/* Copyright (c) 2002-2009 Dovecot authors, see the included COPYING file */

#include "common.h"

#include "buffer.h"

#include "ioloop.h"

#include "network.h"

#include "istream.h"

#include "ostream.h"

#include "str.h"

#include "var-expand.h"

#include "mail-storage.h"

#include "commands.h"

#include "mail-search-build.h"

#include "mail-namespace.h"

#include <stdlib.h>

#include <unistd.h>

/* max. length of input command line (spec says 512) */

#define MAX_INBUF_SIZE 2048

/* Stop reading input when output buffer has this many bytes. Once the buffer

   size has dropped to half of it, start reading input again. */

#define OUTBUF_THROTTLE_SIZE 4096

/* Disconnect client when it sends too many bad commands in a row */

#define CLIENT_MAX_BAD_COMMANDS 20

/* Disconnect client after idling this many milliseconds */

#define CLIENT_IDLE_TIMEOUT_MSECS (10*60*1000)

/* If client starts idling for this many milliseconds, commit the current

   transaction. This allows the mailbox to become unlocked. */

#define CLIENT_COMMIT_TIMEOUT_MSECS (10*1000)

static struct client *my_client; /* we don't need more than one currently */

static void client_input(struct client *client);

static int client_output(struct client *client);

static void client_commit_timeout(struct client *client)

{

	if (client->cmd != NULL) {

		/* Can't commit while commands are running */

		return;

	}

	(void)mailbox_transaction_commit(&client->trans);

	client->trans = mailbox_transaction_begin(client->mailbox, 0);

}

static void client_idle_timeout(struct client *client)

{

	if (client->cmd != NULL) {

		client_destroy(client,

			"Disconnected for inactivity in reading our output");

	} else {

		client_send_line(client, "-ERR Disconnected for inactivity.");

		client_destroy(client, "Disconnected for inactivity");

	}

}

static bool init_mailbox(struct client *client, const char **error_r)

{

	struct mail_search_args *search_args;

        struct mailbox_transaction_context *t;

	struct mail_search_context *ctx;

        struct mailbox_status status;

	struct mail *mail;

	buffer_t *message_sizes_buf;

	uint32_t failed_uid = 0;

	uoff_t size;

	int i;

	bool failed, expunged;

	message_sizes_buf = buffer_create_dynamic(default_pool, 512);

	search_args = mail_search_build_init();

	mail_search_build_add_all(search_args);

	for (i = 0; i < 2; i++) {

		expunged = FALSE;

		if (mailbox_sync(client->mailbox, MAILBOX_SYNC_FLAG_FULL_READ,

				 STATUS_UIDVALIDITY, &status) < 0) {

			client_send_storage_error(client);

			break;

		}

		client->uid_validity = status.uidvalidity;

		t = mailbox_transaction_begin(client->mailbox, 0);

		ctx = mailbox_search_init(t, search_args, NULL);

		client->last_seen = 0;

		client->total_size = 0;

		buffer_set_used_size(message_sizes_buf, 0);

		failed = FALSE;

		mail = mail_alloc(t, MAIL_FETCH_VIRTUAL_SIZE, NULL);

		while (mailbox_search_next(ctx, mail) > 0) {

			if (mail_get_virtual_size(mail, &size) < 0) {

				expunged = mail->expunged;

				failed = TRUE;

				if (failed_uid == mail->uid) {

					i_error("Getting size of message "

						"UID=%u failed", mail->uid);

					break;

				}

				failed_uid = mail->uid;

				break;

			}

			if ((mail_get_flags(mail) & MAIL_SEEN) != 0)

				client->last_seen = mail->seq;

                        client->total_size += size;

			buffer_append(message_sizes_buf, &size, sizeof(size));

		}

		client->messages_count =

			message_sizes_buf->used / sizeof(uoff_t);

		mail_free(&mail);

		if (mailbox_search_deinit(&ctx) < 0 || (failed && !expunged)) {

			client_send_storage_error(client);

			(void)mailbox_transaction_commit(&t);

			break;

		}

		if (!failed) {

			client->trans = t;

			client->message_sizes =

				buffer_free_without_data(&message_sizes_buf);

			mail_search_args_unref(&search_args);

			return TRUE;

		}

		/* well, sync and try again. we might have cached virtual

		   sizes, make sure they get committed. */

		(void)mailbox_transaction_commit(&t);

	}

	mail_search_args_unref(&search_args);

	if (expunged) {

		client_send_line(client,

				 "-ERR [IN-USE] Couldn't sync mailbox.");

		*error_r = "Can't sync mailbox: Messages keep getting expunged";

	} else {

		struct mail_storage *storage = client->inbox_ns->storage;

		enum mail_error error;

		*error_r = mail_storage_get_last_error(storage, &error);

	}

	buffer_free(&message_sizes_buf);

	return FALSE;

}

struct client *client_create(int fd_in, int fd_out, struct mail_user *user)

{

	struct mail_storage *storage;

	const char *inbox;

	struct client *client;

        enum mailbox_open_flags flags;

	const char *errmsg;

	enum mail_error error;

	/* always use nonblocking I/O */

	net_set_nonblock(fd_in, TRUE);

	net_set_nonblock(fd_out, TRUE);

	client = i_new(struct client, 1);

	client->fd_in = fd_in;

	client->fd_out = fd_out;

	client->input = i_stream_create_fd(fd_in, MAX_INBUF_SIZE, FALSE);

	client->output = o_stream_create_fd(fd_out, (size_t)-1, FALSE);

	o_stream_set_flush_callback(client->output, client_output, client);

	client->io = io_add(fd_in, IO_READ, client_input, client);

        client->last_input = ioloop_time;

	client->to_idle = timeout_add(CLIENT_IDLE_TIMEOUT_MSECS,

				      client_idle_timeout, client);

	if (!lock_session) {

		client->to_commit = timeout_add(CLIENT_COMMIT_TIMEOUT_MSECS,

						client_commit_timeout, client);

	}

	client->user = user;

	inbox = "INBOX";

	client->inbox_ns = mail_namespace_find(user->namespaces, &inbox);

	if (client->inbox_ns == NULL) {

		client_send_line(client, "-ERR No INBOX namespace for user.");

		client_destroy(client, "No INBOX namespace for user.");

		return NULL;

	}

	storage = client->inbox_ns->storage;

	flags = MAILBOX_OPEN_POP3_SESSION;

	if (no_flag_updates)

		flags |= MAILBOX_OPEN_KEEP_RECENT;

	if (lock_session)

		flags |= MAILBOX_OPEN_KEEP_LOCKED;

	client->mailbox = mailbox_open(&storage, "INBOX", NULL, flags);

	if (client->mailbox == NULL) {

		errmsg = t_strdup_printf("Couldn't open INBOX: %s",

				mail_storage_get_last_error(storage,

							    &error));

		i_error("%s", errmsg);

		client_send_line(client, "-ERR [IN-USE] %s", errmsg);

		client_destroy(client, "Couldn't open INBOX");

		return NULL;

	}

	if (!init_mailbox(client, &errmsg)) {

		i_error("Couldn't init INBOX: %s", errmsg);

		client_destroy(client, "Mailbox init failed");

		return NULL;

	}

	if (!no_flag_updates && client->messages_count > 0)

		client->seen_bitmask = i_malloc(MSGS_BITMASK_SIZE(client));

	i_assert(my_client == NULL);

	my_client = client;

	if (hook_client_created != NULL)

		hook_client_created(&client);

	return client;

}

static const char *client_stats(struct client *client)

{

	static struct var_expand_table static_tab[] = {

		{ 'p', NULL, "top_bytes" },

		{ 't', NULL, "top_count" },

		{ 'b', NULL, "retr_bytes" },

		{ 'r', NULL, "retr_count" },

		{ 'd', NULL, "deleted_count" },

		{ 'm', NULL, "message_count" },

		{ 's', NULL, "message_bytes" },

		{ 'i', NULL, "input" },

		{ 'o', NULL, "output" },

		{ '\0', NULL, NULL }

	};

	struct var_expand_table *tab;

	string_t *str;

	tab = t_malloc(sizeof(static_tab));

	memcpy(tab, static_tab, sizeof(static_tab));

	tab[0].value = dec2str(client->top_bytes);

	tab[1].value = dec2str(client->top_count);

	tab[2].value = dec2str(client->retr_bytes);

	tab[3].value = dec2str(client->retr_count);

	tab[4].value = dec2str(client->expunged_count);

	tab[5].value = dec2str(client->messages_count);

	tab[6].value = dec2str(client->total_size);

	tab[7].value = dec2str(client->input->v_offset);

	tab[8].value = dec2str(client->output->offset);

	str = t_str_new(128);

	var_expand(str, logout_format, tab);

	return str_c(str);

}

static const char *client_get_disconnect_reason(struct client *client)

{

	errno = client->input->stream_errno != 0 ?

		client->input->stream_errno :

		client->output->stream_errno;

	return errno == 0 || errno == EPIPE ? "Connection closed" :

		t_strdup_printf("Connection closed: %m");

}

void client_destroy(struct client *client, const char *reason)

{

	if (client->seen_change_count > 0)

		client_update_mails(client);

	if (!client->disconnected) {

		if (reason == NULL)

			reason = client_get_disconnect_reason(client);

		i_info("%s %s", reason, client_stats(client));

	}

	if (client->cmd != NULL) {

		/* deinitialize command */

		i_stream_close(client->input);

		o_stream_close(client->output);

		client->cmd(client);

		i_assert(client->cmd == NULL);

	}

	if (client->trans != NULL) {

		/* client didn't QUIT, but we still want to save any changes

		   done in this transaction. especially the cached virtual

		   message sizes. */

		(void)mailbox_transaction_commit(&client->trans);

	}

	if (client->mailbox != NULL)

		mailbox_close(&client->mailbox);

	mail_user_unref(&client->user);

	i_free(client->message_sizes);

	i_free(client->deleted_bitmask);

	i_free(client->seen_bitmask);

	if (client->io != NULL)

		io_remove(&client->io);

	timeout_remove(&client->to_idle);

	if (client->to_commit != NULL)

		timeout_remove(&client->to_commit);

	i_stream_destroy(&client->input);

	o_stream_destroy(&client->output);

	if (close(client->fd_in) < 0)

		i_error("close(client in) failed: %m");

	if (client->fd_in != client->fd_out) {

		if (close(client->fd_out) < 0)

			i_error("close(client out) failed: %m");

	}

	i_free(client);

	/* quit the program */

	my_client = NULL;

	io_loop_stop(ioloop);

}

void client_disconnect(struct client *client, const char *reason)

{

	if (client->disconnected)

		return;

	client->disconnected = TRUE;

	i_info("Disconnected: %s %s", reason, client_stats(client));

	(void)o_stream_flush(client->output);

	i_stream_close(client->input);

	o_stream_close(client->output);

}

int client_send_line(struct client *client, const char *fmt, ...)

{

	va_list va;

	ssize_t ret;

	if (client->output->closed)

		return -1;

	va_start(va, fmt);

	T_BEGIN {

		string_t *str;

		str = t_str_new(256);

		str_vprintfa(str, fmt, va);

		str_append(str, "\r\n");

		ret = o_stream_send(client->output,

				    str_data(str), str_len(str));

		i_assert(ret < 0 || (size_t)ret == str_len(str));

	} T_END;

	if (ret >= 0) {

		if (o_stream_get_buffer_used_size(client->output) <

		    OUTBUF_THROTTLE_SIZE) {

			ret = 1;

			client->last_output = ioloop_time;

		} else {

			ret = 0;

			if (client->io != NULL) {

				/* no more input until client has read

				   our output */

				io_remove(&client->io);

				/* If someone happens to flush output,

				   we want to get our IO handler back in

				   flush callback */

				o_stream_set_flush_pending(client->output,

							   TRUE);

			}

		}

	}

	va_end(va);

	return (int)ret;

}

void client_send_storage_error(struct client *client)

{

	enum mail_error error;

	if (mailbox_is_inconsistent(client->mailbox)) {

		client_send_line(client, "-ERR Mailbox is in inconsistent "

				 "state, please relogin.");

		client_disconnect(client, "Mailbox is in inconsistent state.");

		return;

	}

	client_send_line(client, "-ERR %s",

			 mail_storage_get_last_error(client->inbox_ns->storage,

						     &error));

}

bool client_handle_input(struct client *client)

{

	char *line, *args;

	int ret;

	o_stream_cork(client->output);

	while (!client->output->closed &&

	       (line = i_stream_next_line(client->input)) != NULL) {

		args = strchr(line, ' ');

		if (args != NULL)

			*args++ = '\0';

		T_BEGIN {

			ret = client_command_execute(client, line,

						     args != NULL ? args : "");

		} T_END;

		if (ret >= 0) {

			client->bad_counter = 0;

			if (client->cmd != NULL) {

				o_stream_set_flush_pending(client->output,

							   TRUE);

				client->waiting_input = TRUE;

				break;

			}

		} else if (++client->bad_counter > CLIENT_MAX_BAD_COMMANDS) {

			client_send_line(client, "-ERR Too many bad commands.");

			client_disconnect(client, "Too many bad commands.");

		}

	}

	o_stream_uncork(client->output);

	if (client->output->closed) {

		client_destroy(client, NULL);

		return FALSE;

	}

	return TRUE;

}

static void client_input(struct client *client)

{

	if (client->cmd != NULL) {

		/* we're still processing a command. wait until it's

		   finished. */

		io_remove(&client->io);

		client->waiting_input = TRUE;

		return;

	}

	client->waiting_input = FALSE;

	client->last_input = ioloop_time;

	timeout_reset(client->to_idle);

	if (client->to_commit != NULL)

		timeout_reset(client->to_commit);

	switch (i_stream_read(client->input)) {

	case -1:

		/* disconnected */

		client_destroy(client, NULL);

		return;

	case -2:

		/* line too long, kill it */

		client_send_line(client, "-ERR Input line too long.");

		client_destroy(client, "Input line too long");

		return;

	}

	(void)client_handle_input(client);

}

static int client_output(struct client *client)

{

	int ret;

	if ((ret = o_stream_flush(client->output)) < 0) {

		client_destroy(client, NULL);

		return 1;

	}

	client->last_output = ioloop_time;

	timeout_reset(client->to_idle);

	if (client->to_commit != NULL)

		timeout_reset(client->to_commit);

	if (client->cmd != NULL) {

		o_stream_cork(client->output);

		client->cmd(client);

		o_stream_uncork(client->output);

	}

	if (client->cmd == NULL) {

		if (o_stream_get_buffer_used_size(client->output) <

		    OUTBUF_THROTTLE_SIZE/2 && client->io == NULL) {

			/* enable input again */

			client->io = io_add(i_stream_get_fd(client->input),

					    IO_READ, client_input, client);

		}

		if (client->io != NULL && client->waiting_input)

			client_input(client);

	}

	return client->cmd == NULL;

}

void clients_init(void)

{

	my_client = NULL;

}

void clients_deinit(void)

{

	if (my_client != NULL) {

		client_send_line(my_client, "-ERR Server shutting down.");

		client_destroy(my_client, "Server shutting down");

	}

}