Initial commit

.gitignore

+*~
+\#*
+.#*
+safelinks-cleaner-thunderbird.xpi

.gitlab-ci.yml

+---
+stages:
+  - build
+  - deploy
+
+build:
+  stage: build
+  script:
+    - cd extension
+    - zip -r ../safelinks-cleaner-thunderbird.xpi *
+  artifacts:
+    - ./safelinks-cleaner-thunderbird.xpi
+
+pages:
+  stage: deploy
+  script:
+    - mkdir .public
+    - cp -r site .public
+    - cp safelinks-cleaner-thunderbird.xpi .public
+    - mv .public public
+    - ls -lr public
+  artifacts:
+    paths:
+      - public/
+  only:
+    - master
+  when: always

README.md

+# Safelinks Cleaner MailExtension
+
+This project is a MailExtension that cleans up display of Microsoft
+Advanced Threat Protection Safe Links.
+
+* Displayed plain text links are replaced by the original link.
+
+* A tooltip is added to all rewritten links to display the original link.
+
+
+## Development
+
+Documentation on add-on development:
+
+* https://developer.thunderbird.net/add-ons/about-add-ons
+
+Debugging Thunderbird extensions (ue Ctrl+Shift+I):
+
+* https://developer.thunderbird.net/add-ons/tips-and-tricks
+
+

extension/background.js

+browser.messageDisplayScripts.register({
+    css: [{
+	file: "/style.css",
+    }],
+    js: [{
+	file: "/content.js",
+    }],
+});

extension/content.js

+// Modify the displayed message to clarify where safelinks are
+// inserted and to show the actual link targets.
+
+const safelinksRegexp = new RegExp(
+    'https?://[^.]+[.]safelinks[.]protection[.]outlook[.]com/[?]url=([^&]+)&.*',
+    'gi'
+);
+
+function getTextNodes(elem) {
+    var result = [];
+    if (elem) {
+	for (var nodes = elem.childNodes, i = nodes.length; i--;) {
+	    let node = nodes[i];
+	    let nodeType = node.nodeType;
+	    
+	    if (nodeType == Node.TEXT_NODE) {
+		result.push(node);
+	    }
+	    else if (nodeType == Node.ELEMENT_NODE
+		     || nodeType == Node.DOCUMENT_NODE
+		     || nodeType == Node.DOCUMENT_FRAGMENT_NODE) {
+		result = result.concat(getTextNodes(node));
+	    }
+	}
+    }
+    return result;
+}
+
+for (const link of document.links) {
+    let display = link.innerHTML;
+
+    // Mangle the link text
+    for (const node of getTextNodes(link)) {
+	node.textContent = node.textContent.replaceAll(
+	    safelinksRegexp, (match, url) => {
+		try {
+		    return decodeURIComponent(url);
+		}
+		catch (e) {
+		    return url;
+		}
+	    });	
+    }
+
+    // Generate the tooltip and set link class
+    for (const match of link.href.matchAll(safelinksRegexp)) {
+	link.classList.add('liu_safelinks_link');
+
+	let tooltiptext = match[1];
+	let tooltip = document.createElement('span');
+	tooltip.classList.add('liu_safelinks_tooltip');
+	try {
+	    tooltiptext = decodeURIComponent(tooltiptext);
+	}
+	catch (e) {
+	}
+	tooltip.textContent = tooltiptext;
+	link.appendChild(tooltip);
+	break;
+    }
+}

extension/icon.svg

+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64"><defs><linearGradient id="0" gradientUnits="userSpaceOnUse" y1="227.63" x2="0" y2="171.63"><stop stop-color="#2fae61"/><stop offset="1" stop-color="#4bdf88"/></linearGradient></defs><g transform="matrix(.92857 0 0 .92857-676.99-152.79)"><path d="m789.32 182.93c-.017-1.302-1.019-2.377-2.315-2.496-10.772-1.01-19.563-6.764-22.461-8.87-.606-.442-1.426-.442-2.032 0-2.893 2.106-11.683 7.863-22.456 8.87-1.296.119-2.293 1.194-2.315 2.496-.13 8.497 1.234 37.34 25.14 43.762.425.113.872.113 1.296 0 23.905-6.413 25.27-35.27 25.14-43.762" fill="url(#0)"/><path d="m773.85 193.97l-1.89-1.89c-.259-.259-.574-.389-.945-.389-.371 0-.686.13-.945.389l-9.116 9.13-4.085-4.099c-.259-.259-.574-.389-.945-.389-.371 0-.686.13-.945.389l-1.89 1.89c-.259.259-.389.574-.389.945 0 .37.13.686.389.945l5.03 5.03 1.89 1.89c.259.259.574.389.945.389.37 0 .685-.13.945-.389l1.89-1.89 10.06-10.06c.259-.259.389-.574.389-.945 0-.37-.13-.685-.389-.945" fill="#fff" fill-opacity=".851"/></g></svg>

extension/manifest.json

+{
+    "manifest_version": 2,
+    "name": "Safelinks Cleaner",
+    "description": "Clean up display of Microsoft Advanced Threat Protection Safe Links",
+    "version": "1.0",
+    "author": "David Byers",
+    "homepage_url": "https://gitlab.liu.se/davby02/safelinkscleaner/",
+    "icons": {
+	"48": "icon.svg",
+	"96": "icon.svg",
+	"144": "icon.svg",
+	"192": "icon.svg"
+    },
+    "applications": {
+        "gecko": {
+            "id": "safelinkscleaner@it.liu.se",
+            "strict_min_version": "78.4"
+        }
+    },
+    "background": {
+        "scripts": [
+            "background.js"
+        ]
+    },
+    "permissions": [
+      "messagesModify"
+    ],
+    "web_accessible_resources": [
+	"assets/*.png"
+    ]
+}

extension/style.css

+a:hover .liu_safelinks_tooltip {
+    display: block;
+}
+
+.liu_safelinks_tooltip {
+    display: none;
+    background: #fffff0 url(assets/shield.png) no-repeat 3px;
+    background-size: 14px 14px;
+    color: black;
+    padding: 3px 3px 4px 22px;
+    position: absolute;
+    z-index: 1000;
+    border: 1px solid black;
+    -webkit-box-shadow: 0px 0px 6px 1px rgba(0,0,0,0.5);
+    -moz-box-shadow: 0px 0px 6px 1px rgba(0,0,0,0.5);
+    box-shadow: 0px 0px 6px 1px rgba(0,0,0,0.5);
+    font: 14px sans-serif;
+}