[tls] Split received records over multiple I/O buffers

TLS servers are not obliged to implement the RFC3546 maximum fragment
length extension, and many common servers (including OpenSSL, as used
in Apache's mod_ssl) do not do so.  iPXE may therefore have to cope
with TLS records of up to 16kB.  Allocations for 16kB have a
non-negligible chance of failing, causing the TLS connection to abort.

Fix by maintaining the received record as a linked list of I/O
buffers, rather than a single contiguous buffer.  To reduce memory
pressure, we also decrypt in situ, and deliver the decrypted data via
xfer_deliver_iob() rather than xfer_deliver_raw().

Signed-off-by: Michael Brown <mcb30@ipxe.org>

0 files changed, 0 insertions, 0 deletions