GTK GIO How to read reply sent by server - sockets

I wanted to write a client server thing using gio socket in gtk and I found a sample code to send data to server but, the more thing i want is to read the data/reply sent by the server. The below is sample code
#include <glib.h>
#include <gio/gio.h>
int main (int argc, char *argv[])
{
/* initialize glib */
g_type_init ();
GError * error = NULL;
/* create a new connection */
GSocketConnection * connection = NULL;
GSocketClient * client = g_socket_client_new();
/* connect to the host */
connection = g_socket_client_connect_to_host (client,
(gchar*)"localhost",
1500, /* your port goes here */
NULL,
&error);
/* don't forget to check for errors */
if (error != NULL)
{
g_error (error->message);
}
else
{
g_print ("Connection successful!\n");
}
/* use the connection */
GInputStream * istream = g_io_stream_get_input_stream (G_IO_STREAM (connection));
GOutputStream * ostream = g_io_stream_get_output_stream (G_IO_STREAM (connection));
g_output_stream_write (ostream,
"Hello server!", /* your message goes here */
13, /* length of your message */
NULL,
&error);
/* don't forget to check for errors */
if (error != NULL)
{
g_error (error->message);
}
return 0;
}
The above code works fine for the sending data to server but when i try to read it form input stream it goes in to block state. My read message function look like this
void readMessage()
{
char buffer[2048];
GInputStream * istream = g_io_stream_get_input_stream (G_IO_STREAM(connection));
gssize bytes;
bytes = g_input_stream_read(istream, buffer, sizeof buffer, NULL, NULL);
buffer[bytes] = '\0';
g_print ("%"G_GSSIZE_FORMAT" bytes read: %s\n", bytes, buffer);
}

g_input_stream_read() is documented as blocking until it receives as many bytes as you request (in this case, 2048), or until the connection is closed. Presumably, neither of those things are happening. How big is the reply from the server? Does it close the connection after sending its reply?
Bear in mind that g_socket_client_connect_to_host() opens a TCP connection, so you should expect to be doing stream-based I/O here, rather than message-based I/O. If you expect to be sending messages to and from the server, you will need a framing protocol within TCP.

Related

Why does this code never discover Bonjour instances (mDNS)?

I've taken this code almost directly from the dns-sd SDK sample, and yet, it does not find the services I search for.
There is no error, just none of the callbacks are called. This is linked against the Apple Bonjour SDK on Windows 10 x32.
If I run "dns-sd -B _http._tcp" it finds many instances!
void DNSSD_API IterateServiceInstances(DNSServiceRef sdRef,
DNSServiceFlags flags,
uint32_t interfaceIndex,
DNSServiceErrorType errorCode,
const char * serviceName,
const char * regtype,
const char * replyDomain,
void * context)
{
puts("IterateServiceInstances is never called!");
}
void DiscoverSegments()
{
printf("Discovering Segments...");
DNSServiceRef client = NULL;
DNSServiceErrorType err;
err = DNSServiceBrowse(&client,
0,
0,
"_http._tcp",
"",
IterateServiceInstances,
NULL);
if (kDNSServiceErr_NoError != err)
printf("Error: Unable to enumerate Bonjour to find devices.\n");
int main(int argc, char ** argv)
{
DiscoverSegments();
}
Because your socket message loop must keep track of ALL of the socket handles (client service refs) and pump them all while open...

how can I read and unpack a protobuf c packed message in server side(using sockets)

I,m totally new in protobuf-c
I,m trying to create a socket connection and send protobuf packed message over the socket using c language
I packed the message within client code and send it to the server.But the server failed to receive the packed data and unpack it
my client code is
client.c
void *clientThread(void *arg)
{
Messages t_message = MESSAGES__INIT;
//while(1)
{
void *buf;
unsigned len;
int32_t s32_send_status;
t_message.name="anu";
len=messages__get_packed_size(&t_message);
buf=malloc(len);
messages__pack(&t_message,buf);
s32_send_status=send(gs32_clientSocket ,buf,len,0);
//s32_send_status=send(gs32_clientSocket ,(unsigned char *)
//(&t_message),sizeof(t_message) ,0);
if(s32_send_status>0){
printf("data send to server.\n");
}
else{
printf("failed to send data to server\n");
And my server code is
server.c
void *socketThread(void *arg)
{
Messages *t_message;
uint8_t buf[1024];
int32_t len;
// unsigned length;
//while(1)
{
gs32_valread = read( gs32_new_socket,buf,len);
if(gs32_valread==0){
printf("disconnected\n");
exit(1);
}
else if(gs32_valread<0){
printf("error\n");
exit(1);
}
else{
t_message = messages__unpack(NULL,len,buf);
printf("name=%s\n",t_message->name);
messages__free_unpacked(t_message,NULL);
}
sleep(1);
close(gs32_new_socket);
}
return NULL;
}
if my packing is correct how can I unpack it in the server side.
If anybody know this answer please help me to solve it.Thank you

GIO socket client server for multiple clients

I want to implement a GIO socket client server program where the server can serve up to say 5 clients at the same time. Is this even possible? How can I modify the following standard server to allow multiple clients to connect in a thread safe way? The incoming_callback() function will receive data from a client and do some processing and respond an acknowledgement and this will continue till the client sends an "exit" message at which point the server will close the client connection. I want to do this for a max of say 5 connections at a time for the server. Is it possible and if so how?
int
main (int argc, char **argv)
{
/* initialize glib */
g_type_init();
GError * error = NULL;
/* create the new socketservice */
GSocketService * service = g_socket_service_new ();
/* connect to the port */
g_socket_listener_add_inet_port ((GSocketListener*)service,
1500, /* your port goes here */
NULL,
&error);
/* don't forget to check for errors */
if (error != NULL)
{
g_error (error->message);
}
/* listen to the 'incoming' signal */
g_signal_connect (service,
"incoming",
G_CALLBACK (incoming_callback),
NULL);
/* start the socket service */
g_socket_service_start (service);
/* enter mainloop */
g_print ("Waiting for client!\n");
GMainLoop *loop = g_main_loop_new(NULL, FALSE);
g_main_loop_run(loop);
return 0;
}
The magic should happen within your incoming_callback, returning as fast as possible and pushing the work into another GThread (or even better, a GThreadPool)

ios - Determine if a certain address with a certain port is reachable

I want to know if my server is online via my ios application. Here's what I'm doing:
Boolean result;
CFHostRef hostRef = CFHostCreateWithName(kCFAllocatorDefault, (__bridge CFDataRef)(serverIPAddress)); //serverIPAdress = "10.10.10.100:5010"
if(hostRef) {
result = CFHostStartInfoResolution(hostRef, kCFHostAddresses, NULL); // pass an error instead of NULL here to find out why it failed
}
if (!result) { //This means that the host was unreachable
return ;
}
My server is online and I can access it later on in the code(meaning that my connection to the server works perfectly fine). However, I want to be able to detect if my server, on a certain port, is reachable.
Also, if I remove the ":5010" from the ip address, it detects that my server is online (it doesn't go in the "!result" condition) and detects that my server is offline if I put "10.10.10.253" which corresponds to no ip address on my network.
How can I manage to determine if my server is online or not ?
I've looked at this question : Reachability with Address - Server AND Port - iOS 5 but it doesn't work since it always return that it is reachable no matter what ip address I enter
Thanks in advance
One approach could be to open a socket connection to a specific port to see if you get any response back. If not, then the destination is unreachable. For example
#include <arpa/inet.h> //for PF_INET, SOCK_STREAM, IPPROTO_TCP etc
CFRunLoopSourceRef gSocketSource;
void ConnectCallBack(CFSocketRef socket, CFSocketCallBackType type, CFDataRef address, const void *data, void *info)
{
UInt8 buffer[1024];
bzero(buffer, sizeof(buffer));
CFSocketNativeHandle sock = CFSocketGetNative(socket); // The native socket, used recv()
//check here for correct connect output from server
recv(sock, buffer, sizeof(buffer), 0);
printf("Output: %s\n", buffer);
if (gSocketSource)
{
CFRunLoopRef currentRunLoop = CFRunLoopGetCurrent();
if (CFRunLoopContainsSource(currentRunLoop, gSocketSource, kCFRunLoopDefaultMode))
{
CFRunLoopRemoveSource(currentRunLoop, gSocketSource, kCFRunLoopDefaultMode);
}
CFRelease(gSocketSource);
}
if (socket) //close socket
{
if (CFSocketIsValid(socket))
{
CFSocketInvalidate(socket);
}
CFRelease(socket);
}
}
void ConnectSocket()
{
//socket
CFSocketContext context = {0, NULL, NULL, NULL, NULL};
CFSocketRef theSocket = CFSocketCreate(kCFAllocatorDefault, PF_INET, SOCK_STREAM, IPPROTO_TCP, kCFSocketConnectCallBack , (CFSocketCallBack)ConnectCallBack, &context);
//address
struct sockaddr_in socketAddress;
memset(&socketAddress, 0, sizeof(socketAddress));
socketAddress.sin_len = sizeof(socketAddress);
socketAddress.sin_family = AF_INET;
socketAddress.sin_port = htons(5010);
socketAddress.sin_addr.s_addr = inet_addr("10.10.10.253");
gSocketSource = CFSocketCreateRunLoopSource(kCFAllocatorDefault, theSocket, 0);
CFRunLoopAddSource(CFRunLoopGetCurrent(), gSocketSource, kCFRunLoopDefaultMode);
CFDataRef socketData = CFDataCreate(kCFAllocatorDefault, (const UInt8 *)&socketAddress, sizeof(socketAddress));
CFSocketError status = CFSocketConnectToAddress(theSocket, socketData, 30); //30 second timeout
//check status here
CFRelease(socketData);
}
Basically, if the server is unreachable at that port, you will most likely get a kCFSocketTimeout for CFSocketError status. If you are looking to parse a specific response back from the server to determine if the server is ready or not, the ConnectCallBack function will be called upon successful socket connection.
This is just a simple example, make sure not to block the UI by calling socket connections on the main thread such as recv()

GIO example for opening a server port?

Can you please tell me if there is any example for using GIO Server Socket
(the one which I can open a port and listen on socket requests)?
I would like to use it to 'remote-control' my GTK+ application.
I think you should do something like this:
#define MY_PORT 47110
/* Listener callback, this gets called by GTK+ when
* there's socket activity to handle.
*/
static gboolean cb_listener(GIOChannel *source, GIOCondition condition, gpointer data
{
switch(condition)
{
case G_IO_IN:
/* There's data to be read. */
break;
default:
/* An error has occured, or socket is closed. */
return FALSE; /* This tells GIO to remove the source, might be drastic. */
}
return TRUE; /* This tells GIO that all is fine. */
}
Then elsewhere (in a function, maybe main()):
GSocketListener *listener;
listener = g_socket_listener_new();
g_socket_listener_add_inet_port(listener, MY_PORT, NULL, NULL);
g_io_add_watch(G_IO_CHANNEL(listener), G_IO_IN | G_IO_ERR | G_IO_HUP, cb_listener, NULL);