Bonjour à tous, je suis un newbie sous UNIX / Linux, programmation socket. Il s'agit d'un projet de classe que j'ai eu des problèmes avec.

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J'essayais de faire des "Keep-Alive" les connexions HTTP vers le serveur dans un petit robot d'exploration du Web projet. Voici le problème: lorsque j'ai essayé de recv () de la première page, elle a réussi. Toutefois, le 2e consécutif recv () recevra zéro octets, pour lequel je n'ai aucune idée. J'ai posé une "Keep-Alive" champ de la demande de message quand j'ai demandé d'envoyer ().

Je ne sais pas très bien comment mettre en œuvre des connexions persistantes HTTP en utilisant Keep-Alive. J'ai extrait les socket code relatif à un petit programme ci-jointe.

Voulez-vous s'il vous plaît jeter un coup d'oeil au code et d'expliquer ce qui n'allait pas avec elle pour moi? Ce serait d'une grande aide car je l'ai bloqué sur ce problème pendant des jours.

Par ailleurs, le programme a été établi sous SunOS utiliser g + + et lsocket.
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#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>

#include <string>
#include <iostream>

using namespace std;

// ------------------------------------------------------
const short SOCKET_ERROR = -1;

const short RECV_BUFFER_SIZE = 20;
const short REQUEST_BUFFER_SIZE = 255;

int sock;
char recv_buf [RECV_BUFFER_SIZE + 1];
char req_buf [REQUEST_BUFFER_SIZE + 1];

const static char REQUEST_TEMPLATE [] = 
{
	"GET %s HTTP/1.1\r\n"
	"Host: xxx.xxx.xxx\r\n" // should be replaced with a really host
	"Connection: Keep-Alive\r\n"
	"\r\n"
};

// ------------------------------------------------------
void create_socket ();
void download (const string& path, string& response);

// ------------------------------------------------------

int main (void)
{
	string first_addr = "/~pdu/index.html"; // should be replaced with a really URL
	string second_addr = "/~pdu/a.html"; // should be replaced with a really URL
	string response;

	create_socket ();
	download (first_addr, response);
	cout << response << endl << endl;
	response = "";
	download (second_addr, response);
	if (response.size() > 0)
	{
		cout << response << endl;
	}
	else
	{
		cout << "### The 2nd recv() failed to receive any bytes from the socket!" << endl << endl;
	}
	
	close (sock);

	return 0;
}

void create_socket ()
{
	struct sockaddr_in addr;

	// ------------------------------------------------------
	sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if(sock == SOCKET_ERROR)
    {
        perror ("Could not make a socket.\n");
		exit (-1);
    }

	cout << ">>> Socket created!" << endl;

	// ------------------------------------------------------
	struct hostent* host_info = gethostbyname("cse.unl.edu");	
	
	cout << ">>> DNS done!" << endl;

	long host_addr;

	/* copy address into long */
	memcpy(&host_addr, host_info->h_addr,
		host_info->h_length);

	/* fill address struct */
	addr.sin_addr.s_addr = host_addr;
	addr.sin_port = htons(80);
	addr.sin_family = AF_INET;

	// ------------------------------------------------------
	if( connect(sock, (struct sockaddr*)(&addr),
		sizeof(addr)) == SOCKET_ERROR )
    {
        perror("Could not connect to HTTP server.\n");
		exit (-1);
    }

	cout << ">>> Connection established!" << endl;
}

void download (const string& path, string& response) 
{
	size_t nBytes = snprintf(
		req_buf, 
		REQUEST_BUFFER_SIZE, 
		REQUEST_TEMPLATE, 
		path.c_str());

	if (nBytes >= REQUEST_BUFFER_SIZE)
	{
        cerr << "Buffer is too small for making a request message" << endl;
		exit (-1);
	}

	if (send(sock, req_buf, nBytes, 0) != nBytes)
	{
        perror("Could not send request to the HTTP server.\n");
		exit (-1);
	}
	cout << ">>> Request sent! -> " << path << endl << req_buf << endl;
	
	ssize_t size = 0;
	
	while ((size = recv(sock, recv_buf, 
		RECV_BUFFER_SIZE, 0)) > 0) 
	{
		recv_buf[size] = '\0';
		response.append(recv_buf);
    }

	cout << ">>> Response received!" << endl;
}