+ if (length <= prepend_length) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ msg.msg_control = buf;
+ msg.msg_controllen = sizeof(buf);
+
+ msg_iov.iov_base = p + prepend_length;
+ msg_iov.iov_len = length - prepend_length;
+ msg.msg_iov = &msg_iov;
+ msg.msg_iovlen = 1;
+
+ ret = recvmsg(fd, &msg, 0);
+ if (ret <= 0)
+ return ret;
+
+ if ((msg.msg_flags & (MSG_EOR | MSG_CTRUNC)) != MSG_EOR) {
+ errno = EMSGSIZE;
+ return -1;
+ }
+
+ if (msg.msg_controllen == 0) {
+ errno = EBADMSG;
+ return -1;
+ }
+
+ cmsg = CMSG_FIRSTHDR(&msg);
+ if (cmsg->cmsg_level != IPPROTO_TCP || cmsg->cmsg_type != TLS_GET_RECORD
+ || cmsg->cmsg_len != CMSG_LEN(cmsg_len)) {
+ errno = EBADMSG;
+ return -1;
+ }
+
+ tgr = (struct tls_get_record *)CMSG_DATA(cmsg);
+ p[0] = tgr->tls_type;
+ p[1] = tgr->tls_vmajor;
+ p[2] = tgr->tls_vminor;
+ *(uint16_t *)(p + 3) = htons(ret);
+
+ return ret + prepend_length;
+}
+
+# endif /* OPENSSL_NO_KTLS_RX */
+
+/*
+ * KTLS enables the sendfile system call to send data from a file over
+ * TLS.
+ */
+static ossl_inline ossl_ssize_t ktls_sendfile(int s, int fd, off_t off,
+ size_t size, int flags)
+{
+ off_t sbytes = 0;
+ int ret;
+
+ ret = sendfile(fd, s, off, size, NULL, &sbytes, flags);
+ if (ret == -1 && sbytes == 0)
+ return -1;
+ return sbytes;
+}
+
+# endif /* __FreeBSD__ */
+
+# if defined(OPENSSL_SYS_LINUX)