/* the Music Player Daemon (MPD)
 * Copyright (C) 2003-2007 by Warren Dukes (warren.dukes@gmail.com)
 * This project's homepage is: http://www.musicpd.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "client.h"
#include "command.h"
#include "conf.h"
#include "log.h"
#include "listen.h"
#include "permission.h"
#include "sllist.h"
#include "utils.h"
#include "ioops.h"
#include "myfprintf.h"
#include "os_compat.h"
#include "main_notify.h"
#include "dlist.h"

#include "../config.h"

#define GREETING				"OK MPD " PROTOCOL_VERSION "\n"

#define CLIENT_MAX_BUFFER_LENGTH			(40960)
#define CLIENT_LIST_MODE_BEGIN			"command_list_begin"
#define CLIENT_LIST_OK_MODE_BEGIN			"command_list_ok_begin"
#define CLIENT_LIST_MODE_END				"command_list_end"
#define CLIENT_DEFAULT_OUT_BUFFER_SIZE		(4096)
#define CLIENT_TIMEOUT_DEFAULT			(60)
#define CLIENT_MAX_CONNECTIONS_DEFAULT		(10)
#define CLIENT_MAX_COMMAND_LIST_DEFAULT		(2048*1024)
#define CLIENT_MAX_OUTPUT_BUFFER_SIZE_DEFAULT	(8192*1024)

/* set this to zero to indicate we have no possible clients */
static unsigned int client_max_connections;	/*CLIENT_MAX_CONNECTIONS_DEFAULT; */
static int client_timeout = CLIENT_TIMEOUT_DEFAULT;
static size_t client_max_command_list_size =
    CLIENT_MAX_COMMAND_LIST_DEFAULT;
static size_t client_max_output_buffer_size =
    CLIENT_MAX_OUTPUT_BUFFER_SIZE_DEFAULT;

/* maybe make conf option for this, or... 32 might be good enough */
static long int client_list_cache_size = 32;

/* shared globally between all clients: */
static struct strnode *list_cache;
static struct strnode *list_cache_head;
static struct strnode *list_cache_tail;

struct client {
	struct list_head siblings;

	char buffer[CLIENT_MAX_BUFFER_LENGTH];
	size_t bufferLength;
	size_t bufferPos;
	int fd;	/* file descriptor; -1 if expired */
	int permission;
	time_t lastTime;
	struct strnode *cmd_list;	/* for when in list mode */
	struct strnode *cmd_list_tail;	/* for when in list mode */
	int cmd_list_OK;	/* print OK after each command execution */
	size_t cmd_list_size;	/* mem cmd_list consumes */
	int cmd_list_dup;	/* has the cmd_list been copied to private space? */
	struct sllnode *deferred_send;	/* for output if client is slow */
	size_t deferred_bytes;	/* mem deferred_send consumes */
	unsigned int num;	/* client number */

	char *send_buf;
	size_t send_buf_used;	/* bytes used this instance */
	size_t send_buf_size;	/* bytes usable this instance */
	size_t send_buf_alloc;	/* bytes actually allocated */
};

static LIST_HEAD(clients);
static unsigned num_clients;

static void client_write_deferred(struct client *cl);

static void client_write_output(struct client *cl);

#ifdef SO_SNDBUF
static size_t get_default_snd_buf_size(struct client *cl)
{
	int new_size;
	socklen_t sockOptLen = sizeof(int);

	if (getsockopt(cl->fd, SOL_SOCKET, SO_SNDBUF,
		       (char *)&new_size, &sockOptLen) < 0) {
		DEBUG("problem getting sockets send buffer size\n");
		return CLIENT_DEFAULT_OUT_BUFFER_SIZE;
	}
	if (new_size > 0)
		return (size_t)new_size;
	DEBUG("sockets send buffer size is not positive\n");
	return CLIENT_DEFAULT_OUT_BUFFER_SIZE;
}
#else /* !SO_SNDBUF */
static size_t get_default_snd_buf_size(struct client *cl)
{
	return CLIENT_DEFAULT_OUT_BUFFER_SIZE;
}
#endif /* !SO_SNDBUF */

static void set_send_buf_size(struct client *cl)
{
	size_t new_size = get_default_snd_buf_size(cl);
	if (cl->send_buf_size != new_size) {
		cl->send_buf_size = new_size;
		/* don't resize to get smaller, only bigger */
		if (cl->send_buf_alloc < new_size) {
			if (cl->send_buf)
				free(cl->send_buf);
			cl->send_buf = xmalloc(new_size);
			cl->send_buf_alloc = new_size;
		}
	}
}

static inline int client_is_expired(const struct client *cl)
{
	return cl->fd < 0;
}

static int global_expired;

static inline void client_set_expired(struct client *cl)
{
	if (cl->fd >= 0) {
		xclose(cl->fd);
		cl->fd = -1;
	}

	global_expired = 1;
}

static void client_init(struct client *cl, int fd)
{
	static unsigned int next_client_num;

	assert(fd >= 0);

	cl->cmd_list_size = 0;
	cl->cmd_list_dup = 0;
	cl->cmd_list_OK = -1;
	cl->bufferLength = 0;
	cl->bufferPos = 0;
	cl->fd = fd;
	set_nonblocking(fd);
	cl->lastTime = time(NULL);
	cl->cmd_list = NULL;
	cl->cmd_list_tail = NULL;
	cl->deferred_send = NULL;
	cl->deferred_bytes = 0;
	cl->num = next_client_num++;
	cl->send_buf_used = 0;

	cl->permission = getDefaultPermissions();
	set_send_buf_size(cl);

	xwrite(fd, GREETING, strlen(GREETING));
}

static void free_cmd_list(struct strnode *list)
{
	struct strnode *tmp = list;

	while (tmp) {
		struct strnode *next = tmp->next;
		if (tmp >= list_cache_head && tmp <= list_cache_tail) {
			/* inside list_cache[] array */
			tmp->data = NULL;
			tmp->next = NULL;
		} else
			free(tmp);
		tmp = next;
	}
}

static void cmd_list_clone(struct client *cl)
{
	struct strnode *new = dup_strlist(cl->cmd_list);
	free_cmd_list(cl->cmd_list);
	cl->cmd_list = new;
	cl->cmd_list_dup = 1;

	/* new tail */
	while (new && new->next)
		new = new->next;
	cl->cmd_list_tail = new;
}

static void new_cmd_list_ptr(struct client *cl, char *s, const int size)
{
	int i;
	struct strnode *new;

	if (!cl->cmd_list_dup) {
		for (i = client_list_cache_size - 1; i >= 0; --i) {
			if (list_cache[i].data)
				continue;
			new = &(list_cache[i]);
			new->data = s;
			/* implied in free_cmd_list() and init: */
			/* last->next->next = NULL; */
			goto out;
		}
	}

	/* allocate from the heap */
	new = cl->cmd_list_dup ? new_strnode_dup(s, size)
	                              : new_strnode(s);
out:
	if (cl->cmd_list) {
		cl->cmd_list_tail->next = new;
		cl->cmd_list_tail = new;
	} else
		cl->cmd_list = cl->cmd_list_tail = new;
}

static void client_close(struct client *cl)
{
	struct sllnode *buf;

	assert(num_clients > 0);
	assert(!list_empty(&clients));
	list_del(&cl->siblings);
	--num_clients;

	client_set_expired(cl);

	if (cl->cmd_list) {
		free_cmd_list(cl->cmd_list);
		cl->cmd_list = NULL;
	}

	if ((buf = cl->deferred_send)) {
		do {
			struct sllnode *prev = buf;
			buf = buf->next;
			free(prev);
		} while (buf);
		cl->deferred_send = NULL;
	}

	if (cl->send_buf)
		free(cl->send_buf);

	SECURE("client %i: closed\n", cl->num);
	free(cl);
}

static const char *
sockaddr_to_tmp_string(const struct sockaddr *addr)
{
	const char *hostname;

	switch (addr->sa_family) {
#ifdef HAVE_TCP
	case AF_INET:
		hostname = (const char *)inet_ntoa(((const struct sockaddr_in *)
						    addr)->sin_addr);
		if (!hostname)
			hostname = "error getting ipv4 address";
		break;
#ifdef HAVE_IPV6
	case AF_INET6:
		{
			static char host[INET6_ADDRSTRLEN + 1];
			memset(host, 0, INET6_ADDRSTRLEN + 1);
			if (inet_ntop(AF_INET6, (const void *)
				      &(((const struct sockaddr_in6 *)addr)->
					sin6_addr), host,
				      INET6_ADDRSTRLEN)) {
				hostname = (const char *)host;
			} else {
				hostname = "error getting ipv6 address";
			}
		}
		break;
#endif
#endif /* HAVE_TCP */
#ifdef HAVE_UN
	case AF_UNIX:
		hostname = "local connection";
		break;
#endif /* HAVE_UN */
	default:
		hostname = "unknown";
	}

	return hostname;
}

void client_new(int fd, const struct sockaddr *addr)
{
	struct client *cl;

	if (num_clients >= client_max_connections) {
		ERROR("Max Connections Reached!\n");
		xclose(fd);
		return;
	}

	cl = xcalloc(1, sizeof(struct client));
	list_add(&cl->siblings, &clients);
	++num_clients;
	client_init(cl, fd);
	SECURE("client %i: opened from %s\n", cl->num,
	       sockaddr_to_tmp_string(addr));
}

static int client_process_line(struct client *cl)
{
	int ret = 1;
	char *line = cl->buffer + cl->bufferPos;

	if (cl->cmd_list_OK >= 0) {
		if (strcmp(line, CLIENT_LIST_MODE_END) == 0) {
			DEBUG("client %i: process command "
			      "list\n", cl->num);

			global_expired = 0;
			ret = processListOfCommands(cl->fd,
						    &(cl->permission),
						    &global_expired,
						    cl->cmd_list_OK,
						    cl->cmd_list);
			DEBUG("client %i: process command "
			      "list returned %i\n", cl->num, ret);

			if (ret == COMMAND_RETURN_CLOSE ||
			    client_is_expired(cl))
				return COMMAND_RETURN_CLOSE;

			if (ret == 0)
				commandSuccess(cl->fd);

			client_write_output(cl);
			free_cmd_list(cl->cmd_list);
			cl->cmd_list = NULL;
			cl->cmd_list_OK = -1;
		} else {
			size_t len = strlen(line) + 1;
			cl->cmd_list_size += len;
			if (cl->cmd_list_size >
			    client_max_command_list_size) {
				ERROR("client %i: command "
				      "list size (%lu) is "
				      "larger than the max "
				      "(%lu)\n",
				      cl->num,
				      (unsigned long)cl->cmd_list_size,
				      (unsigned long)
				      client_max_command_list_size);
				return COMMAND_RETURN_CLOSE;
			} else
				new_cmd_list_ptr(cl, line, len);
		}
	} else {
		if (strcmp(line, CLIENT_LIST_MODE_BEGIN) == 0) {
			cl->cmd_list_OK = 0;
			ret = 1;
		} else if (strcmp(line, CLIENT_LIST_OK_MODE_BEGIN) == 0) {
			cl->cmd_list_OK = 1;
			ret = 1;
		} else {
			DEBUG("client %i: process command \"%s\"\n",
			      cl->num, line);
			ret = processCommand(cl->fd,
					     &(cl->permission), line);
			DEBUG("client %i: command returned %i\n",
			      cl->num, ret);

			if (ret == COMMAND_RETURN_CLOSE ||
			    client_is_expired(cl))
				return COMMAND_RETURN_CLOSE;

			if (ret == 0)
				commandSuccess(cl->fd);

			client_write_output(cl);
		}
	}

	return ret;
}

static int client_input_received(struct client *cl, int bytesRead)
{
	int ret;
	char *buf_tail = &(cl->buffer[cl->bufferLength - 1]);

	while (bytesRead > 0) {
		cl->bufferLength++;
		bytesRead--;
		buf_tail++;
		if (*buf_tail == '\n') {
			*buf_tail = '\0';
			if (cl->bufferLength > cl->bufferPos) {
				if (*(buf_tail - 1) == '\r')
					*(buf_tail - 1) = '\0';
			}
			ret = client_process_line(cl);
			if (ret == COMMAND_RETURN_KILL ||
			    ret == COMMAND_RETURN_CLOSE)
				return ret;
			if (client_is_expired(cl))
				return COMMAND_RETURN_CLOSE;
			cl->bufferPos = cl->bufferLength;
		}
		if (cl->bufferLength == CLIENT_MAX_BUFFER_LENGTH) {
			if (cl->bufferPos == 0) {
				ERROR("client %i: buffer overflow\n",
				      cl->num);
				return COMMAND_RETURN_CLOSE;
			}
			if (cl->cmd_list_OK >= 0 &&
			    cl->cmd_list &&
			    !cl->cmd_list_dup)
				cmd_list_clone(cl);
			assert(cl->bufferLength >= cl->bufferPos
			       && "bufferLength >= bufferPos");
			cl->bufferLength -= cl->bufferPos;
			memmove(cl->buffer,
				cl->buffer + cl->bufferPos,
				cl->bufferLength);
			cl->bufferPos = 0;
		}
	}

	return 0;
}

static int client_read(struct client *cl)
{
	int bytesRead;

	bytesRead = read(cl->fd,
			 cl->buffer + cl->bufferLength,
			 CLIENT_MAX_BUFFER_LENGTH - cl->bufferLength);

	if (bytesRead > 0)
		return client_input_received(cl, bytesRead);
	else if (bytesRead < 0 && errno == EINTR)
		/* try again later, after select() */
		return 0;
	else
		/* peer disconnected or I/O error */
		return COMMAND_RETURN_CLOSE;
}

static void client_manager_register_read_fd(fd_set * fds, int *fdmax)
{
	struct client *cl;

	FD_ZERO(fds);
	addListenSocketsToFdSet(fds, fdmax);

	list_for_each_entry(cl, &clients, siblings) {
		if (!client_is_expired(cl) && !cl->deferred_send) {
			FD_SET(cl->fd, fds);
			if (*fdmax < cl->fd)
				*fdmax = cl->fd;
		}
	}
}

static void client_manager_register_write_fd(fd_set * fds, int *fdmax)
{
	struct client *cl;

	FD_ZERO(fds);

	list_for_each_entry(cl, &clients, siblings) {
		if (cl->fd >= 0 && !client_is_expired(cl)
		    && cl->deferred_send) {
			FD_SET(cl->fd, fds);
			if (*fdmax < cl->fd)
				*fdmax = cl->fd;
		}
	}
}

int client_manager_io(void)
{
	fd_set rfds;
	fd_set wfds;
	fd_set efds;
	struct client *cl, *n;
	int ret;
	int fdmax = 0;

	FD_ZERO( &efds );
	client_manager_register_read_fd(&rfds, &fdmax);
	client_manager_register_write_fd(&wfds, &fdmax);

	registered_IO_add_fds(&fdmax, &rfds, &wfds, &efds);

	ret = select(fdmax + 1, &rfds, &wfds, &efds, NULL);

	if (ret < 0) {
		if (errno == EINTR)
			return 0;

		FATAL("select() failed: %s\n", strerror(errno));
	}

	registered_IO_consume_fds(&ret, &rfds, &wfds, &efds);

	getConnections(&rfds);

	list_for_each_entry_safe(cl, n, &clients, siblings) {
		if (FD_ISSET(cl->fd, &rfds)) {
			ret = client_read(cl);
			if (ret == COMMAND_RETURN_KILL)
				return COMMAND_RETURN_KILL;
			if (ret == COMMAND_RETURN_CLOSE) {
				client_close(cl);
				continue;
			}

			assert(!client_is_expired(cl));

			cl->lastTime = time(NULL);
		}
		if (!client_is_expired(cl) &&
		    FD_ISSET(cl->fd, &wfds)) {
			client_write_deferred(cl);
			cl->lastTime = time(NULL);
		}
	}

	return 0;
}

void client_manager_init(void)
{
	char *test;
	ConfigParam *param;

	param = getConfigParam(CONF_CONN_TIMEOUT);

	if (param) {
		client_timeout = strtol(param->value, &test, 10);
		if (*test != '\0' || client_timeout <= 0) {
			FATAL("connection timeout \"%s\" is not a positive "
			      "integer, line %i\n", CONF_CONN_TIMEOUT,
			      param->line);
		}
	}

	param = getConfigParam(CONF_MAX_CONN);

	if (param) {
		client_max_connections = strtol(param->value, &test, 10);
		if (*test != '\0' || client_max_connections <= 0) {
			FATAL("max connections \"%s\" is not a positive integer"
			      ", line %i\n", param->value, param->line);
		}
	} else
		client_max_connections = CLIENT_MAX_CONNECTIONS_DEFAULT;

	param = getConfigParam(CONF_MAX_COMMAND_LIST_SIZE);

	if (param) {
		long tmp = strtol(param->value, &test, 10);
		if (*test != '\0' || tmp <= 0) {
			FATAL("max command list size \"%s\" is not a positive "
			      "integer, line %i\n", param->value, param->line);
		}
		client_max_command_list_size = tmp * 1024;
	}

	param = getConfigParam(CONF_MAX_OUTPUT_BUFFER_SIZE);

	if (param) {
		long tmp = strtol(param->value, &test, 10);
		if (*test != '\0' || tmp <= 0) {
			FATAL("max output buffer size \"%s\" is not a positive "
			      "integer, line %i\n", param->value, param->line);
		}
		client_max_output_buffer_size = tmp * 1024;
	}

	list_cache = xcalloc(client_list_cache_size, sizeof(struct strnode));
	list_cache_head = &(list_cache[0]);
	list_cache_tail = &(list_cache[client_list_cache_size - 1]);
}

static void client_close_all(void)
{
	struct client *cl, *n;

	list_for_each_entry_safe(cl, n, &clients, siblings)
		client_close(cl);
	num_clients = 0;

	free(list_cache);
}

void client_manager_deinit(void)
{
	client_close_all();

	client_max_connections = 0;
}

void client_manager_expire(void)
{
	struct client *cl, *n;

	list_for_each_entry_safe(cl, n, &clients, siblings) {
		if (client_is_expired(cl)) {
			DEBUG("client %i: expired\n", cl->num);
			client_close(cl);
		} else if (time(NULL) - cl->lastTime >
			   client_timeout) {
			DEBUG("client %i: timeout\n", cl->num);
			client_close(cl);
		}
	}
}

static void client_write_deferred(struct client *cl)
{
	struct sllnode *buf;
	ssize_t ret = 0;

	buf = cl->deferred_send;
	while (buf) {
		assert(buf->size > 0);

		ret = write(cl->fd, buf->data, buf->size);
		if (ret < 0)
			break;
		else if ((size_t)ret < buf->size) {
			assert(cl->deferred_bytes >= (size_t)ret);
			cl->deferred_bytes -= ret;
			buf->data = (char *)buf->data + ret;
			buf->size -= ret;
		} else {
			struct sllnode *tmp = buf;
			size_t decr = (buf->size + sizeof(struct sllnode));

			assert(cl->deferred_bytes >= decr);
			cl->deferred_bytes -= decr;
			buf = buf->next;
			free(tmp);
			cl->deferred_send = buf;
		}
		cl->lastTime = time(NULL);
	}

	if (!cl->deferred_send) {
		DEBUG("client %i: buffer empty %lu\n", cl->num,
		      (unsigned long)cl->deferred_bytes);
		assert(cl->deferred_bytes == 0);
	} else if (ret < 0 && errno != EAGAIN && errno != EINTR) {
		/* cause client to close */
		DEBUG("client %i: problems flushing buffer\n",
		      cl->num);
		client_set_expired(cl);
	}
}

static struct client * client_by_fd(int fd)
{
	struct client *cl;

	list_for_each_entry(cl, &clients, siblings)
		if (cl->fd == fd)
			return cl;

	return NULL;
}

int client_print(int fd, const char *buffer, size_t buflen)
{
	size_t copylen;
	struct client *cl;

	assert(fd >= 0);

	cl = client_by_fd(fd);
	if (cl == NULL)
		return -1;

	/* if fd isn't found or client is going to be closed, do nothing */
	if (client_is_expired(cl))
		return 0;

	while (buflen > 0 && !client_is_expired(cl)) {
		size_t left;

		assert(cl->send_buf_size >= cl->send_buf_used);
		left = cl->send_buf_size - cl->send_buf_used;

		copylen = buflen > left ? left : buflen;
		memcpy(cl->send_buf + cl->send_buf_used, buffer,
		       copylen);
		buflen -= copylen;
		cl->send_buf_used += copylen;
		buffer += copylen;
		if (cl->send_buf_used >= cl->send_buf_size)
			client_write_output(cl);
	}

	return 0;
}

static void client_defer_output(struct client *cl,
				const void *data, size_t length)
{
	struct sllnode **buf_r;

	assert(length > 0);

	cl->deferred_bytes += sizeof(struct sllnode) + length;
	if (cl->deferred_bytes > client_max_output_buffer_size) {
		ERROR("client %i: output buffer size (%lu) is "
		      "larger than the max (%lu)\n",
		      cl->num,
		      (unsigned long)cl->deferred_bytes,
		      (unsigned long)client_max_output_buffer_size);
		/* cause client to close */
		client_set_expired(cl);
		return;
	}

	buf_r = &cl->deferred_send;
	while (*buf_r != NULL)
		buf_r = &(*buf_r)->next;
	*buf_r = new_sllnode(data, length);
}

static void client_write(struct client *cl,
			 const char *data, size_t length)
{
	ssize_t ret;

	assert(length > 0);
	assert(cl->deferred_send == NULL);

	if ((ret = write(cl->fd, data, length)) < 0) {
		if (errno == EAGAIN || errno == EINTR) {
			client_defer_output(cl, data, length);
		} else {
			DEBUG("client %i: problems writing\n", cl->num);
			client_set_expired(cl);
			return;
		}
	} else if ((size_t)ret < cl->send_buf_used) {
		client_defer_output(cl, data + ret, length - ret);
	}

	if (cl->deferred_send)
		DEBUG("client %i: buffer created\n", cl->num);
}

static void client_write_output(struct client *cl)
{
	if (client_is_expired(cl) || !cl->send_buf_used)
		return;

	if (cl->deferred_send != NULL)
		client_defer_output(cl, cl->send_buf, cl->send_buf_used);
	else
		client_write(cl, cl->send_buf, cl->send_buf_used);

	cl->send_buf_used = 0;
}