C Beej Unix套接字发送/接收错误

我有一个client.c和server.c程序，用于执行以下操作：客户端向服务器发送一条写有“Get\n”的消息，服务器向客户端发送一个文件。文件传输完成后，连接将关闭

到目前为止，一切都正常，直到服务器应该接收“Get\n”为止，我似乎不知道为什么。我有很多printf（）语句，所以我可以直观地解释所有发生的事情，但这并没有帮助我解决这个问题，所以我真的希望有人能在这里帮助我

这是我客户的代码。c：

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <signal.h>
#include <ctype.h>          
#include <arpa/inet.h>
#include <netdb.h>

#define PORT 43001
#define LENGTH 512 

int main(int argc, char *argv[])
{
    int sockFD, newSockFD;
    char buff[LENGTH];
    struct sockaddr_in remote;

    //Get Socket Descriptor
    if((sockFD = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    {
        printf("Failed to get socket descriptor\n");
        exit(1);
    }

    //Fill sockaddr struct
    remote.sin_family = AF_INET;
    remote.sin_port = htons(PORT);
    inet_pton(AF_INET, "127.0.0.1", &remote.sin_addr);
    bzero(&(remote.sin_zero), 8);

    //Connect to server
    if(connect(sockFD, (struct sockaddr *)&remote, sizeof(struct sockaddr)) == -1)
    {
        printf("Failed to connect()\n");
        exit(1);
    }
    else
    {
        printf("Connect()ed!\n");
    }

    //Send message
    char *msg = "Get\n";
    int len, sentBytes;
    len = strlen(msg);
    printf("Sending: %s\n", msg);
    if((sentBytes = send(sockFD, msg, len, 0)) == -1)
    {
        printf("Error in sending message\n");
        exit(1);
    }
    else
    {
        printf("Message sent successfully!\n");
    }

    //Recieve File
    printf("Getting file from Server\n");
    char* fr_name = "/in.txt";
    FILE *fr = fopen(fr_name, "w");
    if(fr == NULL)
    {
        printf("File could not be opened\n");
    }
    else
    {
        bzero(buff, LENGTH);
        int inBlockSize = 0;
        while((inBlockSize = recv(sockFD, buff, LENGTH, 0)) > 0)
        {
            int writeSize = fwrite(buff, sizeof(char), inBlockSize, fr);
            if(writeSize < inBlockSize)
            {
                printf("File writing failed\n");
            }
            bzero(buff, LENGTH);
            if(inBlockSize == 0 || inBlockSize != 512)
            {
                break;
            }
            if(inBlockSize < 0)
            {
                printf("recv() failed due to some error\n");
            }
        }
         printf("OK received from server\n");
        fclose(fr);
    }
    close(sockFD);
    printf("Connection closed\n");
    return 0;
}

然后，对于server.c，这是我的代码：

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <signal.h>
#include <ctype.h>          
#include <arpa/inet.h>
#include <netdb.h>

#define PORT 43001 
#define BACKLOG 5
#define LENGTH 512 

int main()
{
    int sockFD, newSockFD;
    int num;
    int sin_size;
    struct sockaddr_in local;
    struct sockaddr_in remote;
    char buff[LENGTH]; 
    char* fileName = "1.txt";
    char sendBuff[LENGTH];
    FILE *fs;

    //Get socket descriptor
    if ((sockFD = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    {
        printf("Failed to get socket descriptor.\n");
        exit(1);
    }
    else
    {
        printf("Got socket descriptor successfully\n");
    }

    //Get client socket struct
    local.sin_family = AF_INET;
    local.sin_port = htons(PORT);
    local.sin_addr.s_addr = INADDR_ANY;
    bzero(&(local.sin_zero), 8); //Deals with the rest of the struct

    //Bind
    if(bind(sockFD, (struct sockaddr*)&local, sizeof(struct sockaddr)) == -1)
    {
        printf("Failed to bind to port\n");
        exit(1);
    }
    else
    {
        printf("Binded to port successfully\n");
    }

    //Listen
    if(listen(sockFD, BACKLOG) == -1)
    {
        printf("listen() failed\n");
        exit(1);
    }
    else
    {
        printf("listen()ing to port successfully\n");
    }

    sin_size = sizeof(struct sockaddr_in);

    //Accept
    if(newSockFD = accept(sockFD, (struct sockaddr *)&remote, &sin_size) == -1)
    {
        printf("accept() failed\n");
        exit(1);
    }
    else
    {
        printf("accept()'d connection successfully\n");
    }

    //Get Message from Client
    int blkSize = 0;
    if((blkSize = recv(newSockFD, buff, LENGTH, 0)) == -1)
    {
        printf("recv()ing failed\n");
        exit(1);
    }
    
    buff[blkSize + 1] = "\0";
    printf("Client sent: %s\n", buff);

    //Open File Contents
    printf("Sending file to client\n");
    fs = fopen(fileName, "r");
    if(fs == NULL)
    {
        printf("File not found\n");
        exit(1);
    }

    bzero(sendBuff, LENGTH);
    int sendingBlkSize;

    //Send File
    while((sendingBlkSize = fread(sendBuff, sizeof(char), LENGTH, fs)) > 0)
    {
        if(send(newSockFD, sendBuff, sendingBlkSize, 0) < 0)
        {
            printf("Failed to send the file\n");
            exit(1);
        }
        bzero(sendBuff, LENGTH);
    }
    printf("Sent file to client, closing connection\n");
    close(newSockFD);
    return 0;
}

---

因此，消息已成功发送，但另一端未收到。我已经尽了最大努力来解决这个问题，但我觉得一切都很好。我正在使用Beej的《网络编程指南》在Unix上实现这一点。

考虑您试图打开的文件的路径，

/in.txt

。您在根目录中真的有写权限吗？另外请刷新，尤其是和。同时，也可以阅读一些好的问题和建议。你问的问题是什么？因为显然有两个截然不同的问题。别忘了你的小部分。我理解为什么我会在那里出错，我应该在发布之前修复它，所以很抱歉。另外，你能澄清一下这两个不同的问题是什么意思吗？我相信我遇到的唯一问题是当我的server.c程序收到一条消息时，但是如果你看到另一条消息，我很想知道它可能是什么！使用perror显示故障原因。不管beej怎么说。（最可能的问题是客户端在服务器读取数据之前终止连接。）

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <signal.h>
#include <ctype.h>          
#include <arpa/inet.h>
#include <netdb.h>

#define PORT 43001 
#define BACKLOG 5
#define LENGTH 512 

int main()
{
    int sockFD, newSockFD;
    int num;
    int sin_size;
    struct sockaddr_in local;
    struct sockaddr_in remote;
    char buff[LENGTH]; 
    char* fileName = "1.txt";
    char sendBuff[LENGTH];
    FILE *fs;

    //Get socket descriptor
    if ((sockFD = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    {
        printf("Failed to get socket descriptor.\n");
        exit(1);
    }
    else
    {
        printf("Got socket descriptor successfully\n");
    }

    //Get client socket struct
    local.sin_family = AF_INET;
    local.sin_port = htons(PORT);
    local.sin_addr.s_addr = INADDR_ANY;
    bzero(&(local.sin_zero), 8); //Deals with the rest of the struct

    //Bind
    if(bind(sockFD, (struct sockaddr*)&local, sizeof(struct sockaddr)) == -1)
    {
        printf("Failed to bind to port\n");
        exit(1);
    }
    else
    {
        printf("Binded to port successfully\n");
    }

    //Listen
    if(listen(sockFD, BACKLOG) == -1)
    {
        printf("listen() failed\n");
        exit(1);
    }
    else
    {
        printf("listen()ing to port successfully\n");
    }

    sin_size = sizeof(struct sockaddr_in);

    //Accept
    if(newSockFD = accept(sockFD, (struct sockaddr *)&remote, &sin_size) == -1)
    {
        printf("accept() failed\n");
        exit(1);
    }
    else
    {
        printf("accept()'d connection successfully\n");
    }

    //Get Message from Client
    int blkSize = 0;
    if((blkSize = recv(newSockFD, buff, LENGTH, 0)) == -1)
    {
        printf("recv()ing failed\n");
        exit(1);
    }
    
    buff[blkSize + 1] = "\0";
    printf("Client sent: %s\n", buff);

    //Open File Contents
    printf("Sending file to client\n");
    fs = fopen(fileName, "r");
    if(fs == NULL)
    {
        printf("File not found\n");
        exit(1);
    }

    bzero(sendBuff, LENGTH);
    int sendingBlkSize;

    //Send File
    while((sendingBlkSize = fread(sendBuff, sizeof(char), LENGTH, fs)) > 0)
    {
        if(send(newSockFD, sendBuff, sendingBlkSize, 0) < 0)
        {
            printf("Failed to send the file\n");
            exit(1);
        }
        bzero(sendBuff, LENGTH);
    }
    printf("Sent file to client, closing connection\n");
    close(newSockFD);
    return 0;
}

Got socket descriptor successfully
Binded to port successfully
listen()ing to port successfully
accept()'ed connection successfully
recv()ing failed