1 /***************************************************************************
2 * Copyright (c) 2024 Microsoft Corporation
3 *
4 * This program and the accompanying materials are made available under the
5 * terms of the MIT License which is available at
6 * https://opensource.org/licenses/MIT.
7 *
8 * SPDX-License-Identifier: MIT
9 **************************************************************************/
10
11
12 /**************************************************************************/
13 /**************************************************************************/
14 /** */
15 /** NetX Secure Component */
16 /** */
17 /** Datagram Transport Layer Security (DTLS) */
18 /** */
19 /**************************************************************************/
20 /**************************************************************************/
21
22 #define NX_SECURE_SOURCE_CODE
23
24 #include "nx_secure_dtls.h"
25
26 #ifdef NX_SECURE_ENABLE_DTLS
27 /**************************************************************************/
28 /* */
29 /* FUNCTION RELEASE */
30 /* */
31 /* _nx_secure_dtls_process_handshake_header PORTABLE C */
32 /* 6.1.3 */
33 /* AUTHOR */
34 /* */
35 /* Timothy Stapko, Microsoft Corporation */
36 /* */
37 /* DESCRIPTION */
38 /* */
39 /* This function processes a DTLS Handshake record header, which is */
40 /* at the beginning of each DTLS Handshake message, encapsulated */
41 /* within the DTLS record itself. */
42 /* */
43 /* INPUT */
44 /* */
45 /* packet_buffer Pointer to incoming packet */
46 /* message_type Return message type value */
47 /* header_size Input size of packet buffer */
48 /* Return size of header */
49 /* message_length Return length of message */
50 /* message_seq Return sequence of message */
51 /* fragment_offset Return offset of fragment */
52 /* fragment_length Return length of fragment */
53 /* */
54 /* OUTPUT */
55 /* */
56 /* status Completion status */
57 /* */
58 /* CALLS */
59 /* */
60 /* None */
61 /* */
62 /* CALLED BY */
63 /* */
64 /* _nx_secure_dtls_client_handshake DTLS client state machine */
65 /* _nx_secure_dtls_server_handshake DTLS server state machine */
66 /* */
67 /* RELEASE HISTORY */
68 /* */
69 /* DATE NAME DESCRIPTION */
70 /* */
71 /* 05-19-2020 Timothy Stapko Initial Version 6.0 */
72 /* 09-30-2020 Timothy Stapko Modified comment(s), */
73 /* resulting in version 6.1 */
74 /* 12-31-2020 Timothy Stapko Modified comment(s), */
75 /* improved buffer length */
76 /* verification, */
77 /* resulting in version 6.1.3 */
78 /* */
79 /**************************************************************************/
_nx_secure_dtls_process_handshake_header(UCHAR * packet_buffer,USHORT * message_type,UINT * header_size,UINT * message_length,UINT * message_seq,UINT * fragment_offset,UINT * fragment_length)80 UINT _nx_secure_dtls_process_handshake_header(UCHAR *packet_buffer, USHORT *message_type,
81 UINT *header_size, UINT *message_length,
82 UINT *message_seq, UINT *fragment_offset,
83 UINT *fragment_length)
84 {
85
86 /* Check buffer length. */
87 if (*header_size < NX_SECURE_DTLS_HANDSHAKE_HEADER_SIZE)
88 {
89 return(NX_SECURE_TLS_INCORRECT_MESSAGE_LENGTH);
90 }
91
92 /* The message being passed in to this function should already be stripped of the TLS header
93 so the first byte in the packet/record is our handshake message type. */
94 *message_type = packet_buffer[0];
95 packet_buffer++;
96
97 /* Get the length of the TLS data. */
98 *message_length = (UINT)((packet_buffer[0] << 16) + (packet_buffer[1] << 8) + packet_buffer[2]);
99 packet_buffer += 3;
100
101 /* Extract message sequence number. */
102 *message_seq = (UINT)((packet_buffer[0] << 8) + packet_buffer[1]);
103 packet_buffer += 2;
104
105 /* Extract fragment offset. */
106 *fragment_offset = (UINT)((packet_buffer[0] << 16) + (packet_buffer[1] << 8) + packet_buffer[2]);
107 packet_buffer += 3;
108
109 /* Extract fragment length. */
110 *fragment_length = (UINT)((packet_buffer[0] << 16) + (packet_buffer[1] << 8) + packet_buffer[2]);
111
112 /* We have extracted the DTLS header. */
113 *header_size = NX_SECURE_DTLS_HANDSHAKE_HEADER_SIZE;
114
115 return(NX_SECURE_TLS_SUCCESS);
116 }
117 #endif /* NX_SECURE_ENABLE_DTLS */
118
119
