C winsock2.h WS2_32.lib linking undefined refernce to

Question

I am trying to program a simple server with winsock2. I dont get it to compile right.

#define _WIN32_WINNT 0x0501
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <stdio.h>
#include <string.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include "dump.h"

#pragma comment(lib,"WS2_32.lib")

#define PORT 7890

int main(void)
{
    //fd --> file descriptor
    int sockfd, new_sockfd; //warten an sockfd, neue Verbindung an new_sockfd
    struct sockaddr_in host_addr, client_addr; //Addressinformationen
    //sockaddr_in aus winsock.h

    //Laenge des Inputs --> winsock Alternative suchen
    socklen_t sin_size;

    int recv_length = 1, yes = 1;
    char buffer[1024];
    if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1)
        //PF_INET --> Protocol family
        //AF_INET --> Addres family
        printf("%s\n", "in socket");
    if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (char *)&yes, sizeof(int)) == -1)
        printf("%s\n", "setting socket option SO_REUSEADDR");

    //vorbereiten auf den bind-Befehl
    host_addr.sin_family = AF_INET;
    host_addr.sin_port = htons(PORT);
    //htons --> host to network short
    //Wandelt bei 16 Bit int Hostbytereihenfolge in Netzwerkbytereihenfolge
    host_addr.sin_addr.s_addr = 0; //Automatisch mit meiner IP fuellen
    memset(&(host_addr.sin_zero), '\0', 8); // Rest der Struktur mit 0 fuellen

    if (bind(sockfd, (struct sockaddr *) &host_addr, sizeof(struct sockaddr)) == -1)
        printf("%s\n", "binding to socket");
    if (listen(sockfd, 5) == -1)
    {
        printf("%s\n", "listening on socket");
    }

    //Schleife um am PORT zu lauschen und Verbindungen zu akzeptieren
    while (1)
    {
        sin_size = sizeof(struct sockaddr_in);
        //accept gibt neuen sockfd zurueck !
        new_sockfd =

         accept(sockfd, (struct sockaddr *) &client_addr, &sin_size);
        if (new_sockfd == -1)
        {
            printf("%s\n", "accepting connection");
        }
        printf("server: got connection from %s port %d\n",
               inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
        send(new_sockfd, "Hello, world!\n", 13, 0);
        recv_length = recv(new_sockfd, buffer, 1024, 0);
        while (recv_length > 0)
        {
            printf("RECV: %d bytes \n", recv_length);
            dump(buffer, recv_length);
            recv_length = recv(new_sockfd, buffer, 1024, 0);
        }
        closesocket(new_sockfd);
    }
    return 0;
}

It was first for Linux with socket.h but i tried to implement it with winsock2 under windows7. I manually installed The Windows SDK and found the library Ws2_32.lib which i have to link. I'm compiling with gcc (mingw32) in CLION. I set the paramter flags

-lws2_32 -lwsock32

I know there are many posts here answering this question but nothing seems to work for me.

The Output from CLION:

"C:\Program Files\JetBrains\CLion 2017.2.2\bin\cmake\bin\cmake.exe" --build C:\Users\Marcel\Desktop\Projekte\C-Projekte\Sequenz-Uebungen\Simple_Server\cmake-build-debug --target Simple_Server -- -j 2
[ 50%] Linking C executable Simple_Server.exe
CMakeFiles\Simple_Server.dir/objects.a(main.c.obj): In function `main':
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:49: undefined reference to `socket@12'
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:53: undefined reference to `setsockopt@20'
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:58: undefined reference to `htons@4'
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:64: undefined reference to `bind@12'
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:66: undefined reference to `listen@8'
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:78: undefined reference to `accept@12'
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:84: undefined reference to `ntohs@4'
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:83: undefined reference to `inet_ntoa@4'
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:85: undefined reference to `send@16'
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:86: undefined reference to `recv@16'
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:91: undefined reference to `recv@16'
C:/Users/Marcel/Desktop/Projekte/C-Projekte/Sequenz-Uebungen/Simple_Server/main.c:93: undefined reference to `closesocket@4'
collect2.exe: error: ld returned 1 exit status
CMakeFiles\Simple_Server.dir\build.make:95: recipe for target 'Simple_Server.exe' failed
CMakeFiles\Makefile2:66: recipe for target 'CMakeFiles/Simple_Server.dir/all' failed
CMakeFiles\Makefile2:78: recipe for target 'CMakeFiles/Simple_Server.dir/rule' failed
mingw32-make.exe[3]: *** [Simple_Server.exe] Error 1
mingw32-make.exe[2]: *** [CMakeFiles/Simple_Server.dir/all] Error 2
mingw32-make.exe[1]: *** [CMakeFiles/Simple_Server.dir/rule] Error 2
Makefile:117: recipe for target 'Simple_Server' failed
mingw32-make.exe: *** [Simple_Server] Error 2

I used following command now to compile with gcc:

gcc -Wl,-verbose -lws2_32 -lwsock32 -o simple_server main.c > linker.txt

It gives following output:

==================================================
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../crt2.o succeeded
c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../crt2.o
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/crtbegin.o succeeded
c:/mingw/bin/../lib/gcc/mingw32/6.3.0/crtbegin.o
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/libws2_32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/ws2_32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/libws2_32.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/ws2_32.lib failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/libws2_32.dll failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/ws2_32.dll failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0\libws2_32.a failed
attempt to open c:/mingw/bin/../lib/gcc/libws2_32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/ws2_32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/libws2_32.a failed
attempt to open c:/mingw/bin/../lib/gcc/ws2_32.lib failed
attempt to open c:/mingw/bin/../lib/gcc/libws2_32.dll failed
attempt to open c:/mingw/bin/../lib/gcc/ws2_32.dll failed
attempt to open c:/mingw/bin/../lib/gcc\libws2_32.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/libws2_32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/ws2_32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/libws2_32.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/ws2_32.lib failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/libws2_32.dll failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/ws2_32.dll failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib\libws2_32.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../libws2_32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../ws2_32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../libws2_32.a succeeded
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/libwsock32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/wsock32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/libwsock32.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/wsock32.lib failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/libwsock32.dll failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/wsock32.dll failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0\libwsock32.a failed
attempt to open c:/mingw/bin/../lib/gcc/libwsock32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/wsock32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/libwsock32.a failed
attempt to open c:/mingw/bin/../lib/gcc/wsock32.lib failed
attempt to open c:/mingw/bin/../lib/gcc/libwsock32.dll failed
attempt to open c:/mingw/bin/../lib/gcc/wsock32.dll failed
attempt to open c:/mingw/bin/../lib/gcc\libwsock32.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/libwsock32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/wsock32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/libwsock32.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/wsock32.lib failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/libwsock32.dll failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib/wsock32.dll failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../../mingw32/lib\libwsock32.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../libwsock32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../wsock32.dll.a failed
attempt to open c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../libwsock32.a succeeded

and this at the beginning:

using internal linker script:
==================================================
/* Default linker script, for normal executables */
/* Copyright (C) 2014-2017 Free Software Foundation, Inc.
   Copying and distribution of this script, with or without modification,
   are permitted in any medium without royalty provided the copyright
   notice and this notice are preserved.  */
OUTPUT_FORMAT(pei-i386)
SEARCH_DIR("/mingw/mingw32/lib"); SEARCH_DIR("/mingw/lib"); SEARCH_DIR("/usr/local/lib"); SEARCH_DIR("/lib"); SEARCH_DIR("/usr/lib");

Answer 1

First of all remove #pragma comment(lib, "WS2_32.lib") this is only Visual C++ Compiler directive.

Second one, you are not provided CMakeLists.txt, did you know CLion aims on cross platform solutions and configures make files for your specified environment (at toolchain tab) from CMake. That means you don't need to call gcc and link libraries manually, all you need is target_link_libraries(myexecutable ws2_32) after add_executable(myexecutable) .

Third, you don't need wsock32.lib actually linked to your project, unless you want backward compatibility with Win95 (I'm sure you don't). For further details look into this answer .

Your top-level CMake file should looks like:

# system
cmake_minimum_required(VERSION 3.6)
set(CMAKE_C_STANDARD 99)

# project
project(WinsockExample C)

# sources
set(source_files
    main.c
    )

# build
add_executable(${CMAKE_PROJECT_NAME} ${source_files})
target_link_libraries(${CMAKE_PROJECT_NAME} ws2_32)