/* Copyright (c) 2005-2017 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "lib-signals.h"
#include "array.h"
#include "ioloop.h"
#include "eacces-error.h"
#include "net.h"
#include "istream.h"
#include "ostream.h"
#include "str.h"
#include "strescape.h"
#include "master-interface.h"
#include "auth-master.h"

#include <unistd.h>

#define AUTH_PROTOCOL_MAJOR 1
#define AUTH_PROTOCOL_MINOR 0

#define AUTH_MASTER_IDLE_SECS 60

#define MAX_INBUF_SIZE 8192
#define MAX_OUTBUF_SIZE 1024

#define DEFAULT_USERDB_LOOKUP_PREFIX "userdb lookup"

struct auth_master_connection {
	char *auth_socket_path;
	enum auth_master_flags flags;

	int fd;
	struct ioloop *ioloop, *prev_ioloop;
	struct io *io;
	struct istream *input;
	struct ostream *output;
	struct timeout *to;
	const char *prefix;

	unsigned int request_counter;

	bool (*reply_callback)(const char *cmd, const char *const *args,
			       void *context);
	void *reply_context;

	unsigned int sent_handshake:1;
	unsigned int handshaked:1;
	unsigned int aborted:1;
};

struct auth_master_lookup_ctx {
	struct auth_master_connection *conn;
	const char *user;
	const char *expected_reply;
	int return_value;

	pool_t pool;
	const char **fields;
};

struct auth_master_user_list_ctx {
	struct auth_master_connection *conn;
	string_t *username;
	bool finished;
	bool failed;
};

static void auth_input(struct auth_master_connection *conn);

struct auth_master_connection *
auth_master_init(const char *auth_socket_path, enum auth_master_flags flags)
{
	struct auth_master_connection *conn;

	conn = i_new(struct auth_master_connection, 1);
	conn->auth_socket_path = i_strdup(auth_socket_path);
	conn->fd = -1;
	conn->flags = flags;
	conn->prefix = DEFAULT_USERDB_LOOKUP_PREFIX;
	return conn;
}

static void auth_connection_close(struct auth_master_connection *conn)
{
	if (conn->to != NULL)
		timeout_remove(&conn->to);
	if (conn->fd != -1) {
		if (close(conn->fd) < 0)
			i_error("close(%s) failed: %m", conn->auth_socket_path);
		conn->fd = -1;
	}

	conn->sent_handshake = FALSE;
	conn->handshaked = FALSE;
}

void auth_master_deinit(struct auth_master_connection **_conn)
{
	struct auth_master_connection *conn = *_conn;

	*_conn = NULL;
	auth_connection_close(conn);
	i_free(conn->auth_socket_path);
	i_free(conn);
}

const char *auth_master_get_socket_path(struct auth_master_connection *conn)
{
	return conn->auth_socket_path;
}

static void auth_request_lookup_abort(struct auth_master_connection *conn)
{
	io_loop_stop(conn->ioloop);
	conn->aborted = TRUE;
}

static int auth_input_handshake(struct auth_master_connection *conn)
{
	const char *line, *const *tmp;

	while ((line = i_stream_next_line(conn->input)) != NULL) {
		tmp = t_strsplit_tabescaped(line);
		if (strcmp(tmp[0], "VERSION") == 0 &&
		    tmp[1] != NULL && tmp[2] != NULL) {
			if (strcmp(tmp[1], dec2str(AUTH_PROTOCOL_MAJOR)) != 0) {
				i_error("userdb lookup: "
					"Auth protocol version mismatch "
					"(%s vs %d)", tmp[1],
					AUTH_PROTOCOL_MAJOR);
				auth_request_lookup_abort(conn);
				return -1;
			}
		} else if (strcmp(tmp[0], "SPID") == 0) {
			conn->handshaked = TRUE;
			break;
		}
	}
	return 0;
}

static int parse_reply(const char *cmd, const char *const *args,
		       const char *expected_reply, const char *user, bool debug)
{
	if (strcmp(cmd, expected_reply) == 0)
		return 1;
	if (strcmp(cmd, "NOTFOUND") == 0)
		return 0;
	if (strcmp(cmd, "FAIL") == 0) {
		if (*args == NULL) {
			i_error("user %s: Auth %s lookup failed",
				user, expected_reply);
		} else if (debug) {
			i_debug("user %s: Auth %s lookup returned temporary failure: %s",
				user, expected_reply, *args);
		}
		return -2;
	}
	i_error("Unknown reply: %s", cmd);
	return -1;
}

static const char *const *args_hide_passwords(const char *const *args)
{
	ARRAY_TYPE(const_string) new_args;
	const char *p, *p2;
	unsigned int i;

	/* if there are any keys that contain "pass" string */
	for (i = 0; args[i] != NULL; i++) {
		p = strstr(args[i], "pass");
		if (p != NULL && p < strchr(args[i], '='))
			break;
	}
	if (args[i] == NULL)
		return args;

	/* there are. replace their values with <hidden> */
	t_array_init(&new_args, i + 16);
	array_append(&new_args, args, i);
	for (; args[i] != NULL; i++) {
		p = strstr(args[i], "pass");
		p2 = strchr(args[i], '=');
		if (p != NULL && p < p2) {
			p = t_strconcat(t_strdup_until(args[i], p2),
					"=<hidden>", NULL);
			array_append(&new_args, &p, 1);
		} else {
			array_append(&new_args, &args[i], 1);
		}
	}
	array_append_zero(&new_args);
	return array_idx(&new_args, 0);
}

static bool auth_lookup_reply_callback(const char *cmd, const char *const *args,
				       void *context)
{
	struct auth_master_lookup_ctx *ctx = context;
	unsigned int i, len;
	bool debug = (ctx->conn->flags & AUTH_MASTER_FLAG_DEBUG) != 0;

	io_loop_stop(ctx->conn->ioloop);

	ctx->return_value =
		parse_reply(cmd, args, ctx->expected_reply, ctx->user, debug);

	len = str_array_length(args);
	if (ctx->return_value >= 0) {
		ctx->fields = p_new(ctx->pool, const char *, len + 1);
		for (i = 0; i < len; i++)
			ctx->fields[i] = str_tabunescape(p_strdup(ctx->pool, args[i]));
	} else {
		/* put the reason string into first field */
		ctx->fields = p_new(ctx->pool, const char *, 2);
		for (i = 0; i < len; i++) {
			if (strncmp(args[i], "reason=", 7) == 0) {
				ctx->fields[0] =
					p_strdup(ctx->pool, args[i] + 7);
				break;
			}
		}
	}
	if (debug) {
		args = args_hide_passwords(args);
		i_debug("auth %s input: %s", ctx->expected_reply,
			t_strarray_join(args, " "));
	}
	return TRUE;
}

static bool
auth_handle_line(struct auth_master_connection *conn, const char *line)
{
	const char *cmd, *const *args, *id, *wanted_id;

	args = t_strsplit_tab(line);
	cmd = *args; args++;
	if (*args == NULL)
		id = "";
	else {
		id = *args;
		args++;
	}

	wanted_id = dec2str(conn->request_counter);
	if (strcmp(id, wanted_id) == 0)
		return conn->reply_callback(cmd, args, conn->reply_context);

	if (strcmp(cmd, "CUID") == 0) {
		i_error("%s: %s is an auth client socket. "
			"It should be a master socket.",
			conn->prefix, conn->auth_socket_path);
	} else {
		i_error("%s: BUG: Unexpected input: %s", conn->prefix, line);
	}
	auth_request_lookup_abort(conn);
	return FALSE;
}

static void auth_input(struct auth_master_connection *conn)
{
	const char *line;
	bool ret;

	switch (i_stream_read(conn->input)) {
	case 0:
		return;
	case -1:
		/* disconnected */
		i_error("%s: Disconnected unexpectedly",
			conn->prefix);
		auth_request_lookup_abort(conn);
		return;
	case -2:
		/* buffer full */
		i_error("%s: BUG: Received more than %d bytes",
			conn->prefix, MAX_INBUF_SIZE);
		auth_request_lookup_abort(conn);
		return;
	}

	if (!conn->handshaked) {
		if (auth_input_handshake(conn) < 0)
			return;
	}

	while ((line = i_stream_next_line(conn->input)) != NULL) {
		T_BEGIN {
			io_loop_set_current(conn->prev_ioloop);
			ret = auth_handle_line(conn, line);
			io_loop_set_current(conn->ioloop);
		} T_END;
		if (!ret)
			return;
	}
}

static int auth_master_connect(struct auth_master_connection *conn)
{
	int fd;

	i_assert(conn->fd == -1);

	/* max. 1 second wait here. */
	fd = net_connect_unix_with_retries(conn->auth_socket_path, 1000);
	if (fd == -1) {
		if (errno == EACCES) {
			i_error("userdb lookup: %s",
				eacces_error_get("connect",
						 conn->auth_socket_path));
		} else {
			i_error("userdb lookup: connect(%s) failed: %m",
				conn->auth_socket_path);
		}
		return -1;
	}
	conn->fd = fd;
	return 0;
}

static void auth_request_timeout(struct auth_master_connection *conn)
{
	if (!conn->handshaked)
		i_error("%s: Connecting timed out", conn->prefix);
	else
		i_error("%s: Request timed out", conn->prefix);
	auth_request_lookup_abort(conn);
}

static void auth_idle_timeout(struct auth_master_connection *conn)
{
	auth_connection_close(conn);
}

static void auth_master_set_io(struct auth_master_connection *conn)
{
	if (conn->ioloop != NULL)
		return;

	if (conn->to != NULL)
		timeout_remove(&conn->to);

	conn->prev_ioloop = current_ioloop;
	conn->ioloop = io_loop_create();
	conn->input = i_stream_create_fd(conn->fd, MAX_INBUF_SIZE, FALSE);
	conn->output = o_stream_create_fd(conn->fd, MAX_OUTBUF_SIZE, FALSE);
	conn->io = io_add(conn->fd, IO_READ, auth_input, conn);
	conn->to = timeout_add(1000*MASTER_AUTH_LOOKUP_TIMEOUT_SECS,
			       auth_request_timeout, conn);
	lib_signals_reset_ioloop();
}

static void auth_master_unset_io(struct auth_master_connection *conn)
{
	if (conn->prev_ioloop != NULL) {
		io_loop_set_current(conn->prev_ioloop);
		lib_signals_reset_ioloop();
	}
	if (conn->ioloop != NULL) {
		io_loop_set_current(conn->ioloop);

		timeout_remove(&conn->to);
		io_remove(&conn->io);
		i_stream_unref(&conn->input);
		o_stream_unref(&conn->output);
		io_loop_destroy(&conn->ioloop);
	}

	if ((conn->flags & AUTH_MASTER_FLAG_NO_IDLE_TIMEOUT) == 0) {
		if (conn->prev_ioloop == NULL)
			auth_connection_close(conn);
		else {
			i_assert(conn->to == NULL);
			conn->to = timeout_add(1000*AUTH_MASTER_IDLE_SECS,
					       auth_idle_timeout, conn);
		}
	}
}

static bool is_valid_string(const char *str)
{
	const char *p;

	/* make sure we're not sending any characters that have a special
	   meaning. */
	for (p = str; *p != '\0'; p++) {
		if (*p == '\t' || *p == '\n' || *p == '\r')
			return FALSE;
	}
	return TRUE;
}

static int auth_master_run_cmd_pre(struct auth_master_connection *conn,
				   const char *cmd)
{
	const char *str;

	if (conn->fd == -1) {
		if (auth_master_connect(conn) < 0)
			return -1;
		i_assert(conn->fd != -1);
	}
	auth_master_set_io(conn);

	o_stream_cork(conn->output);
	if (!conn->sent_handshake) {
		str = t_strdup_printf("VERSION\t%d\t%d\n",
				      AUTH_PROTOCOL_MAJOR, AUTH_PROTOCOL_MINOR);
		o_stream_nsend_str(conn->output, str);
		conn->sent_handshake = TRUE;
	}

	o_stream_nsend_str(conn->output, cmd);
	o_stream_uncork(conn->output);

	if (o_stream_nfinish(conn->output) < 0) {
		i_error("write(auth socket) failed: %s",
			o_stream_get_error(conn->output));
		auth_master_unset_io(conn);
		auth_connection_close(conn);
		return -1;
	}
	return 0;
}

static int auth_master_run_cmd_post(struct auth_master_connection *conn)
{
	auth_master_unset_io(conn);
	if (conn->aborted) {
		conn->aborted = FALSE;
		auth_connection_close(conn);
		return -1;
	}
	return 0;
}

static int auth_master_run_cmd(struct auth_master_connection *conn,
			       const char *cmd)
{
	if (auth_master_run_cmd_pre(conn, cmd) < 0)
		return -1;
	io_loop_run(conn->ioloop);
	return auth_master_run_cmd_post(conn);
}

static unsigned int
auth_master_next_request_id(struct auth_master_connection *conn)
{
	if (++conn->request_counter == 0) {
		/* avoid zero */
		conn->request_counter++;
	}
	return conn->request_counter;
}

static void
auth_user_info_export(string_t *str, const struct auth_user_info *info)
{
	if (info->service != NULL) {
		str_append(str, "\tservice=");
		str_append(str, info->service);
	}

	if (info->local_ip.family != 0)
		str_printfa(str, "\tlip=%s", net_ip2addr(&info->local_ip));
	if (info->local_port != 0)
		str_printfa(str, "\tlport=%d", info->local_port);
	if (info->remote_ip.family != 0)
		str_printfa(str, "\trip=%s", net_ip2addr(&info->remote_ip));
	if (info->remote_port != 0)
		str_printfa(str, "\trport=%d", info->remote_port);
	if (info->debug)
		str_append(str, "\tdebug");
}

int auth_master_user_lookup(struct auth_master_connection *conn,
			    const char *user, const struct auth_user_info *info,
			    pool_t pool, const char **username_r,
			    const char *const **fields_r)
{
	struct auth_master_lookup_ctx ctx;
	string_t *str;

	if (!is_valid_string(user) || !is_valid_string(info->service)) {
		/* non-allowed characters, the user can't exist */
		*username_r = NULL;
		*fields_r = NULL;
		return 0;
	}

	i_zero(&ctx);
	ctx.conn = conn;
	ctx.return_value = -1;
	ctx.pool = pool;
	ctx.expected_reply = "USER";
	ctx.user = user;

	conn->reply_callback = auth_lookup_reply_callback;
	conn->reply_context = &ctx;

	str = t_str_new(128);
	str_printfa(str, "USER\t%u\t%s",
		    auth_master_next_request_id(conn), user);
	auth_user_info_export(str, info);
	str_append_c(str, '\n');

	conn->prefix = t_strdup_printf("userdb lookup(%s)", user);
	(void)auth_master_run_cmd(conn, str_c(str));
	conn->prefix = DEFAULT_USERDB_LOOKUP_PREFIX;

	if (ctx.return_value <= 0 || ctx.fields[0] == NULL) {
		*username_r = NULL;
		*fields_r = ctx.fields != NULL ? ctx.fields :
			p_new(pool, const char *, 1);
		if (ctx.return_value > 0) {
			i_error("Userdb lookup didn't return username");
			ctx.return_value = -2;
		}
	} else {
		*username_r = ctx.fields[0];
		*fields_r = ctx.fields + 1;
	}
	conn->reply_context = NULL;
	return ctx.return_value;
}

void auth_user_fields_parse(const char *const *fields, pool_t pool,
			    struct auth_user_reply *reply_r)
{
	i_zero(reply_r);
	reply_r->uid = (uid_t)-1;
	reply_r->gid = (gid_t)-1;
	p_array_init(&reply_r->extra_fields, pool, 64);

	for (; *fields != NULL; fields++) {
		if (strncmp(*fields, "uid=", 4) == 0) {
			if (str_to_uid(*fields + 4, &reply_r->uid) < 0)
				i_error("Invalid uid in reply");
		} else if (strncmp(*fields, "gid=", 4) == 0) {
			if (str_to_gid(*fields + 4, &reply_r->gid) < 0)
				i_error("Invalid gid in reply");
		} else if (strncmp(*fields, "home=", 5) == 0)
			reply_r->home = p_strdup(pool, *fields + 5);
		else if (strncmp(*fields, "chroot=", 7) == 0)
			reply_r->chroot = p_strdup(pool, *fields + 7);
		else if (strcmp(*fields, "anonymous") == 0)
			reply_r->anonymous = TRUE;
		else {
			const char *field = p_strdup(pool, *fields);
			array_append(&reply_r->extra_fields, &field, 1);
		}
	}
}

int auth_master_pass_lookup(struct auth_master_connection *conn,
			    const char *user, const struct auth_user_info *info,
			    pool_t pool, const char *const **fields_r)
{
	struct auth_master_lookup_ctx ctx;
	string_t *str;

	if (!is_valid_string(user) || !is_valid_string(info->service)) {
		/* non-allowed characters, the user can't exist */
		*fields_r = NULL;
		return 0;
	}

	i_zero(&ctx);
	ctx.conn = conn;
	ctx.return_value = -1;
	ctx.pool = pool;
	ctx.expected_reply = "PASS";
	ctx.user = user;

	conn->reply_callback = auth_lookup_reply_callback;
	conn->reply_context = &ctx;

	str = t_str_new(128);
	str_printfa(str, "PASS\t%u\t%s",
		    auth_master_next_request_id(conn), user);
	auth_user_info_export(str, info);
	str_append_c(str, '\n');

	conn->prefix = t_strdup_printf("passdb lookup(%s)", user);
	(void)auth_master_run_cmd(conn, str_c(str));
	conn->prefix = DEFAULT_USERDB_LOOKUP_PREFIX;

	*fields_r = ctx.fields != NULL ? ctx.fields :
		p_new(pool, const char *, 1);
	conn->reply_context = NULL;
	return ctx.return_value;
}

struct auth_master_cache_ctx {
	struct auth_master_connection *conn;
	unsigned int count;
	bool failed;
};

static bool
auth_cache_flush_reply_callback(const char *cmd, const char *const *args,
				void *context)
{
	struct auth_master_cache_ctx *ctx = context;

	if (strcmp(cmd, "OK") != 0)
		ctx->failed = TRUE;
	else if (args[0] == NULL || str_to_uint(args[0], &ctx->count) < 0)
		ctx->failed = TRUE;

	io_loop_stop(ctx->conn->ioloop);
	return TRUE;
}

int auth_master_cache_flush(struct auth_master_connection *conn,
			    const char *const *users, unsigned int *count_r)
{
	struct auth_master_cache_ctx ctx;
	string_t *str;

	i_zero(&ctx);
	ctx.conn = conn;

	conn->reply_callback = auth_cache_flush_reply_callback;
	conn->reply_context = &ctx;

	str = t_str_new(128);
	str_printfa(str, "CACHE-FLUSH\t%u", auth_master_next_request_id(conn));
	if (users != NULL) {
		for (; *users != NULL; users++) {
			str_append_c(str, '\t');
			str_append_tabescaped(str, *users);
		}
	}
	str_append_c(str, '\n');

	conn->prefix = "auth cache flush";
	(void)auth_master_run_cmd(conn, str_c(str));
	conn->prefix = DEFAULT_USERDB_LOOKUP_PREFIX;

	conn->reply_context = NULL;
	*count_r = ctx.count;
	return ctx.failed ? -1 : 0;
}

static bool
auth_user_list_reply_callback(const char *cmd, const char *const *args,
			      void *context)
{
	struct auth_master_user_list_ctx *ctx = context;

	timeout_reset(ctx->conn->to);
	str_truncate(ctx->username, 0);
	io_loop_stop(ctx->conn->ioloop);

	if (strcmp(cmd, "DONE") == 0) {
		if (args[0] != NULL && strcmp(args[0], "fail") == 0) {
			i_error("User listing returned failure");
			ctx->failed = TRUE;
		}
		ctx->finished = TRUE;
	} else if (strcmp(cmd, "LIST") == 0 && args[0] != NULL) {
		/* we'll just read all the users into memory. otherwise we'd
		   have to use a separate connection for listing and there's
		   a higher chance of a failure since the connection could be
		   open to dovecot-auth for a long time. */
		str_append(ctx->username, args[0]);
	} else {
		i_error("User listing returned invalid input");
		ctx->failed = TRUE;
	}
	return FALSE;
}

struct auth_master_user_list_ctx *
auth_master_user_list_init(struct auth_master_connection *conn,
			   const char *user_mask,
			   const struct auth_user_info *info)
{
	struct auth_master_user_list_ctx *ctx;
	string_t *str;

	ctx = i_new(struct auth_master_user_list_ctx, 1);
	ctx->conn = conn;
	ctx->username = str_new(default_pool, 128);

	conn->reply_callback = auth_user_list_reply_callback;
	conn->reply_context = ctx;

	str = t_str_new(128);
	str_printfa(str, "LIST\t%u",
		    auth_master_next_request_id(conn));
	if (*user_mask != '\0')
		str_printfa(str, "\tuser=%s", user_mask);
	if (info != NULL)
		auth_user_info_export(str, info);
	str_append_c(str, '\n');

	conn->prefix = "userdb list";

	if (auth_master_run_cmd_pre(conn, str_c(str)) < 0)
		ctx->failed = TRUE;
	if (conn->prev_ioloop != NULL)
		io_loop_set_current(conn->prev_ioloop);
	conn->prefix = DEFAULT_USERDB_LOOKUP_PREFIX;
	return ctx;
}

const char *auth_master_user_list_next(struct auth_master_user_list_ctx *ctx)
{
	const char *line;

	if (ctx->conn->input == NULL)
		return NULL;

	/* try to read already buffered input */
	line = i_stream_next_line(ctx->conn->input);
	if (line != NULL) {
		T_BEGIN {
			auth_handle_line(ctx->conn, line);
		} T_END;
	} else {
		/* wait for more data */
		io_loop_set_current(ctx->conn->ioloop);
		io_loop_run(ctx->conn->ioloop);
		io_loop_set_current(ctx->conn->prev_ioloop);
	}

	if (ctx->finished || ctx->failed || ctx->conn->aborted)
		return NULL;
	return str_c(ctx->username);
}

int auth_master_user_list_deinit(struct auth_master_user_list_ctx **_ctx)
{
	struct auth_master_user_list_ctx *ctx = *_ctx;
	int ret = ctx->failed ? -1 : 0;

	*_ctx = NULL;
	auth_master_run_cmd_post(ctx->conn);
	str_free(&ctx->username);
	i_free(ctx);
	return ret;
}