Ecore_Con - Creating a client

- Main Page
- Related Pages
- Topics
- Data Structures
- Files
- Examples

Ecore_Con - Creating a client

Following the same idea as the Ecore_Con - Creating a server , this example will demonstrate how to create a client that connects to a specified server through a TCP port. You can see the full source code at ecore_con_client_simple_example.c.

Starting from the `main` function, after reading the command line argument list and initializing the libraries, we try to connect to the server:

main(int argc, const char *argv[])
{
Ecore_Con_Server *svr;
const char *address;
int port = 8080;
if (argc < 2)
{
printf("wrong usage. Command syntax is:\n");
printf("\tecore_con_client_simple_example <address> [port]\n");
exit(1);
}
address = argv[1];
if (argc > 2)
port = atoi(argv[2]);
eina_init();
ecore_init();
ecore_con_init();
if (!(svr = ecore_con_server_connect(ECORE_CON_REMOTE_TCP, address, port, NULL)))
{
printf("could not connect to the server: %s, port %d.\n",
address, port);
exit(2);
ecore_con_init
ECORE_CON_API int ecore_con_init(void)
Initializes the Ecore_Con library.
Definition ecore_con.c:68
ecore_con_server_connect
ECORE_CON_API Ecore_Con_Server * ecore_con_server_connect(Ecore_Con_Type type, const char *name, int port, const void *data)
Creates a connection to the specified server and return an associated object.
Definition ecore_con_legacy.c:2165
ecore_init
EAPI int ecore_init(void)
Sets up connections, signal handlers, sockets etc.
Definition ecore.c:230
eina_init
EINA_API int eina_init(void)
Initializes the Eina library.
Definition eina_main.c:291
}

After doing this, everything else in `main` is setting up callbacks for the client events, starting the main loop and shutting down the libraries after it.

Now let's go to the callbacks. These callbacks are very similar to the server callbacks (our implementation for this example is very simple). On the `_add` callback, we just set a data structure to the server, print some information about the server, and send a welcome message to it:

Eina_Bool
_add(void *data EINA_UNUSED, int type EINA_UNUSED, Ecore_Con_Event_Server_Add *ev)
{
char welcome[] = "hello! - sent from the client";
struct _Server *server = malloc(sizeof(*server));
server->sdata = 0;
ecore_con_server_data_set(ev->server, server);
printf("Server with ip %s, name %s, port %d, connected = %d!\n",
ecore_con_server_ip_get(ev->server),
ecore_con_server_name_get(ev->server),
ecore_con_server_port_get(ev->server),
ecore_con_server_connected_get(ev->server));
ecore_con_server_send(ev->server, welcome, sizeof(welcome));
ecore_con_server_flush(ev->server);
return ECORE_CALLBACK_RENEW;
ecore_con_server_port_get
ECORE_CON_API int ecore_con_server_port_get(const Ecore_Con_Server *svr)
Retrieves the server port in use.
Definition ecore_con_legacy.c:2347
ecore_con_server_data_set
ECORE_CON_API void * ecore_con_server_data_set(Ecore_Con_Server *svr, void *data)
Sets the data associated with the given server.
Definition ecore_con_legacy.c:2322
ecore_con_server_ip_get
ECORE_CON_API const char * ecore_con_server_ip_get(const Ecore_Con_Server *svr)
Gets the IP address of a server that has been connected to.
Definition ecore_con_legacy.c:2398
ecore_con_server_name_get
ECORE_CON_API const char * ecore_con_server_name_get(const Ecore_Con_Server *svr)
Retrieves the name of server.
Definition ecore_con_legacy.c:2260
ecore_con_server_connected_get
ECORE_CON_API Eina_Bool ecore_con_server_connected_get(const Ecore_Con_Server *svr)
Retrieves whether the given server is currently connected.
Definition ecore_con_legacy.c:2334
ecore_con_server_flush
ECORE_CON_API void ecore_con_server_flush(Ecore_Con_Server *svr)
Flushes all pending data to the given server.
Definition ecore_con_legacy.c:2412
ecore_con_server_send
ECORE_CON_API int ecore_con_server_send(Ecore_Con_Server *svr, const void *data, int size)
Sends the given data to the given server.
Definition ecore_con_legacy.c:2354
ECORE_CALLBACK_RENEW
#define ECORE_CALLBACK_RENEW
Return value to keep a callback.
Definition Ecore_Common.h:153
Eina_Bool
unsigned char Eina_Bool
Type to mimic a boolean.
Definition eina_types.h:527
EINA_UNUSED
#define EINA_UNUSED
Used to indicate that a function parameter is purposely unused.
Definition eina_types.h:339
_Ecore_Con_Event_Server_Add
Used as the data param for the ECORE_CON_EVENT_SERVER_ADD event.
Definition Ecore_Con.h:480
_Ecore_Con_Event_Server_Add::server
Ecore_Con_Server * server
the server that was connected to
Definition Ecore_Con.h:481
}

The `_del` callback is as simple as the previous one. We free the data associated with the server, print the uptime of this client, and quit the main loop (since there's nothing to do once we disconnect):

Eina_Bool
_del(void *data EINA_UNUSED, int type EINA_UNUSED, Ecore_Con_Event_Server_Del *ev)
{
if (!ev->server)
{
printf("Failed to establish connection to the server.\nExiting.\n");
ecore_main_loop_quit();
return ECORE_CALLBACK_RENEW;
ecore_main_loop_quit
void ecore_main_loop_quit(void)
Quits the main loop once all the events currently on the queue have been processed.
Definition ecore_main.c:1326
_Ecore_Con_Event_Server_Del
Used as the data param for the ECORE_CON_EVENT_SERVER_DEL event.
Definition Ecore_Con.h:499
_Ecore_Con_Event_Server_Del::server
Ecore_Con_Server * server
the client that was lost
Definition Ecore_Con.h:500
}

The `_data` callback is also similar to the server data callback. it will print any received data, and increase the data counter in the structure associated with this server:

Eina_Bool
_data(void *data EINA_UNUSED, int type EINA_UNUSED, Ecore_Con_Event_Server_Data *ev)
{
char fmt[128];
struct _Server *server = ecore_con_server_data_get(ev->server);
snprintf(fmt, sizeof(fmt),
"Received %i bytes from server:\n"
">>>>>\n"
"%%.%is\n"
">>>>>\n",
ev->size, ev->size);
printf(fmt, ev->data);
server->sdata += ev->size;
return ECORE_CALLBACK_RENEW;
ecore_con_server_data_get
ECORE_CON_API void * ecore_con_server_data_get(Ecore_Con_Server *svr)
Retrieves the data associated with the given server.
Definition ecore_con_legacy.c:2315
_Ecore_Con_Event_Server_Data
Used as the data param for the ECORE_CON_EVENT_SERVER_DATA event.
Definition Ecore_Con.h:529
_Ecore_Con_Event_Server_Data::size
int size
the length of the data sent
Definition Ecore_Con.h:532
_Ecore_Con_Event_Server_Data::server
Ecore_Con_Server * server
the server that was connected to
Definition Ecore_Con.h:530
_Ecore_Con_Event_Server_Data::data
void * data
the data that the server sent
Definition Ecore_Con.h:531
}

You can see the server counterpart functions of the ones used in this example in the Ecore_Con - Creating a server.

This example will connect to the server and start comunicating with it, as demonstrated in the following diagram:

Note
  This example contains a serious security flaw: it doesn't check for the size of data being received, thus allowing to the string to be exploited in some way. However, it is left like this to make the code simpler and just demonstrate the API usage.