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IPProtocol: adopt ifnet hardware assist flags #153

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Merged
rpaulo merged 1 commit into from
Sep 16, 2026
+19 −3
Merged

IPProtocol: adopt ifnet hardware assist flags #153

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22 changes: 19 additions & 3 deletions Sources/SwiftNetwork/Protocols/IPProtocol.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,21 @@ public struct IPProtocol: NetworkProtocol {
// Destination Address: UInt128
}

// Byte offset of the checksum field within the IPv4 header (after version/
// IHL, DiffServ/ECN, total length, identification, fragment offset, TTL, and
// next-protocol). Used to place the header checksum (software or offloaded).
static public var ipv4ChecksumFieldOffset: Int {
10
}

static public var ipv4MinimumMTU: Int {
576
}

static public var ipv6MinimumMTU: Int {
1280
}

public enum Version: UInt8 {
/// Allows any IP version.
case any = 0
Expand Down Expand Up @@ -922,7 +937,7 @@ public struct IPProtocol: NetworkProtocol {

func setChecksumValue(frame: inout Frame, value: UInt16) {
let checksumResult = Serializer.serialize(&frame, claim: false) { write throws(SerializationError) in
try write.skip(10)
try write.skip(IPProtocol.ipv4ChecksumFieldOffset)
try write.uint16(value)
}
if !checksumResult.isValid {
Expand Down Expand Up @@ -1123,7 +1138,8 @@ public struct IPProtocol: NetworkProtocol {
}
} else {
if self.flags.csumOffload {
frame.checksumOffloadFlags = 0x04 // CSUM_IP
// OR in CSUM_IP so we don't clobber a CSUM_PARTIAL flag.
frame.checksumOffloadFlags |= 0x04 // CSUM_IP
} else {
let checksumValue = try frame.ipChecksum(offset: 0, length: 20)
self.setChecksumValue(frame: &frame, value: checksumValue)
Expand Down Expand Up @@ -1961,7 +1977,7 @@ public struct IPProtocol: NetworkProtocol {
if let path {
maximumMessageSize = path.maximumPacketSize
mtu = path.mtu
flags.csumOffload = (path.hardwareChecksumFlags & 0x0000_0001) != 0
flags.csumOffload = (path.hardwareChecksumFlags & IfnetHardwareAssistFlags.ifnetIPHeader) != 0
if let interface = path.directInterface {
netmask = interface.ipv4Netmask?.addressValue ?? 0
broadcast = interface.ipv4Broadcast?.addressValue ?? 0
Expand Down
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