为什么实际文件大小远远小于C中通过TCP套接字接收的数据？

Question

我正在编写C套接字函数，以在公共网络中的系统（运行Windows）之间传输文件。实际上，我可以将整个数据从服务器传递到客户端（作为二进制数据）并将其写入所需的文件。但是当我查看文件的属性时，它的大小远远小于我收到的大小，因此无法打开它。

这是我的服务器代码：

#include<io.h>
#include<stdio.h>
#include<winsock2.h>
#include<string.h>
#include<stdint.h>

#pragma comment(lib,"ws2_32.lib") //Winsock Library

int main(int argc , char *argv[])
{
    WSADATA wsa;
    SOCKET s , new_socket;
    struct sockaddr_in server , client;
    int c;
    char message[10240];
    char filename[100];
    char response[50];
    int k = 0;

    printf("Enter filename :");
    scanf("%s",&filename);

    FILE *f = fopen(filename, "rb");
    fseek(f, 0, SEEK_END);
    long fsize = ftell(f);
    fseek(f, 0, SEEK_SET);  /* same as rewind(f); */

    uint8_t *string = malloc((1024 * sizeof(uint8_t)));


    printf("\nInitialising Winsock...");
    if (WSAStartup(MAKEWORD(2,2),&wsa) != 0)
    {
        printf("Failed. Error Code : %d",WSAGetLastError());
        return 1;
    }

    printf("Initialised.\n");

    //Create a socket
    if((s = socket(AF_INET , SOCK_STREAM , 0 )) == INVALID_SOCKET)
    {
        printf("Could not create socket : %d" , WSAGetLastError());
    }

    printf("Socket created.\n");

    //Prepare the sockaddr_in structure
    server.sin_family = AF_INET;
    server.sin_addr.s_addr = INADDR_ANY;
    server.sin_port = htons( 8888 );

    //Bind
    if( bind(s ,(struct sockaddr *)&server , sizeof(server)) == SOCKET_ERROR)
    {
        printf("Bind failed with error code : %d" , WSAGetLastError());
    }

    puts("Bind done");

    //Listen to incoming connections
    listen(s , 3);

    //Accept and incoming connection
    puts("Waiting for incoming connections...");

    c = sizeof(struct sockaddr_in);
    new_socket = accept(s , (struct sockaddr *)&client, &c);
    if (new_socket == INVALID_SOCKET)
    {
        printf("accept failed with error code : %d" , WSAGetLastError());
    }

    puts("Connection accepted");

    //Reply to client
    // message = "Hello Client , I have received your connection. But I have to go now, bye\n";
    send(new_socket , filename , strlen(filename) , 0);

    int len = recv(new_socket, response, 50, 0);
    response[len] = '\0';

    if(strcmp(response, "OKAY") == 0) printf("SUCCESS");
    else printf("ERROR");

    int i = 0;
    char cn = 'a';
    // getchar();
    getchar(); getchar();

    while(i < fsize){
        printf("%d\n",i);
        len = fread(string, 1, 1024, f);
        i += len;
        send(new_socket, string, len, 0);
    }
    getchar(); getchar();
    /*
    send(new_socket, "...END...CONNECTION...", strlen("...END...CONNECTION..."), 0);
    printf("sent end connection");
    recv(new_socket, response, strlen(response), 0);

    if(strcmp(response, "...END...CONNECTION...") != 0)
        send(new_socket, "...END...CONNECTION...", strlen("...END...CONNECTION..."), 0);
    */ 
    printf("SUCCESS");
    closesocket(s);
    fclose(f);
    WSACleanup();

    return 0;
}

这是我的客户代码

#include<stdio.h>
#include <stdint.h>
#include<winsock2.h>

#pragma comment(lib,&quot;ws2_32.lib&quot;) //Winsock Library

int main(int argc , char *argv[])
{
    WSADATA wsa;
    SOCKET s;
    struct sockaddr_in server;
    uint8_t server_reply[1024];
    int recv_size;

    printf("\nInitialising Winsock...");
    if (WSAStartup(MAKEWORD(2,2),&wsa) != 0)
    {
        printf(";Failed. Error Code : %d",WSAGetLastError());
        return 1;
    }

    printf("Initialised.\n");

    //Create a socket
    if((s = socket(AF_INET , SOCK_STREAM , 0 )) == INVALID_SOCKET)
    {
        printf("Could not create socket : %d" , WSAGetLastError());
    }

    printf("Socket created.\n");


    server.sin_addr.s_addr = inet_addr("127.0.0.1");
    server.sin_family = AF_INET;
    server.sin_port = htons( 8888 );

    //Connect to remote server
    if (connect(s , (struct sockaddr *)&server , sizeof(server)) < 0)
    {
        puts("connect error");
        return 1;
    }

    puts("Connected");

    if((recv_size = recv(s , server_reply , 1024 , 0)) == SOCKET_ERROR)
    {
        puts("recv failed");
    }

    puts("filename : ");
    server_reply[recv_size] = '\0';
    puts(server_reply);

    FILE* fptr = fopen(server_reply, "wb");

    send(s , "OKAY" , strlen("OKAY") , 0);
    int i = 0;
    while(1){
        if((recv_size = recv(s , server_reply , 1024, 0)) == SOCKET_ERROR)
        {
            puts("recv failed"); break;
        }
        fputs(server_reply, fptr);
        i += recv_size;
        printf("%d\n",i);
    }

    // send(s, "...END...CONNECTION...", strlen("...END...CONNECTION..."), 0);
    printf("sent : end connection");
    fclose(fptr);
    puts("File received\n");

    return 0;
}

请指出我在哪里做错了。

Answer 1

就在问题刚好出现之后，我实际上自己就找到了答案。问题是，在我的客户端程序中，我使用fputs()函数将收到的二进制数据写入文件，该函数实际上仅接受char*数据类型。

我将其更改为fwrite()，现在可以正常使用。

这是我的更正程序（仅客户端程序中的while循环部分）

int i = 0;
while(1){
    if((recv_size = recv(s , server_reply , 1024, 0)) == SOCKET_ERROR)
    {
        puts("recv failed"); break;
    }
    //fputs(server_reply, fptr);
    fwrite(server_reply, 1, recv_size, fptr);
    i += recv_size;
    printf("%d\n",i);
}