/*

 * Copyright 2020 Red Hat Inc., Durham, North Carolina.

 * All Rights Reserved.

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 *

 * Authors:

 *      Jan Černý <jcerny@redhat.com>

 */

#ifdef HAVE_CONFIG_H

#include <config.h>

#endif

#include <math.h>

#include <errno.h>

#include <pcre.h>

#include <yaml.h>

#include <yaml-path.h>

#include "yamlfilecontent_probe.h"

#include "sexp-manip.h"

#include "debug_priv.h"

#include "oval_fts.h"

#include "list.h"

#include "probe/probe.h"

#define OSCAP_YAML_STRING_TAG "tag:yaml.org,2002:str"

#define OSCAP_YAML_BOOL_TAG "tag:yaml.org,2002:bool"

#define OSCAP_YAML_FLOAT_TAG "tag:yaml.org,2002:float"

#define OSCAP_YAML_INT_TAG "tag:yaml.org,2002:int"

#define OVECCOUNT 30 /* should be a multiple of 3 */

int yamlfilecontent_probe_offline_mode_supported()

{

	return PROBE_OFFLINE_OWN;

}

static bool match_regex(const char *pattern, const char *value)

{

	const char *errptr;

	int erroroffset;

	pcre *re = pcre_compile(pattern, 0, &errptr, &erroroffset, NULL);

	if (re == NULL) {

		dE("pcre_compile failed on pattern '%s': %s at %d", pattern,

			errptr, erroroffset);

		return false;

	}

	int ovector[OVECCOUNT];

	int rc = pcre_exec(re, NULL, value, strlen(value), 0, 0, ovector, OVECCOUNT);

	if (rc > 0) {

		return true;

	}

	return false;

}

static SEXP_t *yaml_scalar_event_to_sexp(yaml_event_t *event)

{

	char *tag = (char *) event->data.scalar.tag;

	char *value = (char *) event->data.scalar.value;

	/* Nodes lacking an explicit tag are given a non-specific tag:

	 * “!” for non-plain scalars, and “?” for all other nodes

	 */

	if (tag == NULL) {

		if (event->data.scalar.style != YAML_PLAIN_SCALAR_STYLE) {

			tag = "!";

		} else {

			tag = "?";

		}

	}

	/* Nodes with "!" tag can be sequences, maps or strings, but we process

	 * only scalars in this functions, so they can only be strings. */

	if (!strcmp(tag, "!")) {

		tag = OSCAP_YAML_STRING_TAG;

	}

	bool question = !strcmp(tag, "?");

	/* Regular expressions based on https://yaml.org/spec/1.2/spec.html#id2804923 */

	if (question || !strcmp(tag, OSCAP_YAML_BOOL_TAG)) {

		if (match_regex("^(true|True|TRUE)$", value)) {

			return SEXP_number_newb(true);

		} else if (match_regex("^(false|False|FALSE)$", value)) {

			return SEXP_number_newb(false);

		} else if (!question) {

			return NULL;

		}

	}

	if (question || !strcmp(tag, OSCAP_YAML_INT_TAG)) {

		if (match_regex("^[+-]?[0-9]+$", value)) {

			int int_value = strtol(value, NULL, 10);

			return SEXP_number_newi(int_value);

		} else if (match_regex("^0o[0-7]+$", value)) {

			/* strtol doesn't understand 0o as octal prefix, it wants 0 */

			int int_value = strtol(value + 2, NULL, 8);

			return SEXP_number_newi(int_value);

		} else if (match_regex("^0x[0-9a-fA-F]+$", value)) {

			int int_value = strtol(value, NULL, 16);

			return SEXP_number_newi(int_value);

		} else if (!question) {

			return NULL;

		}

	}

	if (question || !strcmp(tag, OSCAP_YAML_FLOAT_TAG)) {

		if (match_regex("^[-+]?(\\.[0-9]+|[0-9]+(\\.[0-9]*)?)([eE][-+]?[0-9]+)?$", value)) {

			double double_value = strtod(value, NULL);

			return SEXP_number_newf(double_value);

		} else if (match_regex("^[-+]?(\\.inf|\\.Inf|\\.INF)$", value)) {

			double double_value = INFINITY;

			if (value[0] == '-') {

				double_value = -INFINITY;

			}

			return SEXP_number_newf(double_value);

		} else if (match_regex("^(\\.nan|\\.NaN|\\.NAN)$", value)) {

			double double_value = NAN;

			return SEXP_number_newf(double_value);

		} else if (!question) {

			return NULL;

		}

	}

	return SEXP_string_new(value, strlen(value));

}

static char *escape_key(char *key)

{

	if (key == NULL)

		return NULL;

	size_t cap_letters = 0;

	size_t key_len = strlen(key);

	for (size_t i = 0; i < key_len; i++)

		if ((key[i] >= 'A' && key[i] <= 'Z') || key[i] == '^')

			cap_letters++;

	if (cap_letters == 0)

		return key;

	char *new_key = realloc(key, key_len + 1 + cap_letters);

	if (new_key == NULL)

		return key;

	new_key[key_len + cap_letters] = '\0';

	for (ssize_t i = key_len; i >= 0; i--) {

		if ((new_key[i] >= 'A' && new_key[i] <= 'Z') || new_key[i] == '^') {

			if (new_key[i] != '^')

				new_key[i] += 32;

			memmove(new_key + i + cap_letters, new_key + i, key_len - i);

			new_key[i + cap_letters - 1] = '^';

			cap_letters--;

			key_len = i;

		}

	}

	return new_key;

}

#define result_error(fmt, args...)                                       \

do {                                                                     \

	SEXP_t *msg = probe_msg_creatf(OVAL_MESSAGE_LEVEL_ERROR, fmt, args); \

	probe_cobj_add_msg(probe_ctx_getresult(ctx), msg);                   \

	SEXP_free(msg);                                                      \

	probe_cobj_set_flag(probe_ctx_getresult(ctx), SYSCHAR_FLAG_ERROR);   \

	ret = -1;                                                            \

} while (0)

static int yaml_path_query(const char *filepath, const char *yaml_path_cstr, struct oscap_list *values, probe_ctx *ctx)

{

	int ret = 0;

	FILE *yaml_file = fopen(filepath, "r");

	if (yaml_file == NULL) {

		result_error("Unable to open file '%s': %s", filepath, strerror(errno));

		return ret;

	}

	yaml_path_t *yaml_path = yaml_path_create();

	if (yaml_path_parse(yaml_path, (char *) yaml_path_cstr)) {

		result_error("Invalid YAML path '%s': %s", yaml_path_cstr, yaml_path_error_get(yaml_path)->message);

		yaml_path_destroy(yaml_path);

		fclose(yaml_file);

		return ret;

	};

	yaml_parser_t parser;

	yaml_parser_initialize(&parser);

	yaml_parser_set_input_file(&parser, yaml_file);

	yaml_event_t event;

	yaml_event_type_t event_type;

	bool sequence = false;

	bool mapping = false;

	int index = 0;

	char *key = strdup("#");

	struct oscap_htable *record = NULL;

	do {

		if (!yaml_parser_parse(&parser, &event)) {

			result_error("YAML parser error: %s", parser.problem);

			goto cleanup;

		}

		if (yaml_path_filter_event(yaml_path, &parser, &event) == YAML_PATH_FILTER_RESULT_OUT) {

			goto next;

		}

		event_type = event.type;

		if (sequence) {

			if (event_type == YAML_SEQUENCE_END_EVENT) {

				sequence = false;

			} else if (event_type == YAML_SEQUENCE_START_EVENT) {

				result_error("YAML path '%s' points to a multi-dimensional structure (sequence containing another sequence)", yaml_path_cstr);

				goto cleanup;

			}

		} else {

			if (event_type == YAML_SEQUENCE_START_EVENT) {

				sequence = true;

			}

		}

		if (mapping) {

			if (event_type == YAML_MAPPING_END_EVENT) {

				mapping = false;

				if (record->itemcount > 0) {

					oscap_list_add(values, record);

				} else {

					// Do not collect empty records

					oscap_htable_free0(record);

				}

				record = NULL;

			} else if (event_type == YAML_MAPPING_START_EVENT) {

				result_error("YAML path '%s' points to a multi-dimensional structure (map containing another map)", yaml_path_cstr);

				goto cleanup;

			}

		} else {

			if (event_type == YAML_MAPPING_START_EVENT) {

				if (record) {

					result_error("YAML path '%s' points to an invalid structure (map containing another map)", yaml_path_cstr);

					goto cleanup;

				}

				mapping = true;

				sequence = false;

				index = 0;

				record = oscap_htable_new();

			}

		}

		if (event_type == YAML_SCALAR_EVENT) {

			if (mapping) {

				if (!sequence) {

					if (index++ % 2 == 0) {

						free(key);

						key = escape_key(strdup((const char *) event.data.scalar.value));

						goto next;

					}

				}

			}

			SEXP_t *sexp = yaml_scalar_event_to_sexp(&event);

			if (sexp == NULL) {

				result_error("Can't convert '%s %s' to SEXP", event.data.scalar.tag, event.data.scalar.value);

				goto cleanup;

			}

			if (!record)

				record = oscap_htable_new();

			struct oscap_list *field = oscap_htable_get(record, key);

			if (!field) {

				field = oscap_list_new();

				oscap_htable_add(record, key, field);

			}

			oscap_list_add(field, sexp);

		}

next:

		yaml_event_delete(&event);

	} while (event_type != YAML_STREAM_END_EVENT);

cleanup:

	if (record)

		oscap_list_add(values, record);

	free(key);

	yaml_parser_delete(&parser);

	yaml_path_destroy(yaml_path);

	fclose(yaml_file);

	return ret;

}

static void record_free(struct oscap_list *items)

{

	oscap_list_free(items, (oscap_destruct_func) SEXP_free);

}

static void values_free(struct oscap_htable *record)

{

	oscap_htable_free(record, (oscap_destruct_func) record_free);

}

static int process_yaml_file(const char *prefix, const char *path, const char *filename, const char *yamlpath, probe_ctx *ctx)

{

	int ret = 0;

	char *filepath = oscap_path_join(path, filename);

	struct oscap_list *values = oscap_list_new();

	char *filepath_with_prefix = oscap_path_join(prefix, filepath);

	if (yaml_path_query(filepath_with_prefix, yamlpath, values, ctx)) {

		ret = -1;

		goto cleanup;

	}

	struct oscap_iterator *values_it = oscap_iterator_new(values);

	if (oscap_iterator_has_more(values_it)) {

		SEXP_t *item = probe_item_create(

			OVAL_INDEPENDENT_YAML_FILE_CONTENT,

			NULL,

			"filepath", OVAL_DATATYPE_STRING, filepath,

			"path", OVAL_DATATYPE_STRING, path,

			"filename", OVAL_DATATYPE_STRING, filename,

			"yamlpath", OVAL_DATATYPE_STRING, yamlpath,

			// TODO: Implement "windows_view",

			NULL

		);

		while (oscap_iterator_has_more(values_it)) {

			SEXP_t *result_ent = probe_ent_creat1("value", NULL, NULL);

			probe_ent_setdatatype(result_ent, OVAL_DATATYPE_RECORD);

			struct oscap_htable *record = oscap_iterator_next(values_it);

			struct oscap_htable_iterator *record_it = oscap_htable_iterator_new(record);

			while(oscap_htable_iterator_has_more(record_it)) {

				const struct oscap_htable_item *record_item = oscap_htable_iterator_next(record_it);

				struct oscap_iterator *item_value_it = oscap_iterator_new(record_item->value);

				SEXP_t se_tmp_mem;

				SEXP_t *key = SEXP_string_new_r(&se_tmp_mem, record_item->key, strlen(record_item->key));

				while(oscap_iterator_has_more(item_value_it)) {

					SEXP_t *value_sexp = oscap_iterator_next(item_value_it);

					SEXP_t *field = probe_ent_creat1("field", NULL, value_sexp);

					probe_item_attr_add(field, "name", key);

					SEXP_list_add(result_ent, field);

				}

				oscap_iterator_free(item_value_it);

				SEXP_free_r(&se_tmp_mem);

			}

			oscap_htable_iterator_free(record_it);

			SEXP_list_add(item, result_ent);

			SEXP_free(result_ent);

		}

		probe_item_collect(ctx, item);

	}

	oscap_iterator_free(values_it);

cleanup:

	oscap_list_free(values, (oscap_destruct_func) values_free);

	free(filepath_with_prefix);

	free(filepath);

	return ret;

}

int yamlfilecontent_probe_main(probe_ctx *ctx, void *arg)

{

	SEXP_t *probe_in = probe_ctx_getobject(ctx);

	SEXP_t *behaviors_ent = probe_obj_getent(probe_in, "behaviors", 1);

	SEXP_t *filepath_ent = probe_obj_getent(probe_in, "filepath", 1);

	SEXP_t *path_ent = probe_obj_getent(probe_in, "path", 1);

	SEXP_t *filename_ent = probe_obj_getent(probe_in, "filename", 1);

	SEXP_t *yamlpath_ent = probe_obj_getent(probe_in, "yamlpath", 1);

	SEXP_t *yamlpath_val = probe_ent_getval(yamlpath_ent);

	char *yamlpath_str = SEXP_string_cstr(yamlpath_val);

	probe_filebehaviors_canonicalize(&behaviors_ent);

	const char *prefix = getenv("OSCAP_PROBE_ROOT");

	OVAL_FTS *ofts = oval_fts_open_prefixed(

		prefix, path_ent, filename_ent, filepath_ent, behaviors_ent,

		probe_ctx_getresult(ctx));

	if (ofts != NULL) {

		OVAL_FTSENT *ofts_ent;

		while ((ofts_ent = oval_fts_read(ofts)) != NULL) {

			if (ofts_ent->fts_info == FTS_F

			    || ofts_ent->fts_info == FTS_SL) {

				process_yaml_file(prefix, ofts_ent->path, ofts_ent->file,

					yamlpath_str, ctx);

			}

			oval_ftsent_free(ofts_ent);

		}

		oval_fts_close(ofts);

	}

	free(yamlpath_str);

	SEXP_free(yamlpath_val);

	SEXP_free(yamlpath_ent);

	SEXP_free(filename_ent);

	SEXP_free(path_ent);

	SEXP_free(filepath_ent);

	SEXP_free(behaviors_ent);

	return 0;

}