/* $OpenBSD: ssl_versions.c,v 1.27 2023/07/02 17:21:32 beck Exp $ */
/*
 * Copyright (c) 2016, 2017 Joel Sing <jsing@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 "ssl_local.h"

static uint16_t
ssl_dtls_to_tls_version(uint16_t dtls_ver)
{
        if (dtls_ver == DTLS1_VERSION)
                return TLS1_1_VERSION;
        if (dtls_ver == DTLS1_2_VERSION)
                return TLS1_2_VERSION;
        return 0;
}

static uint16_t
ssl_tls_to_dtls_version(uint16_t tls_ver)
{
        if (tls_ver == TLS1_1_VERSION)
                return DTLS1_VERSION;
        if (tls_ver == TLS1_2_VERSION)
                return DTLS1_2_VERSION;
        return 0;
}

static int
ssl_clamp_tls_version_range(uint16_t *min_ver, uint16_t *max_ver,
    uint16_t clamp_min, uint16_t clamp_max)
{
        if (clamp_min > clamp_max || *min_ver > *max_ver)
                return 0;
        if (clamp_max < *min_ver || clamp_min > *max_ver)
                return 0;

        if (*min_ver < clamp_min)
                *min_ver = clamp_min;
        if (*max_ver > clamp_max)
                *max_ver = clamp_max;

        return 1;
}

int
ssl_version_set_min(const SSL_METHOD *meth, uint16_t proto_ver,
    uint16_t max_tls_ver, uint16_t *out_tls_ver, uint16_t *out_proto_ver)
{
        uint16_t min_proto, min_version, max_version;

        if (proto_ver == 0) {
                *out_tls_ver = meth->min_tls_version;
                *out_proto_ver = 0;
                return 1;
        }

        min_version = proto_ver;
        max_version = max_tls_ver;

        if (meth->dtls) {
                if ((min_version = ssl_dtls_to_tls_version(proto_ver)) == 0)
                        return 0;
        }

        if (!ssl_clamp_tls_version_range(&min_version, &max_version,
            meth->min_tls_version, meth->max_tls_version))
                return 0;

        min_proto = min_version;
        if (meth->dtls) {
                if ((min_proto = ssl_tls_to_dtls_version(min_version)) == 0)
                        return 0;
        }
        *out_tls_ver = min_version;
        *out_proto_ver = min_proto;

        return 1;
}

int
ssl_version_set_max(const SSL_METHOD *meth, uint16_t proto_ver,
    uint16_t min_tls_ver, uint16_t *out_tls_ver, uint16_t *out_proto_ver)
{
        uint16_t max_proto, min_version, max_version;

        if (proto_ver == 0) {
                *out_tls_ver = meth->max_tls_version;
                *out_proto_ver = 0;
                return 1;
        }

        min_version = min_tls_ver;
        max_version = proto_ver;

        if (meth->dtls) {
                if ((max_version = ssl_dtls_to_tls_version(proto_ver)) == 0)
                        return 0;
        }

        if (!ssl_clamp_tls_version_range(&min_version, &max_version,
            meth->min_tls_version, meth->max_tls_version))
                return 0;

        max_proto = max_version;
        if (meth->dtls) {
                if ((max_proto = ssl_tls_to_dtls_version(max_version)) == 0)
                        return 0;
        }
        *out_tls_ver = max_version;
        *out_proto_ver = max_proto;

        return 1;
}

int
ssl_enabled_tls_version_range(SSL *s, uint16_t *min_ver, uint16_t *max_ver)
{
        uint16_t min_version, max_version;
        unsigned long options;

        /*
         * The enabled versions have to be a contiguous range, which means we
         * cannot enable and disable single versions at our whim, even though
         * this is what the OpenSSL flags allow. The historical way this has
         * been handled is by making a flag mean that all higher versions
         * are disabled, if any version lower than the flag is enabled.
         */

        min_version = 0;
        max_version = TLS1_3_VERSION;
        options = s->options;

        if (SSL_is_dtls(s)) {
                options = 0;
                if (s->options & SSL_OP_NO_DTLSv1)
                        options |= SSL_OP_NO_TLSv1 | SSL_OP_NO_TLSv1_1;
                if (s->options & SSL_OP_NO_DTLSv1_2)
                        options |= SSL_OP_NO_TLSv1 | SSL_OP_NO_TLSv1_2;
        }

        if ((options & SSL_OP_NO_TLSv1_2) == 0)
                min_version = TLS1_2_VERSION;
        else if ((options & SSL_OP_NO_TLSv1_3) == 0)
                min_version = TLS1_3_VERSION;

        if ((options & SSL_OP_NO_TLSv1_3) && min_version < TLS1_3_VERSION)
                max_version = TLS1_2_VERSION;
        if ((options & SSL_OP_NO_TLSv1_2) && min_version < TLS1_2_VERSION)
                max_version = 0;

        /* Everything has been disabled... */
        if (min_version == 0 || max_version == 0)
                return 0;

        /* Limit to configured version range. */
        if (!ssl_clamp_tls_version_range(&min_version, &max_version,
            s->min_tls_version, s->max_tls_version))
                return 0;

        /* QUIC requires a minimum of TLSv1.3. */
        if (SSL_is_quic(s)) {
                if (max_version < TLS1_3_VERSION)
                        return 0;
                if (min_version < TLS1_3_VERSION)
                        min_version = TLS1_3_VERSION;
        }

        if (min_ver != NULL)
                *min_ver = min_version;
        if (max_ver != NULL)
                *max_ver = max_version;

        return 1;
}

int
ssl_supported_tls_version_range(SSL *s, uint16_t *min_ver, uint16_t *max_ver)
{
        uint16_t min_version, max_version;

        if (!ssl_enabled_tls_version_range(s, &min_version, &max_version))
                return 0;

        /* Limit to the versions supported by this method. */
        if (!ssl_clamp_tls_version_range(&min_version, &max_version,
            s->method->min_tls_version, s->method->max_tls_version))
                return 0;

        if (min_ver != NULL)
                *min_ver = min_version;
        if (max_ver != NULL)
                *max_ver = max_version;

        return 1;
}

uint16_t
ssl_tls_version(uint16_t version)
{
        if (version == TLS1_VERSION || version == TLS1_1_VERSION ||
            version == TLS1_2_VERSION || version == TLS1_3_VERSION)
                return version;

        if (version == DTLS1_VERSION)
                return TLS1_1_VERSION;
        if (version == DTLS1_2_VERSION)
                return TLS1_2_VERSION;

        return 0;
}

uint16_t
ssl_effective_tls_version(SSL *s)
{
        if (s->s3->hs.negotiated_tls_version > 0)
                return s->s3->hs.negotiated_tls_version;

        return s->s3->hs.our_max_tls_version;
}

int
ssl_max_supported_version(SSL *s, uint16_t *max_ver)
{
        uint16_t max_version;

        *max_ver = 0;

        if (!ssl_supported_tls_version_range(s, NULL, &max_version))
                return 0;

        if (SSL_is_dtls(s)) {
                if ((max_version = ssl_tls_to_dtls_version(max_version)) == 0)
                        return 0;
        }

        *max_ver = max_version;

        return 1;
}

int
ssl_max_legacy_version(SSL *s, uint16_t *max_ver)
{
        uint16_t max_version;

        if ((max_version = s->s3->hs.our_max_tls_version) > TLS1_2_VERSION)
                max_version = TLS1_2_VERSION;

        if (SSL_is_dtls(s)) {
                if ((max_version = ssl_tls_to_dtls_version(max_version)) == 0)
                        return 0;
        }

        *max_ver = max_version;

        return 1;
}

int
ssl_max_shared_version(SSL *s, uint16_t peer_ver, uint16_t *max_ver)
{
        uint16_t min_version, max_version, peer_tls_version, shared_version;

        *max_ver = 0;
        peer_tls_version = peer_ver;

        if (SSL_is_dtls(s)) {
                if ((peer_ver >> 8) != DTLS1_VERSION_MAJOR)
                        return 0;

                /*
                 * Convert the peer version to a TLS version - DTLS versions are
                 * the 1's complement of TLS version numbers (but not the actual
                 * protocol version numbers, that would be too sensible). Not to
                 * mention that DTLSv1.0 is really equivalent to DTLSv1.1.
                 */
                peer_tls_version = ssl_dtls_to_tls_version(peer_ver);

                /*
                 * This may be a version that we do not know about, if it is
                 * newer than DTLS1_2_VERSION (yes, less than is correct due
                 * to the "clever" versioning scheme), use TLS1_2_VERSION.
                 */
                if (peer_tls_version == 0) {
                        if (peer_ver < DTLS1_2_VERSION)
                                peer_tls_version = TLS1_2_VERSION;
                }
        }

        if (peer_tls_version >= TLS1_3_VERSION)
                shared_version = TLS1_3_VERSION;
        else if (peer_tls_version >= TLS1_2_VERSION)
                shared_version = TLS1_2_VERSION;
        else if (peer_tls_version >= TLS1_1_VERSION)
                shared_version = TLS1_1_VERSION;
        else if (peer_tls_version >= TLS1_VERSION)
                shared_version = TLS1_VERSION;
        else
                return 0;

        if (!ssl_supported_tls_version_range(s, &min_version, &max_version))
                return 0;

        if (shared_version < min_version)
                return 0;

        if (shared_version > max_version)
                shared_version = max_version;

        if (SSL_is_dtls(s)) {
                /*
                 * The resulting shared version will by definition be something
                 * that we know about. Switch back from TLS to DTLS.
                 */
                shared_version = ssl_tls_to_dtls_version(shared_version);
                if (shared_version == 0)
                        return 0;
        }

        if (!ssl_security_version(s, shared_version))
                return 0;

        *max_ver = shared_version;

        return 1;
}

int
ssl_check_version_from_server(SSL *s, uint16_t server_version)
{
        uint16_t min_tls_version, max_tls_version, server_tls_version;

        /* Ensure that the version selected by the server is valid. */

        server_tls_version = server_version;
        if (SSL_is_dtls(s)) {
                server_tls_version = ssl_dtls_to_tls_version(server_version);
                if (server_tls_version == 0)
                        return 0;
        }

        if (!ssl_supported_tls_version_range(s, &min_tls_version,
            &max_tls_version))
                return 0;

        if (server_tls_version < min_tls_version ||
            server_tls_version > max_tls_version)
                return 0;

        return ssl_security_version(s, server_tls_version);
}

int
ssl_legacy_stack_version(SSL *s, uint16_t version)
{
        if (SSL_is_dtls(s))
                return version == DTLS1_VERSION || version == DTLS1_2_VERSION;

        return version == TLS1_VERSION || version == TLS1_1_VERSION ||
            version == TLS1_2_VERSION;
}