp/tcpresolver.h
+++ b/src/linux_tcp/tcpresolver.h
@@ -53,6 +53,12 @@ class TcpResolver : public TcpExtState
      *  @var uint16_t
      */
     uint16_t _port;
+
+    /**
+     *  Timeout for the connect call in seconds.
+     *  @var int
+     */
+    int _timeout;
     
     /**
      *  A pipe that is used to send back the socket that is connected to RabbitMQ
@@ -93,6 +99,9 @@ class TcpResolver : public TcpExtState
             // get address info
             AddressInfo addresses(_hostname.data(), _port);
     
+            // an fdset to monitor for writability
+            fd_set writeset;
+    
             // iterate over the addresses
             for (size_t i = 0; i < addresses.size(); ++i)
             {
@@ -101,12 +110,47 @@ class TcpResolver : public TcpExtState
                 
                 // move on on failure
                 if (_socket < 0) continue;
-                
-                // connect to the socket
+
+                // turn socket into a non-blocking socket and set the close-on-exec bit
+                fcntl(_socket, F_SETFL, O_NONBLOCK | O_CLOEXEC);
+
+                // try to connect non-blocking
                 if (connect(_socket, addresses[i]->ai_addr, addresses[i]->ai_addrlen) == 0) break;
-                
+
+                // we set the timeout to a timeout, with 5 seconds as the default
+                struct timeval timeout{_timeout,0};
+
+                // reset the fdset
+                FD_ZERO(&writeset);
+
+                // set the fd to monitor for writing
+                FD_SET(_socket, &writeset);
+
+                // perform a select, wait for something to happen on one of the fds
+                int ret = select(_socket + 1, nullptr, &writeset, nullptr, &timeout);
+
                 // log the error for the time being
-                _error = strerror(errno);
+                if (ret == 0) _error = "connection timed out";
+                
+                // otherwise, select might've failed
+                else if (ret < 0) _error = strerror(errno);
+
+                // otherwise the connect failed/succeeded
+                else
+                {
+                    // the error
+                    int err = 0;
+                    socklen_t len = 4;
+
+                    // get the options
+                    getsockopt(_socket, SOL_SOCKET, SO_ERROR, &err, &len);
+
+                    // if the error is zero, we break, socket is now valid
+                    if (err == 0) break;
+
+                    // set the error with the value
+                    _error = strerror(err);
+                }
 
                 // close socket because connect failed
                 ::close(_socket);
@@ -118,9 +162,6 @@ class TcpResolver : public TcpExtState
             // connection succeeded, mark socket as non-blocking
             if (_socket >= 0) 
             {
-                // turn socket into a non-blocking socket and set the close-on-exec bit
-                fcntl(_socket, F_SETFL, O_NONBLOCK | O_CLOEXEC);
-                
                 // we want to enable "nodelay" on sockets (otherwise all send operations are s-l-o-w
                 int optval = 1;
                 
@@ -138,11 +179,8 @@ class TcpResolver : public TcpExtState
             _error = error.what();
         }
             
-        // notify the master thread by sending a byte over the pipe
-        if (!_pipe.notify())
-        {
-            _error = strerror(errno);
-        }
+        // notify the master thread by sending a byte over the pipe, store error if this fails
+        if (!_pipe.notify()) _error = strerror(errno);
     }
 
 public:
@@ -152,12 +190,14 @@ class TcpResolver : public TcpExtState
      *  @param  hostname    The hostname for the lookup
      *  @param  portnumber  The portnumber for the lookup
      *  @param  secure      Do we need a secure tls connection when ready?
+     *  @param  timeout     timeout per connection attempt
      */
-    TcpResolver(TcpParent *parent, std::string hostname, uint16_t port, bool secure) : 
+    TcpResolver(TcpParent *parent, std::string hostname, uint16_t port, bool secure, int timeout) : 
         TcpExtState(parent), 
         _hostname(std::move(hostname)),
         _secure(secure),
-        _port(port)
+        _port(port),
+        _timeout(timeout)
     {
         // tell the event loop to monitor the filedescriptor of the pipe
         parent->onIdle(this, _pipe.in(), readable);