Merge pull request #378 from CopernicaMarketingSoftware/poll-replace-select

select only supports upto fd 1024, which can cause stack smashing if using higher ones

src/linux_tcp/poll.h

@@ -11,6 +11,11 @@
  */
 #pragma once
 
+/**
+ *  Includes
+ */
+#include <poll.h>
+
 /**
  *  Begin of namespace
  */
@@ -26,7 +31,7 @@ private:
      *  Set with just one filedescriptor
      *  @var fd_set
      */
-    fd_set _set;
+    pollfd _fd;
 
     /**
      *  The socket filedescriptor
@@ -39,13 +44,10 @@ public:
      *  Constructor
      *  @param  fd      the filedescriptor that we're waiting on
      */
-    Poll(int fd) : _socket(fd)
+    Poll(int fd)
     {
-        // initialize the set
-        FD_ZERO(&_set);
-        
-        // add the one socket
-        FD_SET(_socket, &_set);
+        // set the fd
+        _fd.fd = fd;
     }
     
     /**
@@ -60,66 +62,45 @@ public:
     virtual ~Poll() = default;
     
     /**
-     *  Wait until the filedescriptor becomes readable
-     *  @param  block       block until readable
+     *  Check if a file descriptor is readable.
      *  @return bool
      */
-    bool readable(bool block) 
-    {
-        // wait for the socket
-        if (block) return select(_socket + 1, &_set, nullptr, nullptr, nullptr) > 0;
-        
-        // we do not want to block, so we use a small timeout
-        struct timeval timeout;
-        
-        // no timeout at all
-        timeout.tv_sec = timeout.tv_usec = 0;
-        
-        // no timeout at all
-        return select(_socket + 1, &_set, nullptr, nullptr, &timeout) > 0;
+    bool readable() 
+    {   
+        // check for readable
+        _fd.events = POLLIN;
+        _fd.revents = 0;     
+
+        // poll the fd with no timeout
+        return poll(&_fd, 1, 0) > 0;
     }
         
     /**
      *  Wait until the filedescriptor becomes writable
-     *  @param  block       block until readable
      *  @return bool
      */
-    bool writable(bool block) 
+    bool writable() 
     {
-        // wait for the socket
-        if (block) return select(_socket + 1, nullptr, &_set, nullptr, nullptr) > 0;
+        // check for readable
+        _fd.events = POLLOUT;   
+        _fd.revents = 0;  
 
-        // we do not want to block, so we use a small timeout
-        struct timeval timeout;
-        
-        // no timeout at all
-        timeout.tv_sec = timeout.tv_usec = 0;
-        
-        // no timeout at all
-        return select(_socket + 1, nullptr, &_set, nullptr, &timeout) > 0;
+        // poll the fd with no timeout
+        return poll(&_fd, 1, 0) > 0;
     }
     
     /**
      *  Wait until a filedescriptor becomes active (readable or writable)
-     *  @param  block       block until readable
      *  @return bool
      */
-    bool active(bool block)
+    bool active()
     {
-        // accommodate restrict qualifier on fd_set params
-        fd_set set2 = _set;
+        // check for readable
+        _fd.events = POLLIN | POLLOUT;     
+        _fd.revents = 0;
 
-        // wait for the socket
-        if (block) return select(_socket + 1, &_set, &set2, nullptr, nullptr) > 0;
-
-        // we do not want to block, so we use a small timeout
-        struct timeval timeout;
-        
-        // no timeout at all
-        timeout.tv_sec = timeout.tv_usec = 0;
-        
-        // no timeout at all
-        return select(_socket + 1, &_set, &set2, nullptr, &timeout) > 0;
+        // poll the fd with no timeout
+        return poll(&_fd, 1, 0) > 0;
     }
 };
 

src/linux_tcp/sslconnected.h

@@ -220,8 +220,8 @@ private:
         // object to poll a socket
         Poll poll(_socket);
         
-        // wait until socket is readable, but do not block
-        return poll.readable(false);
+        // check if socket is readable
+        return poll.readable();
     }
 
     /**
@@ -233,8 +233,8 @@ private:
         // object to poll a socket
         Poll poll(_socket);
         
-        // wait until socket is writable, but do not block
-        return poll.writable(false);
+        // check if socket is writable
+        return poll.writable();
     }
     
     /**

src/linux_tcp/tcpresolver.h

@@ -24,6 +24,7 @@
 #include "sslhandshake.h"
 #include <thread>
 #include <netinet/in.h>
+#include <poll.h>
 
 /**
  *  Set up namespace
@@ -99,8 +100,8 @@ private:
             // get address info
             AddressInfo addresses(_hostname.data(), _port);
     
-            // an fdset to monitor for writability
-            fd_set writeset;
+            // the pollfd structure, needed for poll()
+            pollfd fd;
     
             // iterate over the addresses
             for (size_t i = 0; i < addresses.size(); ++i)
@@ -117,17 +118,13 @@ private:
                 // 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);
+                // set the struct members
+                fd.fd = _socket;
+                fd.events = POLLOUT;
+                fd.revents = 0;
+                
+                // perform the poll, with a very long time to allow the event to occur
+                int ret = poll(&fd, 1, _timeout * 1000);
 
                 // log the error for the time being
                 if (ret == 0) _error = "connection timed out";