Soup Server Basics

Soup Server Basics — Server-side tutorial

Creating a SoupSession

As with the client API, there is a single object that will encapsulate most of your interactions with libsoup. In this case, SoupServer.

Warning

Note that SoupServer isn't as polished as SoupSession, and thus not as stable, and the APIs will likely change in incompatible (but not difficult-to-port-to) ways in the future to make things nicer. We apologize in advance for the inconvenience.

You create the server with soup_server_new, and as with the SoupSession constructor, you can specify various additional options:

SOUP_SERVER_PORT

The TCP port to listen on. If 0 (or left unspecified), some unused port will be selected for you. (You can find out what port by calling soup_server_get_port.

SOUP_SERVER_INTERFACE

A SoupAddress, specifying the IP address of the network interface to run the server on. If NULL (or left unspecified), the server will listen on all interfaces.

SOUP_SERVER_SSL_CERT_FILE

Points to a file containing an SSL certificate to use. If this is set, then the server will speak HTTPS; otherwise it will speak HTTP.

SOUP_SERVER_SSL_KEY_FILE

Points to a file containing the private key for the SOUP_SERVER_SSL_CERT_FILE. (It may point to the same file.)

SOUP_SERVER_ASYNC_CONTEXT

A GMainContext which the server will use for asynchronous operations. This can be set if you want to use a SoupServer in a thread other than the main thread.


Adding Handlers

By default, SoupServer returns "404 Not Found" in response to all requests (except ones that it can't parse, which get "400 Bad Request"). To override this behavior, call soup_server_add_handler to set a callback to handle certain URI paths.

soup_server_add_handler (server, "/foo", NULL, server_callback,
			 unregister_callback, data);

The "/foo" indicates the base path for this handler. When a request comes in, if there is a handler registered for exactly the path in the request's Request-URI, then that handler will be called. Otherwise libsoup will strip path components one by one until it finds a matching handler. So for example, a request of the form "GET /foo/bar/baz.html?a=1&b=2 HTTP/1.1" would look for handlers for "/foo/bar/baz.html", "/foo/bar", and "/foo". If a handler has been registered with a NULL base path, then it is used as the default handler for any request that doesn't match any other handler.


Responding to Requests

A handler callback looks something like this:

static void
server_callback (SoupServerContext *context, SoupMessage *msg, gpointer data)
{
	...
}

msg is the request that has been received. data is the same data that was passed to soup_server_add_handler. The context argument contains some additional information related to the request.

By default, libsoup assumes that you have completely finished processing the message when you return from the callback, and that it can therefore begin sending the response. If you are not ready to send a response immediately (eg, you have to contact another server, or wait for data from a database), you must call soup_message_io_pause on the message before returning from the callback. This will delay sending a response until you call soup_message_io_unpause. (You must also connect to the finished signal on the message in this case, so that you can break off processing if the client unexpectedly disconnects before you start sending the data.)

To set the response status, call soup_message_set_status or soup_message_set_status_full. If the response requires a body, the callback must call soup_server_message_set_encoding to indicate whether it will provide the response all at once with Content-Length encoding, or in pieces with chunked encoding.

Responding with Content-Length Encoding

This is the simpler way to set a response body, if you have all of the data available at once.

static void
server_callback (SoupServerContext *context, SoupMessage *msg, gpointer data)
{
	MyServerData *server_data = data;
	SoupUri *uri = soup_message_get_uri (msg);
	const char *mime_type;
	GByteArray *body;

	if (context->method_id != SOUP_METHOD_ID_GET) {
		soup_message_set_status (msg, SOUP_STATUS_NOT_IMPLEMENTED);
		return;
	}

	body = g_hash_table_lookup (server_data->bodies, uri->path);
	mime_type = g_hash_table_lookup (server_data->mime_types, uri->path);
	if (!body || !mime_type) {
		soup_message_set_status (msg, SOUP_STATUS_NOT_FOUND);
		return;
	}

	soup_message_set_status (msg, SOUP_STATUS_OK);
	soup_server_message_set_encoding (SOUP_SERVER_MESSAGE (msg),
					  SOUP_TRANSFER_CONTENT_LENGTH);
	soup_message_set_response (msg, mime_type, SOUP_BUFFER_USER_OWNED,
				   body->data, body->len);
}

Responding with chunked Encoding

If you want to supply the response body in chunks as it becomes available, use chunked encoding instead. In this case, call soup_message_add_chunk with each chunk of the response body as it becomes available, and call soup_message_add_final_chunk when the response is complete. After each of these calls, you must also call soup_message_io_unpause to cause the chunk to be sent. (You do not normally need to call soup_message_io_pause, because I/O is automatically paused when doing a chunked transfer if no chunks are available.)

When using chunked encoding, you must also connect to the finished signal on the message, so that you will be notified if the client disconnects between two chunks; SoupServer will unref the message if that happens, so you must stop adding new chunks to the response at that point.

The simple-proxy example in the tests/ directory gives an example of using chunked encoding.


Handling Authentication

To have SoupServer handle HTTP authentication for you, pass a SoupAuthContext to soup_server_add_handler:

SoupServerAuthContext auth_ctx;

auth_ctx.types            = SOUP_AUTH_TYPE_BASIC;
auth_ctx.callback         = auth_callback;
auth_ctx.user_data        = data;
auth_ctx.basic_info.realm = "My Realm";

soup_server_add_handler (server, "/bar", &auth_ctx, server_callback,
			 unregister_callback, data);

Then, every request that matches that handler will be passed to the auth_callback first before being passed to the server_callback:

static gboolean
auth_callback (SoupServerAuthContext *auth_ctx, SoupServerAuth *auth,
	       SoupMessage *msg, gpointer user_data)
{
	MyServerData *server_data = user_data;
	const char *username, *password;

	if (!auth)
		return FALSE;

	username = soup_server_auth_get_user (auth);
	password = g_hash_table_lookup (server_data->passwords, username);
	if (!password)
		return FALSE;

	return soup_server_auth_check_passwd (auth, password);
}

The auth parameter indicates the authentication information passed by the client. If no WWW-Authenticate header was present, this will be NULL, so we return FALSE from the callback to indicate that the server should return a 401 Unauthorized response. If it is non-NULL, we extract the username from it, and compare it against our stored password. Assuming it matches, we return TRUE, and the server callback is then invoked normally.