some improvements

src/js/login.js

@@ -1,36 +1,67 @@
 const {q, ElemJS, ejs} = require("./basic.js")
+const {S_RE_DOMAIN, S_RE_IPV6, S_RE_IPV4} = require("./re.js")
 
 const password = q("#password")
-const homeserver = q("#homeserver")
+
+// A regex matching a lossy MXID
+// Groups:
+//  1: username/localpart
+//	MAYBE WITH
+//  2: hostname/serverpart
+//		3: domain
+//		OR
+//		4: IP address
+// 			5: IPv4 address
+//			OR
+//			6: IPv6 address
+//		MAYBE WITH
+//		7: port number
+const RE_LOSSY_MXID = new RegExp(`^@?([a-z0-9._=-]+?)(?::((?:(${S_RE_DOMAIN})|((${S_RE_IPV4})|(${S_RE_IPV6})))(?::(\\d+))?))?$`)
+
+window.RE_LOSSY_MXID = RE_LOSSY_MXID
 
 class Username extends ElemJS {
-	constructor() {
+	constructor(homeserver) {
 		super(q("#username"))
 
+		this.homeserver = homeserver;
+
 		this.on("change", this.updateServer.bind(this))
 	}
 
 	isValid() {
-		return !!this.element.value.match(/^@?[a-z0-9._=\/-]+(?::[a-zA-Z0-9.:\[\]-]+)?$/)
+		return !!this.element.value.match(RE_LOSSY_MXID)
 	}
 
 	getUsername() {
-		return this.element.value.match(/^@?([a-z0-9._=\/-]+)/)[1]
+		return this.element.value.match(RE_LOSSY_MXID)[1]
 	}
 
 	getServer() {
-		const server = this.element.value.match(/^@?[a-z0-9._=\?-]+:([a-zA-Z0-9.:\[\]-]+)$/)
-		if (server && server[1]) return server[1]
+		const server = this.element.value.match(RE_LOSSY_MXID)
+		if (server && server[2]) return server[2]
 		else return null
 	}
 
 	updateServer() {
 		if (!this.isValid()) return
-		if (this.getServer()) homeserver.value = this.getServer()
+		if (this.getServer()) this.homeserver.suggest(this.getServer())
 	}
 }
 
-const username = new Username()
+class Homeserver extends ElemJS {
+	constructor() {
+		super(q("#homeserver"));
+	}
+
+	suggest(value) {
+		this.element.placeholder = value
+	}
+
+	getServer() {
+		return this.element.value || this.element.placeholder;
+	}
+}
 
 class Feedback extends ElemJS {
 	constructor() {
@@ -60,13 +91,14 @@ class Feedback extends ElemJS {
 	}
 }
 
-const feedback = new Feedback()
-
 class Form extends ElemJS {
-	constructor() {
+	constructor(username, feedback, homeserver) {
 		super(q("#form"))
 
 		this.processing = false
+		this.username = username
+		this.feedback = feedback
+		this.homeserver = homeserver
 
 		this.on("submit", this.submit.bind(this))
 	}
@@ -74,12 +106,12 @@ class Form extends ElemJS {
 	async submit() {
 		if (this.processing) return
 		this.processing = true
-		if (!username.isValid()) return this.cancel("Username is not valid.")
+		if (!this.username.isValid()) return this.cancel("Username is not valid.")
 
 		// Resolve homeserver address
 		let domain
 		try {
-			domain = await this.findHomeserver(homeserver.value)
+			domain = await this.findHomeserver(this.homeserver.getServer())
 		} catch(e) {
 			return this.cancel(e.message)
 		}
@@ -90,7 +122,7 @@ class Form extends ElemJS {
 			method: "POST",
 			body: JSON.stringify({
 				type: "m.login.password",
-				user: username.getUsername(),
+				user: this.username.getUsername(),
 				password: password.value
 			})
 		}).then(res => res.json())
@@ -153,15 +185,21 @@ class Form extends ElemJS {
 	}
 
 	status(message) {
-		feedback.setLoading(true)
-		feedback.message(message)
+		this.feedback.setLoading(true)
+		this.feedback.message(message)
 	}
 
 	cancel(message) {
 		this.processing = false
-		feedback.setLoading(false)
-		feedback.message(message, true)
+		this.feedback.setLoading(false)
+		this.feedback.message(message, true)
 	}
 }
 
-const form = new Form()
+const homeserver = new Homeserver()
+
+const username = new Username(homeserver)
+
+const feedback = new Feedback()
+
+const form = new Form(username, feedback, homeserver)

src/js/re.js

@@ -0,0 +1,38 @@
+// A valid internet domain, according to https://stackoverflow.com/a/20046959 (cleaned)
+const S_RE_DOMAIN = "(?:[a-zA-Z]|[a-zA-Z][a-zA-Z]|[a-zA-Z]\\d|\\d[a-zA-Z]|[a-zA-Z0-9][a-zA-Z0-9-_]{1,61}[a-zA-Z0-9])\\.(?:[a-zA-Z]{2,6}|[a-zA-Z0-9-]{2,30}\\.[a-zA-Z]{2,3})"
+
+// A valid ipv4 address, one that doesn't check for valid numbers (e.g. not 999) and one that does
+// const S_RE_IPV4_NO_CHECK = "(?:(?:\\d{1,3}\\.){3}\\d{1,3})"
+const S_RE_IPV4_HAS_CHECK = "(?:(?:25[0-5]|(?:2[0-4]|1{0,1}\\d){0,1}\\d)\\.){3}(?:25[0-5]|(?:2[0-4]|1{0,1}\\d){0,1}\\d)"
+
+const S_RE_IPV6_SEG = "[a-fA-F\\d]{1,4}"
+// Yes, this is an ipv6 address.
+const S_RE_IPV6 = `
+(?:
+(?:${S_RE_IPV6_SEG}:){7}(?:${S_RE_IPV6_SEG}|:)|
+(?:${S_RE_IPV6_SEG}:){6}(?:${S_RE_IPV4_HAS_CHECK}|:${S_RE_IPV6_SEG}|:)|
+(?:${S_RE_IPV6_SEG}:){5}(?::${S_RE_IPV4_HAS_CHECK}|(?::${S_RE_IPV6_SEG}){1,2}|:)|
+(?:${S_RE_IPV6_SEG}:){4}(?:(?::${S_RE_IPV6_SEG}){0,1}:${S_RE_IPV4_HAS_CHECK}|(?::${S_RE_IPV6_SEG}){1,3}|:)|
+(?:${S_RE_IPV6_SEG}:){3}(?:(?::${S_RE_IPV6_SEG}){0,2}:${S_RE_IPV4_HAS_CHECK}|(?::${S_RE_IPV6_SEG}){1,4}|:)|
+(?:${S_RE_IPV6_SEG}:){2}(?:(?::${S_RE_IPV6_SEG}){0,3}:${S_RE_IPV4_HAS_CHECK}|(?::${S_RE_IPV6_SEG}){1,5}|:)|
+(?:${S_RE_IPV6_SEG}:){1}(?:(?::${S_RE_IPV6_SEG}){0,4}:${S_RE_IPV4_HAS_CHECK}|(?::${S_RE_IPV6_SEG}){1,6}|:)|
+(?::(?:(?::${S_RE_IPV6_SEG}){0,5}:${S_RE_IPV4_HAS_CHECK}|(?::${S_RE_IPV6_SEG}){1,7}|:))
+)(?:%[0-9a-zA-Z]{1,})?`
+  .replace(/\s*\/\/.*$/gm, '')
+  .replace(/\n/g, '')
+  .trim();
+
+const RE_DOMAIN_EXACT = new RegExp(`^${S_RE_DOMAIN}$`)
+const RE_IPV4_EXACT = new RegExp(`^${S_RE_IPV4_HAS_CHECK}$`)
+const RE_IPV6_EXACT = new RegExp(`^${S_RE_IPV6}$`)
+const RE_IP_ADDR_EXACT = new RegExp(`^${S_RE_IPV6}|${S_RE_IPV4_HAS_CHECK}$`)
+
+module.exports = {
+  S_RE_DOMAIN,
+  S_RE_IPV6,
+  S_RE_IPV4: S_RE_IPV4_HAS_CHECK,
+  RE_DOMAIN_EXACT,
+  RE_IPV4_EXACT,
+  RE_IPV6_EXACT,
+  RE_IP_ADDR_EXACT
+}

src/login.pug

@@ -15,7 +15,7 @@ html
           .data-input
             .form-input-container
               label(for="username") Username
-              input(type="text" name="username" autocomplete="username" placeholder="@username:server.tld" pattern="^@?[a-z0-9._=/-]+(?::[a-zA-Z0-9.:\\[\\]-]+)?$" required)#username
+              input(type="text" name="username" autocomplete="username" placeholder="@username:server.com" pattern="^@?[a-z0-9._=/-]+(?::[a-zA-Z0-9.:\\[\\]-]+)?$" required)#username
 
             .form-input-container
               label(for="password") Password
@@ -23,7 +23,7 @@ html
 
             .form-input-container
               label(for="homeserver") Homeserver
-              input(type="text" name="homeserver" value="matrix.org" placeholder="matrix.org" required)#homeserver
+              input(type="text" name="homeserver" placeholder="matrix.org")#homeserver
 
           #feedback
 

src/sass/login.sass

@@ -78,6 +78,7 @@ button, input[type="submit"]
   padding: 7px
 
   &:hover
+    cursor: pointer
     background-color: c.$milder
 
 label