mirror of
https://github.com/apple/container.git
synced 2026-07-13 13:07:06 +00:00
J Logan
4a8a8a6f89
- Closes #1268. - The types we were using weren't very usable with Swift 6 structured concurrency. - Implements just the subset of records that we use. - Use notImplemented instead of formatError for unknown record types. - Use pure actor for LocalhostDNSHandler now that we have sendable types. - Use DNSName as key for table lookups in LocalhostDNSHandler and HostTableResolver. - Utilize dot-suffixed domain names everywhere in the lookup chain. - Huge thanks to @manojmahapatra and @katiewasnothere for their diligent and patient review :D
284 lines
11 KiB
Swift
284 lines
11 KiB
Swift
//===----------------------------------------------------------------------===//
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// Copyright © 2026 Apple Inc. and the container project authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//===----------------------------------------------------------------------===//
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import Foundation
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/// A DNS message (query or response).
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///
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/// Wire format (RFC 1035):
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/// ```
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/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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/// | ID |
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/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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/// |QR| Opcode |AA|TC|RD|RA| Z | RCODE |
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/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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/// | QDCOUNT |
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/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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/// | ANCOUNT |
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/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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/// | NSCOUNT |
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/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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/// | ARCOUNT |
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/// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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/// ```
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public struct Message: Sendable {
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/// Header size in bytes.
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public static let headerSize = 12
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/// Transaction ID.
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public var id: UInt16
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/// Message type (query or response).
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public var type: MessageType
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/// Operation code.
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public var operationCode: OperationCode
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/// Authoritative answer flag.
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public var authoritativeAnswer: Bool
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/// Truncation flag.
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public var truncation: Bool
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/// Recursion desired flag.
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public var recursionDesired: Bool
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/// Recursion available flag.
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public var recursionAvailable: Bool
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/// Response code.
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public var returnCode: ReturnCode
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/// Questions in this message.
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public var questions: [Question]
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/// Answer resource records.
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public var answers: [ResourceRecord]
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/// Authority resource records.
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public var authorities: [ResourceRecord]
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/// Additional resource records.
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public var additional: [ResourceRecord]
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/// Creates a new DNS message.
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public init(
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id: UInt16 = 0,
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type: MessageType = .query,
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operationCode: OperationCode = .query,
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authoritativeAnswer: Bool = false,
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truncation: Bool = false,
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recursionDesired: Bool = false,
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recursionAvailable: Bool = false,
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returnCode: ReturnCode = .noError,
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questions: [Question] = [],
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answers: [ResourceRecord] = [],
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authorities: [ResourceRecord] = [],
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additional: [ResourceRecord] = []
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) {
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self.id = id
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self.type = type
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self.operationCode = operationCode
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self.authoritativeAnswer = authoritativeAnswer
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self.truncation = truncation
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self.recursionDesired = recursionDesired
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self.recursionAvailable = recursionAvailable
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self.returnCode = returnCode
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self.questions = questions
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self.answers = answers
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self.authorities = authorities
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self.additional = additional
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}
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/// Deserialize a DNS message from raw data.
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public init(deserialize data: Data) throws {
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var buffer = Array(data)
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var offset = 0
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// Read ID
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guard let (newOffset, rawId) = buffer.copyOut(as: UInt16.self, offset: offset) else {
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throw DNSBindError.unmarshalFailure(type: "Message", field: "id")
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}
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self.id = UInt16(bigEndian: rawId)
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offset = newOffset
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// Read flags
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guard let (newOffset, rawFlags) = buffer.copyOut(as: UInt16.self, offset: offset) else {
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throw DNSBindError.unmarshalFailure(type: "Message", field: "flags")
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}
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let flags = UInt16(bigEndian: rawFlags)
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offset = newOffset
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// Parse flags
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self.type = (flags & 0x8000) != 0 ? .response : .query
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guard let opCode = OperationCode(rawValue: UInt8((flags >> 11) & 0x0F)) else {
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throw DNSBindError.unsupportedValue(type: "Message", field: "opcode")
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}
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self.operationCode = opCode
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self.authoritativeAnswer = (flags & 0x0400) != 0
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self.truncation = (flags & 0x0200) != 0
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self.recursionDesired = (flags & 0x0100) != 0
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self.recursionAvailable = (flags & 0x0080) != 0
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guard let returnCode = ReturnCode(rawValue: UInt8(flags & 0x000F)) else {
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throw DNSBindError.unsupportedValue(type: "Message", field: "rcode")
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}
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self.returnCode = returnCode
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// Read counts
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guard let (newOffset, rawQdCount) = buffer.copyOut(as: UInt16.self, offset: offset) else {
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throw DNSBindError.unmarshalFailure(type: "Message", field: "qdcount")
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}
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let qdCount = UInt16(bigEndian: rawQdCount)
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offset = newOffset
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guard let (newOffset, rawAnCount) = buffer.copyOut(as: UInt16.self, offset: offset) else {
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throw DNSBindError.unmarshalFailure(type: "Message", field: "ancount")
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}
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let anCount = UInt16(bigEndian: rawAnCount)
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offset = newOffset
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guard let (newOffset, rawNsCount) = buffer.copyOut(as: UInt16.self, offset: offset) else {
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throw DNSBindError.unmarshalFailure(type: "Message", field: "nscount")
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}
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// nsCount not used for now, but we need to read past it
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_ = UInt16(bigEndian: rawNsCount)
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offset = newOffset
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guard let (newOffset, rawArCount) = buffer.copyOut(as: UInt16.self, offset: offset) else {
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throw DNSBindError.unmarshalFailure(type: "Message", field: "arcount")
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}
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// arCount not used for now, but we need to read past it
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_ = UInt16(bigEndian: rawArCount)
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offset = newOffset
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// Read questions
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self.questions = []
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for _ in 0..<qdCount {
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var question = Question(name: "")
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offset = try question.bindBuffer(&buffer, offset: offset, messageStart: 0)
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self.questions.append(question)
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}
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// Read answers (simplified - skip for now as we only need to parse queries)
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self.answers = []
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self.authorities = []
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self.additional = []
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// Skip answer parsing for now - we primarily receive queries and send responses
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_ = anCount
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}
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/// Serialize this message to raw data.
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public func serialize() throws -> Data {
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// Calculate exact buffer size.
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var bufferSize = Self.headerSize
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for question in questions {
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// name + type + class
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let n = question.name.hasSuffix(".") ? String(question.name.dropLast()) : question.name
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bufferSize += (try DNSName(labels: n.isEmpty ? [] : n.split(separator: ".", omittingEmptySubsequences: false).map(String.init))).size + 4
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}
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for answer in answers {
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// name + type + class + ttl + rdlen + rdata
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let n = answer.name.hasSuffix(".") ? String(answer.name.dropLast()) : answer.name
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let rdataSize = answer.type == .host ? 4 : 16
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bufferSize += (try DNSName(labels: n.isEmpty ? [] : n.split(separator: ".", omittingEmptySubsequences: false).map(String.init))).size + 10 + rdataSize
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}
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var buffer = [UInt8](repeating: 0, count: bufferSize)
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var offset = 0
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// Write ID
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guard let newOffset = buffer.copyIn(as: UInt16.self, value: id.bigEndian, offset: offset) else {
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throw DNSBindError.marshalFailure(type: "Message", field: "id")
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}
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offset = newOffset
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// Build and write flags
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var flags: UInt16 = 0
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flags |= type == .response ? 0x8000 : 0
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flags |= UInt16(operationCode.rawValue) << 11
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flags |= authoritativeAnswer ? 0x0400 : 0
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flags |= truncation ? 0x0200 : 0
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flags |= recursionDesired ? 0x0100 : 0
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flags |= recursionAvailable ? 0x0080 : 0
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flags |= UInt16(returnCode.rawValue)
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guard let newOffset = buffer.copyIn(as: UInt16.self, value: flags.bigEndian, offset: offset) else {
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throw DNSBindError.marshalFailure(type: "Message", field: "flags")
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}
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offset = newOffset
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// Write counts
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guard questions.count <= UInt16.max else {
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throw DNSBindError.marshalFailure(type: "Message", field: "qdcount")
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}
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guard answers.count <= UInt16.max else {
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throw DNSBindError.marshalFailure(type: "Message", field: "ancount")
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}
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guard authorities.count <= UInt16.max else {
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throw DNSBindError.marshalFailure(type: "Message", field: "nscount")
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}
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guard additional.count <= UInt16.max else {
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throw DNSBindError.marshalFailure(type: "Message", field: "arcount")
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}
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guard let newOffset = buffer.copyIn(as: UInt16.self, value: UInt16(questions.count).bigEndian, offset: offset) else {
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throw DNSBindError.marshalFailure(type: "Message", field: "qdcount")
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}
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offset = newOffset
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guard let newOffset = buffer.copyIn(as: UInt16.self, value: UInt16(answers.count).bigEndian, offset: offset) else {
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throw DNSBindError.marshalFailure(type: "Message", field: "ancount")
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}
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offset = newOffset
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guard let newOffset = buffer.copyIn(as: UInt16.self, value: UInt16(authorities.count).bigEndian, offset: offset) else {
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throw DNSBindError.marshalFailure(type: "Message", field: "nscount")
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}
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offset = newOffset
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guard let newOffset = buffer.copyIn(as: UInt16.self, value: UInt16(additional.count).bigEndian, offset: offset) else {
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throw DNSBindError.marshalFailure(type: "Message", field: "arcount")
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}
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offset = newOffset
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// Write questions
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for question in questions {
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offset = try question.appendBuffer(&buffer, offset: offset)
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}
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// Write answers
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for answer in answers {
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offset = try answer.appendBuffer(&buffer, offset: offset)
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}
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// Write authorities
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for authority in authorities {
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offset = try authority.appendBuffer(&buffer, offset: offset)
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}
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// Write additional
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for record in additional {
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offset = try record.appendBuffer(&buffer, offset: offset)
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}
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guard offset == bufferSize else {
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throw DNSBindError.unexpectedOffset(type: "Message", expected: bufferSize, actual: offset)
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}
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return Data(buffer[0..<offset])
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}
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}
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