+#ifndef OPENSSL_NO_PSK
+/* convert the PSK key (psk_key) in ascii to binary (psk) */
+static int psk_key2bn(const char *pskkey, unsigned char *psk,
+ unsigned int max_psk_len)
+ {
+ int ret;
+ BIGNUM *bn = NULL;
+
+ ret = BN_hex2bn(&bn, pskkey);
+ if (!ret)
+ {
+ BIO_printf(bio_err,"Could not convert PSK key '%s' to BIGNUM\n", pskkey);
+ if (bn)
+ BN_free(bn);
+ return 0;
+ }
+ if (BN_num_bytes(bn) > (int)max_psk_len)
+ {
+ BIO_printf(bio_err,"psk buffer of callback is too small (%d) for key (%d)\n",
+ max_psk_len, BN_num_bytes(bn));
+ BN_free(bn);
+ return 0;
+ }
+ ret = BN_bn2bin(bn, psk);
+ BN_free(bn);
+ return ret;
+ }
+
+static unsigned int psk_client_callback(SSL *ssl, const char *hint, char *identity,
+ unsigned int max_identity_len, unsigned char *psk,
+ unsigned int max_psk_len)
+ {
+ int ret;
+ unsigned int psk_len = 0;
+
+ ret = BIO_snprintf(identity, max_identity_len, "Client_identity");
+ if (ret < 0)
+ goto out_err;
+ if (debug)
+ fprintf(stderr, "client: created identity '%s' len=%d\n", identity, ret);
+ ret = psk_key2bn(psk_key, psk, max_psk_len);
+ if (ret < 0)
+ goto out_err;
+ psk_len = ret;
+out_err:
+ return psk_len;
+ }
+
+static unsigned int psk_server_callback(SSL *ssl, const char *identity,
+ unsigned char *psk, unsigned int max_psk_len)
+ {
+ unsigned int psk_len=0;
+
+ if (strcmp(identity, "Client_identity") != 0)
+ {
+ BIO_printf(bio_err, "server: PSK error: client identity not found\n");
+ return 0;
+ }
+ psk_len=psk_key2bn(psk_key, psk, max_psk_len);
+ return psk_len;
+ }
+#endif
+