93 lines
2.5 KiB
Swift
93 lines
2.5 KiB
Swift
import NIO
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/// NIO handler that parses SMTP line-based responses.
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/// SMTP response format: `<3-digit code><separator><text>\r\n`
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/// Separator `-` means continuation, space means final line.
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final class SMTPResponseHandler: ChannelInboundHandler, @unchecked Sendable {
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typealias InboundIn = ByteBuffer
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private var stringBuffer = ""
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private var responseLines: [String] = []
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private var responseCode: Int?
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private var continuation: CheckedContinuation<SMTPResponse, Error>?
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private var greetingContinuation: CheckedContinuation<SMTPResponse, Error>?
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func channelRead(context: ChannelHandlerContext, data: NIOAny) {
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var buffer = unwrapInboundIn(data)
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guard let received = buffer.readString(length: buffer.readableBytes) else { return }
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stringBuffer.append(received)
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while let lineEnd = stringBuffer.range(of: "\r\n") {
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let line = String(stringBuffer[stringBuffer.startIndex..<lineEnd.lowerBound])
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stringBuffer.removeSubrange(stringBuffer.startIndex..<lineEnd.upperBound)
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processLine(line)
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}
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}
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private func processLine(_ line: String) {
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guard line.count >= 3,
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let code = Int(line.prefix(3))
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else { return }
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// Extract text after the code + separator character
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let text: String
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if line.count > 4 {
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text = String(line.dropFirst(4))
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} else {
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text = ""
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}
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responseLines.append(text)
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if responseCode == nil {
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responseCode = code
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}
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// Separator is at index 3: `-` for continuation, space for final
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let isFinal: Bool
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if line.count > 3 {
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isFinal = line[line.index(line.startIndex, offsetBy: 3)] == " "
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} else {
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isFinal = true
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}
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if isFinal {
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let response = SMTPResponse(code: code, lines: responseLines)
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responseLines = []
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responseCode = nil
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if let cont = greetingContinuation {
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greetingContinuation = nil
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cont.resume(returning: response)
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} else if let cont = continuation {
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continuation = nil
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cont.resume(returning: response)
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}
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}
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}
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func errorCaught(context: ChannelHandlerContext, error: Error) {
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if let cont = continuation {
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continuation = nil
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cont.resume(throwing: error)
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}
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if let cont = greetingContinuation {
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greetingContinuation = nil
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cont.resume(throwing: error)
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}
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context.close(promise: nil)
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}
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func waitForGreeting() async throws -> SMTPResponse {
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try await withCheckedThrowingContinuation { cont in
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greetingContinuation = cont
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}
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}
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func waitForResponse() async throws -> SMTPResponse {
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try await withCheckedThrowingContinuation { cont in
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continuation = cont
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}
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}
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}
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