go-chasquid-smtp/internal/queue/dsn_test.go

package queue

import (
	"fmt"
	"slices"
	"strings"
	"testing"
)

const multilineErr = `550 5.7.1 [11:22:33:44::1] Our system has detected that this
5.7.1 message is likely unsolicited mail. To reduce the amount of spam sent
5.7.1 to BlahMail, this message has been blocked. Please visit
5.7.1  https://support.blah/mail/?p=UnsolicitedMessageError
5.7.1  for more information. a1b2c3a1b2c3a1b.123 - bsmtp`

const data = `Message-ID: <msgid-123@zaraza>

Data ñaca.
`

func TestDSN(t *testing.T) {
	item := &Item{
		Message: Message{
			ID:   <-newID,
			From: "from@from.org",
			To:   []string{"ñaca@africa.org", "negra@sosa.org"},
			Rcpt: []*Recipient{
				mkR("poe@rcpt", Recipient_EMAIL, Recipient_FAILED,
					"oh! horror!", "ñaca@africa.org"),
				mkR("muchos@rcpt", Recipient_EMAIL, Recipient_FAILED,
					multilineErr, "pepe@africa.org"),
				mkR("newman@rcpt", Recipient_EMAIL, Recipient_PENDING,
					"oh! the humanity!", "ñaca@africa.org"),
				mkR("ant@rcpt", Recipient_EMAIL, Recipient_SENT,
					"", "negra@sosa.org"),
			},
			Data: []byte(data),
		},
	}

	msg, err := deliveryStatusNotification("dsnDomain", item)
	if err != nil {
		t.Error(err)
	}
	if !flexibleEq(expectedDSN, string(msg)) {
		t.Errorf("generated DSN different than expected")
		printDiff(func(s string) { t.Error(s) }, expectedDSN, string(msg))
	} else {
		t.Log(string(msg))
	}
}

const expectedDSN = `From: Mail Delivery System <postmaster-dsn@dsnDomain>
To: <from@from.org>
Subject: Mail delivery failed: returning message to sender
Message-ID: <chasquid-dsn-???????????@dsnDomain>
Date: *
In-Reply-To: <msgid-123@zaraza>
References: <msgid-123@zaraza>
X-Failed-Recipients: pepe@africa.org, ñaca@africa.org, 
Auto-Submitted: auto-replied
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
    boundary="???????????"


--???????????
Content-Type: text/plain; charset="utf-8"
Content-Disposition: inline
Content-Description: Notification
Content-Transfer-Encoding: 8bit

Delivery of your message to the following recipient(s) failed permanently:

  - pepe@africa.org
  - ñaca@africa.org


Technical details:
- "poe@rcpt" (EMAIL) failed permanently with error:
    oh! horror!
- "muchos@rcpt" (EMAIL) failed permanently with error:
    550 5.7.1 [11:22:33:44::1] Our system has detected that this
    5.7.1 message is likely unsolicited mail. To reduce the amount of spam sent
    5.7.1 to BlahMail, this message has been blocked. Please visit
    5.7.1  https://support.blah/mail/?p=UnsolicitedMessageError
    5.7.1  for more information. a1b2c3a1b2c3a1b.123 - bsmtp
- "newman@rcpt" (EMAIL) failed repeatedly and timed out, last error:
    oh! the humanity!


--???????????
Content-Type: message/global-delivery-status
Content-Description: Delivery Report
Content-Transfer-Encoding: 8bit

Reporting-MTA: dns; dsnDomain

Original-Recipient: utf-8; ñaca@africa.org
Final-Recipient: utf-8; poe@rcpt
Action: failed
Status: 5.0.0
Diagnostic-Code: smtp; oh! horror!

Original-Recipient: utf-8; pepe@africa.org
Final-Recipient: utf-8; muchos@rcpt
Action: failed
Status: 5.0.0
Diagnostic-Code: smtp; 550 5.7.1 [11:22:33:44::1] Our system has detected that this
    5.7.1 message is likely unsolicited mail. To reduce the amount of spam sent
    5.7.1 to BlahMail, this message has been blocked. Please visit
    5.7.1  https://support.blah/mail/?p=UnsolicitedMessageError
    5.7.1  for more information. a1b2c3a1b2c3a1b.123 - bsmtp

Original-Recipient: utf-8; ñaca@africa.org
Final-Recipient: utf-8; newman@rcpt
Action: failed
Status: 4.0.0
Diagnostic-Code: smtp; oh! the humanity!



--???????????
Content-Type: message/rfc822
Content-Description: Undelivered Message
Content-Transfer-Encoding: 8bit

Message-ID: <msgid-123@zaraza>

Data ñaca.


--???????????--
`

// flexibleEq compares two strings, supporting wildcards.
// Not particularly nice or robust, only useful for testing.
func flexibleEq(expected, got string) bool {
	posG := 0
	for i := 0; i < len(expected); i++ {
		if posG >= len(got) {
			return false
		}

		c := expected[i]
		if c == '?' {
			posG++
			continue
		} else if c == '*' {
			for got[posG] != '\n' {
				posG++
			}
			continue
		} else if byte(c) != got[posG] {
			return false
		}

		posG++
	}

	return true
}

// printDiff prints the difference between the strings using the given
// function.  This is a _horrible_ implementation, only useful for testing.
func printDiff(print func(s string), expected, got string) {
	lines := []string{}

	// expected lines and map.
	eM := map[string]int{}
	for l := range strings.SplitSeq(expected, "\n") {
		eM[l]++
		lines = append(lines, l)
	}

	// got lines and map.
	gM := map[string]int{}
	for l := range strings.SplitSeq(got, "\n") {
		gM[l]++
		lines = append(lines, l)
	}

	// sort the lines, to make it easier to see the differences (this works
	// ok when there's few, horrible when there's lots).
	slices.Sort(lines)

	// print diff of expected vs. got
	seen := map[string]bool{}
	print("E  G  | Line")
	for _, l := range lines {
		if !seen[l] && eM[l] != gM[l] {
			print(fmt.Sprintf("%2d %2d | %q", eM[l], gM[l], l))
			seen[l] = true
		}
	}
}