+ /* 'create_empty_fragment' is true only when this function calls itself */
+ if (!clear && !create_empty_fragment && !s->s3->empty_fragment_done)
+ {
+ /* countermeasure against known-IV weakness in CBC ciphersuites
+ * (see http://www.openssl.org/~bodo/tls-cbc.txt) */
+
+ if (s->s3->need_empty_fragments && type == SSL3_RT_APPLICATION_DATA)
+ {
+ /* recursive function call with 'create_empty_fragment' set;
+ * this prepares and buffers the data for an empty fragment
+ * (these 'prefix_len' bytes are sent out later
+ * together with the actual payload) */
+ prefix_len = do_ssl3_write(s, type, buf, 0, 1);
+ if (prefix_len <= 0)
+ goto err;
+
+ if (prefix_len >
+ (SSL3_RT_HEADER_LENGTH + SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD))
+ {
+ /* insufficient space */
+ SSLerr(SSL_F_DO_SSL3_WRITE, ERR_R_INTERNAL_ERROR);
+ goto err;
+ }
+ }
+
+ s->s3->empty_fragment_done = 1;
+ }
+
+ if (create_empty_fragment)
+ {
+#if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
+ /* extra fragment would be couple of cipher blocks,
+ * which would be multiple of SSL3_ALIGN_PAYLOAD, so
+ * if we want to align the real payload, then we can
+ * just pretent we simply have two headers. */
+ align = (long)wb->buf + 2*SSL3_RT_HEADER_LENGTH;
+ align = (-align)&(SSL3_ALIGN_PAYLOAD-1);
+#endif
+ p = wb->buf + align;
+ wb->offset = align;
+ }
+ else if (prefix_len)
+ {
+ p = wb->buf + wb->offset + prefix_len;
+ }
+ else
+ {
+#if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
+ align = (long)wb->buf + SSL3_RT_HEADER_LENGTH;
+ align = (-align)&(SSL3_ALIGN_PAYLOAD-1);
+#endif
+ p = wb->buf + align;
+ wb->offset = align;
+ }