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Close #174: Reduce size field in datapacket header

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Reduce the size from 19 to 16 bits

Signed-off-by: Lee Smet <lee.smet@hotmail.com>
This commit is contained in:
Lee Smet
2024-03-26 11:48:36 +01:00
parent d9e3020e0b
commit 6ecb37628f
3 changed files with 12 additions and 9 deletions
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CHANGELOG.md
+4
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@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
## [Unreleased]
### Changed
- Size of data packets is limited to 65535 bytes.
### Fixed
- The feasibility distance of an existing source key is no longer incorrectly updated
docs/data_packet.md
+5 -5
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@@ -13,7 +13,7 @@ The packet header has a fixed size of 36 bytes, with the following layout:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Reserved | Length | Hop Limit |
| Reserved | Length | Hop Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
@@ -33,11 +33,11 @@ The packet header has a fixed size of 36 bytes, with the following layout:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
```
The first 5 bits are reserved and must be set to 0.
The first 8 bits are reserved and must be set to 0.
The next 19 bits are used to specify the length of the body. It is expected that
the actual length of a packet does not exceed 256K right now, so the 19th bit is
only needed because we have to account for some overhead related to the encryption.
The next 16 bits are used to specify the length of the body. It is expected that
the actual length of a packet does not exceed 65K right now, and overhead related
to encryption should be handled by the client before sending the packet.
The next byte is the hop-limit. Every node decrements this value by 1 before sending
the packet. If a node decrements this value to 0, the packet is discarded.
src/packet/data.rs
+3 -4
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@@ -7,7 +7,7 @@ use tokio_util::codec::{Decoder, Encoder};
const DATA_PACKET_HEADER_SIZE: usize = 4;
/// Mask to extract data length from
const DATA_PACKET_LEN_MASK: u32 = (1 << 19) - 1;
const DATA_PACKET_LEN_MASK: u32 = (1 << 16) - 1;
#[derive(Debug, Clone)]
pub struct DataPacket {
@@ -27,8 +27,7 @@ pub struct Codec {
/// Data from the DataPacket header.
#[derive(Clone, Copy)]
struct HeaderValues {
// At most 19 bits atm but that can't be properly expressed.
len: u32,
len: u16,
hop_limit: u8,
}
@@ -59,7 +58,7 @@ impl Decoder for Codec {
let raw_header = src.get_u32();
// Hop limit is the last 8 bits.
let hop_limit = (raw_header & 0xFF) as u8;
let data_len = (raw_header >> 8) & DATA_PACKET_LEN_MASK;
let data_len = ((raw_header >> 8) & DATA_PACKET_LEN_MASK) as u16;
let header_vals = HeaderValues {
len: data_len,
hop_limit,