//-----------------------------------------------------------------------------
// Copyright (C) 2018 Merlok
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// asn.1 dumping
//-----------------------------------------------------------------------------
#define _POSIX_C_SOURCE 200809L                 // need for strnlen()

#include "asn1dump.h"
#include <ctype.h>
#include <stdlib.h>
#include <unistd.h> 
#include <stdio.h>
#include <string.h>
#include <jansson.h>
#include <mbedtls/asn1.h>
#include <mbedtls/oid.h>
#include "emv/emv_tags.h"
#include "emv/dump.h"
#include "emv/emvjson.h"
#include "util.h"
#include "proxmark3.h"

#ifndef PRINT_INDENT
# define PRINT_INDENT(level) 	{for (int i = 0; i < (level); i++) fprintf(f, "   ");}
#endif

enum asn1_tag_t {
	ASN1_TAG_GENERIC,
	ASN1_TAG_BOOLEAN,
	ASN1_TAG_INTEGER,
	ASN1_TAG_STRING,
	ASN1_TAG_OCTET_STRING,
	ASN1_TAG_UTC_TIME,
	ASN1_TAG_STR_TIME,
	ASN1_TAG_OBJECT_ID,
};

struct asn1_tag {
	tlv_tag_t tag;
	char *name;
	enum asn1_tag_t type;
	const void *data;
};

static const struct asn1_tag asn1_tags[] = {
	// internal
	{ 0x00  , "Unknown ???" },

	// ASN.1
	{ 0x01, "BOOLEAN", ASN1_TAG_BOOLEAN },
	{ 0x02, "INTEGER", ASN1_TAG_INTEGER },
	{ 0x03, "BIT STRING" },
	{ 0x04, "OCTET STRING", ASN1_TAG_OCTET_STRING},
	{ 0x05, "NULL" },
	{ 0x06, "OBJECT IDENTIFIER", ASN1_TAG_OBJECT_ID },
	{ 0x07, "OBJECT DESCRIPTOR" },
	{ 0x08, "EXTERNAL" },
	{ 0x09, "REAL" },
	{ 0x0A, "ENUMERATED" },
	{ 0x0B, "EMBEDDED_PDV" },
	{ 0x0C, "UTF8String", ASN1_TAG_STRING },
	{ 0x10, "SEQUENCE" },
	{ 0x11, "SET" },
	{ 0x12, "NumericString", ASN1_TAG_STRING },
	{ 0x13, "PrintableString", ASN1_TAG_STRING },
	{ 0x14, "T61String" },
	{ 0x15, "VideotexString" },
	{ 0x16, "IA5String" },
	{ 0x17, "UTCTime", ASN1_TAG_UTC_TIME },
	{ 0x18, "GeneralizedTime", ASN1_TAG_STR_TIME },
	{ 0x19, "GraphicString" },
	{ 0x1A, "VisibleString", ASN1_TAG_STRING },
	{ 0x1B, "GeneralString", ASN1_TAG_STRING },
	{ 0x1C, "UniversalString", ASN1_TAG_STRING },
	{ 0x1E, "BMPString" },
	{ 0x30, "SEQUENCE" },
	{ 0x31, "SET" },
	{ 0xa0, "[0]" },
	{ 0xa1, "[1]" },
	{ 0xa2, "[2]" },
	{ 0xa3, "[3]" },
	{ 0xa4, "[4]" },
	{ 0xa5, "[5]" },
};

static int asn1_sort_tag(tlv_tag_t tag) {
	return (int)(tag >= 0x100 ? tag : tag << 8);
}

static int asn1_tlv_compare(const void *a, const void *b) {
	const struct tlv *tlv = a;
	const struct asn1_tag *tag = b;

	return asn1_sort_tag(tlv->tag) - (asn1_sort_tag(tag->tag));
}

static const struct asn1_tag *asn1_get_tag(const struct tlv *tlv) {
	struct asn1_tag *tag = bsearch(tlv, asn1_tags, sizeof(asn1_tags) / sizeof(asn1_tags[0]),
			sizeof(asn1_tags[0]), asn1_tlv_compare);

	return tag ? tag : &asn1_tags[0];
}

static void asn1_tag_dump_str_time(const struct tlv *tlv, const struct asn1_tag *tag, FILE *f, int level, bool longyear, bool *needdump){
	int len = tlv->len;
	*needdump = false;

	int startindx = longyear ? 4 : 2;
	
	if (len > 4) {
		fprintf(f, "\tvalue: '");
		while (true) {
			// year
			if (!longyear)
				fprintf(f, "20");
			fwrite(tlv->value, 1, longyear ? 4 : 2, f);
			fprintf(f, "-");
			if (len < startindx + 2) 
				break;
			// month
			fwrite(&tlv->value[startindx], 1, 2, f);
			fprintf(f, "-");
			if (len < startindx + 4) 
				break;
			// day
			fwrite(&tlv->value[startindx + 2], 1, 2, f);
			fprintf(f, " ");
			if (len < startindx + 6) 
				break;
			// hour
			fwrite(&tlv->value[startindx + 4], 1, 2, f);
			fprintf(f, ":");
			if (len < startindx + 8) 
				break;
			// min
			fwrite(&tlv->value[startindx + 6], 1, 2, f);
			fprintf(f, ":");
			if (len < startindx + 10) 
				break;
			// sec
			fwrite(&tlv->value[startindx + 8], 1, 2, f);
			if (len < startindx + 11) 
				break;
			// time zone
			fprintf(f, " zone: %.*s", len - 10 - (longyear ? 4 : 2), &tlv->value[startindx + 10]);
	
			break;
		}
		fprintf(f, "'\n");
	} else {
		fprintf(f, "\n");
		*needdump = true;
	}	
}

static void asn1_tag_dump_string(const struct tlv *tlv, const struct asn1_tag *tag, FILE *f, int level){
	fprintf(f, "\tvalue: '");
	fwrite(tlv->value, 1, tlv->len, f);
	fprintf(f, "'\n");
}

static void asn1_tag_dump_octet_string(const struct tlv *tlv, const struct asn1_tag *tag, FILE *f, int level, bool *needdump){
	*needdump = false;
	for (int i = 0; i < tlv->len; i++)
		if (!isspace(tlv->value[i]) && !isprint(tlv->value[i])){
			*needdump = true;
			break;
		}
		
	if (*needdump) {
		fprintf(f, "'\n");
	} else {
		fprintf(f, "\t\t");
		asn1_tag_dump_string(tlv, tag, f, level);
	}
}

static unsigned long asn1_value_integer(const struct tlv *tlv, unsigned start, unsigned end) {
	unsigned long ret = 0;
	int i;

	if (end > tlv->len * 2)
		return ret;
	if (start >= end)
		return ret;

	if (start & 1) {
		ret += tlv->value[start/2] & 0xf;
		i = start + 1;
	} else
		i = start;

	for (; i < end - 1; i += 2) {
		ret *= 10;
		ret += tlv->value[i/2] >> 4;
		ret *= 10;
		ret += tlv->value[i/2] & 0xf;
	}

	if (end & 1) {
		ret *= 10;
		ret += tlv->value[end/2] >> 4;
	}

	return ret;
}

static void asn1_tag_dump_boolean(const struct tlv *tlv, const struct asn1_tag *tag, FILE *f, int level) {
	PRINT_INDENT(level);
	if (tlv->len > 0) {
		fprintf(f, "\tvalue: %s\n", tlv->value[0]?"true":"false");
	} else {
		fprintf(f, "n/a\n");
	}
}

static void asn1_tag_dump_integer(const struct tlv *tlv, const struct asn1_tag *tag, FILE *f, int level) {
	PRINT_INDENT(level);
	if (tlv->len == 4) {
		int32_t val = 0;
		for (int i = 0; i < tlv->len; i++)
			val = (val << 8) + tlv->value[i];
		fprintf(f, "\tvalue4b: %d\n", val);
		return;
	}
	fprintf(f, "\tvalue: %lu\n", asn1_value_integer(tlv, 0, tlv->len * 2));
}

static char *asn1_oid_description(const char *oid, bool with_group_desc) {
	json_error_t error;
	json_t *root = NULL;
	char fname[300] = {0};
	static char res[300];
	memset(res, 0x00, sizeof(res));

	size_t len = strlen(get_my_executable_directory());
	if ( len > 300 ) len = 299;
	
	strncpy(fname, get_my_executable_directory(), len);
	strcat(fname, "crypto/oids.json");
	if (access(fname, F_OK) < 0) {
		strncpy(fname, get_my_executable_directory(), len);
		strcat(fname, "oids.json");
		if (access(fname, F_OK) < 0) {
			goto error; // file not found
		}
	}
	
	// load `oids.json`
	root = json_load_file(fname, 0, &error);
	
	if (!root || !json_is_object(root)) {
		goto error;
	}
	
	json_t *elm = json_object_get(root, oid);
	if (!elm) {
		goto error;
	}
	
	if (JsonLoadStr(elm, "$.d", res))
		goto error;

	char strext[300] = {0};
	if (!JsonLoadStr(elm, "$.c", strext)) {
		strcat(res, " (");
		strcat(res, strext);
		strcat(res, ")");
	}
	
	json_decref(root);
	return res;
	
error:
	if (root)
		json_decref(root);
	return NULL;
}

static void asn1_tag_dump_object_id(const struct tlv *tlv, const struct asn1_tag *tag, FILE *f, int level) {
	PRINT_INDENT(level);
	mbedtls_asn1_buf asn1_buf;
	asn1_buf.len = tlv->len;
	asn1_buf.p = (uint8_t *)tlv->value;
	char pstr[300];
	mbedtls_oid_get_numeric_string(pstr, sizeof(pstr), &asn1_buf); 
	fprintf(f, " %s", pstr);
	
	char *jsondesc = asn1_oid_description(pstr, true);
	if (jsondesc) {
		fprintf(f, " -  %s", jsondesc);
	} else {	
		const char *ppstr;
		mbedtls_oid_get_attr_short_name(&asn1_buf, &ppstr); 
		if (ppstr && strnlen(ppstr, 1)) {
			fprintf(f, " (%s)\n", ppstr);
			return;
		}
		mbedtls_oid_get_sig_alg_desc(&asn1_buf, &ppstr);
		if (ppstr && strnlen(ppstr, 1)) {
			fprintf(f, " (%s)\n", ppstr);
			return;
		}
		mbedtls_oid_get_extended_key_usage(&asn1_buf, &ppstr);
		if (ppstr && strnlen(ppstr, 1)) {
			fprintf(f, " (%s)\n", ppstr);
			return;
		}
	}
	fprintf(f, "\n");
}

bool asn1_tag_dump(const struct tlv *tlv, FILE *f, int level, bool *candump) {
	if (!tlv) {
		fprintf(f, "NULL\n");
		return false;
	}

	const struct asn1_tag *tag = asn1_get_tag(tlv);

	PRINT_INDENT(level);
	fprintf(f, "--%2hx[%02zx] '%s':", tlv->tag, tlv->len, tag->name);

	switch (tag->type) {
	case ASN1_TAG_GENERIC:
		fprintf(f, "\n");
		break;
	case ASN1_TAG_STRING:
		asn1_tag_dump_string(tlv, tag, f, level);
		*candump = false;
		break;
	case ASN1_TAG_OCTET_STRING:
		asn1_tag_dump_octet_string(tlv, tag, f, level, candump);
		break;
	case ASN1_TAG_BOOLEAN:
		asn1_tag_dump_boolean(tlv, tag, f, level);
		*candump = false;
		break;
	case ASN1_TAG_INTEGER:
		asn1_tag_dump_integer(tlv, tag, f, level);
		*candump = false;
		break;
	case ASN1_TAG_UTC_TIME:
		asn1_tag_dump_str_time(tlv, tag, f, level, false, candump);
		break;
	case ASN1_TAG_STR_TIME:
		asn1_tag_dump_str_time(tlv, tag, f, level, true, candump);
		break;
	case ASN1_TAG_OBJECT_ID:
		asn1_tag_dump_object_id(tlv, tag, f, level);
		*candump = false;
		break;
	};
	
	return true;
}