Handle Oscore partialIv, kidContext, and kid explicitly
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,92 @@ | ||
| package com.juul.koap | ||
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| import com.juul.koap.Message.Option.Oscore | ||
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| private val PARTIAL_IV_LENGTH_RANGE = 0..5 | ||
| private const val PARTIAL_IV_LENGTH_MASK = 0x07 | ||
| private const val KID_FLAG = 0x08 | ||
| private const val KID_CONTEXT_FLAG = 0x10 | ||
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| data class OscoreParts( | ||
| val partialIv: ByteArray, | ||
| val kidContext: ByteArray?, | ||
| val kid: ByteArray?, | ||
| ) { | ||
| override fun equals(other: Any?): Boolean = | ||
| this === other || | ||
| ( | ||
| other is OscoreParts && | ||
| partialIv.contentEquals(other.partialIv) && | ||
| kidContext.contentEquals(other.kidContext) && | ||
| kid.contentEquals(other.kid) | ||
| ) | ||
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| override fun hashCode(): Int { | ||
| var result = partialIv.contentHashCode() | ||
| result = 31 * result + kidContext.contentHashCode() | ||
| result = 31 * result + kid.contentHashCode() | ||
| return result | ||
| } | ||
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| override fun toString(): String { | ||
| val args = listOfNotNull( | ||
| if (partialIv.isNotEmpty()) "partialIv=${partialIv.toHexString()}" else null, | ||
| if (kidContext != null) "kidContext=${kidContext.toHexString()}" else null, | ||
| if (kid != null) "kid=${kid.toHexString()}" else null, | ||
| ).joinToString(separator = ", ") | ||
| return "Oscore($args)" | ||
| } | ||
| } | ||
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| /** | ||
| * Creates a binary OSCORE option value from an OscoreParts object. | ||
| * | ||
| * - [RFC 8613](https://tools.ietf.org/html/rfc8613#section-2) 2. The OSCORE Option | ||
| * - [RFC 8613](https://tools.ietf.org/html/rfc8613#section-6.1) 6.1. Encoding of the OSCORE Option Value | ||
| */ | ||
| internal fun oscoreOptionValue(oscore: OscoreParts): ByteArray { | ||
| val partialIvLength = oscore.partialIv.size | ||
| require(partialIvLength in PARTIAL_IV_LENGTH_RANGE) { | ||
| "Partial IV length of $partialIvLength is outside allowable range of $PARTIAL_IV_LENGTH_RANGE" | ||
| } | ||
| val kidContextLength = if (oscore.kidContext != null) oscore.kidContext.size else 0 | ||
| val kidFlagBit = if (oscore.kid != null) KID_FLAG else 0 | ||
| val kidContextFlagBit = if (oscore.kidContext != null) KID_CONTEXT_FLAG else 0 | ||
| val flagBits = partialIvLength or kidFlagBit or kidContextFlagBit | ||
| if (flagBits == 0) { | ||
| // If the OSCORE flag bits are all zero (0x00), the option value SHALL be empty | ||
| return byteArrayOf() | ||
| } | ||
| var value = byteArrayOf(flagBits.toByte()) + oscore.partialIv | ||
| if (oscore.kidContext != null) { | ||
| value += byteArrayOf(kidContextLength.toByte()) + oscore.kidContext | ||
|
Contributor
There was a problem hiding this comment. Might be worth a |
||
| } | ||
| if (oscore.kid != null) { | ||
| value += oscore.kid | ||
| } | ||
| return value | ||
| } | ||
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| /** | ||
| * Parses an OscoreParts object from a binary OSCORE option value. | ||
| */ | ||
| internal fun oscorePartsFromOptionValue(value: ByteArray): OscoreParts { | ||
| // TODO: detect if value does not conform to expected oscore format | ||
| if (value.isEmpty()) { | ||
| return OscoreParts(byteArrayOf(), null, null) | ||
| } | ||
| val flagBits = value[0].toInt() | ||
| val partialIvLength = flagBits and PARTIAL_IV_LENGTH_MASK | ||
| val kidFlag = (flagBits and KID_FLAG) != 0 | ||
| val kidContextFlag = (flagBits and KID_CONTEXT_FLAG) != 0 | ||
| val partialIv = value.sliceArray(1 until 1 + partialIvLength) | ||
| val kidContextLength = if (kidContextFlag) value[1 + partialIvLength].toInt() else 0 | ||
| val kidContext = if (kidContextFlag) { | ||
| value.sliceArray(2 + partialIvLength until 2 + partialIvLength + kidContextLength) | ||
| } else { | ||
| null | ||
| } | ||
| val kidOffset = (if (kidContextFlag) 2 else 1) + partialIvLength + kidContextLength | ||
| val kid = if (kidFlag) value.sliceArray(kidOffset until value.size) else null | ||
| return OscoreParts(partialIv, kidContext, kid) | ||
| } | ||
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oscorePartsFromOptionValuecan throw on malformed input data. It may be surprising to a system that catches a parsing exception and then uses thistoStringmethod to log the failure - they won't be expecting the log invoke tothrowwhich may cause a crash. I'd recommend ensuring thattoStringcannot throw as it is typically considered a safe operation.