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Added helper functions for creating various Tcp packets #32

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Oct 16, 2024
Merged

Added helper functions for creating various Tcp packets #32

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2 changes: 2 additions & 0 deletions knet/src/main/kotlin/com/jasonernst/knet/network/ip/IpHeader.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,7 @@ interface IpHeader {
}
return when (sourceAddress) {
is Inet4Address -> {
destinationAddress as Inet4Address
val totalLength = (IP4_MIN_HEADER_LENGTH + payloadSize.toUShort()).toUShort()
Ipv4Header(
sourceAddress = sourceAddress,
Expand All @@ -76,6 +77,7 @@ interface IpHeader {
)
}
is Inet6Address -> {
destinationAddress as Inet6Address
Ipv6Header(
sourceAddress = sourceAddress,
destinationAddress = destinationAddress,
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8 changes: 4 additions & 4 deletions knet/src/main/kotlin/com/jasonernst/knet/network/ip/v4/Ipv4Header.kt
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Expand Up @@ -10,9 +10,9 @@ import com.jasonernst.knet.network.ip.v4.options.Ipv4Option
import com.jasonernst.knet.network.ip.v4.options.Ipv4Option.Companion.parseOptions
import org.slf4j.LoggerFactory
import java.net.Inet4Address
import java.net.InetAddress
import java.nio.ByteBuffer
import java.nio.ByteOrder
import java.util.concurrent.atomic.AtomicInteger
import kotlin.experimental.or
import kotlin.math.ceil
import kotlin.math.min
Expand Down Expand Up @@ -51,9 +51,9 @@ data class Ipv4Header(
// https://en.wikipedia.org/wiki/IPv4#Header_checksum
var headerChecksum: UShort = 0u,
// 32-bits, source address
override val sourceAddress: InetAddress = Inet4Address.getLocalHost(),
override val sourceAddress: Inet4Address = Inet4Address.getLocalHost() as Inet4Address,
// 32-bits, destination address
override val destinationAddress: InetAddress = Inet4Address.getLocalHost(),
override val destinationAddress: Inet4Address = Inet4Address.getLocalHost() as Inet4Address,
val options: List<Ipv4Option> = emptyList(),
) : IpHeader {
// 3-bits: set from mayFragment and lastFragment
Expand Down Expand Up @@ -81,7 +81,6 @@ data class Ipv4Header(

// calculate the checksum for packet creation based on the set fields
if (headerChecksum == 0u.toUShort()) {
logger.debug("Calculating checksum for IPv4 header")
val buffer = toByteArray()
// ^ this will compute the checksum and put it in the buffer
// note: it's tempting to call the checksum function here but if we do we'll get a zero
Expand All @@ -92,6 +91,7 @@ data class Ipv4Header(

companion object {
private val logger = LoggerFactory.getLogger(Ipv4Header::class.java)
val packetCounter: AtomicInteger = AtomicInteger(0) // used to generate monotonic ids for Ipv4 packets
private const val CHECKSUM_OFFSET = 10
const val IP4_WORD_LENGTH: UByte = 4u
val IP4_MIN_HEADER_LENGTH: UByte = (IP4_WORD_LENGTH * 5u).toUByte()
Expand Down
5 changes: 2 additions & 3 deletions knet/src/main/kotlin/com/jasonernst/knet/network/ip/v6/Ipv6Header.kt
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Expand Up @@ -10,7 +10,6 @@ import com.jasonernst.knet.network.ip.v6.extenions.Ipv6Fragment
import com.jasonernst.knet.network.nextheader.NextHeader
import org.slf4j.LoggerFactory
import java.net.Inet6Address
import java.net.InetAddress
import java.nio.ByteBuffer
import java.nio.ByteOrder

Expand All @@ -31,9 +30,9 @@ data class Ipv6Header(
// 8-bits: hop limit, decremented by 1 at each hop, if 0, packet is discarded, similar to TTL
val hopLimit: UByte = 0u,
// 128-bits: source address
override val sourceAddress: InetAddress = Inet6Address.getByName("::1"),
override val sourceAddress: Inet6Address = Inet6Address.getByName("::1") as Inet6Address,
// 128-bits: destination address
override val destinationAddress: InetAddress = Inet6Address.getByName("::1"),
override val destinationAddress: Inet6Address = Inet6Address.getByName("::1") as Inet6Address,
val extensionHeaders: List<Ipv6ExtensionHeader> = emptyList(),
) : IpHeader {
init {
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2 changes: 0 additions & 2 deletions knet/src/main/kotlin/com/jasonernst/knet/transport/TransportHeader.kt
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Expand Up @@ -9,7 +9,6 @@ import com.jasonernst.knet.network.ip.v6.Ipv6Header.Companion.IP6_HEADER_SIZE
import com.jasonernst.knet.network.nextheader.NextHeader
import com.jasonernst.knet.transport.tcp.TcpHeader
import com.jasonernst.knet.transport.udp.UdpHeader
import com.jasonernst.packetdumper.stringdumper.StringPacketDumper
import org.slf4j.LoggerFactory
import java.nio.ByteBuffer

Expand Down Expand Up @@ -79,7 +78,6 @@ interface TransportHeader : NextHeader {
}
}
pseudoHeader.rewind()
logger.debug("Pseudo header: {}", StringPacketDumper().dumpBufferToString(pseudoHeader))
val computedChecksum = Checksum.calculateChecksum(pseudoHeader)

if (verify) {
Expand Down
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