如何在C中通过TCP套接字通过HTTP发送文件？

Question

I am implementing a client and server in C (on linux) and i want to send a text file to a server from the client using an HTTP PUT message.

I'm not really sure how to do this. Do I first send the HTTP request and header line over the socket, and then send the file over the socket piece by piece using a buffer? or do I need to prepend every piece of the text file with its own HTTP request and header line before I send them over?

I also read about this function called sendfile that seems like it would make this easier, but I wasn't sure how I would prepend an HTTP header and request line to the file if sendfile just sends the file straight to the socket.

Thank you for your help.

Answer 1

Do I first send the HTTP request and header line over the socket, and then send the file over the socket piece by piece using a buffer?

Yes.

or do I need to prepend every piece of the text file with its own HTTP request and header line before I send them over?

No.

I also read about this function called sendfile that seems like it would make this easier, but I wasn't sure how I would prepend an HTTP header and request line to the file if sendfile just sends the file straight to the socket.

First send the header with a normal send , then call sendfile . However you should read the documentation, which says

Note that a successful call to sendfile() may write fewer bytes than requested; the caller should be prepared to retry the call if there were unsent bytes.

This means that your life is not that much easier with sendfile . It is more efficient than a combination of read and write , but the amount of work the programmer needs to do is similar in both cases.

Answer 2

if you want to implement HTTP transmission protocol then check this RFC http://www.w3.org/Protocols/rfc2616/rfc2616-sec8.html#sec8.2.2

else if you want your own easy method then you can for example implement an API such DWORD(cmdPut)+filename+'\\0'+DWORD(fileLen)+fileBinaryData.