C++ , TCP Socket cannot receive data - c++

Question

I created a BSD-POSIX TCP Socket class and now i have a problem.I have two wifi networks.One of them is an ADSL Router , and another one is hotspoted by an Android device.When i connect to ADSL Router wifi , i can't receive any data at all.The socket can send data , but there is no response.But when i connect to hotspoted wifi (Android device) , the program can receive data.I don't know what is the problem.Both WIFI Networks working fine.And also i used Wireshark to capture data.Data sent successful , but there is no receive.Here is my code:
-------------------ESocket.cpp---------------------
#include "ESocket.h"
#include "stdio.h"
SOCKET s = NULL;
ESocket::ESocket(string ip,int port)
{
struct sockaddr_in server;
if((s = socket(AF_INET , SOCK_STREAM , 0 )) == -1)
{
s = NULL;
}
server.sin_addr.s_addr = inet_addr(ip.c_str());
server.sin_family = AF_INET;
server.sin_port = htons( port );
if (connect(s , (struct sockaddr *)&server , sizeof(server)) < 0)
{
s = NULL;
}
}
ESocket::ESocket(SOCKET e)
{
s = e;
}
ESocket::~ESocket()
{
Destruct();
}
bool ESocket::isConnected()
{
return (s != NULL);
}
int ESocket::Destruct()
{
#ifdef _WIN32
return WSACleanup();
#else
return 0;
#endif
}
int ESocket::Close()
{
int status = 0;
#ifdef _WIN32
status = shutdown(s, SD_BOTH);
if (status == 0) { status = closesocket(s); }
#else
status = shutdown(s, SHUT_RDWR);
if (status == 0) { status = close(s); }
#endif
return status;
}
bool ESocket::SendData(string data)
{
if( send(s , data.c_str() , data.length() , 0) < 0)
{
s = NULL;
return false;
}
return true;
}
string ESocket::ReceiveData(int len)
{
int recv_size;
char reply[len];
if((recv_size = recv(s , reply , len , 0)) < 0)
{
return "";
}
if (recv_size == 0)
{
s = NULL;
return "";
}
printf("%i",recv_size);
reply[recv_size] = '\0';
return reply;
}
int ESocket::setAsNonBlock()
{
int res;
#ifdef _WIN32
u_long iMode = 1;
res = ioctlsocket(s, FIONBIO, &iMode);
#else
int opts;
opts = fcntl(s, F_GETFL);
if(opts < 0)
{
res = -1;
}
opts = (opts | O_NONBLOCK);
if(fcntl(s, F_SETFL, opts) < 0)
{
res = -1;
}
#endif
return res;
}
-------------------ESocket.h---------------------
#ifndef ESOCKET_H
#define ESOCKET_H
#include <string>
#include <stdio.h>
#include <cstring>
using namespace std;
#ifdef _WIN32
#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0501
#endif
#include <winsock2.h>
#else
typedef int SOCKET;
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <unistd.h>
#include <fcntl.h>
#endif
class ESocket
{
public:
ESocket(string ip,int port);
ESocket(SOCKET e);
virtual ~ESocket();
int Destruct();
int Close();
int setAsNonBlock();
bool SendData(string data);
bool isConnected();
string ReceiveData(int len);
static int Init()
{
#ifdef _WIN32
WSADATA wsa_data;
return WSAStartup(MAKEWORD(1,1), &wsa_data);
#else
return 0;
#endif
}
static string getIP(char* host)
{
struct hostent *he;
struct in_addr **addr_list;
char ip[100];
int i;
if ( (he = gethostbyname( host ) ) == NULL)
{
return "";
}
addr_list = (struct in_addr **) he->h_addr_list;
for(i = 0; addr_list[i] != NULL; i++)
{
strcpy(ip , inet_ntoa(*addr_list[i]) );
}
string x = ip;
return x;
}
protected:
private:
};
#endif // ESOCKET_H
------------------------MAIN-----------------------
ESocket::Init();
ESocket e(ESocket::getIP("www.google.com").c_str(),80);
if (e.isConnected())
{
cout<<e.SendData("GET / HTTP/1.1\r\nHost: www.google.com\r\nConnection: keep-alive\r\n\r\n");
}
else
{
printf("Not connected");
return 0;
}
while (e.isConnected()){
cout<<e.ReceiveData(100);
}
printf("\nEND OF CONNECTION");
EDIT: Solved by reset wifi router.

Answer 1

You have several serious bugs:
Your receive function has no code to support the "would block" condition and so it will not work reliably with non-blocking sockets.
Your receive function provides no reliable way to tell whether it got an error or not (as opposed to an empty string). It corrupts the socket value on an error, so calling it again after an error is potentially disastrous. Yet it provides no way at all to avoid this.
You set the socket to NULL. But nothing makes NULL an invalid value for a socket. On WIN32, use INVALID_SOCKET. On other platforms, use -1.
You also have a more minor issue. Your request claims HTTP 1.1 compliance, but it is not an HTTP 1.1 compliant request. For example, HTTP 1.1 makes "Host" headers mandatory. Don't claim compliance with a protocol you have no intention of supporting. What happens if you get back a reply that uses chunked encoding?
Likely what's happening is that receive is encountering a "would block" condition, corrupting the socket, and then you call receive again with an invalid socket which, of course, fails.