BadVPN – Blame information for rev 1
?pathlinks?
Rev | Author | Line No. | Line |
---|---|---|---|
1 | office | 1 | /** |
2 | * @file fragmentproto.h |
||
3 | * @author Ambroz Bizjak <ambrop7@gmail.com> |
||
4 | * |
||
5 | * @section LICENSE |
||
6 | * |
||
7 | * Redistribution and use in source and binary forms, with or without |
||
8 | * modification, are permitted provided that the following conditions are met: |
||
9 | * 1. Redistributions of source code must retain the above copyright |
||
10 | * notice, this list of conditions and the following disclaimer. |
||
11 | * 2. Redistributions in binary form must reproduce the above copyright |
||
12 | * notice, this list of conditions and the following disclaimer in the |
||
13 | * documentation and/or other materials provided with the distribution. |
||
14 | * 3. Neither the name of the author nor the |
||
15 | * names of its contributors may be used to endorse or promote products |
||
16 | * derived from this software without specific prior written permission. |
||
17 | * |
||
18 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND |
||
19 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
||
20 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
||
21 | * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
||
22 | * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
||
23 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
||
24 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
||
25 | * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
||
26 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
||
27 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
||
28 | * |
||
29 | * @section DESCRIPTION |
||
30 | * |
||
31 | * Definitions for FragmentProto, a protocol that allows sending of arbitrarily sized packets over |
||
32 | * a link with a fixed MTU. |
||
33 | * |
||
34 | * All multi-byte integers in structs are little-endian, unless stated otherwise. |
||
35 | * |
||
36 | * A FragmentProto packet consists of a number of chunks. |
||
37 | * Each chunk consists of: |
||
38 | * - the chunk header (struct {@link fragmentproto_chunk_header}) |
||
39 | * - the chunk payload, i.e. part of the frame specified in the header |
||
40 | */ |
||
41 | |||
42 | #ifndef BADVPN_PROTOCOL_FRAGMENTPROTO_H |
||
43 | #define BADVPN_PROTOCOL_FRAGMENTPROTO_H |
||
44 | |||
45 | #include <stdint.h> |
||
46 | |||
47 | #include <misc/balign.h> |
||
48 | #include <misc/packed.h> |
||
49 | |||
50 | typedef uint16_t fragmentproto_frameid; |
||
51 | |||
52 | /** |
||
53 | * FragmentProto chunk header. |
||
54 | */ |
||
55 | B_START_PACKED |
||
56 | struct fragmentproto_chunk_header { |
||
57 | /** |
||
58 | * Identifier of the frame this chunk belongs to. |
||
59 | * Frames should be given ascending identifiers as they are encoded |
||
60 | * into chunks (except when the ID wraps to zero). |
||
61 | */ |
||
62 | fragmentproto_frameid frame_id; |
||
63 | |||
64 | /** |
||
65 | * Position in the frame where this chunk starts. |
||
66 | */ |
||
67 | uint16_t chunk_start; |
||
68 | |||
69 | /** |
||
70 | * Length of the chunk's payload. |
||
71 | */ |
||
72 | uint16_t chunk_len; |
||
73 | |||
74 | /** |
||
75 | * Whether this is the last chunk of the frame, i.e. |
||
76 | * the total length of the frame is chunk_start + chunk_len. |
||
77 | */ |
||
78 | uint8_t is_last; |
||
79 | } B_PACKED; |
||
80 | B_END_PACKED |
||
81 | |||
82 | /** |
||
83 | * Calculates how many chunks are needed at most for encoding one frame of the |
||
84 | * given maximum size with FragmentProto onto a carrier with a given MTU. |
||
85 | * This includes the case when the first chunk of a frame is not the first chunk |
||
86 | * in a FragmentProto packet. |
||
87 | * |
||
88 | * @param carrier_mtu MTU of the carrier, i.e. maximum length of FragmentProto packets. Must be >sizeof(struct fragmentproto_chunk_header). |
||
89 | * @param frame_mtu maximum frame size. Must be >=0. |
||
90 | * @return maximum number of chunks needed. Will be >0. |
||
91 | */ |
||
92 | static int fragmentproto_max_chunks_for_frame (int carrier_mtu, int frame_mtu) |
||
93 | { |
||
94 | ASSERT(carrier_mtu > sizeof(struct fragmentproto_chunk_header)) |
||
95 | ASSERT(frame_mtu >= 0) |
||
96 | |||
97 | return (bdivide_up(frame_mtu, (carrier_mtu - sizeof(struct fragmentproto_chunk_header))) + 1); |
||
98 | } |
||
99 | |||
100 | #endif |