/*
 * ldnssec-utils
 *
 * Written in 2021 by Lucas
 *
 * To the extent possible under law, the author(s) have dedicated all
 * copyright and related and neighboring rights to this software to the
 * public domain worldwide. This software is distributed without any
 * warranty.
 *
 * You should have received a copy of the CC0 Public Domain Dedication
 * along with this software. If not, see
 * <http://creativecommons.org/publicdomain/zero/1.0/>.
 */

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <ldns/ldns.h>

#include "util.h"

static void
usage(void)
{
	const char *p = getprogname();

	fprintf(stderr, "usage:\n"
	    "\t%s dnskey [-d domain] [-k]\n"
	    "\t%s ds [-a algorithm] [-d domain]\n"
	    "\t%s filename [-d domain] [-k]\n"
	    "\t%s gen [-a algorithm] [-b bits]\n",
	    p, p, p, p);
	exit(1);
}

static void
cmd_dnskey_usage(void)
{
	fprintf(stderr, "usage: %s dnskey [-d domain] [-k]\n", getprogname());
	exit(1);
}

static void
cmd_ds_usage(void)
{
	fprintf(stderr, "usage: %s ds [-a algorithm] [-d domain]\n",
	    getprogname());
	exit(1);
}

static void
cmd_filename_usage(void)
{
	fprintf(stderr, "usage: %s filename [-d domain] [-k]\n",
	    getprogname());
	exit(1);
}

static void
cmd_gen_usage(void)
{
	fprintf(stderr, "usage: %s gen [-a algorithm] [-b bits]\n",
	    getprogname());
	exit(1);
}

static void
ds_dnskey_rr_filename_print(const char *domain, int sep, ldns_hash hash,
    int do_filename)
{
	ldns_key *key;
	ldns_rr *dnskey_rr, *ds_rr = NULL;
	ldns_rdf *rdf_dname;
	ldns_status s;
	char *str;
	uint16_t flags;
	int do_ds, line_nr;

	s = ldns_key_new_frm_fp_l(&key, stdin, &line_nr);
	if (s != LDNS_STATUS_OK)
		errx(1, "ldns_key_new_frm_fp_l: (stdin) line %d: %s",
		    line_nr, ldns_get_errorstr_by_id(s));

	s = ldns_str2rdf_dname(&rdf_dname, domain);
	if (s != LDNS_STATUS_OK)
		errx(1, "ldns_str2rdf_dname: %s: %s", domain,
		    ldns_get_errorstr_by_id(s));

	flags = LDNS_KEY_ZONE_KEY;
	if (sep)
		flags |= LDNS_KEY_SEP_KEY;

	ldns_key_set_pubkey_owner(key, rdf_dname);
	ldns_key_set_flags(key, flags);

	dnskey_rr = ldns_key2rr(key);
	if (dnskey_rr == NULL)
		errx(1, "ldns_key2rr");

	if (do_filename) {
		ldns_key_set_keytag(key, ldns_calc_keytag(dnskey_rr));
		str = ldns_key_get_file_base_name(key);
		if (str == NULL)
			errx(1, "ldns_key_get_file_base_name");
		printf("%s\n", str);
	} else {
		do_ds = hash != 0;
		if (do_ds) {
			ds_rr = ldns_key_rr2ds(dnskey_rr, hash);
			if (ds_rr == NULL)
				errx(1, "ldns_key_rr2ds");
		}

		str = ldns_rr2str(do_ds ? ds_rr : dnskey_rr);
		if (str == NULL)
			errx(1, "ldns_rr2str");
		fputs(str, stdout);
	}

	free(str);
	ldns_rr_free(dnskey_rr);
	ldns_rr_free(ds_rr);
	ldns_key_deep_free(key);
}

static int
cmd_dnskey_main(int argc, char *argv[])
{
	const char *domain;
	int ch, sep;

	domain = ".";
	sep = 0;
	while ((ch = getopt(argc, argv, "d:k")) != -1) {
		switch (ch) {
		case 'd':
			domain = optarg;
			break;
		case 'k':
			sep = 1;
			break;
		default:
			cmd_dnskey_usage();
		}
	}
	argc -= optind;
	argv += optind;

	if (argc != 0)
		cmd_ds_usage();

	ds_dnskey_rr_filename_print(domain, sep, 0, 0);

	return 0;
}

static int
cmd_ds_main(int argc, char *argv[])
{
	ldns_hash alg;
	const char *domain;
	int ch;

	alg = LDNS_SHA256;
	domain = ".";
	while ((ch = getopt(argc, argv, "a:d:")) != -1) {
		switch (ch) {
		case 'a':
			alg = ldnssec_get_hash_algorithm_by_name(optarg);
			if (ldns_lookup_by_id(ldnssec_hashes, alg) == NULL)
				errx(1, "-a: unsupported algorithm %s",
				    optarg);
			break;
		case 'd':
			domain = optarg;
			break;
		default:
			cmd_ds_usage();
		}
	}
	argc -= optind;
	argv += optind;

	if (argc != 0)
		cmd_ds_usage();

	ds_dnskey_rr_filename_print(domain, 1, alg, 0);

	return 0;
}

static int
cmd_filename_main(int argc, char *argv[])
{
	const char *domain;
	int ch, sep;

	domain = ".";
	sep = 0;
	while ((ch = getopt(argc, argv, "d:k")) != -1) {
		switch (ch) {
		case 'd':
			domain = optarg;
			break;
		case 'k':
			sep = 1;
			break;
		default:
			cmd_filename_usage();
		}
	}
	argc -= optind;
	argv += optind;

	if (argc != 0)
		cmd_filename_usage();

	ds_dnskey_rr_filename_print(domain, sep, 0, 1);

	return 0;
}

static int
cmd_gen_main(int argc, char *argv[])
{
	ldns_key *key;
	ldns_signing_algorithm alg;
	const char *errstr;
	char *str;
	long long n;
	int ch;
	uint16_t bits;

	alg = LDNS_SIGN_ECDSAP256SHA256;
	bits = 0;
	while ((ch = getopt(argc, argv, "a:b:")) != -1) {
		switch (ch) {
		case 'a':
			alg = ldns_get_signing_algorithm_by_name(optarg);
			/*
			 * ldns_key_algo_supported can't be used here as
			 * it uses ldns_signing_algorithms lookup table, which
			 * includes algorithms for TSIG.
			 */
			if (ldns_lookup_by_id(ldns_algorithms, alg) == NULL)
				errx(1, "-a: unsupported algorithm %s",
				    optarg);
			break;
		case 'b':
			n = strtonum(optarg, 0, UINT16_MAX, &errstr);
			if (errstr != NULL)
				errx(1, "-b: bits is %s: %s", errstr, optarg);
			bits = n;
			break;
		default:
			cmd_gen_usage();
		}
	}
	argc -= optind;
	argv += optind;

	if (argc != 0)
		cmd_gen_usage();

	key = ldns_key_new_frm_algorithm(alg, bits);
	if (key == NULL)
		errx(1, "error generating key of type %s", argv[0]);

	/* ldns_key_print uses stdout to signal errors */
	str = ldns_key2str(key);
	if (str == NULL)
		errx(1, "ldns_key2str");
	fputs(str, stdout);

	free(str);
	ldns_key_deep_free(key);

	return 0;
}

int
main(int argc, char *argv[])
{
	const char *cmd;
	int rc;

	if (argc < 2)
		usage();
	cmd = argv[1];

	rc = 1;
	optind = 2;
	if (strcmp(cmd, "ds") == 0)
		rc = cmd_ds_main(argc, argv);
	else if (strcmp(cmd, "dnskey") == 0)
		rc = cmd_dnskey_main(argc, argv);
	else if (strcmp(cmd, "filename") == 0)
		rc = cmd_filename_main(argc, argv);
	else if (strcmp(cmd, "gen") == 0)
		rc = cmd_gen_main(argc, argv);
	else
		usage();

	return rc;
}