Pierre-Olivier Mercier
1b8627ef86
Parse k=, h=, a= tags and derive RSA key bit-length from the public key so consumers can detect weak configurations (SHA-1, short keys). Scoring now penalises rsa-sha1 (cap 60), RSA <1024 bit (cap 25), and RSA <2048 bit (cap 75); Ed25519 receives no penalty. Fixes: #37
409 lines
14 KiB
Go
409 lines
14 KiB
Go
// This file is part of the happyDeliver (R) project.
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// Copyright (c) 2025 happyDomain
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// Authors: Pierre-Olivier Mercier, et al.
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//
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// This program is offered under a commercial and under the AGPL license.
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// For commercial licensing, contact us at <contact@happydomain.org>.
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//
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// For AGPL licensing:
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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package analyzer
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import (
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"crypto/rand"
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"crypto/rsa"
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"crypto/x509"
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"encoding/base64"
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"testing"
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"time"
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)
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func TestParseDKIMSignatures(t *testing.T) {
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tests := []struct {
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name string
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signatures []string
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expected []DKIMHeader
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}{
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{
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name: "Empty input",
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signatures: nil,
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expected: nil,
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},
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{
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name: "Empty string",
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signatures: []string{""},
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expected: nil,
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},
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{
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name: "Simple Gmail-style",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:subject:date:message-id; bh=abcdef1234567890=; b=SIGNATURE_DATA_HERE==`,
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},
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expected: []DKIMHeader{{Domain: "gmail.com", Selector: "20210112", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Microsoft 365 style",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=contoso.com; s=selector1; h=From:Date:Subject:Message-ID; bh=UErATeHehIIPIXPeUA==; b=SIGNATURE_DATA==`,
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},
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expected: []DKIMHeader{{Domain: "contoso.com", Selector: "selector1", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Tab-folded multiline (Postfix-style)",
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signatures: []string{
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"v=1; a=rsa-sha256; c=relaxed/simple; d=nemunai.re; s=thot;\r\n\tt=1760866834; bh=YNB7c8Qgm8YGn9X1FAXTcdpO7t4YSZFiMrmpCfD/3zw=;\r\n\th=From:To:Subject;\r\n\tb=T4TFaypMpsHGYCl3PGLwmzOYRF11rYjC7lF8V5VFU+ldvG8WBpFn==",
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},
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expected: []DKIMHeader{{Domain: "nemunai.re", Selector: "thot", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Space-folded multiline (RFC-style)",
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signatures: []string{
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"v=1; a=rsa-sha256; c=relaxed/relaxed;\r\n d=football.example.com; i=@football.example.com;\r\n q=dns/txt; s=test; t=1528637909; h=from:to:subject;\r\n bh=2jUSOH9NhtVGCQWNr9BrIAPreKQjO6Sn7XIkfJVOzv8=;\r\n b=F45dVWDfMbQDGHJFlXUNB2HKfbCeLRyhDXgFpEL8Gwps==",
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},
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expected: []DKIMHeader{{Domain: "football.example.com", Selector: "test", Algorithm: "rsa-sha256"}},
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},
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{
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name: "d= and s= on separate continuation lines",
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signatures: []string{
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"v=1; a=rsa-sha256;\r\n\tc=relaxed/relaxed;\r\n\td=mycompany.com;\r\n\ts=selector1;\r\n\tbh=hash=;\r\n\tb=sig==",
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},
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expected: []DKIMHeader{{Domain: "mycompany.com", Selector: "selector1", Algorithm: "rsa-sha256"}},
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},
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{
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name: "No space after semicolons",
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signatures: []string{
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`v=1;a=rsa-sha256;c=relaxed/relaxed;d=example.net;s=mail;h=from:to:subject;bh=abc=;b=xyz==`,
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},
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expected: []DKIMHeader{{Domain: "example.net", Selector: "mail", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Multiple spaces after semicolons",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=example.com; s=myselector; bh=hash=; b=sig==`,
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},
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expected: []DKIMHeader{{Domain: "example.com", Selector: "myselector", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Ed25519 signature (RFC 8463)",
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signatures: []string{
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"v=1; a=ed25519-sha256; c=relaxed/relaxed;\r\n d=football.example.com; i=@football.example.com;\r\n q=dns/txt; s=brisbane; t=1528637909; h=from:to:subject;\r\n bh=2jUSOH9NhtVGCQWNr9BrIAPreKQjO6Sn7XIkfJVOzv8=;\r\n b=/gCrinpcQOoIfuHNQIbq4pgh9kyIK3AQ==",
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},
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expected: []DKIMHeader{{Domain: "football.example.com", Selector: "brisbane", Algorithm: "ed25519-sha256"}},
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},
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{
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name: "Multiple signatures (ESP double-signing)",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=mydomain.com; s=mail; h=from:to:subject; bh=hash1=; b=sig1==`,
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=sendib.com; s=mail; h=from:to:subject; bh=hash1=; b=sig2==`,
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},
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expected: []DKIMHeader{
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{Domain: "mydomain.com", Selector: "mail", Algorithm: "rsa-sha256"},
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{Domain: "sendib.com", Selector: "mail", Algorithm: "rsa-sha256"},
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},
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},
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{
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name: "Dual-algorithm signing (Ed25519 + RSA, same domain, different selectors)",
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signatures: []string{
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`v=1; a=ed25519-sha256; c=relaxed/relaxed; d=football.example.com; s=brisbane; h=from:to:subject; bh=hash=; b=edSig==`,
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=football.example.com; s=test; h=from:to:subject; bh=hash=; b=rsaSig==`,
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},
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expected: []DKIMHeader{
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{Domain: "football.example.com", Selector: "brisbane", Algorithm: "ed25519-sha256"},
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{Domain: "football.example.com", Selector: "test", Algorithm: "rsa-sha256"},
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},
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},
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{
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name: "Amazon SES long selectors",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/simple; d=amazonses.com; s=224i4yxa5dv7c2xz3womw6peuabd; h=from:to:subject; bh=sesHash=; b=sesSig==`,
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`v=1; a=rsa-sha256; c=relaxed/simple; d=customerdomain.io; s=ug7nbtf4gccmlpwj322ax3p6ow6fovbt; h=from:to:subject; bh=sesHash=; b=customSig==`,
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},
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expected: []DKIMHeader{
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{Domain: "amazonses.com", Selector: "224i4yxa5dv7c2xz3womw6peuabd", Algorithm: "rsa-sha256"},
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{Domain: "customerdomain.io", Selector: "ug7nbtf4gccmlpwj322ax3p6ow6fovbt", Algorithm: "rsa-sha256"},
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},
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},
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{
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name: "Subdomain in d=",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=mail.example.co.uk; s=dkim2025; h=from:to:subject; bh=hash=; b=sig==`,
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},
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expected: []DKIMHeader{{Domain: "mail.example.co.uk", Selector: "dkim2025", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Deeply nested subdomain",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=bounce.transactional.mail.example.com; s=s2048; h=from:to:subject; bh=hash=; b=sig==`,
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},
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expected: []DKIMHeader{{Domain: "bounce.transactional.mail.example.com", Selector: "s2048", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Selector with hyphens (Microsoft 365 custom domain style)",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=example.com; s=selector1-contoso-com; h=from:to:subject; bh=hash=; b=sig==`,
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},
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expected: []DKIMHeader{{Domain: "example.com", Selector: "selector1-contoso-com", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Selector with dots",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=example.com; s=smtp.mail; h=from:to:subject; bh=hash=; b=sig==`,
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},
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expected: []DKIMHeader{{Domain: "example.com", Selector: "smtp.mail", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Single-character selector",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=tiny.io; s=x; h=from:to:subject; bh=hash=; b=sig==`,
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},
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expected: []DKIMHeader{{Domain: "tiny.io", Selector: "x", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Postmark-style timestamp selector, s= before d=",
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signatures: []string{
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`v=1; a=rsa-sha1; c=relaxed/relaxed; s=20130519032151pm; d=postmarkapp.com; h=From:Date:Subject; bh=vYFvy46eesUDGJ45hyBTH30JfN4=; b=iHeFQ+7rCiSQs3DPjR2eUSZSv4i==`,
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},
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expected: []DKIMHeader{{Domain: "postmarkapp.com", Selector: "20130519032151pm", Algorithm: "rsa-sha1"}},
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},
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{
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name: "d= and s= at the very end",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; h=from:to:subject; bh=hash=; b=sig==; d=example.net; s=trailing`,
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},
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expected: []DKIMHeader{{Domain: "example.net", Selector: "trailing", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Full tag set",
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signatures: []string{
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`v=1; a=rsa-sha256; d=example.com; s=selector1; c=relaxed/simple; q=dns/txt; i=user@example.com; t=1255993973; x=1256598773; h=From:Sender:Reply-To:Subject:Date:Message-Id:To:Cc; bh=+7qxGePcmmrtZAIVQAtkSSGHfQ/ftNuvUTWJ3vXC9Zc=; b=dB85+qM+If1KGQmqMLNpqLgNtUaG5dhGjYjQD6/QXtXmViJx8tf9gLEjcHr+musLCAvr0Fsn1DA3ZLLlUxpf4AR==`,
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},
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expected: []DKIMHeader{{Domain: "example.com", Selector: "selector1", Algorithm: "rsa-sha256"}},
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},
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{
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name: "Missing d= tag",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; s=selector1; h=from:to; bh=hash=; b=sig==`,
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},
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expected: nil,
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},
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{
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name: "Missing s= tag",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=example.com; h=from:to; bh=hash=; b=sig==`,
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},
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expected: nil,
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},
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{
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name: "Missing both d= and s= tags",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; h=from:to; bh=hash=; b=sig==`,
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},
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expected: nil,
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},
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{
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name: "Mix of valid and invalid signatures",
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signatures: []string{
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=good.com; s=sel1; h=from:to; bh=hash=; b=sig==`,
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`v=1; a=rsa-sha256; c=relaxed/relaxed; s=orphan; h=from:to; bh=hash=; b=sig==`,
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`v=1; a=rsa-sha256; c=relaxed/relaxed; d=also-good.com; s=sel2; h=from:to; bh=hash=; b=sig==`,
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},
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expected: []DKIMHeader{
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{Domain: "good.com", Selector: "sel1", Algorithm: "rsa-sha256"},
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{Domain: "also-good.com", Selector: "sel2", Algorithm: "rsa-sha256"},
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},
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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result := parseDKIMSignatures(tt.signatures)
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if len(result) != len(tt.expected) {
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t.Fatalf("parseDKIMSignatures() returned %d results, want %d\n got: %+v\n want: %+v", len(result), len(tt.expected), result, tt.expected)
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}
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for i := range tt.expected {
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if result[i].Domain != tt.expected[i].Domain {
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t.Errorf("result[%d].Domain = %q, want %q", i, result[i].Domain, tt.expected[i].Domain)
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}
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if result[i].Selector != tt.expected[i].Selector {
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t.Errorf("result[%d].Selector = %q, want %q", i, result[i].Selector, tt.expected[i].Selector)
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}
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if result[i].Algorithm != tt.expected[i].Algorithm {
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t.Errorf("result[%d].Algorithm = %q, want %q", i, result[i].Algorithm, tt.expected[i].Algorithm)
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}
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}
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})
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}
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}
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func TestValidateDKIM(t *testing.T) {
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tests := []struct {
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name string
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record string
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expected bool
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}{
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{
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name: "Valid DKIM with version",
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record: "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQ...",
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expected: true,
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},
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{
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name: "Valid DKIM without version",
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record: "k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQ...",
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expected: true,
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},
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{
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name: "Invalid DKIM - no public key",
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record: "v=DKIM1; k=rsa",
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expected: false,
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},
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{
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name: "Invalid DKIM - wrong version",
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record: "v=DKIM2; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQ...",
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expected: false,
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},
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{
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name: "Invalid DKIM - empty",
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record: "",
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expected: false,
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},
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}
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analyzer := NewDNSAnalyzer(5 * time.Second)
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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result := analyzer.validateDKIM(tt.record)
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if result != tt.expected {
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t.Errorf("validateDKIM(%q) = %v, want %v", tt.record, result, tt.expected)
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}
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})
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}
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}
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func TestParseDKIMTags(t *testing.T) {
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tests := []struct {
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name string
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record string
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wantTags map[string]string
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}{
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{
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name: "standard RSA record",
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record: "v=DKIM1; k=rsa; p=MIIBI; h=sha256",
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wantTags: map[string]string{"v": "DKIM1", "k": "rsa", "p": "MIIBI", "h": "sha256"},
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},
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{
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name: "ed25519 record",
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record: "v=DKIM1; k=ed25519; p=11qYAYKxCrfVS",
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wantTags: map[string]string{"v": "DKIM1", "k": "ed25519", "p": "11qYAYKxCrfVS"},
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},
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{
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name: "missing k= defaults",
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record: "v=DKIM1; p=MIIBI",
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wantTags: map[string]string{"v": "DKIM1", "p": "MIIBI"},
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},
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{
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name: "empty record",
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record: "",
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wantTags: map[string]string{},
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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got := parseDKIMTags(tt.record)
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for key, want := range tt.wantTags {
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if got[key] != want {
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t.Errorf("tag %q = %q, want %q", key, got[key], want)
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}
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}
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})
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}
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}
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func TestParseKeySize(t *testing.T) {
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// Generate a real RSA key for testing
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rsaKey1024, _ := rsa.GenerateKey(rand.Reader, 1024)
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rsaKey2048, _ := rsa.GenerateKey(rand.Reader, 2048)
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der1024, _ := x509.MarshalPKIXPublicKey(&rsaKey1024.PublicKey)
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der2048, _ := x509.MarshalPKIXPublicKey(&rsaKey2048.PublicKey)
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p1024 := base64.StdEncoding.EncodeToString(der1024)
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p2048 := base64.StdEncoding.EncodeToString(der2048)
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tests := []struct {
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name string
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keyType string
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p string
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want *int
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}{
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{
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name: "RSA 1024",
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keyType: "rsa",
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p: p1024,
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want: intPtr(1024),
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},
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{
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name: "RSA 2048",
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keyType: "rsa",
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p: p2048,
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want: intPtr(2048),
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},
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{
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name: "Ed25519 always 256",
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keyType: "ed25519",
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p: "11qYAYKxCrfVS",
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want: intPtr(256),
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},
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{
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name: "Unknown key type",
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keyType: "unknown",
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p: "somedata",
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want: nil,
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},
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{
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name: "Invalid RSA base64",
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keyType: "rsa",
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p: "!!!not-base64!!!",
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want: nil,
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},
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{
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name: "Empty k= defaults to RSA",
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keyType: "",
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p: p2048,
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want: intPtr(2048),
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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got := parseKeySize(tt.keyType, tt.p)
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if tt.want == nil {
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if got != nil {
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t.Errorf("parseKeySize(%q, ...) = %d, want nil", tt.keyType, *got)
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}
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return
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}
|
|
if got == nil {
|
|
t.Fatalf("parseKeySize(%q, ...) = nil, want %d", tt.keyType, *tt.want)
|
|
}
|
|
if *got != *tt.want {
|
|
t.Errorf("parseKeySize(%q, ...) = %d, want %d", tt.keyType, *got, *tt.want)
|
|
}
|
|
})
|
|
}
|
|
}
|
|
|
|
func intPtr(v int) *int { return &v }
|