Question

我正在读取一个文件并将其传输到C ++服务器。以下是我的代码的主要部分：

客户端：

long Begin;
long End;
char * block;

    //Open the file for reading
ifstream myfile;
myfile.open(path, ios::in | ios::binary);

    //Calculate the dize of file
Begin = myfile.tellg();
myfile.seekg(0,ios::end);
End = myfile.tellg();
unsigned long size = End - Begin;

int Div = (int)size / 1024;
int Mod = (int)size % 1024;
int len = strlen(name);

    //Send Length of filename
send(theSocket,(const char*)&len,sizeof(int),0);
recv(theSocket, ack,sizeof(ack),0);

    //Send Filename
send(theSocket,name,strlen(name),0);
recv(theSocket, ack,sizeof(ack),0);

    //Send size of file
send(theSocket, (const char*)&size, sizeof(unsigned long), 0);
recv(theSocket, ack,sizeof(ack),0);

    //send file in parts of 1024 bytes
for (int i=0; i<Div; i++)
{
    block = new char[1025];
    myfile.seekg(i*1024);
    myfile.get(block,1024);
            block[1024] = 0;
    send(theSocket,block,1025,0);
    recv(theSocket, ack,sizeof(ack),0);
}

    //send remaining part of file
if (Mod != 0)
{
    block = new char[Mod];
    myfile.seekg(Div*1024);
    myfile.get(block,Mod);
            block[Mod] = 0;
    send(theSocket,block,Mod+1,0);
    recv(theSocket, ack,sizeof(ack),0);
}

myfile.close();
closesocket(theSocket);
WSACleanup();

服务器

while(true)
{
        theClient = accept(listeningSocket,NULL,NULL);
        int namelen;
        unsigned long filelen;
        char * block;
        char * Filename;
        char ack[10] = "Ack";

            //Receive Length of Filename
        recv(theClient,(char *)&namelen,sizeof(int),0);
        send(theClient,ack,sizeof(ack),0);
        Filename = new char [namelen];

            //Receive Filename
        recv(theClient,Filename,namelen,0);
        send(theClient,ack,sizeof(ack),0);

            //open file for writing         
        ofstream myfile;
        myfile.open(Filename, ios::out | ios::binary | ios::app);

            //Receive Length of File
        recv(theClient,(char *)&filelen,sizeof(unsigned long),0);
        send(theClient,ack,sizeof(ack),0);

        int Div = (int)filelen / 1024;
        int Mod = (int)filelen % 1024;
        block = new char[1024];

            //receive the file in parts and write to the stream
        for (int i=0; i<Div; i++)
        {
            recv(theClient,block,1025,0);
            myfile << block;
            send(theClient,ack,sizeof(ack),0);
        }

            //write the remaining part of file
        if (Mod != 0)
        {
            block = new char[Mod+1];
            recv(theClient,block,Mod,0);
            myfile << block;
            send(theClient,ack,sizeof(ack),0);
        }
        myfile.close();
    }

我已经成功创建了套接字并建立了连接。所以给这个代码没用。我遇到了两个问题：

我错过了服务器上的每个1024th字节。这是因为我将zero放在block的最后一个字节中。但是我通过分配zero字节为1025保留了空间。
我无法处理CR/LF个字符。当我以二进制模式传输文件时，我也必须处理CR/LF。无论文件类型如何，我都需要传输文件。因此，如果观察到CR/LF，则终止字符串，并且数据不会作为服务器写入文件中。

请帮助解决。提前谢谢。

Answer 1

我注意到服务器只分配1024个字节到block。

Answer 2

您忽略了每个recv()调用的结果，并假设它填充了您提供的缓冲区。

TCP或Berkely Sockets API规范中没有任何内容可以让您这样做。 recv()可以提供1个字节和指定的缓冲区长度之间的任何值，或者为0，表示流结束或错误。你永远不能忽视这个结果。

读取文件并通过套接字发送时出错

2 个答案: