add SMTPClient module: connection layer, message formatter, public API, tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-14 05:25:03 +01:00
parent 427f197bb3
commit 54ce92e280
9 changed files with 695 additions and 1 deletions
@@ -0,0 +1,112 @@
+import Foundation
+import Models
+
+/// Orchestrates SMTP command sequences on top of SMTPConnection.
+struct SMTPCommandRunner {
+	private let connection: SMTPConnection
+
+	init(connection: SMTPConnection) {
+		self.connection = connection
+	}
+
+	/// Send EHLO and parse capability lines from response.
+	func ehlo(hostname: String) async throws -> [String] {
+		let response = try await connection.sendCommand("EHLO \(hostname)")
+		guard response.isSuccess else {
+			throw SMTPError.unexpectedResponse(code: response.code, message: response.message)
+		}
+		return response.lines
+	}
+
+	/// Initiate STARTTLS upgrade.
+	func startTLS() async throws {
+		let response = try await connection.sendCommand("STARTTLS")
+		guard response.code == 220 else {
+			throw SMTPError.tlsUpgradeFailed
+		}
+		try await connection.upgradeToTLS()
+	}
+
+	/// Authenticate using AUTH PLAIN, falling back to AUTH LOGIN.
+	func authenticate(credentials: Credentials) async throws {
+		// Try AUTH PLAIN first
+		let plainToken = authPlainToken(
+			username: credentials.username,
+			password: credentials.password
+		)
+		let response = try await connection.sendCommand("AUTH PLAIN \(plainToken)")
+
+		if response.code == 235 {
+			return
+		}
+
+		// Fallback to AUTH LOGIN
+		let loginResponse = try await connection.sendCommand("AUTH LOGIN")
+		guard loginResponse.code == 334 else {
+			throw SMTPError.authenticationFailed(response.message)
+		}
+
+		let userResponse = try await connection.sendCommand(
+			Data(credentials.username.utf8).base64EncodedString()
+		)
+		guard userResponse.code == 334 else {
+			throw SMTPError.authenticationFailed(userResponse.message)
+		}
+
+		let passResponse = try await connection.sendCommand(
+			Data(credentials.password.utf8).base64EncodedString()
+		)
+		guard passResponse.code == 235 else {
+			throw SMTPError.authenticationFailed(passResponse.message)
+		}
+	}
+
+	func mailFrom(_ address: String) async throws {
+		let response = try await connection.sendCommand("MAIL FROM:<\(address)>")
+		guard response.isSuccess else {
+			throw SMTPError.sendFailed("MAIL FROM rejected: \(response.message)")
+		}
+	}
+
+	func rcptTo(_ address: String) async throws {
+		let response = try await connection.sendCommand("RCPT TO:<\(address)>")
+		guard response.isSuccess else {
+			throw SMTPError.recipientRejected(address)
+		}
+	}
+
+	/// Send the DATA command, then the message content, then the terminating dot.
+	func data(_ content: String) async throws {
+		let response = try await connection.sendCommand("DATA")
+		guard response.code == 354 else {
+			throw SMTPError.sendFailed("DATA rejected: \(response.message)")
+		}
+
+		// sendCommand appends \r\n, so sending "content\r\n." produces "content\r\n.\r\n"
+		// which is the correct DATA termination sequence
+		let payload = content + "\r\n."
+		let dataResponse = try await connection.sendCommand(payload)
+
+		guard dataResponse.isSuccess else {
+			throw SMTPError.sendFailed("DATA content rejected: \(dataResponse.message)")
+		}
+	}
+
+	func quit() async throws {
+		let response = try await connection.sendCommand("QUIT")
+		// 221 is the expected quit response, but don't throw on failure
+		_ = response
+	}
+
+	// MARK: - Private
+
+	private func authPlainToken(username: String, password: String) -> String {
+		// AUTH PLAIN format: \0username\0password (base64 encoded)
+		var token = Data()
+		token.append(0)
+		token.append(Data(username.utf8))
+		token.append(0)
+		token.append(Data(password.utf8))
+		return token.base64EncodedString()
+	}
+}