mixnet/core/
request_builder.rs

1// Copyright 2022 Parity Technologies (UK) Ltd.
2//
3// Permission is hereby granted, free of charge, to any person obtaining a
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.
12//
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
16// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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19// DEALINGS IN THE SOFTWARE.
20
21//! Mixnet request builder. This module simply plugs together the topology and Sphinx modules.
22
23use super::{
24	packet_queues::AddressedPacket,
25	sphinx::{
26		build_surb, complete_request_packet, mut_payload_data, Delay, MixnodeIndex, PayloadData,
27		Surb, SurbId, SurbPayloadEncryptionKeys,
28	},
29	topology::{NetworkStatus, RouteGenerator, RouteKind, Topology, TopologyErr},
30	util::default_boxed_array,
31};
32use arrayvec::ArrayVec;
33use rand::{CryptoRng, Rng};
34
35pub struct RouteMetrics {
36	pub num_hops: usize,
37	pub forwarding_delay: Delay,
38}
39
40pub struct RequestBuilder<'topology, X> {
41	route_generator: RouteGenerator<'topology, X>,
42	destination_index: MixnodeIndex,
43}
44
45impl<'topology, X> RequestBuilder<'topology, X> {
46	pub fn new(
47		rng: &mut (impl Rng + CryptoRng),
48		topology: &'topology Topology<X>,
49		ns: &dyn NetworkStatus,
50		destination_index: Option<MixnodeIndex>,
51	) -> Result<Self, TopologyErr> {
52		let route_generator = RouteGenerator::new(topology, ns);
53		let destination_index = match destination_index {
54			Some(index) => index,
55			None => route_generator.choose_destination_index(rng)?,
56		};
57		Ok(Self { route_generator, destination_index })
58	}
59
60	pub fn destination_index(&self) -> MixnodeIndex {
61		self.destination_index
62	}
63
64	pub fn build_packet<R: Rng + CryptoRng>(
65		&self,
66		rng: &mut R,
67		write_payload_data: impl FnOnce(&mut PayloadData, &mut R) -> Result<(), TopologyErr>,
68		num_hops: usize,
69	) -> Result<(AddressedPacket, RouteMetrics), TopologyErr> {
70		// Generate route
71		let mut targets = ArrayVec::new();
72		let mut their_kx_publics = ArrayVec::new();
73		let first_mixnode_index = self.route_generator.gen_route(
74			&mut targets,
75			&mut their_kx_publics,
76			rng,
77			RouteKind::ToMixnode(self.destination_index),
78			num_hops,
79		)?;
80		let peer_id =
81			self.route_generator.topology().mixnode_index_to_peer_id(first_mixnode_index)?;
82
83		// Build packet
84		let mut packet = default_boxed_array();
85		write_payload_data(mut_payload_data(&mut packet), rng)?;
86		let forwarding_delay =
87			complete_request_packet(&mut packet, rng, &targets, &their_kx_publics);
88
89		let packet = AddressedPacket { peer_id, packet };
90		let metrics = RouteMetrics { num_hops: their_kx_publics.len(), forwarding_delay };
91		Ok((packet, metrics))
92	}
93
94	pub fn build_surb(
95		&self,
96		surb: &mut Surb,
97		payload_encryption_keys: &mut SurbPayloadEncryptionKeys,
98		rng: &mut (impl Rng + CryptoRng),
99		id: &SurbId,
100		num_hops: usize,
101	) -> Result<RouteMetrics, TopologyErr> {
102		// Generate route
103		let mut targets = ArrayVec::new();
104		let mut their_kx_publics = ArrayVec::new();
105		let first_mixnode_index = self.route_generator.gen_route(
106			&mut targets,
107			&mut their_kx_publics,
108			rng,
109			RouteKind::FromMixnode(self.destination_index),
110			num_hops,
111		)?;
112
113		// Build SURB
114		let forwarding_delay = build_surb(
115			surb,
116			payload_encryption_keys,
117			rng,
118			first_mixnode_index,
119			&targets,
120			&their_kx_publics,
121			id,
122		);
123
124		Ok(RouteMetrics { num_hops: their_kx_publics.len(), forwarding_delay })
125	}
126}
mixnet/core/request_builder.rs

mixnet/core/
request_builder.rs
