/* $OpenBSD: verify.c,v 1.2 2020/09/13 15:06:17 beck Exp $ */
/*
 * Copyright (c) 2020 Joel Sing <jsing@openbsd.org>
 * Copyright (c) 2020 Bob Beck <beck@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <err.h>
#include <string.h>

#include <openssl/bio.h>
#include <openssl/err.h>
#include <openssl/pem.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include <openssl/x509_verify.h>

#define MODE_MODERN_VFY	0
#define MODE_LEGACY_VFY 1
#define MODE_VERIFY	2

static int verbose = 1;

static int
passwd_cb(char *buf, int size, int rwflag, void *u)
{
	memset(buf, 0, size);
	return (0);
}

static int
certs_from_file(const char *filename, STACK_OF(X509) **certs)
{
	STACK_OF(X509_INFO) *xis = NULL;
	STACK_OF(X509) *xs = NULL;
	BIO *bio = NULL;
	X509 *x;
	int i;

	if ((xs = sk_X509_new_null()) == NULL)
		errx(1, "failed to create X509 stack");
	if ((bio = BIO_new_file(filename, "r")) == NULL) {
		ERR_print_errors_fp(stderr);
		errx(1, "failed to create bio");
	}
	if ((xis = PEM_X509_INFO_read_bio(bio, NULL, passwd_cb, NULL)) == NULL)
		errx(1, "failed to read PEM");

	for (i = 0; i < sk_X509_INFO_num(xis); i++) {
		if ((x = sk_X509_INFO_value(xis, i)->x509) == NULL)
			continue;
		if (!sk_X509_push(xs, x))
			errx(1, "failed to push X509");
		X509_up_ref(x);
	}

	*certs = xs;
	xs = NULL;

	sk_X509_INFO_pop_free(xis, X509_INFO_free);
	sk_X509_pop_free(xs, X509_free);
	BIO_free(bio);

	return 1;
}

static int
verify_cert_cb(int ok, X509_STORE_CTX *xsc)
{
	X509 *current_cert;
	int verify_err;

	current_cert = X509_STORE_CTX_get_current_cert(xsc);
	if (current_cert != NULL) {
		X509_NAME_print_ex_fp(stderr,
		    X509_get_subject_name(current_cert), 0,
		    XN_FLAG_ONELINE);
		fprintf(stderr, "\n");
	}

	verify_err = X509_STORE_CTX_get_error(xsc);
	if (verify_err != X509_V_OK) {
		fprintf(stderr, "verify error at depth %d: %s\n",
		    X509_STORE_CTX_get_error_depth(xsc),
		    X509_verify_cert_error_string(verify_err));
	}

	return ok;
}

static void
verify_cert(const char *roots_file, const char *bundle_file, int *chains,
    int mode)
{
	STACK_OF(X509) *roots = NULL, *bundle = NULL;
	X509_STORE_CTX *xsc = NULL;
	unsigned long flags;
	X509 *leaf = NULL;
	int verify_err;

	*chains = 0;

	if (!certs_from_file(roots_file, &roots))
		errx(1, "failed to load roots from '%s'", roots_file);
	if (!certs_from_file(bundle_file, &bundle))
		errx(1, "failed to load bundle from '%s'", bundle_file);
	if (sk_X509_num(bundle) < 1)
		errx(1, "not enough certs in bundle");
	leaf = sk_X509_shift(bundle);

	if ((xsc = X509_STORE_CTX_new()) == NULL)
		errx(1, "X509_STORE_CTX");
	if (!X509_STORE_CTX_init(xsc, NULL, leaf, bundle)) {
		ERR_print_errors_fp(stderr);
		errx(1, "failed to init store context");
	}
	if (mode == MODE_LEGACY_VFY) {
		flags = X509_VERIFY_PARAM_get_flags(xsc->param);
		flags |= X509_V_FLAG_LEGACY_VERIFY;
		X509_VERIFY_PARAM_set_flags(xsc->param, flags);
	} else {
		flags = X509_VERIFY_PARAM_get_flags(xsc->param);
		flags &= ~X509_V_FLAG_LEGACY_VERIFY;
		X509_VERIFY_PARAM_set_flags(xsc->param, flags);
	}

	if (verbose)
		X509_STORE_CTX_set_verify_cb(xsc, verify_cert_cb);
	X509_STORE_CTX_set0_trusted_stack(xsc, roots);
	if (X509_verify_cert(xsc) == 1) {
		*chains = 1; /* XXX */
		goto done;
	}

	verify_err = X509_STORE_CTX_get_error(xsc);
	fprintf(stderr, "failed to verify at %d: %s\n",
	    X509_STORE_CTX_get_error_depth(xsc),
	    X509_verify_cert_error_string(verify_err));

 done:
	sk_X509_pop_free(roots, X509_free);
	sk_X509_pop_free(bundle, X509_free);
	X509_STORE_CTX_free(xsc);
	X509_free(leaf);
}

struct verify_cert_test {
	const char *id;
	int want_chains;
	int failing;
};

static void
verify_cert_new(const char *roots_file, const char *bundle_file, int *chains)
{
	STACK_OF(X509) *roots = NULL, *bundle = NULL;
	X509_STORE_CTX *xsc = NULL;
	X509 *leaf = NULL;
	struct x509_verify_ctx *ctx;

	*chains = 0;

	if (!certs_from_file(roots_file, &roots))
		errx(1, "failed to load roots from '%s'", roots_file);
	if (!certs_from_file(bundle_file, &bundle))
		errx(1, "failed to load bundle from '%s'", bundle_file);
	if (sk_X509_num(bundle) < 1)
		errx(1, "not enough certs in bundle");
	leaf = sk_X509_shift(bundle);

        if ((xsc = X509_STORE_CTX_new()) == NULL)
		errx(1, "X509_STORE_CTX");
	if (!X509_STORE_CTX_init(xsc, NULL, leaf, bundle)) {
		ERR_print_errors_fp(stderr);
		errx(1, "failed to init store context");
	}
	if (verbose)
		X509_STORE_CTX_set_verify_cb(xsc, verify_cert_cb);

	if ((ctx = x509_verify_ctx_new(roots)) == NULL)
		errx(1, "failed to create ctx");
	if (!x509_verify_ctx_set_intermediates(ctx, bundle))
		errx(1, "failed to set intermediates");

	if ((*chains = x509_verify(ctx, leaf, NULL)) == 0) {
		fprintf(stderr, "failed to verify at %lu: %s\n",
		    x509_verify_ctx_error_depth(ctx),
		    x509_verify_ctx_error_string(ctx));
	} else {
		for (int c = 0; verbose && c < *chains; c++) {
			fprintf(stderr, "Chain %d\n--------\n", c);
			STACK_OF(X509) * chain = x509_verify_ctx_chain(ctx, c);
			for (int i = 0; i < sk_X509_num(chain); i++) {
				X509 *cert = sk_X509_value(chain, i);
				X509_NAME_print_ex_fp(stderr,
				    X509_get_subject_name(cert), 0,
				    XN_FLAG_ONELINE);
				fprintf(stderr, "\n");
			}
		}
	}
	sk_X509_pop_free(roots, X509_free);
	sk_X509_pop_free(bundle, X509_free);
	X509_free(leaf);
}

struct verify_cert_test verify_cert_tests[] = {
	{
		.id = "1a",
		.want_chains = 1,
	},
	{
		.id = "2a",
		.want_chains = 1,
	},
	{
		.id = "2b",
		.want_chains = 0,
	},
	{
		.id = "3a",
		.want_chains = 1,
	},
	{
		.id = "3b",
		.want_chains = 0,
	},
	{
		.id = "3c",
		.want_chains = 0,
	},
	{
		.id = "3d",
		.want_chains = 0,
	},
	{
		.id = "3e",
		.want_chains = 1,
	},
	{
		.id = "4a",
		.want_chains = 2,
	},
	{
		.id = "4b",
		.want_chains = 1,
	},
	{
		.id = "4c",
		.want_chains = 1,
		.failing = 1,
	},
	{
		.id = "4d",
		.want_chains = 1,
	},
	{
		.id = "4e",
		.want_chains = 1,
	},
	{
		.id = "4f",
		.want_chains = 2,
	},
	{
		.id = "4g",
		.want_chains = 1,
		.failing = 1,
	},
	{
		.id = "4h",
		.want_chains = 1,
	},
	{
		.id = "5a",
		.want_chains = 2,
	},
	{
		.id = "5b",
		.want_chains = 1,
		.failing = 1,
	},
	{
		.id = "5c",
		.want_chains = 1,
	},
	{
		.id = "5d",
		.want_chains = 1,
	},
	{
		.id = "5e",
		.want_chains = 1,
		.failing = 1,
	},
	{
		.id = "5f",
		.want_chains = 1,
	},
	{
		.id = "5g",
		.want_chains = 2,
	},
	{
		.id = "5h",
		.want_chains = 1,
	},
	{
		.id = "5i",
		.want_chains = 1,
		.failing = 1,
	},
	{
		.id = "6a",
		.want_chains = 1,
	},
	{
		.id = "6b",
		.want_chains = 1,
		.failing = 1,
	},
	{
		.id = "7a",
		.want_chains = 1,
		.failing = 1,
	},
	{
		.id = "7b",
		.want_chains = 1,
	},
	{
		.id = "8a",
		.want_chains = 0,
	},
	{
		.id = "9a",
		.want_chains = 0,
	},
	{
		.id = "10a",
		.want_chains = 1,
	},
	{
		.id = "10b",
		.want_chains = 1,
	},
	{
		.id = "11a",
		.want_chains = 1,
		.failing = 1,
	},
	{
		.id = "11b",
		.want_chains = 1,
	},
	{
		.id = "12a",
		.want_chains = 1,
	},
	{
		.id = "13a",
		.want_chains = 1,
	},
};

#define N_VERIFY_CERT_TESTS \
    (sizeof(verify_cert_tests) / sizeof(*verify_cert_tests))

static int
verify_cert_test(const char *certs_path, int mode)
{
	char *roots_file, *bundle_file;
	struct verify_cert_test *vct;
	int failed = 0;
	int chains;
	size_t i;

	for (i = 0; i < N_VERIFY_CERT_TESTS; i++) {
		vct = &verify_cert_tests[i];

		if (asprintf(&roots_file, "%s/%s/roots.pem", certs_path,
		    vct->id) == -1)
			errx(1, "asprintf");
		if (asprintf(&bundle_file, "%s/%s/bundle.pem", certs_path,
		    vct->id) == -1)
			errx(1, "asprintf");

		fprintf(stderr, "== Test %zu (%s)\n", i, vct->id);
		if (mode == MODE_VERIFY)
			verify_cert_new(roots_file, bundle_file, &chains);
		else
			verify_cert(roots_file, bundle_file, &chains, mode);
		if ((mode == 2 && chains == vct->want_chains) ||
		    (chains == 0 && vct->want_chains == 0) ||
		    (chains == 1 && vct->want_chains > 0)) {
			fprintf(stderr, "INFO: Succeeded with %d chains%s\n",
			    chains, vct->failing ? " (legacy failure)" : "");
			if (mode == MODE_LEGACY_VFY && vct->failing)
				failed |= 1;
		} else {
			fprintf(stderr, "FAIL: Failed with %d chains%s\n",
			    chains, vct->failing ? " (legacy failure)" : "");
			if (!vct->failing)
				failed |= 1;
		}
		fprintf(stderr, "\n");

		free(roots_file);
		free(bundle_file);
	}

	return failed;
}

int
main(int argc, char **argv)
{
	int failed = 0;

	if (argc != 2) {
		fprintf(stderr, "usage: %s <certs_path>\n", argv[0]);
		exit(1);
	}

	fprintf(stderr, "\n\nTesting legacy x509_vfy\n");
	failed |= verify_cert_test(argv[1], MODE_LEGACY_VFY);
	fprintf(stderr, "\n\nTesting modern x509_vfy\n");
	failed |= verify_cert_test(argv[1], MODE_MODERN_VFY);
	fprintf(stderr, "\n\nTesting x509_verify\n");
	failed |= verify_cert_test(argv[1], MODE_VERIFY);

	return (failed);
}