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import java.net.InetAddress
import kotlin.contracts.ExperimentalContracts
import kotlin.contracts.InvocationKind
import kotlin.contracts.contract
@OptIn(ExperimentalContracts::class)
class SMTPReceiveProtocol(val localHost: String, val inetAddress: InetAddress) : Protocol() {
class Commands(val line: String, private val io: IO) : IO by io {
var matched = false
suspend inline fun command(vararg name: String, block: suspend IO.(String) -> Unit) {
contract { callsInPlace(block, InvocationKind.AT_MOST_ONCE) }
for (n in name) commandOnce(n, block)
}
suspend inline fun commandOnce(name: String, block: suspend IO.(String) -> Unit) {
contract { callsInPlace(block, InvocationKind.AT_MOST_ONCE) }
if (matched) return
if (!line.startsWith(name, ignoreCase = true)) return
matched = true
block(line.substring(name.length).trimStart())
}
suspend inline fun otherwise(block: suspend IO.(String) -> Unit) {
contract { callsInPlace(block, InvocationKind.AT_MOST_ONCE) }
if (matched) return
matched = true
block(line)
}
}
suspend inline fun IO.commands(line: String, block: suspend Commands.() -> Unit) {
contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) }
Commands(line, this).block()
}
data class Mail(val sender: String, val recipient: List<String>, val text: String)
class MailTransaction(
var isHelod: Boolean = false,
var isEhlod: Boolean = false,
var recipients: MutableList<String> = mutableListOf(),
var sender: String? = null,
) {
fun reset() {
recipients = mutableListOf()
sender = null
}
}
override suspend fun IO.execute() {
send("220 $localHost\r\n")
val messages = mutableListOf<Mail>()
val trans = MailTransaction()
while (isOpen()) {
commands(readLine()) {
println(line)
command("EHLO") {
send("250 hello advanced $it\r\n")
trans.isHelod = true
trans.isEhlod = true
}
command("HELO") {
send("250 Hello $it, how are you on this fine day?\r\n")
trans.isHelod = true
}
command("MAIL FROM:") {
send("250 Sender ok\r\n")
trans.sender = it
}
command("RCPT TO:") {
send("250 Receipient ok\r\n")
trans.recipients.add(it)
}
command("DATA") {
send("354 Enter mail, end with \".\" on a line by itself\r\n")
var text = readUntil("\r\n.\r\n".encodeToByteArray())
messages.add(Mail(trans.sender!!, trans.recipients.toList(), text.decodeToString()))
trans.reset()
send("250 Message accepted for delivery\r\n")
}
command("QUIT") {
send("221 $localHost closing connection\r\n")
close()
}
otherwise {
send("500 ERROR UNKNOWN CODE $it\r\n")
}
}
}
println("Got ${messages.size} messages")
messages.forEach {
println("Message:")
println("MAIL FROM: ${it.sender}")
println("RCPTS TO: ${it.recipient}")
println("CONTENT: ${it.text}")
}
}
}
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