/*
 * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file send_common.c Functions used by more than one paraslash sender. */

#include <dirent.h>
#include "para.h"
#include "error.h"
#include "string.h"
#include "fd.h"
#include "net.h"
#include "list.h"
#include "afh.h"
#include "afs.h"
#include "server.h"
#include "acl.h"
#include "send.h"
#include "close_on_fork.h"
#include "chunk_queue.h"
#include "vss.h"

/** Clients will be kicked if there are more than that many bytes pending. */
#define MAX_CQ_BYTES 40000

/**
 * Open a passive socket of given layer4 type.
 *
 * Set the resulting file descriptor to nonblocking mode and add it to the list
 * of fds that are being closed in the child process when the server calls
 * fork().
 *
 * \param l4type The transport-layer protocol.
 * \param port The port number.
 *
 * \return The listening fd on success, negative on errors.
 */
static int open_sender(unsigned l4type, int port)
{
	int fd, ret = para_listen(AF_UNSPEC, l4type, port);

	if (ret < 0)
		return ret;
	fd = ret;
	ret = mark_fd_nonblocking(fd);
	if (ret < 0) {
		close(fd);
		return ret;
	}
	add_close_on_fork_list(fd);
	return fd;
}

/**
 * Shut down a client connected to a paraslash sender.
 *
 * \param sc The client to shut down.
 * \param ss The sender whose clients are to be shut down.
 *
 * Close the file descriptor given by \a sc, remove it from the close-on-fork
 * list, destroy the chunk queue of this client, delete the client from the
 * list of connected clients and free the sender_client struct.
 *
 * \sa shutdown_clients().
 */
void shutdown_client(struct sender_client *sc, struct sender_status *ss)
{
	PARA_INFO_LOG("shutting down %s on fd %d\n", sc->name, sc->fd);
	free(sc->name);
	close(sc->fd);
	del_close_on_fork_list(sc->fd);
	cq_destroy(sc->cq);
	list_del(&sc->node);
	free(sc->private_data);
	free(sc);
	ss->num_clients--;
}

/**
 * Shut down all clients connected to a paraslash sender.
 *
 * \param ss The sender whose clients are to be shut down.
 *
 * This just loops over all connected clients and calls shutdown_client()
 * for each client.
 */
void shutdown_clients(struct sender_status *ss)
{
	struct sender_client *sc, *tmp;
	list_for_each_entry_safe(sc, tmp, &ss->client_list, node)
		shutdown_client(sc, ss);
}

static int queue_chunk_or_shutdown(struct sender_client *sc,
		struct sender_status *ss, const char *buf, size_t num_bytes)
{
	int ret = cq_enqueue(sc->cq, buf, num_bytes);
	if (ret < 0)
		shutdown_client(sc, ss);
	return ret;
}

/**
 * Try to empty the chunk queue for this fd.
 *
 * \param fd The file descriptor.
 * \param cq The list of queued chunks.
 * \param max_bytes_per_write Do not send more than this in one go.
 *
 * \return Negative on errors, zero if not everything was sent, one otherwise.
 */
int send_queued_chunks(int fd, struct chunk_queue *cq,
		size_t max_bytes_per_write)
{
	struct queued_chunk *qc;
	while ((qc = cq_peek(cq))) {
		const char *buf;
		size_t len;
		int ret;
		cq_get(qc, &buf, &len);
		ret = write_nonblock(fd, buf, len, max_bytes_per_write);
		if (ret < 0)
			return ret;
		cq_update(cq, ret);
		if (ret != len)
			return 0;
		cq_dequeue(cq);
	}
	return 1;
}

/**
 * Send one chunk of audio data to a connected client.
 *
 * \param sc The client.
 * \param ss The sender.
 * \param max_bytes_per_write Split writes to chunks of at most that many bytes.
 * \param current_chunk The number of the chunk to write.
 * \param buf The data to write.
 * \param len The number of bytes of \a buf.
 * \param header_buf The audio file header.
 * \param header_len The number of bytes of \a header_buf.
 *
 * On errors, the client is shut down. If only a part of the buffer could be
 * written, the remainder is put into the chunk queue for that client.
 */
void send_chunk(struct sender_client *sc, struct sender_status *ss,
		size_t max_bytes_per_write, long unsigned current_chunk,
		const char *buf, size_t len, const char *header_buf,
		size_t header_len)
{
	int ret;

	if (!sc->header_sent && current_chunk) {
		if (header_buf && header_len > 0) {
			ret = queue_chunk_or_shutdown(sc, ss, header_buf, header_len);
			if (ret < 0)
				goto out;
		}
	}
	sc->header_sent = 1;
	ret = send_queued_chunks(sc->fd, sc->cq, max_bytes_per_write);
	if (ret < 0) {
		shutdown_client(sc, ss);
		goto out;
	}
	if (!len)
		goto out;
	if (!ret) { /* still data left in the queue */
		ret = queue_chunk_or_shutdown(sc, ss, buf, len);
		goto out;
	}
	ret = write_nonblock(sc->fd, buf, len, max_bytes_per_write);
	if (ret < 0) {
		shutdown_client(sc, ss);
		goto out;
	}
	if (ret != len)
		ret = queue_chunk_or_shutdown(sc, ss, buf + ret, len - ret);
out:
	if (ret < 0)
		PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
}

/**
 * Initialize a struct sender status.
 *
 * \param ss The struct to initialize.
 * \param access_arg The array of access arguments given at the command line.
 * \param num_access_args The number of elements in \a access_arg.
 * \param port The tcp or dccp port to listen on.
 * \param max_clients The maximal number of simultaneous connections.
 * \param default_deny Whether a blacklist should be used for access control.
 */
void init_sender_status(struct sender_status *ss, char **access_arg,
	int num_access_args, int port, int max_clients, int default_deny)
{
	ss->listen_fd = -1;
	INIT_LIST_HEAD(&ss->client_list);
	ss->port = port;
	acl_init(&ss->acl, access_arg, num_access_args);
	ss->num_clients = 0;
	ss->max_clients = max_clients;
	ss->default_deny = default_deny;
}

/**
 * Return a string containing the current status of a sender.
 *
 * \param ss The sender.
 * \param name Used for printing the header line.
 *
 * \return The string printed in the "si" command.
 */
char *get_sender_info(struct sender_status *ss, char *name)
{
	char *clnts = NULL, *ret;
	struct sender_client *sc, *tmp_sc;

	char *acl_contents = acl_get_contents(&ss->acl);
	list_for_each_entry_safe(sc, tmp_sc, &ss->client_list, node) {
		char *tmp = make_message("%s%s ", clnts? clnts : "", sc->name);
		free(clnts);
		clnts = tmp;
	}
	ret = make_message(
		"%s sender:\n"
		"\tstatus: %s\n"
		"\tport: %d\n"
		"\tnumber of connected clients: %d\n"
		"\tmaximal number of clients: %d%s\n"
		"\tconnected clients: %s\n"
		"\taccess %s list: %s\n",
		name,
		(ss->listen_fd >= 0)? "on" : "off",
		ss->port,
		ss->num_clients,
		ss->max_clients,
		ss->max_clients > 0? "" : " (unlimited)",
		clnts? clnts : "(none)",
		ss->default_deny? "allow" : "deny",
		acl_contents? acl_contents : "(empty)"
	);
	free(acl_contents);
	free(clnts);
	return ret;
}

/**
 * Allow connections from the given range of IP addresses.
 *
 * \param scd Contains the IP and the netmask.
 * \param ss The sender.
 *
 * \sa generic_com_deny().
 */
void generic_com_allow(struct sender_command_data *scd,
		struct sender_status *ss)
{
	acl_allow(scd->host, scd->netmask, &ss->acl, ss->default_deny);
}

/**
 * Deny connections from the given range of IP addresses.
 *
 * \param scd see \ref generic_com_allow().
 * \param ss see \ref generic_com_allow().
 *
 * \sa generic_com_allow().
 */
void generic_com_deny(struct sender_command_data *scd,
		struct sender_status *ss)
{
	acl_deny(scd->host, scd->netmask, &ss->acl, ss->default_deny);
}

/**
 * Activate a paraslash sender.
 *
 * \param ss The sender to activate.
 * \param protocol The symbolic name of the transport-layer protocol.
 *
 * \return Standard.
 */
int generic_com_on(struct sender_status *ss, unsigned protocol)
{
	int ret;

	if (ss->listen_fd >= 0)
		return 1;
	ret = open_sender(protocol, ss->port);
	if (ret < 0)
		return ret;
	ss->listen_fd = ret;
	return 1;
}

/**
 * Deactivate a paraslash sender.
 *
 * Shutdown all connected clients and stop listening on the TCP/DCCP socket.
 *
 * \param ss The sender to deactivate.
 *
 * \sa \ref del_close_on_fork_list(), shutdown_clients().
 */
void generic_com_off(struct sender_status *ss)
{
	if (ss->listen_fd < 0)
		return;
	PARA_NOTICE_LOG("closing port %d\n", ss->port);
	close(ss->listen_fd);
	del_close_on_fork_list(ss->listen_fd);
	shutdown_clients(ss);
	ss->listen_fd = -1;
}

/**
 * Accept a connection on the socket this server is listening on.
 *
 * \param ss The sender whose listening fd is ready for reading.
 *
 * This must be called only if the socket fd of \a ss is ready for reading.  It
 * calls para_accept() to accept the connection and performs the following
 * actions on the resulting file descriptor \a fd:
 *
 *	- Checks whether the maximal number of connections are exceeded.
 *	- Sets \a fd to nonblocking mode.
 *	- Checks the acl of the sender to find out whether connections
 *	  are allowed from the IP of the connecting peer.
 * 	- Increases the number of connections for this sender.
 *	- Creates and initializes a new chunk queue for queuing network
 *	  packets that can not be sent immediately.
 *	- Allocates a new struct sender_client and fills in its \a fd, \a cq
 *	  and \a name members.
 *	- Adds \a fd to the list of connected clients for this sender.
 *	- Adds \a fd to the list of file descriptors that should be closed
 *	  in the child process when the server calls fork().
 *
 * \return A pointer to the allocated sender_client structure on success, \p
 * NULL on errors.
 *
 * \sa \ref para_accept(), \ref mark_fd_nonblocking(), \ref acl_check_access(),
 * \ref cq_new(), \ref add_close_on_fork_list().
 */
struct sender_client *accept_sender_client(struct sender_status *ss)
{
	struct sender_client *sc;
	int fd, ret = para_accept(ss->listen_fd, NULL, 0);
	if (ret < 0) {
		PARA_ERROR_LOG("%s\n", para_strerror(-ret));
		return NULL;
	}
	fd = ret;
	ret = -E_MAX_CLIENTS;
	if (ss->max_clients > 0 && ss->num_clients >= ss->max_clients)
		goto err_out;
	ret = mark_fd_nonblocking(fd);
	if (ret < 0)
		goto err_out;
	ret = acl_check_access(fd, &ss->acl, ss->default_deny);
	if (ret < 0)
		goto err_out;
	ss->num_clients++;
	sc = para_calloc(sizeof(*sc));
	sc->fd = fd;
	sc->name = make_message("%s", remote_name(fd));
	sc->cq = cq_new(MAX_CQ_BYTES);
	para_list_add(&sc->node, &ss->client_list);
	add_close_on_fork_list(fd);
	PARA_INFO_LOG("accepted client #%d: %s (fd %d)\n", ss->num_clients,
		sc->name, fd);
	return sc;
err_out:
	PARA_WARNING_LOG("%s\n", para_strerror(-ret));
	close(fd);
	return NULL;
}

/**
 * Get the generic help text.
 *
 * \return A dynamically allocated string containing the help text for
 * a paraslash sender.
 */
char *generic_sender_help(void)
{
	return make_message(
		"usage: {on|off}\n"
		"usage: {allow|deny} IP[/netmask]\n"
		"       where mask defaults to 32\n"
		"example: allow 192.168.0.1/24\n"
	);
}

static int parse_fec_parms(const char *arg, struct sender_command_data *scd)
{
	int32_t val;
	char *a = para_strdup(arg), *b = a, *e = strchr(b, ':');
	int ret = -E_COMMAND_SYNTAX;

	/* parse max slice bytes */
	if (!e)
		goto out;
	*e = '\0';
	ret = para_atoi32(b, &val);
	if (ret < 0)
		goto out;
	ret = -ERRNO_TO_PARA_ERROR(EINVAL);
	if (val < 0 || val > 65535)
		goto out;
	scd->max_slice_bytes = val;
	/* parse data_slices_per_group */
	b = e + 1;
	e = strchr(b, ':');
	ret = -E_COMMAND_SYNTAX;
	if (!e)
		goto out;
	*e = '\0';
	ret = para_atoi32(b, &val);
	if (ret < 0)
		goto out;
	ret = -ERRNO_TO_PARA_ERROR(EINVAL);
	if (val < 0 || val > 255)
		goto out;
	scd->data_slices_per_group = val;
	/* parse slices_per_group */
	b = e + 1;
	ret = para_atoi32(b, &val);
	if (ret < 0)
		goto out;
	ret = -ERRNO_TO_PARA_ERROR(EINVAL);
	if (val < 0 || val < scd->data_slices_per_group)
		goto out;
	scd->slices_per_group = val;
	ret = 0;
out:
	free(a);
	return ret;
}

/**
 * Parse a FEC URL string.
 *
 * \param arg the URL string to parse.
 * \param scd The structure containing host, port and the FEC parameters.
 *
 * \return Standard.
 *
 * A FEC URL consists of an ordinary URL string according to RFC 3986,
 * optionally followed by a slash and the three FEC parameters slice_size,
 * data_slices_per_group and slices_per_group. The three FEC parameters are
 * separated by colons.
 *
 * \sa \ref parse_url().
 */
int parse_fec_url(const char *arg, struct sender_command_data *scd)
{
	int ret;
	ssize_t len = sizeof(scd->host);
	char *a = para_strdup(arg), *p = strchr(a, '/');

	if (p) {
		*p = '\0';
		len = strlen(a);
	}
	ret = -ERRNO_TO_PARA_ERROR(EINVAL);
	if (!parse_url(a, scd->host, len, &scd->port))
		goto out;
	if (p) {
		ret = parse_fec_parms(p + 1, scd);
		goto out;
	}
	/* use default fec parameters. */
	scd->max_slice_bytes = 1490;
	scd->slices_per_group = 16;
	scd->data_slices_per_group = 14;
	ret = 0;
out:
	free(a);
	return ret;
}