I am having terrible trouble intercommunicating processes, using UNIX sockets. My server is written in c++, but I can't get past calling the bind method.
c++ code.
OutputDebugString(_T("My Sample Service: ServiceWorkerThread: Entry"));
WCHAR strbuf[256];
WSADATA wsaData;
int iResult;
// Initialize Winsock
iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (iResult != 0) {
wsprintfW(strbuf, L"My Sample Service : WSAStartup failed with error: %d", iResult);
OutputDebugString(strbuf);
OutputDebugString(_T("My Sample Service: ServiceWorkerThread: Exit"));
return 1;
}
int opt = TRUE;
int master_socket, addrlen, new_socket, client_socket[30],
max_clients = 30, activity, i, valread, sd;
int max_sd;
struct sockaddr_in address;
char buffer[1025]; //data buffer of 1K
//set of socket descriptors
fd_set readfds;
TIMEVAL tv = { 2, 0 };
//a message
char *message = "ECHO Daemon v1.0 \r\n";
//initialise all client_socket[] to 0 so not checked
for (i = 0; i < max_clients; i++)
{
client_socket[i] = 0;
}
/*struct addrinfo *result = NULL;
struct addrinfo hints;
ZeroMemory(&hints, sizeof(hints));
hints.ai_family = AF_UNIX;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = 0;
hints.ai_flags = AI_PASSIVE;
iResult = getaddrinfo("localhost", DEFAULT_PORT, &hints, &result);
if (iResult != 0) {
wsprintfW(strbuf, L"My Sample Service : getaddrinfo failed with error: %d", iResult);
OutputDebugString(strbuf);
OutputDebugString(_T("My Sample Service: ServiceWorkerThread: Exit 2"));
WSACleanup();
return 1;
}*/
//create a master socket
if ((master_socket = socket(AF_UNIX, SOCK_STREAM, 0)) == 0)
{
OutputDebugString(_T("My Sample Service : socket failed with error"));
OutputDebugString(_T("My Sample Service: ServiceWorkerThread: Exit"));
return 1;
}
//set master socket to allow multiple connections ,
//this is just a good habit, it will work without this
if (setsockopt(master_socket, SOL_SOCKET, SO_REUSEADDR, (char *)&opt,
sizeof(opt)) < 0)
{
OutputDebugString(_T("My Sample Service : setsockopt failed with error"));
OutputDebugString(_T("My Sample Service: ServiceWorkerThread: Exit"));
return 1;
}
//type of socket created
address.sin_family = AF_UNIX;
address.sin_addr.s_addr = inet_addr("127.0.0.1"); //I really don't know what to put here
//address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons(PORT);
////bind the socket to localhost port 8000
//if (bind(master_socket, (struct sockaddr *)&address, sizeof(address))<0)
//{
// wsprintfW(strbuf, L"My Sample Service : bind failed with error: %d", WSAGetLastError());
// OutputDebugString(strbuf);
// OutputDebugString(_T("My Sample Service: ServiceWorkerThread: Exit 2"));
// closesocket(master_socket);
// WSACleanup();
// return 1;
//}
// Setup the TCP listening socket
iResult = bind(master_socket, (struct sockaddr *)&address, sizeof(address));
if (iResult == SOCKET_ERROR) {
wsprintfW(strbuf, L"My Sample Service : bind failed with error: %d", WSAGetLastError());
OutputDebugString(strbuf);
OutputDebugString(_T("My Sample Service: ServiceWorkerThread: Exit"));
closesocket(master_socket);
WSACleanup();
return 1;
}
//freeaddrinfo(result);
//try to specify maximum of 3 pending connections for the master socket
if (listen(master_socket, 3) < 0)
{
wsprintfW(strbuf, L"My Sample Service : listen failed with error: %d\n", WSAGetLastError());
OutputDebugString(strbuf);
OutputDebugString(_T("My Sample Service: ServiceWorkerThread: Exit"));
closesocket(master_socket);
WSACleanup();
return 1;
}
addrlen = sizeof(address);
//accept the incoming connection
wsprintfW(strbuf, L"My Sample Service : Listener on port %d", PORT);
OutputDebugString(strbuf);
OutputDebugString(_T("My Sample Service: Waiting for connections ..."));
// Periodically check if the servC:\Users\Administrator\Desktopice has been requested to stop
while (WaitForSingleObject(g_ServiceStopEvent, 0) != WAIT_OBJECT_0)
{
/*
* Perform main service function here
*/
//clear the socket set
FD_ZERO(&readfds);
//add master socket to set
FD_SET(master_socket, &readfds);
max_sd = master_socket;
//add child sockets to set
for (i = 0; i < max_clients; i++)
{
//socket descriptor
sd = client_socket[i];
//if valid socket descriptor then add to read list
if (sd > 0)
FD_SET(sd, &readfds);
//highest file descriptor number, need it for the select function
if (sd > max_sd)
max_sd = sd;
}
//wait for an activity on one of the sockets , timeout is NULL ,
//so wait indefinitely
activity = select(max_sd + 1, &readfds, NULL, NULL, &tv);
if ((activity < 0) && (errno != EINTR))
{
OutputDebugString(_T("My Sample Service: select failed with error"));
}
//If something happened on the master socket ,
//then its an incoming connection
if (FD_ISSET(master_socket, &readfds))
{
if ((new_socket = accept(master_socket,
(struct sockaddr *)&address, (socklen_t*)&addrlen))<0)
{
wsprintfW(strbuf, L"My Sample Service : accept failed with error: %d", WSAGetLastError());
OutputDebugString(strbuf);
OutputDebugString(_T("My Sample Service: ServiceWorkerThread: Exit"));
closesocket(master_socket);
WSACleanup();
return 1;
}
//inform user of socket number - used in send and receive commands
wsprintfW(strbuf, L"My Sample Service : New connection , socket fd is %d , ip is : %s , port : %d" , new_socket , inet_ntoa(address.sin_addr) , ntohs(address.sin_port));
OutputDebugString(strbuf);
//send new connection greeting message
if (send(new_socket, message, strlen(message), 0) != strlen(message))
{
OutputDebugString(_T("My Sample Service: Welcome message sent failed with error"));
}
else
{
OutputDebugString(_T("My Sample Service: Welcome message sent successfully"));
}
//add new socket to array of sockets
for (i = 0; i < max_clients; i++)
{
//if position is empty
if (client_socket[i] == 0)
{
client_socket[i] = new_socket;
wsprintfW(strbuf, L"My Sample Service: Adding to list of sockets as %d", i);
OutputDebugString(strbuf);
break;
}
}
}
//else its some IO operation on some other socket
for (i = 0; i < max_clients; i++)
{
sd = client_socket[i];
if (FD_ISSET(sd, &readfds))
{
//Check if it was for closing , and also read the
//incoming message
if ((valread = recv(sd, buffer, 1024, 0)) == 0)
{
//Somebody disconnected , get his details and print
getpeername(sd, (struct sockaddr*)&address, \
(socklen_t*)&addrlen);
wsprintfW(strbuf, L"My Sample Service: Host disconnected , ip %s , port %d",
inet_ntoa(address.sin_addr), ntohs(address.sin_port));
OutputDebugString(strbuf);
//Close the socket and mark as 0 in list for reuse
closesocket(sd);
client_socket[i] = 0;
}
//Echo back the message that came in
else
{
//set the string terminating NULL byte on the end
//of the data read
buffer[valread] = '\0';
send(sd, buffer, strlen(buffer), 0);
}
}
}
}
The error returned by the bind method is 10022. I only want to accept connections from my own machine. The commented part of the code is because somewhere, I read that for UNIX sockets, getaddrinfo should not be done. Can someone help me to solve my problem??
I can't find any complete example project of process intercommunication using winsock either, if you point me to one it would also be very helpful.
THANK
EDIT
I am trying to intercommunicate two processes in windows. The link left by @Hans_Passant in the comments, points out that for this I must Download the Windows Insiders SDK for the Windows build 17061, but it is not available to everyone, it says: "To access this page, you need to be a member of the Windows Insider Program". so how can I do it?
Unix sockets are already local, you must put nothing but the address family in the address:
memset(&my_addr, 0, sizeof(my_addr));
my_addr.sun_family = AF_UNIX;
Example (source: doc):
int sfd, cfd;
struct sockaddr_un my_addr, peer_addr;
socklen_t peer_addr_size;
sfd = socket(AF_UNIX, SOCK_STREAM, 0);
if (sfd == -1)
handle_error("socket");
memset(&my_addr, 0, sizeof(my_addr));
my_addr.sun_family = AF_UNIX;
strncpy(my_addr.sun_path, MY_SOCK_PATH,
sizeof(my_addr.sun_path) - 1);
if (bind(sfd, (struct sockaddr *) &my_addr,
sizeof(my_addr)) == -1)
handle_error("bind");
if (listen(sfd, LISTEN_BACKLOG) == -1)
handle_error("listen");
/* Now we can accept incoming connections one
at a time using accept(2). */
peer_addr_size = sizeof(peer_addr);
cfd = accept(sfd, (struct sockaddr *) &peer_addr,
&peer_addr_size);
Update: I would recommend you to stick to TCP sockets:
master_socket = socket(AF_INET, SOCK_STREAM, 0)
and then:
memset(&address, 0, sizeof(address));
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_LOOPBACK;
address.sin_port = htons(PORT);
Listening in the loopback interface ensures that no connections from the outside world will ever reach the socket.