38 lines
1.1 KiB
Swift
38 lines
1.1 KiB
Swift
//
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// Copyright 2024 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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//
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import Foundation
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enum PreKeyId {
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private enum Constants {
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static let upperBound: UInt32 = 0x1000000
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}
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static func random() -> UInt32 {
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return UInt32.random(in: 1..<Constants.upperBound)
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}
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static func randomSigned() -> UInt32 {
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return UInt32.random(in: 1..<UInt32(Int32.max))
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}
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static func nextPreKeyIds(lastPreKeyId: UInt32?, count: Int) -> ClosedRange<UInt32> {
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owsPrecondition(count >= 1)
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let result = nextPreKeyId(lastPreKeyId: lastPreKeyId, count: count)
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return result...(result.advanced(by: count - 1))
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}
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private static func nextPreKeyId(lastPreKeyId: UInt32?, count: Int) -> UInt32 {
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guard let lastPreKeyId, (1..<Constants.upperBound).contains(lastPreKeyId) else {
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return UInt32.random(in: 1...(Constants.upperBound - UInt32(count)))
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}
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// We need `minimumCapacity` *after* `lastPreKeyId`.
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if lastPreKeyId + UInt32(count) < Constants.upperBound {
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return lastPreKeyId + 1
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}
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return 1
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}
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}
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