From 0bfff97029d1f88dfd17f6c1f9c593c954d0c2e2 Mon Sep 17 00:00:00 2001
From: Russell Dempsey <1173416+SgtPooki@users.noreply.github.com>
Date: Mon, 11 Mar 2024 14:14:45 -0700
Subject: [PATCH] fix: redirect to proper encoded dnslink subdomain

---
 src/dns-link-labels.ts | 32 +++++++++++++++++++++++++++-----
 src/heliaServer.ts     |  7 ++++++-
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/src/dns-link-labels.ts b/src/dns-link-labels.ts
index 55666b8..1e65edc 100644
--- a/src/dns-link-labels.ts
+++ b/src/dns-link-labels.ts
@@ -1,13 +1,35 @@
+import { CID } from 'multiformats/cid'
+
 /**
  * For dnslinks see https://specs.ipfs.tech/http-gateways/subdomain-gateway/#host-request-header
  * DNSLink names include . which means they must be inlined into a single DNS label to provide unique origin and work with wildcard TLS certificates.
  */
 
+// DNS label can have up to 63 characters, consisting of alphanumeric
+// characters or hyphens -, but it must not start or end with a hyphen.
+const dnsLabelRegex = /^[a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?$/
+
+/**
+ * We can receive either IPNS Name string or DNSLink label string here.
+ * IPNS Names do not have dots or dashes.
+ */
+export function isValidDnsLabel (label: string): boolean {
+  // If string is not a valid IPNS Name (CID)
+  // then we assume it may be a valid DNSLabel.
+  try {
+    CID.parse(label)
+    return false
+  } catch {
+    return dnsLabelRegex.test(label)
+  }
+}
+
 /**
- * We can receive either a peerId string or dnsLink label string here. PeerId strings do not have dots or dashes.
+ * Checks if label looks like inlined DNSLink.
+ * (https://specs.ipfs.tech/http-gateways/subdomain-gateway/#host-request-header)
  */
-export function isDnsLabel (label: string): boolean {
-  return ['-', '.'].some((char) => label.includes(char))
+export function isInlinedDnsLink (label: string): boolean {
+  return isValidDnsLabel(label) && label.includes('-') && !label.includes('.')
 }
 
 /**
@@ -18,7 +40,7 @@ export function isDnsLabel (label: string): boolean {
  * @example en-wikipedia--on--ipfs-org.ipns.example.net -> example.net/ipns/en.wikipedia-on-ipfs.org
  */
 export function dnsLinkLabelDecoder (linkLabel: string): string {
-  return linkLabel.replace(/--/g, '-').replace(/-/g, '.')
+  return linkLabel.replace(/--/g, '%').replace(/-/g, '.').replace(/%/g, '-')
 }
 
 /**
@@ -29,5 +51,5 @@ export function dnsLinkLabelDecoder (linkLabel: string): string {
  * @example example.net/ipns/en.wikipedia-on-ipfs.org → Host: en-wikipedia--on--ipfs-org.ipns.example.net
  */
 export function dnsLinkLabelEncoder (linkLabel: string): string {
-  return linkLabel.replace(/\./g, '-').replace(/-/g, '--')
+  return linkLabel.replace(/-/g, '--').replace(/\./g, '-')
 }
diff --git a/src/heliaServer.ts b/src/heliaServer.ts
index 333e7af..7d1c32f 100644
--- a/src/heliaServer.ts
+++ b/src/heliaServer.ts
@@ -3,6 +3,7 @@ import { createVerifiedFetch, type VerifiedFetch } from '@helia/verified-fetch'
 import { type FastifyReply, type FastifyRequest, type RouteGenericInterface } from 'fastify'
 import { USE_SUBDOMAINS } from './constants.js'
 import { contentTypeParser } from './content-type-parser.js'
+import { dnsLinkLabelEncoder, isInlinedDnsLink } from './dns-link-labels.js'
 import { getCustomHelia } from './getCustomHelia.js'
 import { getIpnsAddressDetails } from './ipns-address-utils.js'
 import type { ComponentLogger, Logger } from '@libp2p/interface'
@@ -152,8 +153,12 @@ export class HeliaServer {
       // }
       // finalUrl += encodeURIComponent(`?${new URLSearchParams(request.query).toString()}`)
     }
+    let encodedDnsLink = address
+    if (!isInlinedDnsLink(address)) {
+      encodedDnsLink = dnsLinkLabelEncoder(address)
+    }
 
-    const finalUrl = `//${cidv1Address ?? address}.${namespace}.${request.hostname}/${relativePath ?? ''}`
+    const finalUrl = `//${cidv1Address ?? encodedDnsLink}.${namespace}.${request.hostname}/${relativePath ?? ''}`
     this.log('redirecting to final URL:', finalUrl)
     await reply
       .headers({