Fix bug in DNSSD IPv6 address string conversion.

Package.swift

@@ -12,7 +12,7 @@ var caresExclude = [
 ]
 
 do {
- if !(try FileManager.default.contentsOfDirectory(atPath: "./Sources/CAsyncDNSResolver/c-ares/CMakeFiles").isEmpty) {
+ if try !(FileManager.default.contentsOfDirectory(atPath: "./Sources/CAsyncDNSResolver/c-ares/CMakeFiles").isEmpty) {
  caresExclude.append("./c-ares/CMakeFiles/")
  }
 } catch {

Sources/AsyncDNSResolver/AsyncDNSResolver.swift

@@ -26,7 +26,7 @@ public struct AsyncDNSResolver {
  #if canImport(Darwin)
  self.init(DNSSDDNSResolver())
  #else
- self.init(try CAresDNSResolver())
+ try self.init(CAresDNSResolver())
  #endif
  }
 
@@ -44,7 +44,7 @@ public struct AsyncDNSResolver {
  /// - Parameters:
  /// - options: Options to create ``CAresDNSResolver`` with.
  public init(options: CAresDNSResolver.Options) throws {
- self.init(try CAresDNSResolver(options: options))
+ try self.init(CAresDNSResolver(options: options))
  }
 
  /// See ``DNSResolver/queryA(name:)``.

Sources/AsyncDNSResolver/dnssd/DNSResolver_dnssd.swift

@@ -220,19 +220,14 @@ extension DNSSD {
  throw AsyncDNSResolver.Error.noData()
  }
 
- let bufferPtr = UnsafeBufferPointer(start: ptr, count: Int(length))
- var buffer = ByteBuffer(bytes: bufferPtr)
-
- guard let addressBytes = buffer.readInteger(as: UInt32.self) else {
- throw AsyncDNSResolver.Error.badResponse("failed to read address")
- }
-
- let address = withUnsafeBytes(of: addressBytes) { buffer in
- let buffer = buffer.bindMemory(to: UInt8.self)
- return "\(buffer[3]).\(buffer[2]).\(buffer[1]).\(buffer[0])"
+ guard length >= MemoryLayout<in_addr>.size else {
+ throw AsyncDNSResolver.Error.badResponse()
  }
 
- return ARecord(address: .IPv4(address), ttl: nil)
+ var parsedAddressBytes = [CChar](repeating: 0, count: Int(INET_ADDRSTRLEN))
+ inet_ntop(AF_INET, ptr, &parsedAddressBytes, socklen_t(INET_ADDRSTRLEN))
+ let parsedAddress = String(cString: parsedAddressBytes)
+ return ARecord(address: .IPv4(parsedAddress), ttl: nil)
  }
 
  func generateReply(records: [ARecord]) throws -> [ARecord] {
@@ -248,18 +243,14 @@ extension DNSSD {
  throw AsyncDNSResolver.Error.noData()
  }
 
- let bufferPtr = UnsafeBufferPointer(start: ptr, count: Int(length))
- var buffer = ByteBuffer(bytes: bufferPtr)
-
- guard let addressBytes = buffer.readBytes(length: 16) else {
- throw AsyncDNSResolver.Error.badResponse("failed to read address")
+ guard length >= MemoryLayout<in6_addr>.size else {
+ throw AsyncDNSResolver.Error.badResponse()
  }
 
- let address = stride(from: 0, to: addressBytes.endIndex, by: 2).map {
- "\(String(addressBytes[$0], radix: 16))\(String(addressBytes[$0.advanced(by: 1)], radix: 16))"
- }.joined(separator: ":")
-
- return AAAARecord(address: .IPv6(address), ttl: nil)
+ var parsedAddressBytes = [CChar](repeating: 0, count: Int(INET6_ADDRSTRLEN))
+ inet_ntop(AF_INET6, ptr, &parsedAddressBytes, socklen_t(INET6_ADDRSTRLEN))
+ let parsedAddress = String(cString: parsedAddressBytes)
+ return AAAARecord(address: .IPv6(parsedAddress), ttl: nil)
  }
 
  func generateReply(records: [AAAARecord]) throws -> [AAAARecord] {

Tests/AsyncDNSResolverTests/dnssd/DNSSDDNSResolverTests.swift

@@ -104,6 +104,36 @@ final class DNSSDDNSResolverTests: XCTestCase {
  XCTAssertFalse(reply.isEmpty, "should have SRV record(s)")
  }
 
+ func test_parseA() throws {
+ let addrBytes: [UInt8] = [38, 32, 1, 73]
+ try addrBytes.withUnsafeBufferPointer {
+ let record = try DNSSD.AQueryReplyHandler.instance.parseRecord(data: $0.baseAddress, length: UInt16($0.count))
+ XCTAssertEqual(record, ARecord(address: .IPv4("38.32.1.73"), ttl: nil))
+ }
+ }
+
+ func test_parseATooShort() throws {
+ let addrBytes: [UInt8] = [38, 32, 1]
+ try addrBytes.withUnsafeBufferPointer {
+ XCTAssertThrowsError(
+ try DNSSD.AQueryReplyHandler.instance.parseRecord(
+ data: $0.baseAddress, length: UInt16($0.count)
+ )
+ )
+ }
+ }
+
+ func test_parseAAAATooShort() throws {
+ let addrBytes: [UInt8] = [38, 32, 1, 73, 17, 11, 71, 14, 0, 0, 0, 0, 0, 0, 14]
+ try addrBytes.withUnsafeBufferPointer {
+ XCTAssertThrowsError(
+ try DNSSD.AAAAQueryReplyHandler.instance.parseRecord(
+ data: $0.baseAddress, length: UInt16($0.count)
+ )
+ )
+ }
+ }
+
  func test_concurrency() async throws {
  func run(
  times: Int = 100,

scripts/soundness.sh

@@ -21,6 +21,12 @@ function replace_acceptable_years() {
  sed -e 's/202[012]-202[123]/YEARS/' -e 's/202[0123]/YEARS/'
 }
 
+if ! hash swiftformat &> /dev/null
+then
+ printf "\033[0;31mPlease install swiftformat (https:/nicklockwood/SwiftFormat) and run again.\033[0m\n"
+ exit 1
+fi
+
 printf "=> Checking format... "
 FIRST_OUT="$(git status --porcelain)"
 swiftformat . > /dev/null 2>&1