Going off a different post that helped explain the source of the symptoms of my issue: https://superuser.com/questions/1348102/windows-10-ephemeral-port-exhaustion-but-netstat-says-otherwise
I am having a very similar issue - except the problem is the program eating up all the ports is one I created myself.
See the top 2 results
See the top 2 results - 6072 ports used by one instance and 545 by the other - if I understand that result set correctly.
There are 2 instances listed as there are 2 instances running - this is a program that connects to a machine every 60 seconds, asks if it has information, retrieves it if it does, and then closes the connection.
It was written in C++ using winsock TCP connections.
Is there anything someone could suggest I modify to prevent this from happening?
Currently, after about a month and a half of the program running, we run into the issue of not being able to RDC into the server "due to a time and date difference" even though the time and date are perfectly in sync with the NTP server and the rest of the computers, and of course it will seize being able to connect to anything.
We can still connect to the server directly through IP address, but not hostname.
I haven't yet found any solutions to this other than rebooting the server.
The mechanism for connecting is a simple and primitive:
void Connect(string ipA)
{
// Initialize Winsock
Debug("Connecting to socket...");
iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (iResult != NO_ERROR)
{
Debug("Client: Error at WSAStartup().");
}
else
{
Debug("Client: WSAStartup() is OK.");
}
// Create a SOCKET for connecting to server
u_long mode = (u_long)0;
ConnectSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
GPT_ATTRIBUTE_NO_BLOCK_IO_PROTOCOL;
if (ConnectSocket == INVALID_SOCKET)
{
printf("Client: Error at socket(): %ld.\n", WSAGetLastError());
WSACleanup();
return;
}
iResult = ioctlsocket(ConnectSocket, FIONBIO, &mode);
if (iResult != NO_ERROR)
printf("ioctlsocket failed with error: %ld\n", iResult);
sockaddr_in clientService;
clientService.sin_family = AF_INET;
clientService.sin_addr.s_addr = inet_addr(ipA.c_str());
clientService.sin_port = htons(port);
// Connect to server.
if (connect(ConnectSocket, (SOCKADDR*)&clientService, sizeof(clientService)) == SOCKET_ERROR)
{
Debug("Connection failed...");
WSACleanup();
return;
}
else
Debug("Connection successful.");
}
This method is called with the IP address supplied as a parameter and results in a successful connection.
After that, several request-response packets are sent using these:
void SendPacket(int iResult, SOCKET ConnectSocket, const char* a)
{
Debug("Sending message to CW: " + (string)a);
iResult = send(ConnectSocket, a, strlen(a), 0);
if (iResult == SOCKET_ERROR) {
Debug("Send failed");
closesocket(ConnectSocket);
WSACleanup();
}
else
Debug("Send successful.");
}
And
iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
And once we're done with the particular session, we close the connection:
void ShutDown(int iResult, SOCKET ConnectSocket)
{
iResult = shutdown(ConnectSocket, SD_SEND);
Debug("Shutting down socket...");
if (iResult == SOCKET_ERROR) {
Debug("Shutdown failed");
closesocket(ConnectSocket);
WSACleanup();
}
else
Debug("Shutdown successful.");
}
There are a couple hundred lines of code that handles the data received, but those won't be relevant as they don't deal with any sort of network connection.
To say I have no experience with C++ would be an understatement, I simply slapped this together using basic MS templates until it worked exactly as we needed it and haven't touched it since.
So if there is anything someone can point out that I could change to avoid port exhaustion, I would be very grateful.
Just to add a bit of clarity - the program will ALWAYS connect to the machine on the same port. I have tried to bind the outgoing connection (from Windows) port to the same one also, but I have been unsuccessful - wasted many hours trying to get this 1 simple thing right, but I presume that would resolve my issues.
I see that you are calling shutdown when you are done with a connection and if we consult the documentation for that we see:
The shutdown function does not close the socket. Any resources attached to the socket will not be freed until closesocket is invoked.
Which I take to mean that any ports associated with the socket remain in use.
Further down that page, we also read:
An application should not rely on being able to reuse a socket after it has been shut down. In particular, a Windows Sockets provider is not required to support the use of connect on a socket that has been shut down.
So, all-in-all, I would call closesocket instead of shutdown and then request a new socket from Winsock when you need one.
Related
i am working on a chat.
i can start my server and client on the same computer using the 127.0.0.1 ip address and can talk fine, but if I try using my own IP address in the client to connect to the server, it does not connect. If someone else also tries to do it, it doesn't work
i have portforwarded in my router like this:
external host: my ip
internal host: my internal ip i got with ipconfig (192.168.1.4)
internal port: 54444
external port: 54444
even then, I think I should still be able to connect to my IP address without a portforward since the server is hosted on 127.0.0.1/localhost, right?
this is my client code:
WSADATA wsa;
if (!WSAStartup(MAKEWORD(2, 2), &wsa))
{
printf("started server\n");
SOCKET listen_sock = socket(AF_INET, SOCK_STREAM, 0);
if (listen_sock)
{
printf("created listen socket\n");
sockaddr_in addr;
addr.sin_family = AF_INET;
inet_pton(AF_INET, "92.83.235.216", &addr.sin_addr);
addr.sin_port = htons(54444);
if (!connect(listen_sock, reinterpret_cast<sockaddr*>(&addr), sizeof(addr)))
{
printf("connected to server\n");
char buffer[2048];
char input[2048];
for(;;)
{
printf("message: ");
scanf_s("%s", input);
if (send(listen_sock, input, strlen(input) + 1, 0))
{
printf("\nsent message \"%s\"", input);
}
memset(input, 0, sizeof(input));
printf("\n");
}
}
}
}
printf("%d\n", WSAGetLastError());
WSACleanup();
it stops after it shows "creating listen socket", right at the connect() call
Any ideas?
EDIT: server code is very jumbled because of me making it into a class to make it easier to use + adding a thread to handle multiple connections, but like I said it does work internall
only thing different in the server code besides the listen and accept calls is these rules i added:
char opt_val = 1;
setsockopt(this->m_listen_sock, SOL_SOCKET, SO_REUSEADDR, &opt_val, sizeof(opt_val));
setsockopt(this->m_listen_sock, IPPROTO_TCP, TCP_NODELAY, &opt_val, sizeof(opt_val));
What you're describing sounds like your SYN packets are being dropped (SYN... no SYN/ACK or RST). You can use wireshark to see what is happening with the actual tcp connection (filter on port).
You might want to eliminate the server as a source of error by listening on localhost and connecting that way. You can verify it is listening on the correct address and port using netstat.
Otherwise, it would help if you posted your server code.
So I recently decided to dabble into winsock and network programming a bit by using a guide I found and searching the net, but I have run into a problem which I am not really sure how i should solve.
I'm trying to make a very simple chat system, I've got a working server program and client program, and if I only use on client (sending the message back to the same client) It seems to work perfectly fine. The problem appears when I try to have multiple clients connect. I get error 10048 from WSAgetlasterror and it seems to be the bind function that is the source, more specificly the fact that I am trying to bind on the same port twice, (once for each client). From looking around on msdn and forums it seems to be possible to get around this problem by using setsockopt, but I'm not really sure what changes I should make, and also if this is the smartest solution.
I mean I want the clients to connect to the same port don't I? How else will the client program know what to connect to? Or am I just missing something? As I said I have no prior experience with winsock or any other network programming so I might be doing things in a stupid way.
int listenOnPort(int portno, SOCKET& reciever, SOCKET s){
int error = WSAStartup(0x0202, &w);
if (error)
{
cout << "Error starting WSA";
return false; //for some reason we couldn't start Winsock
}
if (w.wVersion != 0x0202) //Wrong Winsock version?
{
cout << "Wrong Winsock version";
WSACleanup();
return false;
}
SOCKADDR_IN addr; // The address structure for a TCP socket
addr.sin_family = AF_INET; // Address family
addr.sin_port = htons(portno); // Assign port no to this socket
//Accept a connection from any IP using INADDR_ANY
//You could pass inet_addr("0.0.0.0") instead to accomplish the
//same thing. If you want only to watch for a connection from a
//specific IP, specify that //instead.
addr.sin_addr.s_addr = htonl(INADDR_ANY);
s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); // Create a socket
if (s == INVALID_SOCKET)
{
cout << "Couldn't create the socket";
return false; //Don't continue if we couldn't create a //socket!!
}
if (bind(s, (LPSOCKADDR)&addr, sizeof(addr)) == SOCKET_ERROR)
{
//We couldn't bind (this will happen if you try to bind to the same
//socket more than once)
cout << "Error binding the socket";
return false;
}
//Now we can start listening (allowing as many connections as possible to
//be made at the same time using SOMAXCONN). You could specify any
//integer value equal to or lesser than SOMAXCONN instead for custom
//purposes). The function will not //return until a connection request is
//made
listen(s, 1);
reciever = accept(s, NULL, NULL);
cout << "connection established\n\n";
//Don't forget to clean up with CloseConnection()!}
int main(){
e = WSAGetLastError();
listenOnPort(1337, r1, s1);
cout << "First Client connected\n\n";
e = WSAGetLastError();
listenOnPort(1338, r2, s2);
cout << "Second Client connected\n\n";
e = WSAGetLastError();
std::thread com1(communicate, r1, r2);
std::thread com2(communicate, r2, r1);
com1.join();
com2.join();
//system("pause");
closeConnection();}
You have to have 1 thread in the server dedicated to accept new connections.
The process listens to new connections and assigns a new port (in the server) for that connection, making the default port available for new connections.
in the server you will have N+1 socket ports open at any time when N is the number of clients the server has and 1 is the socket listening to new connections.
Take a look at this:
http://www.codeproject.com/Articles/7785/Single-Server-With-Multiple-Clients-a-Simple-C-Imp
I have a C++ program, using mpi, that follows a typical client server model. Each mpi instance of the client connects to a corresponding mpi instance of the server. This has worked relatively well until I have had to do some testing with added latency (1 second of added latency to be precise).
Problem:
Sometimes one of the server processes do not think the client has connected but the client thinks it has connected. i.e. After using gdb, the server is waiting at accept() but the client has continued on past connect(). Thus, it appears the client thinks it has connected when the server does not think it has connected.
My best guess is that I need to set an sock-option somewhere, however talking to fellow programmers and googling has not yielded any helpful results.
EDIT:
There are two sets of MPI processes (so two different calls to mpirun), the accept() and connect() calls are for the sockets, which are between the two sets of MPI processes. It is openmpi.
The code (from someone else's code, actually) [reduced]:
Client (connect code): (m_socket is the actual socket)
if (-1 == m_socket)
{
perror("cannot create socket");
exit(EXIT_FAILURE);
}
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(port);
res = inet_pton(AF_INET, host_ip, &addr.sin_addr);
if (0 > res)
{
perror("error: first parameter is not a valid address family");
close(m_socket);
exit(EXIT_FAILURE);
}
else if (0 == res)
{
perror("error: second parameter does not contain valid IP address");
close(m_socket);
exit(EXIT_FAILURE);
}
//backoff
for (int sec = 1; sec < 20000; sec++ )
{
int ret;
if (0 == (ret = connect(m_socket, (struct sockaddr *)&addr, sizeof(addr))))
{
return;
}
sleep(1);
close(m_socket);
m_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
}
perror("connect failed");
close(m_socket);
exit(EXIT_FAILURE);
Server: (m_socket is the actual socket)
int socket = ::accept(m_socket, NULL, NULL);
if(socket < 0)
{
fprintf(stderr, "accept() failed: %s\n", strerror(errno));
close(m_socket);
exit(EXIT_FAILURE);
}
It looks like you're trying to do your connect/accept manually rather than with MPI. You might take a look at the example on Deino (http://mpi.deino.net/mpi_functions/MPI_Comm_accept.html) if you're trying to use MPI for your connections.
Alternatively, you might just need to look at a more general tutorial (some available here: http://www.mcs.anl.gov/research/projects/mpi/tutorial/) of MPI to get a feel for how communication works. Most of the time and application doesn't use Connect/Accept to communicate, but uses MPI Communicators to set up communication mechanisms between processes. It's a different model (SPMD as opposed to MPMD).
I have a connection protocol that has been defined by our customer. Data are sent between two linux computers using UDP and TCP protocols. The IP addresses and ports are fixed on startup.
We are sending messages at 200 Hz and I have been using connect to save some time on the transmissions.
My problem is that if there is a communication error, I need to tear down the connections and reinitialise.
I have a problem with one of the UDP connections as it will not rebind to the required address and returns errno 22.
The code I am using is something like:
int
doConnect(int& sock, int local_port, char *local_ip, int remote_port, char *remote_ip)
{
sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
struct sockaddr_in addr;
memset(&addr, 0, sizeof(sockaddr_in);
addr.sin_family = AF_INET;
addr.sin_port = htons(local_port);
inet_pton(local_ip,&addr.sin_addr.s_addr);
if (0 > bind(sock, (struct sockaddr*)&addr, sizeof(addr)))
{
printf("Bind Error errno = %d\n", errno);
return ERR_BIND;
}
memset(&addr, 0, sizeof(sockaddr_in);
addr.sin_family = AF_INET;
addr.sin_port = htons(remote_port);
inet_pton(remote_ip,&addr.sin_addr.s_addr);
if (0 > connect(sock, (struct sockaddr*)&addr, sizeof(addr)))
{
printf("Connect Error errno = %d\n", errno);
return ERR_CONNECT;
}
return ERR_OK;
}
The way that this is used is like this:
int s1(-1), s2(-1);
doConnect(s1, 31003, "172.17.21.255", 31006, "172.17.21.1");
doConnect(s2, 31001, "172.17.21.3", 31004, "172.17.21.1");
When an error occurs
close(s1);
close(s2);
doConnect(s1, 31003, "172.17.21.255", 31006, "172.17.21.1");
doConnect(s2, 31001, "172.17.21.3", 31004, "172.17.21.1");
Here the local address is 172.17.21.3 and I am connecting to 172.17.21.1. s1 listens to a broadcast message.
s1 successfully reconnects to the remote machine, but s2 fails with error 22 from the call to bind.
I have tried explicitly calling bind and connect to an AF_UNSPEC address immediately before I close the socket. This doesn't solve the problem.
Are there any options that I should be using?
Perhaps you could try:
int val = 1;
setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
I also suggest you double check that you're not passing the same socket to the two consecutive doConnect() calls (as errno 22 = EINVAL, which in the case of bind() appears to mean that the socket is already bound to an address).
The underlying socket layer might hold the port & IP address still open, even after your call to close. Try some of the following:
do a sleep(10) (or more) between the close and the call to doConnect again
configure the sockets using setsockopt with the SO_LINGER set to off
This actually happens more commonly with TCP connections, but I see no reason UDP can't have this problem as well.
I am working on a small networking project using Winsock2. I am using a TCP connection and actually am working with IRC as an example since IRC is fairly simple. What I am doing is connecting to the server and sending an initial buffer so the server recognizes a connection. This works fine.
What concerns me is that I cannot write to the socket again. It seems my program hangs if I do not use shutdown() (on SD_SEND) after I send the initial buffer.
So the next data (based on RFC 1459) I want to send is the USER and NICK information, however, I feel like using shutdown() is what is causing my current issue. Is there a way to reinitialize the write socket?
Thanks!
ADDED CODE
Note that these are located within a class so it still may be slightly obscured. I am writing it into a simpler example using the elements I have. Everything is properly defined, so if I forget to define things, I apologize, but many of my recurring variables are defined for the scope of the class.
int main(int argc,char *argv[])
{
int iResult;
SOCKET Connection;
iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
if(iResult != 0)
throw "Startup failed!";
// Prep stuff
ZeroMemory(&hints,sizeof(hints)); // This struct is defined addrinfo
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
// Now resolve server addr
iResult = getaddrinfo(argv[1],argv[2],&hints,&result);
if(iResult != 0)
throw "getaddrinfo() failed!";
// Now try to connect
for(ptr=result;ptr != NULL;ptr = ptr->ai_next)
{
Connection = socket(ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol); // defined in that "hints" struct. argument number 2
if(Connection == INVALID_SOCKET)
{
freeaddrinfo(result);
WSACleanup();
throw "Error at socket();";
}
// Connect to server
iResult = connect(Connection, ptr->ai_addr, (int)ptr->ai_addrlen);
if(iResult != 0)
{
closesocket(Connection);
Connection = INVALID_SOCKET;
continue;
}
break;
}
freeaddrinfo(result);
// Send initial buffer so server know you're there :)
iResult = send(Connection, "", 1, 0);
if(iResult == SOCKET_ERROR)
{
close();
throw "Could not send initial buffer!";
}
// Close this connection for the inital buffer
iResult = shutdown(Connection, SD_SEND);
if(iResult == SOCKET_ERROR)
{
close();
throw "Could not close initial buffer socket!";
}
bool connected = true;
// This is taken from my read function within the class
// BEGIN READ FUNCTION
iResult = 0; // Reset
std::string data = ""; // Capture the output and send it all at once!
// This only works if we're connected sweet cakes <3
if(connected)
{
do
{
iResult = recv(socket, recvbuf, BUFLEN, 0);
if(iResult > 0)
{
// Working properly
// Save all data even if there is more than BUFLEN sent
continue;
}
else if(iResult == 0)
// Connection closed properly
break;
else
printf("ERROR!");
} while(iResult > 0);
}
data += recvbuf;
ZeroMemory(&recvbuf,sizeof(recvbuf));
// Function returns std::string but essentially this is what happens
printf("%s",data.c_str());
// END READ FUNCTION
// BEGIN WRITE FUNCTION
iResult = 0; // Reset
SOCKET socket = Connection; // Write function arg 1
char *data; // Write function arg 2
iResult = send(socket,data,(int)strlen(data),0);
if(iResult == SOCKET_ERROR)
{
close();
printf("Could not write data: %ld",WSAGetLastError());
return 1;
}
// Data sent, let's close the write socket
iResult = shutdown(socket, SD_SEND);
if(iResult != 0)
{
close();
printf("Could not close write socket!");
return 1;
}
//return iResult;
// END WRITE FUNCTION
// Now that will produce "Could not write data: 0" for any value of data
// So realistically I want to send the USER and NICK data, then read
// and probably process a PING string from the server and send my PONG response
return 0;
}
I hope that clarifies things!
EDIT
I think I have figured out what is going wrong. I made the corrections listed below to my code; thanks guys. However, it's my read loop which is messing with things. Even after it has all the information it seems that it is waiting for the connection to be closed before it sends the output. Any ideas? My output currently looks like this (the bytes written/total is something I added to make sure everything was going down the wire correctly)
Bytes Written: 41
Bytes Total: 41
Data: ERROR :Closing Link: raged123[127.0.0.1] 6667 (Ping timeout)
...
:irc.foonet.com NOTICE AUTH :*** Found your hostname (cached)
PING :2ED39CE5
[A bunch of funny characters]WinSock 2.0
So it appears to have timed out because the PING did not receive PONG in time, however, I cannot send the PONG without first processing the PING request which means I would need to be able to read the output before the connection is closed. Any ideas?
May I suggest a fun document on the subject? Chapter's 6 and 7 of Beej's Guide to Network Programming
It has several examples.
There shouldn't be any need to send an "initial buffer" like you've done. The server will receive notification when a client connects, it doesn't depend on the client actually sending anything. (And in particular, the IRC protocol says that the server will start sending you stuff as soon as you connect.)
The call to shutdown() is highly suspicious. Why did you expect to need to do this? Shutting down a socket is something you do when you're done with the connection, not when you're just starting. You should remove this completely.
I'm not sure what type recvbuf is, but it looks like you're using it incorrectly. Something that can be appended to a std::string probably can't also have ZeroMemory() called on it, without one or the other of those being wrong. You also aren't using iResult which is the actual number of bytes received from the server.
Your write function also contains a call to shutdown(), which you should remove.
According to man send(2)
On success, these calls return the
number of characters sent. On error,
-1 is returned, and errno is set appropriately.
What happens is probably that send does not send the full buffer at once, you must use a loop around it.
This might not be your actual problem however since you,re sending an empty string...
I'd highly recommend using Wireshark so you can check what goes down to the wire
data += recvbuf;
This can't work. There's no way string::operator+= to know how many bytes have been received. This function expects a C-style string, not an arbitrary chunk of bytes.
But you also have a very fundamental design problem. You're expecting your program to speak the IRC protocol, but it contains no implementation of that protocol whatsoever. For example, the IRC protocol specifies a particular way that messages are delimited, and you have no code whatsoever to parse those messages.
As a result, your transition from reading to writing occurs at essentially a random time determined by the vagaries of TCP timing and how the server chooses to segment its output. Since the server is permitted to segment its output however it pleases (the protocol is clear that the client cannot rely on segmentation to parse the protocol but instead must rely on the line-oriented nature), your program's behavior is unpredictable.