C ++ WinSock是否从PHP页面获取数据？

Question

Hello I'm quite new to using sockets and am not that familiar with them yet, Basically all i am trying to do is pass a string variable to a web address (eg www.example.com/index.php?Example=StringExample ) and then get a response, so for example it would return "Test Example" if index.php looked like this:

<?php

if($_GET['Example'] == "StringExample")
{
    echo "Test Example";
}

?>

Here is what I've tried in c++:

struct sockaddr_in SocketAddress;
hostent* addr = gethostbyname("www.example.com/index.php?Example=StringExample");
int sizeofaddr = sizeof(addr);
SocketAddress.sin_addr.s_addr = inet_addr(addr->h_name);
SocketAddress.sin_port = htons(80);
SocketAddress.sin_family = AF_INET; 

SOCKET Connection = socket(AF_INET, SOCK_STREAM, NULL); 
if (connect(Connection, (SOCKADDR*)&addr, sizeofaddr) != 0) 
{
    return 0; //Failed to Connect
}

char buffff[256];
recv(Connection, buffff, sizeof(buffff), NULL);
//"Test Example" now stored in    buffff

What am i doing wrong?

Btw in my case i would not like to use any libraries like boost or anything like that. Thanks for the help :)

Answer 1

gethostbyname("www.example.com/index.php?Example=StringExample");

"www.example.com/index.php?Example=StringExample" is not a valid server name. This is an entire URL; a server name would be "www.example.com". gethostbyname() takes the name of a server, and not a URL, and returns its IP address. Additionally, gethostbyname() has been obsoleted. New code should use the getaddrinfo(3) function, instead.

This is obviously an HTTP URL. To download a document via HTTP it is a lot more work than just connecting a socket. Establishing a socket connection is just the first step in the process of downloading a document from an HTTP server. This must be followed by sending a valid HTTP request, and then receiving an HTTP response from the server.

There are many libraries, such as curl , that implement the entire client-side process needed to download an HTTP document, that will handle the socket connection themselves.

But there's nothing wrong with trying to implement this yourself, either. It's a good programming excersize.

So, after resolving www.example.com 's IP address, you will need to

1) Connect to the server's port 80, the default HTTP port.

2) Send an HTTP request for "/index.php?Example=StringExample".

3) Parse the HTTP response.

The specification for HTTP requests and responses is defined by RFC 2616 , which you can consult for complete documentation of how HTTP requests and responses are structured.

Answer 2

If you want to access a web server with sockets, you have to keep in mind:

• You can open a tcp/ip connection to your web server
• BUT afterwards you have to do the http protocol by yourself

In case of your example:

hostent* addr = gethostbyname("www.example.com");
//...
const char* request = "GET index.html"
send(Connection, request, strlen(request), NULL)
//fetch index.html with a recv and parse it

To be more precise, if you want to access your server, you have to take a look how GET, PUT, POST, etc. are implemented in the http protocol, send the proper commands to your web server and recv() the replies