From 03545aa78b0e7bd177e22432e4842b0580a11d7d Mon Sep 17 00:00:00 2001
From: Richard Moore <github@ricmoo.com>
Date: Mon, 24 Jan 2022 16:39:50 -0500
Subject: [PATCH] Support invalid but popular IPFS URI format (#2271, #2527,
 #2590).

---
 packages/providers/src.ts/base-provider.ts | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/packages/providers/src.ts/base-provider.ts b/packages/providers/src.ts/base-provider.ts
index 299b2ab6cd..79bdad55b0 100644
--- a/packages/providers/src.ts/base-provider.ts
+++ b/packages/providers/src.ts/base-provider.ts
@@ -267,7 +267,15 @@ function _parseBytes(result: string): null | string {
 
 // Trim off the ipfs:// prefix and return the default gateway URL
 function getIpfsLink(link: string): string {
-    return `https:/\/gateway.ipfs.io/ipfs/${ link.substring(7) }`;
+    if (link.match(/^ipfs:\/\/ipfs\//i)) {
+        link = link.substring(12);
+    } else if (link.match(/^ipfs:\/\//i)) {
+        link = link.substring(7);
+    } else {
+        logger.throwArgumentError("unsupported IPFS format", "link", link);
+    }
+
+    return `https:/\/gateway.ipfs.io/ipfs/${ link }`;
 }
 
 export class Resolver implements EnsResolver {
@@ -471,9 +479,10 @@ export class Resolver implements EnsResolver {
                             to: this.provider.formatter.address(comps[0]),
                             data: hexConcat([ selector, tokenId ])
                         };
+
                         let metadataUrl = _parseString(await this.provider.call(tx))
                         if (metadataUrl == null) { return null; }
-                        linkage.push({ type: "metadata-url", content: metadataUrl });
+                        linkage.push({ type: "metadata-url-base", content: metadataUrl });
 
                         // ERC-1155 allows a generic {id} in the URL
                         if (scheme === "erc1155") {
@@ -481,6 +490,13 @@ export class Resolver implements EnsResolver {
                             linkage.push({ type: "metadata-url-expanded", content: metadataUrl });
                         }
 
+                        // Transform IPFS metadata links
+                        if (metadataUrl.match(/^ipfs:/i)) {
+                            metadataUrl = getIpfsLink(metadataUrl);
+                        }
+
+                        linkage.push({ type: "metadata-url", content: metadataUrl });
+
                         // Get the token metadata
                         const metadata = await fetchJson(metadataUrl);
                         if (!metadata) { return null; }