C winsock2.h WS2_32.lib链接未定义的引用

Question

我正在尝试使用winsock2编程一个简单的服务器。 我没有正确编译它。

#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;
}

它最初是针对Linux使用socket.h的，但是我尝试在Windows7下使用winsock2来实现它。 我手动安装了Windows SDK，并找到了必须链接的库Ws2_32.lib。 我在CLION中使用gcc（mingw32）进行编译。 我设置了参数标志

-lws2_32 -lwsock32

我知道这里有很多帖子可以回答这个问题，但似乎对我没有任何帮助。

CLION的输出：

"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

我现在使用以下命令与gcc进行编译：

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

它给出以下输出：

==================================================
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

并在开始时：

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

首先删除#pragma comment(lib, "WS2_32.lib")这只是Visual C ++编译器指令。

第二，没有提供CMakeLists.txt，您是否知道CLion致力于跨平台解决方案并通过CMake为指定环境（在工具链选项卡上）配置make文件。 这意味着你不需要手动调用gcc和链接库，所有你需要的是target_link_libraries(myexecutable ws2_32)后add_executable(myexecutable)

第三，您不需要将wsock32.lib实际链接到您的项目，除非您想与Win95向后兼容（我确定您不需要）。 有关更多详细信息，请查看此答案 。

您的顶级CMake文件应如下所示：

# 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)