extensions_clnt.c

/*
 * Copyright 2016-2017 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <openssl/ocsp.h>
#include "../ssl_locl.h"
#include "internal/cryptlib.h"
#include "statem_locl.h"

EXT_RETURN tls_construct_ctos_renegotiate(SSL *s, WPACKET *pkt,
                                          unsigned int context, X509 *x,
                                          size_t chainidx)
{
    /* Add RI if renegotiating */
    if (!s->renegotiate)
        return EXT_RETURN_NOT_SENT;

    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_renegotiate)
            || !WPACKET_start_sub_packet_u16(pkt)
            || !WPACKET_sub_memcpy_u8(pkt, s->s3->previous_client_finished,
                               s->s3->previous_client_finished_len)
            || !WPACKET_close(pkt)) {
        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_RENEGOTIATE,
                 ERR_R_INTERNAL_ERROR);
        return EXT_RETURN_FAIL;
    }

    return EXT_RETURN_SENT;
}

EXT_RETURN tls_construct_ctos_server_name(SSL *s, WPACKET *pkt,
                                          unsigned int context, X509 *x,
                                          size_t chainidx)
{
    if (s->ext.hostname == NULL)
        return EXT_RETURN_NOT_SENT;

    /* Add TLS extension servername to the Client Hello message */
    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_server_name)
               /* Sub-packet for server_name extension */
            || !WPACKET_start_sub_packet_u16(pkt)
               /* Sub-packet for servername list (always 1 hostname)*/
            || !WPACKET_start_sub_packet_u16(pkt)
            || !WPACKET_put_bytes_u8(pkt, TLSEXT_NAMETYPE_host_name)
            || !WPACKET_sub_memcpy_u16(pkt, s->ext.hostname,
                                       strlen(s->ext.hostname))
            || !WPACKET_close(pkt)
            || !WPACKET_close(pkt)) {
        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_SERVER_NAME,
                 ERR_R_INTERNAL_ERROR);
        return EXT_RETURN_FAIL;
    }

    return EXT_RETURN_SENT;
}

/* Push a Max Fragment Len extension into ClientHello */
EXT_RETURN tls_construct_ctos_maxfragmentlen(SSL *s, WPACKET *pkt,
                                             unsigned int context, X509 *x,
                                             size_t chainidx)
{
    if (s->ext.max_fragment_len_mode == TLSEXT_max_fragment_length_DISABLED)
        return EXT_RETURN_NOT_SENT;

    /* Add Max Fragment Length extension if client enabled it. */
    /*-
     * 4 bytes for this extension type and extension length
     * 1 byte for the Max Fragment Length code value.
     */
    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_max_fragment_length)
            /* Sub-packet for Max Fragment Length extension (1 byte) */
            || !WPACKET_start_sub_packet_u16(pkt)
            || !WPACKET_put_bytes_u8(pkt, s->ext.max_fragment_len_mode)
            || !WPACKET_close(pkt)) {
        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
                 SSL_F_TLS_CONSTRUCT_CTOS_MAXFRAGMENTLEN, ERR_R_INTERNAL_ERROR);
        return EXT_RETURN_FAIL;
    }

    return EXT_RETURN_SENT;
}

#ifndef OPENSSL_NO_SRP
EXT_RETURN tls_construct_ctos_srp(SSL *s, WPACKET *pkt, unsigned int context,
                                  X509 *x, size_t chainidx)
{
    /* Add SRP username if there is one */
    if (s->srp_ctx.login == NULL)
        return EXT_RETURN_NOT_SENT;

    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_srp)
               /* Sub-packet for SRP extension */
            || !WPACKET_start_sub_packet_u16(pkt)
            || !WPACKET_start_sub_packet_u8(pkt)
               /* login must not be zero...internal error if so */
            || !WPACKET_set_flags(pkt, WPACKET_FLAGS_NON_ZERO_LENGTH)
            || !WPACKET_memcpy(pkt, s->srp_ctx.login,
                               strlen(s->srp_ctx.login))
            || !WPACKET_close(pkt)
            || !WPACKET_close(pkt)) {
        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_CTOS_SRP,
                 ERR_R_INTERNAL_ERROR);
        return EXT_RETURN_FAIL;
    }

    return EXT_RETURN_SENT;
}
#endif

#ifndef OPENSSL_NO_EC
static int use_ecc(SSL *s)
{
    int i, end;
    unsigned long alg_k, alg_a;
    STACK_OF(SSL_CIPHER) *cipher_stack = NULL;

    /* See if we support any ECC ciphersuites */
    if (s->version == SSL3_VERSION)
        return 0;

    cipher_stack = SSL_get_ciphers(s);
    end = sk_SSL_CIPHER_num(cipher_stack);
    for (i = 0; i < end; i++) {
        const SSL_CIPHER *c = sk_SSL_CIPHER_value(cipher_stack, i);

        alg_k = c->algorithm_mkey;
        alg_a = c->algorithm_auth;
        if ((alg_k & (SSL_kECDHE | SSL_kECDHEPSK))
                || (alg_a & SSL_aECDSA)
                || c->min_tls >= TLS1_3_VERSION)
            return 1;
    }

    return 0;
}

EXT_RETURN tls_construct_ctos_ec_pt_formats(SSL *s, WPACKET *pkt,
                                            unsigned int context, X509 *x,
                                            size_t chainidx)
{
    const unsigned char *pformats;
    size_t num_formats;

    if (!use_ecc(s))
        return EXT_RETURN_NOT_SENT;

    /* Add TLS extension ECPointFormats to the ClientHello message */
    tls1_get_formatlist(s, &pformats, &num_formats);

    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_ec_point_formats)
               /* Sub-packet for formats extension */
            || !WPACKET_start_sub_packet_u16(pkt)
            || !WPACKET_sub_memcpy_u8(pkt, pformats, num_formats)
            || !WPACKET_close(pkt)) {
        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
                 SSL_F_TLS_CONSTRUCT_CTOS_EC_PT_FORMATS, ERR_R_INTERNAL_ERROR);
        return EXT_RETURN_FAIL;
    }

    return EXT_RETURN_SENT;
}

EXT_RETURN tls_construct_ctos_supported_groups(SSL *s, WPACKET *pkt,
                                               unsigned int context, X509 *x,
                                               size_t chainidx)
{
    const uint16_t *pgroups = NULL;
    size_t num_groups = 0, i;

    if (!use_ecc(s))
        return EXT_RETURN_NOT_SENT;

    /*
     * Add TLS extension supported_groups to the ClientHello message
     */
    /* TODO(TLS1.3): Add support for DHE groups */
    tls1_get_supported_groups(s, &pgroups, &num_groups);

    if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_supported_groups)
               /* Sub-packet for supported_groups extension */
            || !WPACKET_start_sub_packet_u16(pkt)
            || !WPACKET_start_sub_packet_u16(pkt)) {
        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
                 SSL_F_TLS_CONSTRUCT_CTOS_SUPPORTED_GROUPS,
                 ERR_R_INTERNAL_ERROR);
        return EXT_RETURN_FAIL;
    }
    /* Copy curve ID if supported */
    for (i = 0; i < num_groups; i++) {
        uint16_t ctmp = pgroups[i];

        if (tls_curve_allowed(s, ctmp, SSL_SECOP_CURVE_SUPPORTED)) {
            if (!WPACKET_put_bytes_u16(pkt, ctmp)) {
                    SSLfatal(s, SSL_AD_INTERNAL_ERROR,
                             SSL_F_TLS_CONSTRUCT_CTOS_SUPPORTED_GROUPS,