libp2p_gossipsub/
transform.rs

1// Copyright 2020 Sigma Prime Pty Ltd.
2//
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4// copy of this software and associated documentation files (the "Software"),
5// to deal in the Software without restriction, including without limitation
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7// and/or sell copies of the Software, and to permit persons to whom the
8// Software is furnished to do so, subject to the following conditions:
9//
10// The above copyright notice and this permission notice shall be included in
11// all copies or substantial portions of the Software.
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13// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
14// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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19// DEALINGS IN THE SOFTWARE.
20
21//! This trait allows of extended user-level decoding that can apply to message-data before a
22//! message-id is calculated.
23//!
24//! This is primarily designed to allow applications to implement their own custom compression
25//! algorithms that can be topic-specific. Once the raw data is transformed the message-id is then
26//! calculated, allowing for applications to employ message-id functions post compression.
27
28use crate::{Message, RawMessage, TopicHash};
29
30/// A general trait of transforming a [`RawMessage`] into a [`Message`]. The
31///
32/// [`RawMessage`] is obtained from the wire and the [`Message`] is used to
33/// calculate the [`crate::MessageId`] of the message and is what is sent to the application.
34///
35/// The inbound/outbound transforms must be inverses. Applying the inbound transform and then the
36/// outbound transform MUST leave the underlying data un-modified.
37///
38/// By default, this is the identity transform for all fields in [`Message`].
39pub trait DataTransform {
40    /// Takes a [`RawMessage`] received and converts it to a [`Message`].
41    fn inbound_transform(&self, raw_message: RawMessage) -> Result<Message, std::io::Error>;
42
43    /// Takes the data to be published (a topic and associated data) transforms the data. The
44    /// transformed data will then be used to create a [`crate::RawMessage`] to be sent to peers.
45    fn outbound_transform(
46        &self,
47        topic: &TopicHash,
48        data: Vec<u8>,
49    ) -> Result<Vec<u8>, std::io::Error>;
50}
51
52/// The default transform, the raw data is propagated as is to the application layer gossipsub.
53#[derive(Default, Clone)]
54pub struct IdentityTransform;
55
56impl DataTransform for IdentityTransform {
57    fn inbound_transform(&self, raw_message: RawMessage) -> Result<Message, std::io::Error> {
58        Ok(Message {
59            source: raw_message.source,
60            data: raw_message.data,
61            sequence_number: raw_message.sequence_number,
62            topic: raw_message.topic,
63        })
64    }
65
66    fn outbound_transform(
67        &self,
68        _topic: &TopicHash,
69        data: Vec<u8>,
70    ) -> Result<Vec<u8>, std::io::Error> {
71        Ok(data)
72    }
73}
libp2p_gossipsub/transform.rs

libp2p_gossipsub/
transform.rs
