socket programming c++ windows, can't see received message from server [closed] - c++

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I am writing a network client-server program:
Server side:
#include "stdafx.h"
#include <winsock.h>
#include <stdio.h>
#include<stdlib.h>
#define PROTOPORT 5193
#define QLEN 6
#define BUFFERSIZE 512
void ErrorHandler(char *errorMessage)
{
printf(errorMessage);
}
void ClearWinSock()
{
#if defined WIN32
WSACleanup();
#endif
}
int main(int argc, char *argv[])
{
int port;
if (argc > 1)
port = atoi(argv[1]);
else
port = PROTOPORT;
if (port < 0) {
printf("Bad port number %s \n", argv[1]);
return 0;
}
#if defined WIN32
WSADATA wsaData;
int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (iResult != 0) {
ErrorHandler("Error at WSAStartup()\n");
return 0;
}
#endif
//creazione della socket
int MySocket;
MySocket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
if (MySocket < 0) {
ErrorHandler("socket creation failed.\n");
ClearWinSock();
return 0;
}
//ASSEGNAZIONE DI UN INDIRIZZO ALLA SOCKET
struct sockaddr_in sad;
memset(&sad, 0, sizeof(sad)); // ensures that extra bytes contain 0
sad.sin_family = AF_INET;
sad.sin_addr.s_addr = inet_addr("127.0.0.1");
sad.sin_port = htons(port); /* converts values between the host and
network byte order. Specifically, htons() converts 16-bit quantities
from host byte order to network byte order. */
if (bind(MySocket, (struct sockaddr*) &sad, sizeof(sad)) < 0) {
ErrorHandler("bind() failed.\n");
closesocket(MySocket);
ClearWinSock();
return 0;
}
// SETTAGGIO DELLA SOCKET ALL'ASCOLTO
if (listen(MySocket, QLEN) < 0) {
ErrorHandler("listen() failed.\n");
closesocket(MySocket);
ClearWinSock();
return 0;
}
// ACCETTARE UNA NUOVA CONNESSIONE
struct sockaddr_in cad; // structure for the client address
int clientSocket; // socket descriptor for the client
int clientLen; // the size of the client address
printf("Waiting for a client to connect...");
while (1) {
clientLen = sizeof(cad); // set the size of the client address
if ((clientSocket = accept(MySocket, (struct sockaddr *)&cad,
&clientLen)) < 0) {
ErrorHandler("accept() failed.\n");
//RICEZIONE DATI TEST
int bytesRcvd;
int totalBytesRcvd = 0;
int Csocket;
Csocket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
char buf[BUFFERSIZE]; // buffer for data from the server
printf("Received: "); // Setup to print the echoed string
if ((bytesRcvd = recv(Csocket, buf, BUFFERSIZE - 1, 0)) <= 0) {
ErrorHandler("recv() failed or connection closed prematurely");
closesocket(Csocket);
ClearWinSock();
return 0;
}
totalBytesRcvd += bytesRcvd; // Keep tally of total bytes
buf[bytesRcvd] = '\0'; // Add \0 so printf knows where to stop
printf("%s", buf); // Print the echo buffer
// CHIUSURA DELLA CONNESSIONE
closesocket(MySocket);
ClearWinSock();
return 0;
}
printf("Handling client %s\n", inet_ntoa(cad.sin_addr));
}
}
and client side:
#include "stdafx.h"
#include <winsock.h>
#include <stdio.h>
#include <stdlib.h>
#define BUFFERSIZE 512
#define PROTOPORT 5193
void ErrorHandler(char *errorMessage) {
printf(errorMessage);
}
void ClearWinSock() {
WSACleanup();
}
int main(void) {
WSADATA wsaData;
int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (iResult != 0) {
printf("error at WSASturtup\n");
return 0;
}
// CREAZIONE DELLA SOCKET
int Csocket;
Csocket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
if (Csocket < 0) {
ErrorHandler("socket creation failed.\n");
closesocket(Csocket);
ClearWinSock();
return 0;
}
// COSTRUZIONE DELL’INDIRIZZO DEL SERVER
struct sockaddr_in sad;
memset(&sad, 0, sizeof(sad));
sad.sin_family = AF_INET;
sad.sin_addr.s_addr = inet_addr("127.0.0.1"); // IP del server
sad.sin_port = htons(5193); // Server port
// CONNESSIONE AL SERVER
if (connect(Csocket, (struct sockaddr *)&sad, sizeof(sad)) < 0)
{
ErrorHandler("Failed to connect.\n");
closesocket(Csocket);
ClearWinSock();
return 0;
}
char* inputString = "prova"; // Stringa da inviare
int stringLen = strlen(inputString); // Determina la lunghezza
// INVIARE DATI AL SERVER
if (send(Csocket, inputString, stringLen, 0) != stringLen) {
ErrorHandler("send() sent a different number of bytes than expected");
closesocket(Csocket);
ClearWinSock();
return 0;
}
// RICEVERE DATI DAL SERVER
int bytesRcvd;
int totalBytesRcvd = 0;
char buf[BUFFERSIZE]; // buffer for data from the server
printf("Received: "); // Setup to print the echoed string
while (totalBytesRcvd < stringLen) {
if ((bytesRcvd = recv(Csocket, buf, BUFFERSIZE - 1, 0)) <= 0) {
ErrorHandler("recv() failed or connection closed prematurely");
closesocket(Csocket);
ClearWinSock();
return 0;
}
totalBytesRcvd += bytesRcvd; // Keep tally of total bytes
buf[bytesRcvd] = '\0'; // Add \0 so printf knows where to stop
printf("%s", buf); // Print the echo buffer
}
// CHIUSURA DELLA CONNESSIONE
closesocket(Csocket);
ClearWinSock();
printf("\n"); // Print a final linefeed
system("pause");
return(0);
}
I have problems in output the string i've passed from client to server: "prova".
Can someone tell me where is error? The code doesn't give me any error.

Answer 1

You are receiving data only when accept failed:
if ((clientSocket = accept(MySocket, (struct sockaddr *)&cad,
&clientLen)) < 0) {
ErrorHandler("accept() failed.\n");
int bytesRcvd;
int totalBytesRcvd = 0;
...
What you need to do is just add a else case:
if ((clientSocket = accept(MySocket, (struct sockaddr *)&cad,
&clientLen)) < 0) {
ErrorHandler("accept() failed.\n");
} else {
int bytesRcvd;
int totalBytesRcvd = 0;
... // receive code here
// clientSocket is the socket to communicate with client
// call recv on it, not the other socket you created in the loop
}

Answer 2

The accept() call returns 'clientSocket', which you promptly ignore and dream up some new 'Csocket' to receive on.
Don't do that.
if ((bytesRcvd = recv(clientSocket, buf, BUFFERSIZE - 1, 0)) <= 0) {

Answer 3

This is the new Server side:
#include "stdafx.h"
#include <winsock.h>
#include <stdio.h>
#include<stdlib.h>
#define PROTOPORT 5193
#define QLEN 6
#define BUFFERSIZE 512
void ErrorHandler(char *errorMessage)
{
printf(errorMessage);
}
void ClearWinSock()
{
#if defined WIN32
WSACleanup();
#endif
}
int main(int argc, char *argv[])
{
int port;
if (argc > 1)
port = atoi(argv[1]);
else
port = PROTOPORT;
if (port < 0) {
printf("Bad port number %s \n", argv[1]);
return 0;
}
#if defined WIN32
WSADATA wsaData;
int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (iResult != 0) {
ErrorHandler("Error at WSAStartup()\n");
return 0;
}
#endif
//creazione della socket
int MySocket;
MySocket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
if (MySocket < 0) {
ErrorHandler("socket creation failed.\n");
ClearWinSock();
return 0;
}
//ASSEGNAZIONE DI UN INDIRIZZO ALLA SOCKET
struct sockaddr_in sad;
memset(&sad, 0, sizeof(sad)); // ensures that extra bytes contain 0
sad.sin_family = AF_INET;
sad.sin_addr.s_addr = inet_addr("127.0.0.1");
sad.sin_port = htons(port); /* converts values between the host and
network byte order. Specifically, htons() converts 16-bit quantities
from host byte order to network byte order. */
if (bind(MySocket, (struct sockaddr*) &sad, sizeof(sad)) < 0) {
ErrorHandler("bind() failed.\n");
closesocket(MySocket);
ClearWinSock();
return 0;
}
// SETTAGGIO DELLA SOCKET ALL'ASCOLTO
if (listen(MySocket, QLEN) < 0) {
ErrorHandler("listen() failed.\n");
closesocket(MySocket);
ClearWinSock();
return 0;
}
// ACCETTARE UNA NUOVA CONNESSIONE
struct sockaddr_in cad; // structure for the client address
int clientSocket; // socket descriptor for the client
int clientLen; // the size of the client address
printf("Waiting for a client to connect...");
while (1) {
clientLen = sizeof(cad); // set the size of the client address
if ((clientSocket = accept(MySocket, (struct sockaddr *)&cad,
&clientLen)) < 0) {
ErrorHandler("accept() failed.\n");
}else{
//RICEZIONE DATI TEST
int bytesRcvd;
int totalBytesRcvd = 0;
char buf[BUFFERSIZE]; // buffer for data from the server
printf("Received: "); // Setup to print the echoed string
if ((bytesRcvd = recv(clientSocket, buf, BUFFERSIZE - 1, 0)) <= 0) {
ErrorHandler("recv() failed or connection closed prematurely");
closesocket(clientSocket);
ClearWinSock();
return 0;
totalBytesRcvd += bytesRcvd; // Keep tally of total bytes
buf[bytesRcvd] = '\0'; // Add \0 so printf knows where to stop
printf("%s", buf); // Print the echo buffer
} Sleep(10);
// CHIUSURA DELLA CONNESSIONE
closesocket(MySocket);
ClearWinSock();
return 0;
}
printf("Handling client %s\n", inet_ntoa(cad.sin_addr));
system("pause");
}
}