path: root/pigeonhole/src/lib-sieve/plugins/enotify/ext-enotify-common.c

/* Copyright (c) 2002-2018 Pigeonhole authors, see the included COPYING file
 */

#include "lib.h"
#include "str.h"
#include "str-sanitize.h"
#include "array.h"

#include "sieve-common.h"
#include "sieve-ast.h"
#include "sieve-stringlist.h"
#include "sieve-code.h"
#include "sieve-commands.h"
#include "sieve-validator.h"
#include "sieve-interpreter.h"
#include "sieve-result.h"

#include "ext-enotify-limits.h"
#include "ext-enotify-common.h"

#include <ctype.h>

/* FIXME: (from draft RFC)
 
   Header/envelope tests [Sieve] together with Sieve variables can be used to
   extract the list of users to receive notifications from the incoming email
   message or its envelope. This is potentially quite dangerous, as this can be
   used for Deny Of Service attacks on recipients controlled by the message
   sender. For this reason implementations SHOULD NOT allow use of variables
   containing values extracted from the email message in the method parameter to
   the notify action.  Note that violation of this SHOULD NOT may result in* the
   creation of an open relay, i.e. any sender would be able to create specially
   crafted email messages that would result in notifications delivered to
   recipients under the control of the sender. In worst case this might result
   in financial loss by user controlling the Sieve script and/or by recipients
   of notifications (e.g. if a notification is an SMS message).

   --> This is currently not possible to check.
 */

/*
 * Notify capability
 */

static const char *
ext_notify_get_methods_string(const struct sieve_extension *ntfy_ext);

const struct sieve_extension_capabilities notify_capabilities = {
	"notify",
	ext_notify_get_methods_string
};

/*
 * Core notification methods
 */

extern const struct sieve_enotify_method_def mailto_notify;

/*
 * Notify method registry
 */

static const struct sieve_enotify_method *
ext_enotify_method_register(struct sieve_instance *svinst,
			    struct ext_enotify_context *ectx,
			    const struct sieve_enotify_method_def *nmth_def)
{
	struct sieve_enotify_method *nmth;
	int nmth_id = (int)array_count(&ectx->notify_methods);

	nmth = array_append_space(&ectx->notify_methods);
	nmth->def = nmth_def;
	nmth->id = nmth_id;
	nmth->svinst = svinst;

	if (nmth_def->load != NULL)
		nmth_def->load(nmth, &nmth->context);

	return nmth;
}

void ext_enotify_methods_init(struct sieve_instance *svinst,
			      struct ext_enotify_context *ectx)
{
	p_array_init(&ectx->notify_methods, default_pool, 4);

	ext_enotify_method_register(svinst, ectx, &mailto_notify);
}

void ext_enotify_methods_deinit(struct ext_enotify_context *ectx)
{
	const struct sieve_enotify_method *methods;
	unsigned int meth_count, i;

	methods = array_get(&ectx->notify_methods, &meth_count);
	for (i = 0; i < meth_count; i++) {
		if (methods[i].def != NULL && methods[i].def->unload != NULL)
			methods[i].def->unload(&methods[i]);
	}

	array_free(&ectx->notify_methods);
}

const struct sieve_enotify_method *
sieve_enotify_method_register(struct sieve_instance *svinst,
			      const struct sieve_enotify_method_def *nmth_def)
{
	const struct sieve_extension *ntfy_ext =
		sieve_extension_get_by_name(svinst, "enotify");

	if (ntfy_ext != NULL) {
		struct ext_enotify_context *ectx =
			(struct ext_enotify_context *) ntfy_ext->context;

		return ext_enotify_method_register(svinst, ectx, nmth_def);
	}
	return NULL;
}

void sieve_enotify_method_unregister(const struct sieve_enotify_method *nmth)
{
	struct sieve_instance *svinst = nmth->svinst;
	const struct sieve_extension *ntfy_ext =
		sieve_extension_get_by_name(svinst, "enotify");

	if (ntfy_ext != NULL) {
		struct ext_enotify_context *ectx =
			(struct ext_enotify_context *) ntfy_ext->context;
		int nmth_id = nmth->id;

		if (nmth_id >= 0 &&
		    nmth_id < (int)array_count(&ectx->notify_methods)) {
			struct sieve_enotify_method *nmth_mod =
				array_idx_modifiable(&ectx->notify_methods,
						     nmth_id);

			nmth_mod->def = NULL;
		}
	}
}

const struct sieve_enotify_method *
ext_enotify_method_find(const struct sieve_extension *ntfy_ext,
			const char *identifier)
{
	struct ext_enotify_context *ectx =
		(struct ext_enotify_context *)ntfy_ext->context;
	unsigned int meth_count, i;
	const struct sieve_enotify_method *methods;

	methods = array_get(&ectx->notify_methods, &meth_count);
	for (i = 0; i < meth_count; i++) {
		if (methods[i].def == NULL)
			continue;

		if (strcasecmp(methods[i].def->identifier, identifier) == 0)
			return &methods[i];
	}
	return NULL;
}

static const char *
ext_notify_get_methods_string(const struct sieve_extension *ntfy_ext)
{
	struct ext_enotify_context *ectx =
		(struct ext_enotify_context *) ntfy_ext->context;
	unsigned int meth_count, i;
	const struct sieve_enotify_method *methods;
	string_t *result = t_str_new(128);

	methods = array_get(&ectx->notify_methods, &meth_count);
	if (meth_count > 0) {
		for (i = 0; i < meth_count; i++) {
			if (str_len(result) > 0)
				str_append_c(result, ' ');
			if (methods[i].def != NULL)
				str_append(result, methods[i].def->identifier);
		}
		return str_c(result);
	}
	return NULL;
}

/*
 * Compile-time argument validation
 */

static const char *ext_enotify_uri_scheme_parse(const char **uri_p)
{
	string_t *scheme = t_str_new(EXT_ENOTIFY_MAX_SCHEME_LEN);
	const char *p = *uri_p;
	unsigned int len = 0;

	/* RFC 3968:
	  
	     scheme  = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
	  
	   FIXME: we do not allow '%' in schemes. Is this correct?
	 */

	if (!i_isalpha(*p))
		return NULL;

	str_append_c(scheme, *p);
	p++;

	while (*p != '\0' && len < EXT_ENOTIFY_MAX_SCHEME_LEN) {
		if (!i_isalnum(*p) && *p != '+' && *p != '-' && *p != '.')
			break;

		str_append_c(scheme, *p);
		p++;
		len++;
	}

	if (*p != ':')
		return NULL;
	p++;

	*uri_p = p;
	return str_c(scheme);
}

static bool
ext_enotify_option_parse(struct sieve_enotify_env *nenv,
			 const char *option, bool name_only,
			 const char **opt_name_r, const char **opt_value_r)
{
	const char *p = option;

	/* "<optionname>=<value>".
	
	   l-d = ALPHA / DIGIT
	   l-d-p = l-d / "." / "-" / "_"
	   optionname = l-d *l-d-p
	   value = *(%x01-09 / %x0B-0C / %x0E-FF)
	 */

	/*
	 * Parse option name
	 */

	/* optionname = l-d *l-d-p
	 */

	/* Explicitly report empty option as such */
	if (*p == '\0') {
		sieve_enotify_error(nenv, "empty option specified");
		return FALSE;
	}

	/* l-d = ALPHA / DIGIT */
	if (i_isalnum(*p)) {
		p++;

		/* l-d-p = l-d / "." / "-" / "_" */
		while (i_isalnum(*p) || *p == '.' || *p == '-' || *p == '_')
			p++;
	}

	/* Parsing must end at '=' and we must parse at least one character */
	if (*p != '=' || p == option) {
		sieve_enotify_error(
			nenv, "invalid option name specified in option '%s'",
			str_sanitize(option, 80));
		return FALSE;
	}

	/* Assign option name */
	if (opt_name_r != NULL)
		*opt_name_r = t_strdup_until(option, p);

	/* Skip '=' */
	p++;

	/* Exit now if only the option name is of interest */
	if (name_only)
		return TRUE;

	/*
	 * Parse option value
	 */

	/* value = *(%x01-09 / %x0B-0C / %x0E-FF) */
	while (*p != '\0' && *p != 0x0A && *p != 0x0D)
		p++;

	/* Parse must end at end of string */
	if (*p != '\0') {
		sieve_enotify_error(
			nenv, "notify command: "
			"invalid option value specified in option '%s'",
			str_sanitize(option, 80));
		return FALSE;
	}

	/* Assign option value */
	if (opt_value_r != NULL)
		*opt_value_r = p;

	return TRUE;
}

struct _ext_enotify_option_check_context {
	struct sieve_instance *svinst;
	struct sieve_validator *valdtr;
	const struct sieve_enotify_method *method;
};

static int
_ext_enotify_option_check(void *context, struct sieve_ast_argument *arg)
{
	struct _ext_enotify_option_check_context *optn_context =
		(struct _ext_enotify_option_check_context *) context;
	struct sieve_validator *valdtr = optn_context->valdtr;
	const struct sieve_enotify_method *method = optn_context->method;
	struct sieve_enotify_env nenv;
	const char *option = sieve_ast_argument_strc(arg);
	const char *opt_name = NULL, *opt_value = NULL;
	bool check = TRUE;
	int result = 1;

	/* Compose log structure */
	i_zero(&nenv);
	nenv.svinst = optn_context->svinst;
	nenv.method = method;
	nenv.ehandler = sieve_validator_error_handler(valdtr);
	nenv.location = sieve_error_script_location(
		sieve_validator_script(valdtr), arg->source_line);
	nenv.event = event_create(nenv.svinst->event);
	event_set_append_log_prefix(nenv.event, "notify command: ");

	/* Parse option */
	if (!sieve_argument_is_string_literal(arg)) {
		/* Variable string: partial option parse

		   If the string item is not a string literal, it cannot be
		   validated fully at compile time. We can however check whether
		   the '=' is in the string specification and whether the part
		   before the '=' is a valid option name. In that case, the
		   method option check function is called with the value
		   parameter equal to NULL, meaning that it should only check
		   the validity of the option itself and not the assigned value.
		 */
		if (!ext_enotify_option_parse(NULL, option, TRUE,
					      &opt_name, &opt_value))
			check = FALSE;
	} else {
		/* Literal string: full option parse */
		if (!ext_enotify_option_parse(&nenv, option, FALSE,
					      &opt_name, &opt_value))
			result = -1;
	}

	/* Call method's option check function */
	if (result > 0 && check && method->def != NULL &&
	    method->def->compile_check_option != NULL) {
		result = (method->def->compile_check_option(&nenv, opt_name,
							    opt_value) ?
			  1 : -1 );
	}

	event_unref(&nenv.event);
	return result;
}

bool ext_enotify_compile_check_arguments(struct sieve_validator *valdtr,
					 struct sieve_command *cmd,
					 struct sieve_ast_argument *uri_arg,
					 struct sieve_ast_argument *msg_arg,
					 struct sieve_ast_argument *from_arg,
					 struct sieve_ast_argument *options_arg)
{
	const struct sieve_extension *this_ext = cmd->ext;
	struct sieve_instance *svinst = this_ext->svinst;
	const char *uri = sieve_ast_argument_strc(uri_arg);
	const char *scheme;
	const struct sieve_enotify_method *method;
	struct sieve_enotify_env nenv;
	bool result = TRUE;

	/* If the uri string is not a constant literal, we cannot determine
	   which method is used, so we bail out successfully and defer checking
	   to runtime.
	 */
	if (!sieve_argument_is_string_literal(uri_arg))
		return TRUE;

	/* Parse scheme part of URI */
	if ((scheme = ext_enotify_uri_scheme_parse(&uri)) == NULL) {
		sieve_argument_validate_error(
			valdtr, uri_arg, "notify command: "
			"invalid scheme part for method URI '%s'",
			str_sanitize(sieve_ast_argument_strc(uri_arg), 80));
		return FALSE;
	}

	/* Find used method with the parsed scheme identifier */
	if ((method = ext_enotify_method_find(this_ext, scheme)) == NULL) {
		sieve_argument_validate_error(
			valdtr, uri_arg, "notify command: "
			"invalid method '%s'", scheme);
		return FALSE;
	}

	if (method->def == NULL)
		return TRUE;

	/* Compose log structure */
	i_zero(&nenv);
	nenv.svinst = svinst;
	nenv.method = method;

	/* Check URI itself */
	if (result && method->def->compile_check_uri != NULL) {
		/* Set log location to location of URI argument */
		nenv.ehandler = sieve_validator_error_handler(valdtr);
		nenv.location = sieve_error_script_location(
			sieve_validator_script(valdtr), uri_arg->source_line);
		nenv.event = event_create(nenv.svinst->event);
		event_set_append_log_prefix(nenv.event, "notify command: ");

		/* Execute method check function */
		result = method->def->compile_check_uri(
			&nenv, sieve_ast_argument_strc(uri_arg), uri);
	}

	/* Check :message argument */
	if (result && msg_arg != NULL &&
	    sieve_argument_is_string_literal(msg_arg) &&
	    method->def->compile_check_message != NULL ) {
		/* Set log location to location of :message argument */
		event_unref(&nenv.event);
		nenv.ehandler = sieve_validator_error_handler(valdtr);
		nenv.location = sieve_error_script_location(
			sieve_validator_script(valdtr), msg_arg->source_line);
		nenv.event = event_create(nenv.svinst->event);
		event_set_append_log_prefix(nenv.event, "notify command: ");

		/* Execute method check function */
		result = method->def->compile_check_message(
			&nenv, sieve_ast_argument_str(msg_arg));
	}

	/* Check :from argument */
	if (result && from_arg != NULL &&
	    sieve_argument_is_string_literal(from_arg) &&
	    method->def->compile_check_from != NULL ) {
		/* Set log location to location of :from argument */
		event_unref(&nenv.event);
		nenv.ehandler = sieve_validator_error_handler(valdtr);
		nenv.location = sieve_error_script_location(
			sieve_validator_script(valdtr), from_arg->source_line);
		nenv.event = event_create(nenv.svinst->event);
		event_set_append_log_prefix(nenv.event, "notify command: ");

		/* Execute method check function */
		result = method->def->compile_check_from(
			&nenv, sieve_ast_argument_str(from_arg));
	}

	event_unref(&nenv.event);

	/* Check :options argument */
	if (result && options_arg != NULL) {
		struct sieve_ast_argument *option = options_arg;
		struct _ext_enotify_option_check_context optn_context = {
			svinst, valdtr, method };

		/* Parse and check options */
		result = (sieve_ast_stringlist_map(
			&option, (void *) &optn_context,
			_ext_enotify_option_check) > 0);

		/* Discard argument if options are not accepted by method */
		if (result && method->def->compile_check_option == NULL) {
			sieve_argument_validate_warning(
				valdtr, options_arg, "notify command: "
				"method '%s' accepts no options", scheme);
			(void)sieve_ast_arguments_detach(options_arg, 1);
		}
	}
	return result;
}

/*
 * Runtime operand checking
 */

bool ext_enotify_runtime_method_validate(const struct sieve_runtime_env *renv,
					 string_t *method_uri)
{
	const struct sieve_execute_env *eenv = renv->exec_env;
	const struct sieve_extension *this_ext = renv->oprtn->ext;
	const struct sieve_enotify_method *method;
	const char *uri = str_c(method_uri);
	const char *scheme;
	bool result = TRUE;

	/* Get the method */

	if ((scheme = ext_enotify_uri_scheme_parse(&uri)) == NULL)
		return FALSE;
	if ((method = ext_enotify_method_find(this_ext, scheme)) == NULL)
		return FALSE;

	/* Validate the provided URI */

	if (method->def != NULL && method->def->runtime_check_uri != NULL) {
		struct sieve_enotify_env nenv;

		i_zero(&nenv);
		nenv.svinst = eenv->svinst;
		nenv.method = method;
		nenv.ehandler = renv->ehandler;
		nenv.location = sieve_runtime_get_full_command_location(renv),
		nenv.event = event_create(nenv.svinst->event);
		event_set_append_log_prefix(nenv.event,
					    "valid_notify_method test: ");

		/* Use the method check function to validate the URI */
		result = method->def->runtime_check_uri(
			&nenv, str_c(method_uri), uri);

		event_unref(&nenv.event);
	}

	return result;
}

static const struct
sieve_enotify_method *ext_enotify_get_method(
	const struct sieve_runtime_env *renv, string_t *method_uri,
	const char **uri_body_r)
{
	const struct sieve_extension *this_ext = renv->oprtn->ext;
	const struct sieve_enotify_method *method;
	const char *uri = str_c(method_uri);
	const char *scheme;

	/* Parse part before ':' of the uri (the scheme) and use it to identify
	   notify method.
	 */
	if ((scheme = ext_enotify_uri_scheme_parse(&uri)) == NULL) {
		sieve_runtime_error(
			renv, NULL, "invalid scheme part for method URI '%s'",
			str_sanitize(str_c(method_uri), 80));
		return NULL;
	}

	/* Find the notify method */
	if ((method = ext_enotify_method_find(this_ext, scheme)) == NULL) {
		sieve_runtime_error(renv, NULL,	"invalid notify method '%s'",
				    scheme);
		return NULL;
	}

	/* Return the parse pointer and the found method */
	*uri_body_r = uri;
	return method;
}

const char *
ext_enotify_runtime_get_method_capability(const struct sieve_runtime_env *renv,
					  string_t *method_uri,
					  const char *capability)
{
	const struct sieve_execute_env *eenv = renv->exec_env;
	const struct sieve_enotify_method *method;
	const char *uri_body;
	const char *result = NULL;

	/* Get method */
	method = ext_enotify_get_method(renv, method_uri, &uri_body);
	if ( method == NULL ) return NULL;

	/* Get requested capability */
	if (method->def != NULL &&
	    method->def->runtime_get_method_capability != NULL) {
		struct sieve_enotify_env nenv;

		i_zero(&nenv);
		nenv.svinst = eenv->svinst;
		nenv.method = method;
		nenv.ehandler = renv->ehandler;
		nenv.location = sieve_runtime_get_full_command_location(renv),
		nenv.event = event_create(nenv.svinst->event);
		event_set_append_log_prefix(nenv.event,
					    "notify_method_capability test: ");

		/* Execute method function to acquire capability value */
		result = method->def->runtime_get_method_capability(
			&nenv, str_c(method_uri), uri_body, capability);

		event_unref(&nenv.event);
	}

	return result;
}

int ext_enotify_runtime_check_operands(
	const struct sieve_runtime_env *renv, string_t *method_uri,
	string_t *message, string_t *from, struct sieve_stringlist *options,
	const struct sieve_enotify_method **method_r, void **method_context)
{
	const struct sieve_execute_env *eenv = renv->exec_env;
	const struct sieve_enotify_method *method;
	const char *uri_body;

	/* Get method */
	method = ext_enotify_get_method(renv, method_uri, &uri_body);
	if (method == NULL)
		return SIEVE_EXEC_FAILURE;

	/* Check provided operands */
	if (method->def != NULL &&
	    method->def->runtime_check_operands != NULL) {
		struct sieve_enotify_env nenv;
		int result = SIEVE_EXEC_OK;

		i_zero(&nenv);
		nenv.svinst = eenv->svinst;
		nenv.method = method;
		nenv.ehandler = renv->ehandler;
		nenv.location = sieve_runtime_get_full_command_location(renv),
		nenv.event = event_create(nenv.svinst->event);
		event_set_append_log_prefix(nenv.event, "notify_action: ");

		/* Execute check function */
		if (method->def->runtime_check_operands(
			&nenv, str_c(method_uri), uri_body, message, from,
			sieve_result_pool(renv->result), method_context)) {

			/* Check any provided options */
			if (options != NULL) {
				string_t *option = NULL;
				int ret;

				/* Iterate through all provided options */
				while ((ret = sieve_stringlist_next_item(
					options, &option)) > 0) {
					const char *opt_name = NULL;
					const char *opt_value = NULL;

					/* Parse option into <optionname> and
					   <value> */
					if (ext_enotify_option_parse(
						&nenv, str_c(option), FALSE,
						&opt_name, &opt_value)) {

						/* Set option */
						if (method->def->runtime_set_option != NULL) {
							(void)method->def->runtime_set_option(
								&nenv, *method_context,
								opt_name, opt_value);
						}
					}
				}

				/* Check for binary corruptions encountered
				   during string list iteration */
				if (ret >= 0) {
					*method_r = method;
				} else {
					/* Binary corrupt */
					sieve_runtime_trace_error(
						renv, "invalid item in options string list");
					result = SIEVE_EXEC_BIN_CORRUPT;
				}

			} else {
				/* No options */
				*method_r = method;
			}

		} else {
			/* Operand check failed */
			result = SIEVE_EXEC_FAILURE;
		}

		event_unref(&nenv.event);
		return result;
	}

	/* No check function defined: a most unlikely situation */
	*method_context = NULL;
	*method_r = method;
	return SIEVE_EXEC_OK;
}

/*
 * Notify method printing
 */

void sieve_enotify_method_printf(const struct sieve_enotify_print_env *penv,
				 const char *fmt, ...)
{
	va_list args;

	va_start(args, fmt);
	sieve_result_vprintf(penv->result_penv, fmt, args);
	va_end(args);
}

/*
 * Action execution
 */

struct event_passthrough *
sieve_enotify_create_finish_event(const struct sieve_enotify_exec_env *nenv)
{
	struct event_passthrough *e =
		event_create_passthrough(nenv->event)->
		set_name("sieve_action_finished");

	return e;
}