capabilities.c

/*
 * Copyright 2019-2025 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (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 <assert.h>
#include <string.h>
#include <openssl/core_dispatch.h>
#include <openssl/core_names.h>
/* For TLS1_VERSION etc */
#include <openssl/prov_ssl.h>
#include <openssl/params.h>
#include "internal/nelem.h"
#include "internal/tlsgroups.h"
#include "prov/providercommon.h"
#include "internal/e_os.h"
#include "crypto/ml_kem.h"

/*
 * If none of EC, DH OR ML-KEM are available then we have no TLS-GROUP
 * capabilities.
 */
#if !defined(OPENSSL_NO_EC) || !defined(OPENSSL_NO_DH) || !defined(OPENSSL_NO_ML_KEM)
typedef struct tls_group_constants_st {
    unsigned int group_id; /* Group ID */
    unsigned int secbits; /* Bits of security */
    int mintls; /* Minimum TLS version, -1 unsupported */
    int maxtls; /* Maximum TLS version (or 0 for undefined) */
    int mindtls; /* Minimum DTLS version, -1 unsupported */
    int maxdtls; /* Maximum DTLS version (or 0 for undefined) */
    int is_kem; /* Indicates utility as KEM */
} TLS_GROUP_CONSTANTS;

/*
 * The indices of entries in this table must be independent of which TLS groups
 * we do or not support.  It just lists basic facts about the groups, and is
 * used by (numeric slot number) reference in the "param_group_list" below.
 * Therefore, there must be no #ifdefs in this table, the index of each entry
 * must be independent of compile-time options.
 *
 * For the FFDHE groups, the security bit values are as given by
 * BN_security_bits().  For the ML-KEM hybrids these are the ML-KEM security
 * bits.
 */
static const TLS_GROUP_CONSTANTS group_list[] = {
    /*  0 */ { OSSL_TLS_GROUP_ID_sect163k1, 80, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /*  1 */ { OSSL_TLS_GROUP_ID_sect163r1, 80, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /*  2 */ { OSSL_TLS_GROUP_ID_sect163r2, 80, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /*  3 */ { OSSL_TLS_GROUP_ID_sect193r1, 80, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /*  4 */ { OSSL_TLS_GROUP_ID_sect193r2, 80, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /*  5 */ { OSSL_TLS_GROUP_ID_sect233k1, 112, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /*  6 */ { OSSL_TLS_GROUP_ID_sect233r1, 112, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /*  7 */ { OSSL_TLS_GROUP_ID_sect239k1, 112, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /*  8 */ { OSSL_TLS_GROUP_ID_sect283k1, 128, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /*  9 */ { OSSL_TLS_GROUP_ID_sect283r1, 128, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 10 */ { OSSL_TLS_GROUP_ID_sect409k1, 192, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 11 */ { OSSL_TLS_GROUP_ID_sect409r1, 192, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 12 */ { OSSL_TLS_GROUP_ID_sect571k1, 256, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 13 */ { OSSL_TLS_GROUP_ID_sect571r1, 256, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 14 */ { OSSL_TLS_GROUP_ID_secp160k1, 80, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 15 */ { OSSL_TLS_GROUP_ID_secp160r1, 80, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 16 */ { OSSL_TLS_GROUP_ID_secp160r2, 80, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 17 */ { OSSL_TLS_GROUP_ID_secp192k1, 80, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 18 */ { OSSL_TLS_GROUP_ID_secp192r1, 80, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 19 */ { OSSL_TLS_GROUP_ID_secp224k1, 112, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 20 */ { OSSL_TLS_GROUP_ID_secp224r1, 112, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 21 */ { OSSL_TLS_GROUP_ID_secp256k1, 128, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 22 */ { OSSL_TLS_GROUP_ID_secp256r1, 128, TLS1_VERSION, 0, DTLS1_VERSION, 0, 0 },
    /* 23 */ { OSSL_TLS_GROUP_ID_secp384r1, 192, TLS1_VERSION, 0, DTLS1_VERSION, 0, 0 },
    /* 24 */ { OSSL_TLS_GROUP_ID_secp521r1, 256, TLS1_VERSION, 0, DTLS1_VERSION, 0, 0 },
    /* 25 */ { OSSL_TLS_GROUP_ID_brainpoolP256r1, 128, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 26 */ { OSSL_TLS_GROUP_ID_brainpoolP384r1, 192, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 27 */ { OSSL_TLS_GROUP_ID_brainpoolP512r1, 256, TLS1_VERSION, TLS1_2_VERSION, DTLS1_VERSION, DTLS1_2_VERSION, 0 },
    /* 28 */ { OSSL_TLS_GROUP_ID_x25519, 128, TLS1_VERSION, 0, DTLS1_VERSION, 0, 0 },
    /* 29 */ { OSSL_TLS_GROUP_ID_x448, 224, TLS1_VERSION, 0, DTLS1_VERSION, 0, 0 },
    /* 30 */ { OSSL_TLS_GROUP_ID_brainpoolP256r1_tls13, 128, TLS1_3_VERSION, 0, -1, -1, 0 },
    /* 31 */ { OSSL_TLS_GROUP_ID_brainpoolP384r1_tls13, 192, TLS1_3_VERSION, 0, -1, -1, 0 },
    /* 32 */ { OSSL_TLS_GROUP_ID_brainpoolP512r1_tls13, 256, TLS1_3_VERSION, 0, -1, -1, 0 },
    /* 33 */ { OSSL_TLS_GROUP_ID_ffdhe2048, 112, TLS1_3_VERSION, 0, -1, -1, 0 },
    /* 34 */ { OSSL_TLS_GROUP_ID_ffdhe3072, 128, TLS1_3_VERSION, 0, -1, -1, 0 },
    /* 35 */ { OSSL_TLS_GROUP_ID_ffdhe4096, 128, TLS1_3_VERSION, 0, -1, -1, 0 },
    /* 36 */ { OSSL_TLS_GROUP_ID_ffdhe6144, 128, TLS1_3_VERSION, 0, -1, -1, 0 },
    /* 37 */ { OSSL_TLS_GROUP_ID_ffdhe8192, 192, TLS1_3_VERSION, 0, -1, -1, 0 },
    /* 38 */ { OSSL_TLS_GROUP_ID_mlkem512, ML_KEM_512_SECBITS, TLS1_3_VERSION, 0, -1, -1, 1 },
    /* 39 */ { OSSL_TLS_GROUP_ID_mlkem768, ML_KEM_768_SECBITS, TLS1_3_VERSION, 0, -1, -1, 1 },
    /* 40 */ { OSSL_TLS_GROUP_ID_mlkem1024, ML_KEM_1024_SECBITS, TLS1_3_VERSION, 0, -1, -1, 1 },
    /* 41 */ { OSSL_TLS_GROUP_ID_X25519MLKEM768, ML_KEM_768_SECBITS, TLS1_3_VERSION, 0, -1, -1, 1 },
    /* 42 */ { OSSL_TLS_GROUP_ID_SecP256r1MLKEM768, ML_KEM_768_SECBITS, TLS1_3_VERSION, 0, -1, -1, 1 },
    /* 43 */ { OSSL_TLS_GROUP_ID_SecP384r1MLKEM1024, ML_KEM_1024_SECBITS, TLS1_3_VERSION, 0, -1, -1, 1 },
};

#define TLS_GROUP_ENTRY(tlsname, realname, algorithm, idx)              \
    {                                                                   \
        OSSL_PARAM_utf8_string(OSSL_CAPABILITY_TLS_GROUP_NAME,          \
            tlsname,                                                    \
            sizeof(tlsname)),                                           \
        OSSL_PARAM_utf8_string(OSSL_CAPABILITY_TLS_GROUP_NAME_INTERNAL, \
            realname,                                                   \
            sizeof(realname)),                                          \
        OSSL_PARAM_utf8_string(OSSL_CAPABILITY_TLS_GROUP_ALG,           \
            algorithm,                                                  \
            sizeof(algorithm)),                                         \
        OSSL_PARAM_uint(OSSL_CAPABILITY_TLS_GROUP_ID,                   \
            (unsigned int *)&group_list[idx].group_id),                 \
        OSSL_PARAM_uint(OSSL_CAPABILITY_TLS_GROUP_SECURITY_BITS,        \
            (unsigned int *)&group_list[idx].secbits),                  \
        OSSL_PARAM_int(OSSL_CAPABILITY_TLS_GROUP_MIN_TLS,               \
            (unsigned int *)&group_list[idx].mintls),                   \
        OSSL_PARAM_int(OSSL_CAPABILITY_TLS_GROUP_MAX_TLS,               \
            (unsigned int *)&group_list[idx].maxtls),                   \
        OSSL_PARAM_int(OSSL_CAPABILITY_TLS_GROUP_MIN_DTLS,              \
            (unsigned int *)&group_list[idx].mindtls),                  \
        OSSL_PARAM_int(OSSL_CAPABILITY_TLS_GROUP_MAX_DTLS,              \
            (unsigned int *)&group_list[idx].maxdtls),                  \
        OSSL_PARAM_int(OSSL_CAPABILITY_TLS_GROUP_IS_KEM,                \
            (unsigned int *)&group_list[idx].is_kem),                   \
        OSSL_PARAM_END                                                  \
    }

/*-
 * - The 4th field of each entry is an index into "group_list" above.
 *
 * - The 3rd field is the key management algorithm name.

 * - The 2nd field is the GROUP_NAME used with the provider, needed for
 *   providers that implement a family of related algorithms, but required
 *   non-null even when the provider implements just one.
 *
 * - The 1st field is the TLS group name used in SSL_CTX_set_group_list(),
 *   aliases repeat everything but the first field.
 *
 * Curves 1..22 were deprecated in:
 *
 *   https://www.rfc-editor.org/rfc/rfc8422.html
 *
 * leaving just:
 *
 *   enum {
 *       deprecated(1..22),
 *       secp256r1 (23), secp384r1 (24), secp521r1 (25),
 *       x25519(29), x448(30),
 *       reserved (0xFE00..0xFEFF),
 *       deprecated(0xFF01..0xFF02),
 *       (0xFFFF)
 *   } NamedCurve;
 *
 * and those added later (FFDHE, brainpool, ML-KEM)
 */
static const OSSL_PARAM param_group_list[][11] = {
#ifndef OPENSSL_NO_EC
#if !defined(OPENSSL_NO_ML_KEM)
#if !defined(OPENSSL_NO_ECX)
    TLS_GROUP_ENTRY("X25519MLKEM768", "", "X25519MLKEM768", 41),
#endif
#endif
#ifndef FIPS_MODULE
    TLS_GROUP_ENTRY("x25519", "X25519", "X25519", 28),
    TLS_GROUP_ENTRY("x448", "X448", "X448", 29),
#endif
    TLS_GROUP_ENTRY("secp256r1", "prime256v1", "EC", 22),
    TLS_GROUP_ENTRY("P-256", "prime256v1", "EC", 22), /* Alias of above */
    TLS_GROUP_ENTRY("secp384r1", "secp384r1", "EC", 23),
    TLS_GROUP_ENTRY("P-384", "secp384r1", "EC", 23), /* Alias of above */
    TLS_GROUP_ENTRY("secp521r1", "secp521r1", "EC", 24),
    TLS_GROUP_ENTRY("P-521", "secp521r1", "EC", 24), /* Alias of above */
#endif /* OPENSSL_NO_EC */
#ifndef OPENSSL_NO_DH
    /* Security bit values for FFDHE groups are as per RFC 7919 */
    TLS_GROUP_ENTRY("ffdhe2048", "ffdhe2048", "DH", 33),
    TLS_GROUP_ENTRY("ffdhe3072", "ffdhe3072", "DH", 34),
#endif
#if !defined(OPENSSL_NO_ML_KEM)
    /* https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-8 */
    TLS_GROUP_ENTRY("MLKEM512", "", "ML-KEM-512", 38),
    TLS_GROUP_ENTRY("MLKEM768", "", "ML-KEM-768", 39),
    TLS_GROUP_ENTRY("MLKEM1024", "", "ML-KEM-1024", 40),
#endif
#ifndef OPENSSL_NO_EC
#ifndef FIPS_MODULE
    TLS_GROUP_ENTRY("brainpoolP256r1", "brainpoolP256r1", "EC", 25),
    TLS_GROUP_ENTRY("brainpoolP384r1", "brainpoolP384r1", "EC", 26),
    TLS_GROUP_ENTRY("brainpoolP512r1", "brainpoolP512r1", "EC", 27),
    TLS_GROUP_ENTRY("brainpoolP256r1tls13", "brainpoolP256r1", "EC", 30),
    TLS_GROUP_ENTRY("brainpoolP384r1tls13", "brainpoolP384r1", "EC", 31),
    TLS_GROUP_ENTRY("brainpoolP512r1tls13", "brainpoolP512r1", "EC", 32),
#endif
#ifndef OPENSSL_NO_ML_KEM
    TLS_GROUP_ENTRY("SecP256r1MLKEM768", "", "SecP256r1MLKEM768", 42),
    TLS_GROUP_ENTRY("SecP384r1MLKEM1024", "", "SecP384r1MLKEM1024", 43),
#endif
#endif
#ifndef OPENSSL_NO_DH
    TLS_GROUP_ENTRY("ffdhe4096", "ffdhe4096", "DH", 35),
    TLS_GROUP_ENTRY("ffdhe6144", "ffdhe6144", "DH", 36),
    TLS_GROUP_ENTRY("ffdhe8192", "ffdhe8192", "DH", 37),
#endif
#ifndef OPENSSL_NO_TLS_DEPRECATED_EC
#ifndef OPENSSL_NO_EC2M
    TLS_GROUP_ENTRY("sect163k1", "sect163k1", "EC", 0),
    TLS_GROUP_ENTRY("K-163", "sect163k1", "EC", 0), /* Alias of above */
#endif
#ifndef FIPS_MODULE
    TLS_GROUP_ENTRY("sect163r1", "sect163r1", "EC", 1),
#endif
#ifndef OPENSSL_NO_EC2M
    TLS_GROUP_ENTRY("sect163r2", "sect163r2", "EC", 2),
    TLS_GROUP_ENTRY("B-163", "sect163r2", "EC", 2), /* Alias of above */
#endif
#ifndef FIPS_MODULE
    TLS_GROUP_ENTRY("sect193r1", "sect193r1", "EC", 3),
    TLS_GROUP_ENTRY("sect193r2", "sect193r2", "EC", 4),
#endif
#ifndef OPENSSL_NO_EC2M
    TLS_GROUP_ENTRY("sect233k1", "sect233k1", "EC", 5),
    TLS_GROUP_ENTRY("K-233", "sect233k1", "EC", 5), /* Alias of above */
    TLS_GROUP_ENTRY("sect233r1", "sect233r1", "EC", 6),
    TLS_GROUP_ENTRY("B-233", "sect233r1", "EC", 6), /* Alias of above */
#endif
#ifndef FIPS_MODULE
    TLS_GROUP_ENTRY("sect239k1", "sect239k1", "EC", 7),
#endif
#ifndef OPENSSL_NO_EC2M
    TLS_GROUP_ENTRY("sect283k1", "sect283k1", "EC", 8),
    TLS_GROUP_ENTRY("K-283", "sect283k1", "EC", 8), /* Alias of above */
    TLS_GROUP_ENTRY("sect283r1", "sect283r1", "EC", 9),
    TLS_GROUP_ENTRY("B-283", "sect283r1", "EC", 9), /* Alias of above */
    TLS_GROUP_ENTRY("sect409k1", "sect409k1", "EC", 10),
    TLS_GROUP_ENTRY("K-409", "sect409k1", "EC", 10), /* Alias of above */
    TLS_GROUP_ENTRY("sect409r1", "sect409r1", "EC", 11),
    TLS_GROUP_ENTRY("B-409", "sect409r1", "EC", 11), /* Alias of above */
    TLS_GROUP_ENTRY("sect571k1", "sect571k1", "EC", 12),
    TLS_GROUP_ENTRY("K-571", "sect571k1", "EC", 12), /* Alias of above */
    TLS_GROUP_ENTRY("sect571r1", "sect571r1", "EC", 13),
    TLS_GROUP_ENTRY("B-571", "sect571r1", "EC", 13), /* Alias of above */
#endif
#ifndef FIPS_MODULE
    TLS_GROUP_ENTRY("secp160k1", "secp160k1", "EC", 14),
    TLS_GROUP_ENTRY("secp160r1", "secp160r1", "EC", 15),
    TLS_GROUP_ENTRY("secp160r2", "secp160r2", "EC", 16),
    TLS_GROUP_ENTRY("secp192k1", "secp192k1", "EC", 17),
#endif
    TLS_GROUP_ENTRY("secp192r1", "prime192v1", "EC", 18),
    TLS_GROUP_ENTRY("P-192", "prime192v1", "EC", 18), /* Alias of above */
#ifndef FIPS_MODULE
    TLS_GROUP_ENTRY("secp224k1", "secp224k1", "EC", 19),
#endif
    TLS_GROUP_ENTRY("secp224r1", "secp224r1", "EC", 20),
    TLS_GROUP_ENTRY("P-224", "secp224r1", "EC", 20), /* Alias of above */
#ifndef FIPS_MODULE
    TLS_GROUP_ENTRY("secp256k1", "secp256k1", "EC", 21),
#endif
#endif /* !defined(OPENSSL_NO_TLS_DEPRECATED_EC) */
};
#endif /* !defined(OPENSSL_NO_EC) || !defined(OPENSSL_NO_DH) || !defined(OPENSSL_NO_ML_KEM) */

static int tls_group_capability(OSSL_CALLBACK *cb, void *arg)
{
#if !defined(OPENSSL_NO_EC) || !defined(OPENSSL_NO_DH) || !defined(OPENSSL_NO_ML_KEM)
    size_t i;

    for (i = 0; i < OSSL_NELEM(param_group_list); i++)
        if (!cb(param_group_list[i], arg))
            return 0;
#endif

    return 1;
}

/* --------------------------------------------------------------- */

#if !defined(OPENSSL_NO_ML_DSA)

typedef struct tls_sigalg_constants_st {
    unsigned int code_point;
    unsigned int sec_bits; /* Bits of security */
    int min_tls; /* Minimum TLS version, -1 unsupported */
    int max_tls; /* Maximum TLS version (or 0 for undefined) */
    int min_dtls; /* Minimum DTLS version, -1 unsupported */
    int max_dtls; /* Maximum DTLS version (or 0 for undefined) */
} TLS_SIGALG_CONSTANTS;

static const TLS_SIGALG_CONSTANTS sigalg_constants_list[3] = {
    { 0x0904, 128, TLS1_3_VERSION, 0, -1, -1 },
    { 0x0905, 192, TLS1_3_VERSION, 0, -1, -1 },
    { 0x0906, 256, TLS1_3_VERSION, 0, -1, -1 },
};

#define TLS_SIGALG_ENTRY(tlsname, algorithm, oid, idx)               \
    {                                                                \
        OSSL_PARAM_utf8_string(OSSL_CAPABILITY_TLS_SIGALG_IANA_NAME, \
            tlsname, sizeof(tlsname)),                               \
        OSSL_PARAM_utf8_string(OSSL_CAPABILITY_TLS_SIGALG_NAME,      \
            algorithm, sizeof(algorithm)),                           \
        OSSL_PARAM_utf8_string(OSSL_CAPABILITY_TLS_SIGALG_OID,       \
            oid, sizeof(oid)),                                       \
        OSSL_PARAM_uint(OSSL_CAPABILITY_TLS_SIGALG_CODE_POINT,       \
            (unsigned int *)&sigalg_constants_list[idx].code_point), \
        OSSL_PARAM_uint(OSSL_CAPABILITY_TLS_SIGALG_SECURITY_BITS,    \
            (unsigned int *)&sigalg_constants_list[idx].sec_bits),   \
        OSSL_PARAM_int(OSSL_CAPABILITY_TLS_SIGALG_MIN_TLS,           \
            (unsigned int *)&sigalg_constants_list[idx].min_tls),    \
        OSSL_PARAM_int(OSSL_CAPABILITY_TLS_SIGALG_MAX_TLS,           \
            (unsigned int *)&sigalg_constants_list[idx].max_tls),    \
        OSSL_PARAM_int(OSSL_CAPABILITY_TLS_SIGALG_MIN_DTLS,          \
            (unsigned int *)&sigalg_constants_list[idx].min_dtls),   \
        OSSL_PARAM_int(OSSL_CAPABILITY_TLS_SIGALG_MAX_DTLS,          \
            (unsigned int *)&sigalg_constants_list[idx].max_dtls),   \
        OSSL_PARAM_END                                               \
    }

static const OSSL_PARAM param_sigalg_list[][10] = {
    TLS_SIGALG_ENTRY("mldsa44", "ML-DSA-44", "2.16.840.1.101.3.4.3.17", 0),
    TLS_SIGALG_ENTRY("mldsa65", "ML-DSA-65", "2.16.840.1.101.3.4.3.18", 1),
    TLS_SIGALG_ENTRY("mldsa87", "ML-DSA-87", "2.16.840.1.101.3.4.3.19", 2),
};
#endif /* OPENSSL_NO_ML_DSA */

static int tls_sigalg_capability(OSSL_CALLBACK *cb, void *arg)
{
#if !defined(OPENSSL_NO_ML_DSA)
    size_t i;

    for (i = 0; i < OSSL_NELEM(param_sigalg_list); i++)
        if (!cb(param_sigalg_list[i], arg))
            return 0;
#endif
    return 1;
}

int ossl_prov_get_capabilities(void *provctx, const char *capability,
    OSSL_CALLBACK *cb, void *arg)
{
    if (OPENSSL_strcasecmp(capability, "TLS-GROUP") == 0)
        return tls_group_capability(cb, arg);
    if (OPENSSL_strcasecmp(capability, "TLS-SIGALG") == 0)
        return tls_sigalg_capability(cb, arg);

    /* We don't support this capability */
    return 0;
}