C: TCP server could not receive message from client

Question

I am a C beginner. I want to send a file by TCP. The client reads content from a txt file and sent it to server. Read method is ok. It reads the specified bytes from the file. Send method dose not throw any exception. However the server receives nothing. I try to solve it for a whole day. I fail.

Please help me check what is wrong with my code.

As comment advice, I edit my code again. Now there are two problem. One is that in the client loop the return values from client fread() and send() is greater than 0 for the first two times while the server accept() is still blcoked without getting message from client.

The second problem. In the third client loop, the return value of client fread() is still greater than 0, but the return value of send() is -1.I try to open the file in binary mode rb instead of r. It is the same problem.

the edited client code:

#include <stdio.h>
#include <winsock.h>
#include <time.h>

#pragma comment(lib, "WS2_32.lib")
#define    MAXLINE        1024*4


SOCKET sockClient;// = socket(AF_INET,SOCK_DGRAM,0);
SOCKADDR_IN servAddr;


int main(void) {
    WSADATA wsd;
    FILE *fp;
    int read_len;
    char buf2[MAXLINE];
    time_t t_start, t_end;

    if ((fp = fopen("file.txt", "r")) == NULL) {
        perror("Open file failed\n");
        exit(0);
    }

    if (WSAStartup(MAKEWORD(2, 2), &wsd) != 0) {
        printf("WSAStartup failed !\n");
        return 1;
    }

    sockClient = socket(AF_INET, SOCK_STREAM, 0);

    servAddr.sin_family = AF_INET;
    servAddr.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");
    servAddr.sin_port = htons(5000);

    /* connect the server commanted by guoqingbo*/
    int i_ret = connect(sockClient, (struct sockaddr *) &servAddr, sizeof(struct sockaddr));
    if (-1 == i_ret) {
        perror("Connect socket failed!\n");
        exit(0);
    }

    printf("client starts\n");
    t_start = time(NULL);

    while (1) {
        read_len = fread(buf2, sizeof(char), MAXLINE, fp);
        if (read_len < 0) {
            perror("read data failed\n");
            break;
        } else if (read_len == 0) {
            printf("read finished\n");
        }
        int send_len = send(sockClient, buf2, read_len, 0);
        if (send_len < 0) {
            perror("Send data failed\n");
            exit(0);
        } else if (send_len == 0) {
            printf("send finished\n");
            break;
        }
    }
    t_end = time(NULL);
    printf("The time used %f s\n", difftime(t_end, t_start));
    fclose(fp);
    closesocket(sockClient);
    WSACleanup();
    return 0;
}

the edited server code:

#include <stdio.h>
#include <WINSOCK2.H>
#include <strings.h>
#include <stdlib.h>


#pragma comment(lib, "WS2_32.lib")
#define BUF_SIZE    1024*4

SOCKET socketSrv;
SOCKADDR_IN addrSrv;
SOCKADDR_IN addrClient;
char buf[BUF_SIZE];


int main(void) {
    WSADATA wsd;
    int nRet;
    int recv_len;
    FILE *fp;
    if ((fp = fopen("file.txt", "w")) == NULL) {
        perror("Creat file failed");
        exit(0);
    }
    
    if (WSAStartup(MAKEWORD(2, 2), &wsd) != 0) {
        printf("WSAStartup failed !\n");
        return 1;
    }

    socketSrv = socket(AF_INET, SOCK_STREAM, 0);
    int len = sizeof(SOCKADDR);

    ZeroMemory(buf, BUF_SIZE);
    addrSrv.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
    addrSrv.sin_family = AF_INET;
    addrSrv.sin_port = htons(5000);

    nRet = bind(socketSrv, (SOCKADDR *) &addrSrv, sizeof(SOCKADDR));
    if (SOCKET_ERROR == nRet) {
        printf("bind failed !\n");
        closesocket(socketSrv);
        WSACleanup();
        return -1;
    }

    if (SOCKET_ERROR == listen(socketSrv, 10)) {
        printf("Server Listen Failed: %d", WSAGetLastError());
        exit(1);
    }


    printf("server started..\n");
    while (1) {
        SOCKET m_New_Socket = accept(socketSrv, (SOCKADDR *) &addrClient, &len);
        if (SOCKET_ERROR == m_New_Socket) {
            printf("Server Accept Failed: %d", WSAGetLastError());
            break;
        }
        if (recv_len = recv(socketSrv, buf, BUF_SIZE, 0) < 0) {
            printf("Server Receive Data Failed!");
            break;
        }
        int write_length = fwrite(buf, sizeof(char), recv_len, fp);
        if (write_length < recv_len) {
            printf("File write failed\n");
            break;
        }
    }
    fclose(fp);
    closesocket(socketSrv);
    WSACleanup();
    return 0;
}