/*
 * Copyright (C) 2005-2007 Andre Noll <maan@systemlinux.org>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file http_send.c paraslash's http sender */


#include "server.cmdline.h"
#include "server.h"
#include "http.h"
#include "vss.h"
#include "send.h"
#include "list.h"
#include "close_on_fork.h"
#include "error.h"
#include "net.h"
#include "string.h"
#include "fd.h"
#include "chunk_queue.h"

/** \cond convert sock_addr_in to ascii */
#define CLIENT_ADDR(hc) inet_ntoa((hc)->addr.sin_addr)
/* get the port number of a struct http_client */
#define CLIENT_PORT(hc) (hc)->addr.sin_port
#define HTTP_ERR_MSG "HTTP/1.0 400 Bad Request\n"
/** \endcond */

/** The possible states of a client from the server's POV. */
enum http_status {
	/** We accepted the connection on the tcp socket. */
	HTTP_CONNECTED,
	/** Successfully received the get request. */
	HTTP_GOT_GET_REQUEST,
	/** We sent the OK message back to the client. */
	HTTP_SENT_OK_MSG,
	/** Connection established, we might need to send the audio file header. */
	HTTP_READY_TO_STREAM,
	/** Connection is ready for sending audio data. */
	HTTP_STREAMING,
	/** We didn't receive a valid get request. */
	HTTP_INVALID_GET_REQUEST
};

/** Clients will be kicked if there are more than that many bytes pending. */
#define MAX_BACKLOG 400000
/** The list of connected clients. */
static struct list_head clients;
/** The whitelist/blacklist. */
static struct list_head access_perm_list;

/** Describes one client that connected the tcp port of the http sender. */
struct http_client {
	/** The file descriptor of the client. */
	int fd;
	/** Address information about the client. */
	struct sockaddr_in addr;
	/** The client's current status. */
	enum http_status status;
	/** Non-zero if we included \a fd in the read set.*/
	int check_r;
	/** Non-zero if we included \a fd in the write set. */
	int check_w;
	/** The position of this client in the client list. */
	struct list_head node;
	/** The list of pending chunks for this client. */
	struct chunk_queue *cq;
};

/**
 * Describes one entry in the blacklist/whitelist of the http sender.
 */
struct access_info {
	/** The address to be black/whitelisted. */
	struct in_addr addr;
	/** The netmask for this entry. */
	unsigned netmask;
	/** The position of this entry in the access_perm_list. */
	struct list_head node;
};

static int server_fd = -1, numclients;
static struct sender *self;


static void http_shutdown_client(struct http_client *hc, const char *msg)
{
	PARA_INFO_LOG("shutting down %s on fd %d (%s)\n", CLIENT_ADDR(hc),
		hc->fd, msg);
	numclients--;
	close(hc->fd);
	del_close_on_fork_list(hc->fd);
	cq_destroy(hc->cq);
	list_del(&hc->node);
	free(hc);
}

static void http_shutdown_clients(void)
{
	struct http_client *hc, *tmp;
	list_for_each_entry_safe(hc, tmp, &clients, node)
		http_shutdown_client(hc, "vss request");
}

static int http_send_msg(struct http_client *hc, const char *msg)
{
	int ret = send_buffer(hc->fd, msg);

	if (ret < 0)
		http_shutdown_client(hc, "send msg failed");
	return ret;
}

static void http_send_ok_msg(struct http_client *hc)
{
	PARA_INFO_LOG("sending http ok message to fd %d\n", hc->fd);
	http_send_msg(hc, HTTP_OK_MSG);
}

static int http_send_err_msg(struct http_client *hc)
{
	PARA_NOTICE_LOG("sending bad request message to fd %d\n", hc->fd);
	return http_send_msg(hc, HTTP_ERR_MSG);
}

static int send_queued_chunks(struct http_client *hc)
{
	struct queued_chunk *qc;
	while ((qc = cq_peek(hc->cq))) {
		char *buf;
		size_t len;
		int ret = write_ok(hc->fd);
		if (ret <= 0)
			return ret? -E_WRITE_OK : 0;
		cq_get(qc, &buf, &len);
		ret = write(hc->fd, buf, len);
		if (ret < 0)
			return -E_SEND_QUEUED_CHUNK;
		cq_update(hc->cq, ret);
		if (ret != len)
			return 1;
		cq_dequeue(hc->cq);
	}
	return 1;
}

static int queue_chunk_or_shutdown(struct http_client *hc, long unsigned chunk_num,
	size_t sent)
{
	int ret = cq_enqueue(hc->cq, chunk_num, sent);
	if (ret < 0)
		http_shutdown_client(hc, "queue error");
	return ret;
}

static void http_send( long unsigned current_chunk,
	__a_unused long unsigned chunks_sent, const char *buf, size_t len)
{
	struct http_client *hc, *tmp;
	int ret;

	list_for_each_entry_safe(hc, tmp, &clients, node) {
		if (hc->status != HTTP_STREAMING &&
				hc->status != HTTP_READY_TO_STREAM)
			continue;
		if (hc->status == HTTP_READY_TO_STREAM) {
			size_t hlen;
			char *hbuf = vss_get_header(&hlen);
			if (hbuf && hlen > 0 && current_chunk) {
				/* need to send header */
				PARA_INFO_LOG("queueing header: %zu\n", hlen);
				if (queue_chunk_or_shutdown(hc, -1U, 0) < 0)
					continue;
			} else
				PARA_INFO_LOG("no need to queue header\n");
			hc->status = HTTP_STREAMING;
		}
		ret = send_queued_chunks(hc);
		if (ret < 0) {
			http_shutdown_client(hc, "queue send error");
			continue;
		}
		if (!len)
			continue;
		if (!ret || write_ok(hc->fd) <= 0) {
			queue_chunk_or_shutdown(hc, current_chunk, 0);
			continue;
		}
//		PARA_DEBUG_LOG("sending %d -> %s\n", len, CLIENT_ADDR(hc));
		ret = write(hc->fd, buf, len);
//		PARA_DEBUG_LOG("ret: %d\n", ret);
		if (ret < 0) {
			http_shutdown_client(hc, "send error");
			continue;
		}
		if (ret != len)
			queue_chunk_or_shutdown(hc, current_chunk, ret);
	}
}

static int host_in_access_perm_list(struct http_client *hc)
{
	struct access_info *ai, *tmp;
	list_for_each_entry_safe(ai, tmp, &access_perm_list, node) {
		unsigned mask = ((~0U) >> ai->netmask);
		if ((hc->addr.sin_addr.s_addr & mask) == (ai->addr.s_addr & mask))
			return 1;
	}
	return 0;
}

static void http_post_select(fd_set *rfds, fd_set *wfds)
{
	int i = -1, match;
	struct http_client *hc, *tmp;
	const char *err_msg;

	list_for_each_entry_safe(hc, tmp, &clients, node) {
		i++;
//		PARA_DEBUG_LOG("handling client %d: %s\n", i, CLIENT_ADDR(hc));
		switch (hc->status) {
		case HTTP_STREAMING: /* nothing to do */
		case HTTP_READY_TO_STREAM:
			break;
		case HTTP_CONNECTED: /* need to recv get request */
			if (hc->check_r && FD_ISSET(hc->fd, rfds)) {
				if (recv_pattern(hc->fd, HTTP_GET_MSG, MAXLINE)
						< 0) {
					hc->status = HTTP_INVALID_GET_REQUEST;
				} else {
					hc->status = HTTP_GOT_GET_REQUEST;
					PARA_INFO_LOG("%s",
						"received get request\n");
				}
			}
			break;
		case HTTP_GOT_GET_REQUEST: /* need to send ok msg */
			if (hc->check_w && FD_ISSET(hc->fd, wfds)) {
				hc->status = HTTP_SENT_OK_MSG;
				http_send_ok_msg(hc);
			}
			break;
		case HTTP_INVALID_GET_REQUEST: /* need to send err msg */
			if (hc->check_w && FD_ISSET(hc->fd, wfds)) {
				if (http_send_err_msg(hc) >= 0)
					http_shutdown_client(hc,
						"invalid get request");
			}
			break;
		case HTTP_SENT_OK_MSG: /* need to send header? */
			if (hc->check_w && FD_ISSET(hc->fd, wfds))
				hc->status = HTTP_READY_TO_STREAM;
			break;
		}
	}
	if (!FD_ISSET(server_fd, rfds))
		return;
	hc = para_calloc(sizeof(struct http_client));
	err_msg = "accept error";
	hc->fd = para_accept(server_fd, &hc->addr, sizeof(struct sockaddr_in));
	if (hc->fd <= 0)
		goto err_out;
	PARA_NOTICE_LOG("connection from %s (fd %d)\n", CLIENT_ADDR(hc), hc->fd);
	if (conf.http_max_clients_arg > 0 && numclients >=
			conf.http_max_clients_arg) {
		err_msg = "server full";
		goto err_out;
	}
	match = host_in_access_perm_list(hc);
	PARA_DEBUG_LOG("host_in_access_perm_list: %d\n", match);
	if ((match && !conf.http_default_deny_given) ||
			(!match && conf.http_default_deny_given)) {
		err_msg = "permission denied";
		goto err_out;
	}
	hc->status = HTTP_CONNECTED;
	hc->cq = cq_new(MAX_BACKLOG);
	PARA_INFO_LOG("accepted client #%d: %s (fd %d)\n", numclients,
		CLIENT_ADDR(hc), hc->fd);
	numclients++;
	para_list_add(&hc->node, &clients);
	add_close_on_fork_list(hc->fd);
	mark_fd_nonblock(hc->fd);
	return;
err_out:
	PARA_WARNING_LOG("ignoring connect request from %s (%s)\n",
		CLIENT_ADDR(hc), err_msg);
	if (hc->fd > 0)
		close(hc->fd);
	free(hc);
}

static void http_pre_select(int *max_fileno, fd_set *rfds, fd_set *wfds)
{
	struct http_client *hc, *tmp;

	if (server_fd < 0)
		return;
	para_fd_set(server_fd, rfds, max_fileno);
	list_for_each_entry_safe(hc, tmp, &clients, node) {
		//PARA_DEBUG_LOG("hc %p on fd %d: status %d\n", hc, hc->fd, hc->status);
		hc->check_r = 0;
		hc->check_w = 0;
		switch (hc->status) {
		case HTTP_STREAMING:
		case HTTP_READY_TO_STREAM:
			break;
		case HTTP_CONNECTED: /* need to recv get request */
			para_fd_set(hc->fd, rfds, max_fileno);
			hc->check_r = 1;
			break;
		case HTTP_GOT_GET_REQUEST: /* need to send ok msg */
		case HTTP_INVALID_GET_REQUEST: /* need to send err msg */
			para_fd_set(hc->fd, wfds, max_fileno);
			hc->check_w = 1;
			break;
		case HTTP_SENT_OK_MSG:
			if (!vss_playing())
				break; /* wait until server starts playing */
			para_fd_set(hc->fd, wfds, max_fileno);
			hc->check_w = 1;
			break;
		}
	}
}

static int open_tcp_port(int port)
{
	int ret;

	server_fd = init_tcp_socket(port);
	if (server_fd < 0) {
		http_shutdown_clients();
		self->status = SENDER_OFF;
		return server_fd;
	}
	ret = mark_fd_nonblock(server_fd);
	if (ret < 0) {
		PARA_EMERG_LOG("%s\n", PARA_STRERROR(-ret));
		exit(EXIT_FAILURE);
	}
	self->status = SENDER_ON;
	add_close_on_fork_list(server_fd);
	return 1;
}

static int http_com_on(__a_unused struct sender_command_data *scd)
{
	if (self->status == SENDER_ON)
		return 1;
	return open_tcp_port(conf.http_port_arg);
}

static int http_com_off(__a_unused struct sender_command_data *scd)
{
	self->status = SENDER_OFF;
	if (server_fd > 0) {
		close(server_fd);
		del_close_on_fork_list(server_fd);
		server_fd = -1;
	}
	http_shutdown_clients();
	return 1;
}

static void del_perm_list_entry(struct sender_command_data *scd)
{
	struct access_info *ai, *tmp;

	list_for_each_entry_safe(ai, tmp, &access_perm_list, node) {
		char *nad = para_strdup(inet_ntoa(ai->addr));
		if (!strcmp(nad, inet_ntoa(scd->addr)) &&
				ai->netmask == scd->netmask) {
			PARA_NOTICE_LOG("removing %s/%i from access list\n",
				nad, ai->netmask);
			list_del(&ai->node);
			free(ai);
		}
		free(nad);
	}
}

static void add_perm_list_entry(struct sender_command_data *scd)
{
	struct access_info *ai = para_malloc(sizeof(struct access_info));
	ai->addr = scd->addr;
	ai->netmask = scd->netmask;
	PARA_INFO_LOG("adding %s/%i to access list\n", inet_ntoa(ai->addr),
		ai->netmask);
	para_list_add(&ai->node, &access_perm_list);
}

static int http_com_deny(struct sender_command_data *scd)
{
	if (conf.http_default_deny_given)
		del_perm_list_entry(scd);
	else
		add_perm_list_entry(scd);
	return 1;
}

static int http_com_allow(struct sender_command_data *scd)
{
	if (conf.http_default_deny_given)
		add_perm_list_entry(scd);
	else
		del_perm_list_entry(scd);
	return 1;
}

static char *http_info(void)
{
	char *clnts = NULL, *ap = NULL, *ret;
	struct access_info *ai, *tmp_ai;
	struct http_client *hc, *tmp_hc;

	list_for_each_entry_safe(ai, tmp_ai, &access_perm_list, node) {
		char *tmp = make_message("%s%s/%d ", ap? ap : "",
			inet_ntoa(ai->addr), ai->netmask);
		free(ap);
		ap = tmp;
	}
	list_for_each_entry_safe(hc, tmp_hc, &clients, node) {
		char *tmp = make_message("%s%s:%d ", clnts? clnts : "",
			CLIENT_ADDR(hc), CLIENT_PORT(hc));
		free(clnts);
		clnts = tmp;
	}
	ret = make_message(
		"http status: %s\n"
		"http tcp port: %d\n"
		"http clients: %d\n"
		"http maximal number of clients: %d%s\n"
		"http connected clients: %s\n"
		"http access %s list: %s\n",
		(self->status == SENDER_ON)? "on" : "off",
		conf.http_port_arg,
		numclients,
		conf.http_max_clients_arg,
		conf.http_max_clients_arg > 0? "" : " (unlimited)",
		clnts? clnts : "(none)",
		conf.http_default_deny_given? "allow" : "deny",
		ap? ap : "(none)"
	);
	free(ap);
	free(clnts);
	return ret;
}

static void init_access_control_list(void)
{
	int i;
	struct sender_command_data scd;

	INIT_LIST_HEAD(&access_perm_list);
	for (i = 0; i < conf.http_access_given; i++) {
		char *arg = para_strdup(conf.http_access_arg[i]);
		char *p = strchr(arg, '/');
		if (!p)
			goto err;
		*p = '\0';
		if (!inet_aton(arg, &scd.addr))
			goto err;
		scd.netmask = atoi(++p);
		if (scd.netmask < 0 || scd.netmask > 32)
			goto err;
		add_perm_list_entry(&scd);
		goto success;
err:
		PARA_CRIT_LOG("syntax error for http_access option "
			"#%d, ignoring\n", i);
success:
		free(arg);
		continue;
	}
}

static char *http_help(void)
{
	return make_message(
		"usage: {on|off}\n"
		"usage: {allow|deny} IP mask\n"
		"example: allow 127.0.0.1 32\n"
	);
}

/**
 * The init function of the http sender.
 *
 * \param s Pointer to the http sender struct.
 *
 * It initializes all function pointers of \a s, the client list and the access
 * control list. If the autostart option was given, the tcp port is opened.
 */
void http_send_init(struct sender *s)
{
	INIT_LIST_HEAD(&clients);
	s->info = http_info;
	s->send = http_send;
	s->pre_select = http_pre_select;
	s->post_select = http_post_select;
	s->shutdown_clients = http_shutdown_clients;
	s->help = http_help;
	s->client_cmds[SENDER_ON] = http_com_on;
	s->client_cmds[SENDER_OFF] = http_com_off;
	s->client_cmds[SENDER_DENY] = http_com_deny;
	s->client_cmds[SENDER_ALLOW] = http_com_allow;
	s->client_cmds[SENDER_ADD] = NULL;
	s->client_cmds[SENDER_DELETE] = NULL;
	self = s;
	init_access_control_list();
	if (!conf.http_no_autostart_given)
		open_tcp_port(conf.http_port_arg); /* ignore errors */
	PARA_DEBUG_LOG("%s", "http sender init complete\n");
}