Fragmentation in TSL

The record layer fragments information blocks into TLSPlaintext
records carrying data in chunks of 2^14 bytes or less.Client
message boundaries are not preserved in the record layer (i.e.,
multiple client messages of the same ContentType MAY be coalesced
into a single TLSPlaintext record, or a single message MAY be
fragmented across several records).

struct {
uint8 major;
uint8 minor;
} ProtocolVersion;

enum {
change_cipher_spec(20), alert(21), handshake(22),
application_data(23), (255)
} ContentType;

struct {
ContentType type;
ProtocolVersion version;
uint16 length;
opaque fragment[TLSPlaintext.length];
} TLSPlaintext;

type
The higher-level protocol used to process the enclosed fragment.

version
The version of the protocol being employed.This document
describes TLS Version 1.2, which uses the version { 3, 3 }.The
version value 3.3 is historical, deriving from the use of {3, 1}
for TLS 1.0.(See Appendix A.1.)Note that a client that
supports multiple versions of TLS may not know what version will
be employed before it receives the ServerHello.See Appendix E
for discussion about what record layer version number should be
employed for ClientHello.

length
The length (in bytes) of the following TLSPlaintext.fragment.The
length MUST NOT exceed 2^14.

fragment
The application data.This data is transparent and treated as an
independent block to be dealt with by the higher-level protocol
specified by the type field.

Implementations MUST NOT send zero-length fragments of Handshake,
Alert, or ChangeCipherSpec content types.Zero-length fragments of
Application data MAY be sent as they are potentially useful as a
traffic analysis countermeasure.

Note: Data of different TLS record layer content types MAY be
interleaved.Application data is generally of lower precedence for
transmission than other content types.However, records MUST be
delivered to the network in the same order as they are protected by
the record layer.Recipients MUST receive and process interleaved
application layer traffic during handshakes subsequent to the first
one on a connection.