int tls12_check_peer_sigalg(const EVP_MD **pmd, SSL *s,
                            const unsigned char *sig, EVP_PKEY *pkey)
{
    const unsigned char *sent_sigs;
    size_t sent_sigslen, i;
    int sigalg = tls12_get_sigid(pkey);
    /* Should never happen */
    if (sigalg == -1)
        return -1;
    /* Check key type is consistent with signature */
    if (sigalg != (int)sig[1]) {
        SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG, SSL_R_WRONG_SIGNATURE_TYPE);
        return 0;
    }
# ifndef OPENSSL_NO_EC
    if (pkey->type == EVP_PKEY_EC) {
        unsigned char curve_id[2], comp_id;
        /* Check compression and curve matches extensions */
        if (!tls1_set_ec_id(curve_id, &comp_id, pkey->pkey.ec))
            return 0;
        if (!s->server && !tls1_check_ec_key(s, curve_id, &comp_id)) {
            SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG, SSL_R_WRONG_CURVE);
            return 0;
        }
        /* If Suite B only P-384+SHA384 or P-256+SHA-256 allowed */
        if (tls1_suiteb(s)) {
            if (curve_id[0])
                return 0;
            if (curve_id[1] == TLSEXT_curve_P_256) {
                if (sig[0] != TLSEXT_hash_sha256) {
                    SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG,
                           SSL_R_ILLEGAL_SUITEB_DIGEST);
                    return 0;
                }
            } else if (curve_id[1] == TLSEXT_curve_P_384) {
                if (sig[0] != TLSEXT_hash_sha384) {
                    SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG,
                           SSL_R_ILLEGAL_SUITEB_DIGEST);
                    return 0;
                }
            } else
                return 0;
        }
    } else if (tls1_suiteb(s))
        return 0;
# endif

    /* Check signature matches a type we sent */
    sent_sigslen = tls12_get_psigalgs(s, &sent_sigs);
    for (i = 0; i < sent_sigslen; i += 2, sent_sigs += 2) {
        if (sig[0] == sent_sigs[0] && sig[1] == sent_sigs[1])
            break;
    }
    /* Allow fallback to SHA1 if not strict mode */
    if (i == sent_sigslen
        && (sig[0] != TLSEXT_hash_sha1
            || s->cert->cert_flags & SSL_CERT_FLAGS_CHECK_TLS_STRICT)) {
        SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG, SSL_R_WRONG_SIGNATURE_TYPE);
        return 0;
    }
    *pmd = tls12_get_hash(sig[0]);
    if (*pmd == NULL) {
        SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG, SSL_R_UNKNOWN_DIGEST);
        return 0;
    }
    /*
     * Store the digest used so applications can retrieve it if they wish.
     */
    if (s->session && s->session->sess_cert)
        s->session->sess_cert->peer_key->digest = *pmd;
    return 1;
}

Unknown