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90 changes: 90 additions & 0 deletions
90
knet/src/main/kotlin/com/jasonernst/knet/ip/options/Ipv4Option.kt
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,90 @@ | ||
| package com.jasonernst.knet.ip.options | ||
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| import com.jasonernst.knet.PacketTooShortException | ||
| import java.nio.ByteBuffer | ||
| import java.nio.ByteOrder | ||
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| // because kotlin doesn't have a direct conversion function apparently... | ||
| // https://stackoverflow.com/questions/46401879/boolean-int-conversion-in-kotlin | ||
| fun Boolean.toInt() = if (this) 1 else 0 | ||
|
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| /** | ||
| * From RFC791, page 15: | ||
| * | ||
| * The option field is variable in length. There may be zero or more | ||
| * options. There are two cases for the format of an option: | ||
| * | ||
| * Case 1: A single octet of option-type. | ||
| * | ||
| * Case 2: An option-type octet, an option-length octet, and the | ||
| * actual option-data octets. | ||
| * | ||
| * The option-length octet counts the option-type octet and the | ||
| * option-length octet as well as the option-data octets. | ||
| * | ||
| * The option-type octet is viewed as having 3 fields: | ||
| * | ||
| * 1 bit copied flag, | ||
| * 2 bits option class, | ||
| * 5 bits option number. | ||
| * | ||
| * The copied flag indicates that this option is copied into all | ||
| * fragments on fragmentation. | ||
| * | ||
| * 0 = not copied | ||
| * 1 = copied | ||
| */ | ||
| abstract class Ipv4Option( | ||
| open val isCopied: Boolean = true, | ||
| open val optionClass: Ipv4OptionClassType, | ||
| open val type: Ipv4OptionType, | ||
| open val size: UByte, | ||
| ) { | ||
| companion object { | ||
| fun parseOptions( | ||
| stream: ByteBuffer, | ||
| limit: Int, | ||
| ): List<Ipv4Option> { | ||
| val options = ArrayList<Ipv4Option>() | ||
| while (stream.position() + 1 <= limit) { | ||
| val kindOctet = stream.get().toUByte() | ||
| // high bit is copied flag | ||
| val isCopied = kindOctet.toInt() and 0b10000000 == 0b10000000 | ||
| val classByte = kindOctet.toInt() and 0b01100000 shr 5 | ||
| val optionClass = Ipv4OptionClassType.fromKind(classByte.toUByte()) | ||
| val kind = (kindOctet.toInt() and 0b00011111).toUByte() | ||
| if (kind == Ipv4OptionType.EndOfOptionList.kind) { | ||
| options.add(Ipv4OptionEndOfOptionList(isCopied, optionClass)) | ||
| break | ||
| } else if (kind == Ipv4OptionType.NoOperation.kind) { | ||
| options.add(Ipv4OptionNoOperation(isCopied, optionClass)) | ||
| } else { | ||
| if (stream.remaining() < 1) { | ||
| throw PacketTooShortException("Can't determine length of ipv4 option because we have no bytes left") | ||
| } | ||
| // this length includes the previous two bytes | ||
| val length = (stream.get().toUByte() - 2u).toUByte() | ||
| if (stream.remaining() < length.toInt()) { | ||
| throw PacketTooShortException("Can't parse ipv4 option because we don't have enough bytes left for the data") | ||
| } | ||
| val data = ByteArray(length.toInt()) | ||
| stream.get(data) | ||
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| val type = | ||
| try { | ||
| Ipv4OptionType.fromKind(kind) | ||
| } catch (e: NoSuchElementException) { | ||
| Ipv4OptionType.Unknown | ||
| } | ||
| options.add(Ipv4OptionUnknown(isCopied, optionClass, type, length, data)) | ||
| } | ||
| } | ||
| return options | ||
| } | ||
| } | ||
|
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| open fun toByteArray(order: ByteOrder = ByteOrder.BIG_ENDIAN): ByteArray { | ||
| val typeInt = isCopied.toInt() shl 7 or (optionClass.kind.toInt() shl 5) or type.kind.toInt() | ||
| return byteArrayOf(typeInt.toByte()) | ||
| } | ||
| } |
26 changes: 26 additions & 0 deletions
26
knet/src/main/kotlin/com/jasonernst/knet/ip/options/Ipv4OptionClassType.kt
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,26 @@ | ||
| package com.jasonernst.knet.ip.options | ||
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| /** | ||
| * The option classes are: | ||
| * | ||
| * 0 = control | ||
| * 1 = reserved for future use | ||
| * 2 = debugging and measurement | ||
| * 3 = reserved for future use | ||
| * | ||
| * Since we only have 2 bits, any other value makes no sense and should | ||
| * rightfully throw an exception when trying to parse it. | ||
| */ | ||
| enum class Ipv4OptionClassType( | ||
| val kind: UByte, | ||
| ) { | ||
| Control(0u), | ||
| Reserved1(1u), | ||
| DebuggingAndMeasurement(2u), | ||
| Reserved2(3u), | ||
| ; | ||
|
|
||
| companion object { | ||
| fun fromKind(kind: UByte) = entries.first { it.kind == kind } | ||
| } | ||
| } |
8 changes: 8 additions & 0 deletions
8
knet/src/main/kotlin/com/jasonernst/knet/ip/options/Ipv4OptionEndOfOptionList.kt
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,8 @@ | ||
| package com.jasonernst.knet.ip.options | ||
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| data class Ipv4OptionEndOfOptionList( | ||
| override val isCopied: Boolean, | ||
| override val optionClass: Ipv4OptionClassType, | ||
| override val type: Ipv4OptionType = Ipv4OptionType.EndOfOptionList, | ||
| override val size: UByte = 1u, | ||
| ) : Ipv4Option(isCopied, optionClass, type, size) |
8 changes: 8 additions & 0 deletions
8
knet/src/main/kotlin/com/jasonernst/knet/ip/options/Ipv4OptionNoOperation.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,8 @@ | ||
| package com.jasonernst.knet.ip.options | ||
|
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| data class Ipv4OptionNoOperation( | ||
| override val isCopied: Boolean, | ||
| override val optionClass: Ipv4OptionClassType, | ||
| override val type: Ipv4OptionType = Ipv4OptionType.NoOperation, | ||
| override val size: UByte = 1u, | ||
| ) : Ipv4Option(isCopied, optionClass, type, size) |
25 changes: 25 additions & 0 deletions
25
knet/src/main/kotlin/com/jasonernst/knet/ip/options/Ipv4OptionType.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,25 @@ | ||
| package com.jasonernst.knet.ip.options | ||
|
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| /** | ||
| * https://datatracker.ietf.org/doc/html/rfc791 page 15 | ||
| */ | ||
| enum class Ipv4OptionType( | ||
| val kind: UByte, | ||
| ) { | ||
| EndOfOptionList(0u), | ||
| NoOperation(1u), | ||
| Security(2u), | ||
| LooseSourceRouting(3u), | ||
| StrictSourceRouting(9u), | ||
| RecordRoute(7u), | ||
| StreamId(8u), | ||
| TimeStamp(4u), | ||
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| // fake type we defined for when we don't have the type in the enum | ||
| Unknown(99u), | ||
| ; | ||
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| companion object { | ||
| fun fromKind(kind: UByte) = entries.first { it.kind == kind } | ||
| } | ||
| } |
20 changes: 20 additions & 0 deletions
20
knet/src/main/kotlin/com/jasonernst/knet/ip/options/Ipv4OptionUnknown.kt
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,20 @@ | ||
| package com.jasonernst.knet.ip.options | ||
|
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| import java.nio.ByteBuffer | ||
| import java.nio.ByteOrder | ||
|
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| data class Ipv4OptionUnknown( | ||
| override val isCopied: Boolean, | ||
| override val optionClass: Ipv4OptionClassType, | ||
| override val type: Ipv4OptionType, | ||
| override val size: UByte, | ||
| val data: ByteArray, | ||
| ) : Ipv4Option(isCopied, optionClass, type, size) { | ||
| override fun toByteArray(order: ByteOrder): ByteArray { | ||
| val buffer = ByteBuffer.allocate(2 + data.size) | ||
| buffer.put(super.toByteArray(order)) // get the type byte sorted out | ||
| buffer.put(size.toByte()) | ||
| buffer.put(data) | ||
| return buffer.array() | ||
| } | ||
| } |
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43 changes: 43 additions & 0 deletions
43
knet/src/test/kotlin/com/jasonernst/knet/ip/options/Ipv4OptionTest.kt
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,43 @@ | ||
| package com.jasonernst.knet.ip.options | ||
|
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| import org.junit.jupiter.api.Assertions.assertEquals | ||
| import org.junit.jupiter.api.Assertions.assertTrue | ||
| import org.junit.jupiter.api.Test | ||
| import org.slf4j.LoggerFactory | ||
| import java.nio.ByteBuffer | ||
|
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| class Ipv4OptionTest { | ||
| private val logger = LoggerFactory.getLogger(javaClass) | ||
|
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| @Test fun parseOptions() { | ||
| val options = | ||
| arrayListOf( | ||
| Ipv4OptionNoOperation(true, Ipv4OptionClassType.Control), | ||
| Ipv4OptionEndOfOptionList(true, Ipv4OptionClassType.Control), | ||
| ) | ||
| val optionSize = options.sumOf { it.size.toInt() } | ||
| val stream = ByteBuffer.allocate(optionSize) | ||
| for (option in options) { | ||
| stream.put(option.toByteArray()) | ||
| } | ||
| stream.rewind() | ||
| val parsedOptions = Ipv4Option.parseOptions(stream, optionSize) | ||
| assertEquals(options, parsedOptions) | ||
| } | ||
|
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| @Test fun unknownOption() { | ||
| // unhandled option, but in list | ||
| val stream = ByteBuffer.wrap(byteArrayOf(0xFE.toByte(), 0x04, 0x00, 0x00)) | ||
| val parsedOptions = Ipv4Option.parseOptions(stream, 4) | ||
| assertTrue(parsedOptions[0] is Ipv4OptionUnknown) | ||
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| // unhandled option, not in list | ||
| val stream2 = ByteBuffer.wrap(byteArrayOf(0x02.toByte(), 0x04, 0x00, 0x00)) | ||
| val parsedOptions2 = Ipv4Option.parseOptions(stream2, 4) | ||
| assertTrue(parsedOptions2[0] is Ipv4OptionUnknown) | ||
| } | ||
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| @Test fun unknownOptionTooShort() { | ||
| // wip | ||
| } | ||
| } |