OpenSSL socket: Select always returns 0 - c++

Question

I made a small socket echo server with a blocking socket (see code below), but the select statement always returns 0 even when there is a message to be read. Everything else works. If you replace the select statement by simple assigning 1 to selectResult, the server works.
The server runs on Ubuntu in a VM, while the client is on the Host system (Windows 7 professional). My IDE for the server is Eclipse 3.8 and it uses OpenSSL 1.0.1j.
To get this code to work, you only need to include OpenSSL's root directory, add its library path to the linker and link to ssl, crypto and dl (in that order). Also you need a certificate and private key.
Thanks in advance!
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <sys/socket.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <iostream>
using namespace std;
#define MAX_BUFFER 1024
int main()
{
// Initializing...
SSL_CTX*_ctx = NULL;
SSL* _ssl = NULL;
fd_set _fdSet;
int _serverSocket = 0;
int _port = 9090;
timeval t;
const char* certPath = "/home/alex/Certificate/cacert.pem";
const char* pKeyPath = "/home/alex/Certificate/privkey.pem";
// Init OpenSSL
SSL_library_init();
SSL_load_error_strings();
OpenSSL_add_all_algorithms();
_ctx = SSL_CTX_new(TLSv1_1_server_method());
if (_ctx == NULL)
{
ERR_print_errors_fp(stderr);
abort();
}
// Set certificate and private key.
if (SSL_CTX_use_certificate_file(_ctx, certPath, SSL_FILETYPE_PEM) <= 0)
{
ERR_print_errors_fp(stderr);
abort();
}
if (SSL_CTX_use_PrivateKey_file(_ctx, pKeyPath, SSL_FILETYPE_PEM) <= 0)
{
ERR_print_errors_fp(stderr);
abort();
}
if (!SSL_CTX_check_private_key(_ctx))
{
fprintf(stderr, "Private key does not match the public certificate\n");
abort();
}
// Initialize server socket:
// 1. set address
struct sockaddr_in addr;
int optval = 1;
bzero(&addr, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(_port);
addr.sin_addr.s_addr = INADDR_ANY;
// 2. init socket, set socket options, bind it to address
_serverSocket = socket(PF_INET, SOCK_STREAM, 0);
setsockopt(_serverSocket, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval));
if (bind(_serverSocket, (struct sockaddr*) &addr, sizeof(addr)) != 0)
{
perror("can't bind port");
abort();
}
// 3. Prepare the socket to accept connections
if (listen(_serverSocket, 1) != 0)
{
perror("Can't configure listening port");
abort();
}
cout << "Server finished initializing." << endl;
bool bServerStayAlive = true;
while (bServerStayAlive)
{
cout << "Waiting for connection..." << endl;
struct sockaddr_in addr;
unsigned int len = sizeof(addr);
int client = accept(_serverSocket, (struct sockaddr*) &addr, &len);
printf("Connection: %s:%d\n", inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
_ssl = SSL_new(_ctx);
SSL_set_fd(_ssl, client);
if (SSL_accept(_ssl) == -1) /* do SSL-protocol accept */
ERR_print_errors_fp(stderr);
else
{
while (bServerStayAlive)
{
FD_ZERO(&_fdSet);
FD_SET(_serverSocket, &_fdSet);
t.tv_sec = 1;
t.tv_usec = 0;
int selectResult = select(_serverSocket + 1, &_fdSet, NULL, NULL, &t);
if (selectResult == 0)
{
cout << "timeout" << endl;
continue;
}
if (selectResult < 0)
{
cout << "Select error: " << selectResult << endl;
bServerStayAlive = false;
break;
}
cout << "Going to read something\n";
unsigned char buffer[MAX_BUFFER];
memset(buffer, 0, MAX_BUFFER);
int bytes = SSL_read(_ssl, buffer, MAX_BUFFER); /* get request */
if (bytes > 0)
{
cout << "Received message: " << endl;
for (int i = 0; i < bytes; i++)
cout << buffer[i];
cout << endl;
SSL_write(_ssl, buffer, bytes);
}
else
{
ERR_print_errors_fp(stderr);
break;
}
}
}
int sd = SSL_get_fd(_ssl); /* get socket connection */
SSL_free(_ssl); /* release SSL state */
close(sd); /* close connection */
cout << "Connection was closed.\n";
}
// Uninitializing
close(_serverSocket);
SSL_CTX_free(_ctx);
return 0;
}

Answer 1

I think you meant to select on the client socket that you just accepted, not the _serverSocket that you're accepting connections on.