Deno.connect failed to read full bytes

[Srabutdotcom]

Version: Deno 2.2.4

Expected output are:
"250-smtp.gmail.com at your servi.."
"250-SIZE 3..."
"....etc..."

but got only
"250-smtp.gmail.com at your servi.."

Here is my codes:

async function send_response(conn, command) {
   await sendCommand(conn, command)
   const reader = conn.readable.getReader();
   
   const { value, done } = await reader.read();
   const response = decoder.decode(value, { stream: true });
   reader.releaseLock();
   return response;
}

async function sendCommand(conn, command) {
   await conn.write(encoder.encode(command))
}

and

const conn = await Deno.connect({ hostname: SMTP_SERVER, port: SMTP_PORT, tcp: 'tcp' });
const response = await send_response(conn, "EHLO mail.example.com\r\n");

Appreciate for any suggestion;

[marvinhagemeister]

FYI: I've edited the issue description to properly format the code snippets to make it easier to read. Using single backticks doesn't work well with code multiline code snippets. These are typically formatted with three backticks and a language specifier so that you get nice syntax highlighting. Example:

```ts
console.log("hey")
```

...looks like this:

console.log("hey")

You can learn more about how to format code on GitHub here https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/creating-and-highlighting-code-blocks

[WWRS]

With

const encoder = new TextEncoder();
const decoder = new TextDecoder();

// your code

const conn = await Deno.connect({ hostname: 'smtp.gmail.com', port: 25, tcp: 'tcp' });
const response = await send_response(conn, "EHLO mail.example.com\r\n");
console.log(response);
const response2 = await send_response(conn, "EHLO mail.example.com\r\n");
console.log(response2);

I am receiving

220 smtp.gmail.com ESMTP ... - gsmtp

250-smtp.gmail.com at your service, [...]
250-SIZE 3...
...

More details may be necessary to replicate your issue. Is this the same server and port you're using? And what source are you getting the expected output from? Do you get the expected value when you connect to the SMTP server using a platform other than Deno?

[Srabutdotcom]

@WWRS you made twice call and the output are as expected., but it raises the uncertainty, the needed to call it once or twice or even more.
to note, I can't connect to port 25 from my pc, port 587 succeed.
Anyway, thanks for the initial solution.,

[WWRS]

Oh, I see the issue. When you connect, the first chunk

220 smtp.gmail.com ESMTP ... - gsmtp

is loaded into the readable stream of conn. When you EHLO, the second chunk

250-smtp.gmail.com at your service, [...]
250-SIZE 3...
...

is loaded. If you haven't consumed the first chunk, it gets printed the first time you call send_response. The EHLO chunk is still in the readable stream at this point, you just haven't accessed it. If you were to, say, send_response(conn, "QUIT") at this time, the EHLO chunk would print and the QUIT chunk would still be in the stream.

const conn = await Deno.connect({ hostname: 'smtp.gmail.com', port: 587, tcp: 'tcp' });
const reader = conn.readable.getReader();
await reader.read();  // Consume the 220 chunk
reader.releaseLock();

const response = await send_response(conn, "EHLO mail.example.com\r\n");
console.log(response);

will drop the first chunk and synchronize send_response.

[Srabutdotcom]

I got the point now,

When connecting to smtp server the first thing to do is read the response instead of send "EHLO..." message;
So, my code was written in the wrong order making the first chunk unread in the stream.

However, it should be noted that one on one message should be complied when making peer to peer communication. Otherwise, we should make a loop that will make the process take a longer time.

Thanks anyway.,
this case can be closed.

[iuioiua]

@Srabutdotcom You can close the issue.