Why does my VIsual Studio compilation keep failing after including winsock and ws2_32 libraries?

Question

So I cannot figure out what went wrong with my code or CMakeLists.txt. I am trying to create a DLL that is basically going to have functionality of UDP socket communication. This is my current code:

// UDPSocketComm.h
#ifndef _UDP_SOCKET_COMM_H_
#define _UDP_SOCKET_COMM_H_
#pragma comment(lib, "ws2_32.lib")
#include <windows.h>
#include <winsock2.h>
#include <WS2tcpip.h>
#include <string>

class UDPSocketComm
{
private : 
    SOCKET receiverSocket;
    std::string serverAddr;
    uint32_t receiverPort;
    struct sockaddr_in receiver;

public:
    int OpenSocket(const char* serverAddr, uint32_t portNum);
    int SendData(const char* data, unsigned long length);
    int EndConnection();
};

#endif

This is my implementation:

// UDPSocketComm.cpp
#include "UDPSocketComm.h"

int UDPSocketComm::OpenSocket(const char* serverAddr, uint32_t port)
{

    this->serverAddr = serverAddr;
    this->receiverPort = port;

    WSADATA wsaData;
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
    {
        return WSAGetLastError();
    }

    if ((this->receiverSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == SOCKET_ERROR)
    {
        return WSAGetLastError();
    }

    memset((char*)&receiver, 0, sizeof(this->receiver));
    this->receiver.sin_family = AF_INET;
    this->receiver.sin_port = htons(this->receiverPort);
    this->receiver.sin_addr.S_un.S_addr = inet_addr(serverAddr);

    if (bind(this->receiverSocket, (SOCKADDR*)&this->receiver, sizeof(this->receiver)) == SOCKET_ERROR)
    {
        return WSAGetLastError();
    }

    return 0;
}

int UDPSocketComm::EndConnection()
{
    if (closesocket(this->receiverSocket) == SOCKET_ERROR) 
    {
        return WSAGetLastError();
    };

    if (WSACleanup() == SOCKET_ERROR)
    {
        return WSAGetLastError();
    }
    
    return 0;
}

There is a wrapper class on top of this:

// MyDLL
#include "UDPSocketComm.h"

UDPSocketComm comObj;

#ifdef __cplusplus
extern "C" 
{
__declspec(dllexport) int Init(const char* server, uint32_t port)
{
   return comObj.OpenSocket(server, port);
}
__declspec(dllexport) int Terminate()
{
  return comObj.EndConnection();
}
}
#endif

This is my CMake:

cmake_minimum_required (VERSION 3.10)

project ("MyDLL" VERSION 0.0.0)

set (SOURCEFILES "src/UDPSocketComm.cpp" "src/MyDll.cpp" )

add_library(MyDll SHARED ${SOURCEFILES})

target_include_directories(MyDll PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/inc)
target_link_libraries(MyDll PUBLIC ws2_32 wsock32) 

if (WIN32)
  # Do not use the library file name prefix 'lib' on windows platforms (x86 and x64).
  set_target_properties(MyDll PROPERTIES PREFIX "")
else()
  # Do not export all functions by default
  target_compile_options(MyDll PUBLIC "-fvisibility=hidden")
endif()

This throws a huge list of errors, like so :

>------ Build All started: Project: MyDLL, Configuration: x64-Debug ------
  [1/3] Building CXX object CMakeFiles\MyDLL.dir\src\MyDLL.cpp.obj
  FAILED: CMakeFiles/MyDLL.dir/src/MyDLL.cpp.obj 
  C:\PROGRA~2\MIB055~1\2019\PROFES~1\VC\Tools\MSVC\1429~1.301\bin\Hostx64\x64\cl.exe  /nologo /TP -DMyDLL_EXPORTS -I..\..\..\inc /DWIN32 /D_WINDOWS /W3 /GR /EHsc /MDd /Zi /Ob0 /Od /RTC1 /showIncludes /FoCMakeFiles\MyDLL.dir\src\MyDLL.cpp.obj /FdCMakeFiles\MyDLL.dir\ /FS -c ..\..\..\src\MyDLL.cpp
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(103): warning C4005: 'AF_IPX': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(457): note: see previous definition of 'AF_IPX'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(147): warning C4005: 'AF_MAX': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(476): note: see previous definition of 'AF_MAX'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(187): warning C4005: 'SO_DONTLINGER': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(399): note: see previous definition of 'SO_DONTLINGER'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(240): error C2011: 'sockaddr': 'struct' type redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(482): note: see declaration of 'sockaddr'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(442): error C2143: syntax error: missing '}' before 'constant'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(442): error C2059: syntax error: 'constant'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(496): error C2143: syntax error: missing ';' before '}'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(496): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(496): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(577): warning C4005: 'IN_CLASSA': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(284): note: see previous definition of 'IN_CLASSA'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(583): warning C4005: 'IN_CLASSB': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(290): note: see previous definition of 'IN_CLASSB'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(589): warning C4005: 'IN_CLASSC': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(296): note: see previous definition of 'IN_CLASSC'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(600): warning C4005: 'INADDR_ANY': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(301): note: see previous definition of 'INADDR_ANY'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(602): warning C4005: 'INADDR_BROADCAST': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(303): note: see previous definition of 'INADDR_BROADCAST'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\shared\ws2def.h(638): error C2011: 'sockaddr_in': 'struct' type redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(309): note: see declaration of 'sockaddr_in'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(136): error C2011: 'fd_set': 'struct' type redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(65): note: see declaration of 'fd_set'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(156): warning C4005: 'FD_CLR': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(94): note: see previous definition of 'FD_CLR'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(171): warning C4005: 'FD_SET': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(99): note: see previous definition of 'FD_SET'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(180): error C2011: 'timeval': 'struct' type redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(108): note: see declaration of 'timeval'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(236): error C2011: 'hostent': 'struct' type redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(164): note: see declaration of 'hostent'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(249): error C2011: 'netent': 'struct' type redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(177): note: see declaration of 'netent'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(256): error C2011: 'servent': 'struct' type redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(184): note: see declaration of 'servent'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(268): error C2011: 'protoent': 'struct' type redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(196): note: see declaration of 'protoent'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(364): error C2011: 'WSAData': 'struct' type redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(319): note: see declaration of 'WSAData'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(462): error C2011: 'sockproto': 'struct' type redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(491): note: see declaration of 'sockproto'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(504): error C2011: 'linger': 'struct' type redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(528): note: see declaration of 'linger'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(517): warning C4005: 'SOMAXCONN': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(541): note: see previous definition of 'SOMAXCONN'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(552): warning C4005: 'FD_READ': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(559): note: see previous definition of 'FD_READ'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(555): warning C4005: 'FD_WRITE': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(560): note: see previous definition of 'FD_WRITE'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(558): warning C4005: 'FD_OOB': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(561): note: see previous definition of 'FD_OOB'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(561): warning C4005: 'FD_ACCEPT': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(562): note: see previous definition of 'FD_ACCEPT'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(564): warning C4005: 'FD_CONNECT': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(563): note: see previous definition of 'FD_CONNECT'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(567): warning C4005: 'FD_CLOSE': macro redefinition
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(564): note: see previous definition of 'FD_CLOSE'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1625): error C2375: 'accept': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(739): note: see declaration of 'accept'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1647): error C2375: 'bind': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(744): note: see declaration of 'bind'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1668): error C2375: 'closesocket': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(749): note: see declaration of 'closesocket'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1685): error C2375: 'connect': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(751): note: see declaration of 'connect'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1706): error C2375: 'ioctlsocket': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(756): note: see declaration of 'ioctlsocket'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1729): error C2375: 'getpeername': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(761): note: see declaration of 'getpeername'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1750): error C2375: 'getsockname': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(766): note: see declaration of 'getsockname'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1771): error C2375: 'getsockopt': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(771): note: see declaration of 'getsockopt'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1796): error C2375: 'htonl': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(778): note: see declaration of 'htonl'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1813): error C2375: 'htons': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(780): note: see declaration of 'htons'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1831): error C2375: 'inet_addr': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(782): note: see declaration of 'inet_addr'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1849): error C2375: 'inet_ntoa': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(784): note: see declaration of 'inet_ntoa'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1949): error C2375: 'listen': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(786): note: see declaration of 'listen'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1968): error C2375: 'ntohl': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(790): note: see declaration of 'ntohl'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(1985): error C2375: 'ntohs': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(792): note: see declaration of 'ntohs'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(2002): error C2375: 'recv': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(794): note: see declaration of 'recv'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(2025): error C2375: 'recvfrom': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(800): note: see declaration of 'recvfrom'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(2052): error C2375: 'select': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(808): note: see declaration of 'select'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(2077): error C2375: 'send': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(815): note: see declaration of 'send'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(2100): error C2375: 'sendto': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(821): note: see declaration of 'sendto'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(2127): error C2375: 'setsockopt': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(829): note: see declaration of 'setsockopt'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(2152): error C2375: 'shutdown': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(836): note: see declaration of 'shutdown'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(2172): error C2375: 'socket': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(840): note: see declaration of 'socket'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(2197): error C2375: 'gethostbyaddr': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(847): note: see declaration of 'gethostbyaddr'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(2219): error C2375: 'gethostbyname': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(852): note: see declaration of 'gethostbyname'
C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock2.h(2236): error C2375: 'gethostname': redefinition; different linkage
  C:\Program Files (x86)\Windows Kits\10\include\10.0.19041.0\um\winsock.h(854): note: see declaration of 'gethostname'

Can someone help me figure out what is happening here? How do I resolve this problem?

Those you list are IntelliSense (heuristic) errors. Please show what actual compiler/linker errors (from the Output tab, not from the Error List tab) do you get. — heap underrun, Jul 07 '23 at 12:48
Also, make sure you `#define WIN32_LEAN_AND_MEAN` before you `#include ` (or at the project level), otherwise some old, deprecated sockets stuff will get included. — heap underrun, Jul 07 '23 at 12:54
@heapunderrun thank you for the suggestion. I have edited the question to include errors from the Output tab. — doa4321, Jul 07 '23 at 13:16
All the errors seem to be multiple definitions between `shared\ws2def.h` and `um\winsock2.h` I am not sure how to fix that or why it happens. — drescherjm, Jul 07 '23 at 14:08

score 0 · Answer 1 · answered Jul 10 '23 at 08:13

0

You are using the deprecated Winsocket api:

 this->receiver.sin_addr.S_un.S_addr = inet_addr(serverAddr);

Remove the headers and I am able to build the DLL:

//#include <winsock2.h>
//#include <WS2tcpip.h>

answered Jul 10 '23 at 08:13

Minxin Yu - MSFT

2,234
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Why does my VIsual Studio compilation keep failing after including winsock and ws2_32 libraries?

1 Answers1