From 72490f7ed04494b5d96bae06476faff472bc37a9 Mon Sep 17 00:00:00 2001
From: Steven Allen <steven@stebalien.com>
Date: Thu, 14 Mar 2019 16:09:00 -0700
Subject: [PATCH] gateway: simplify/improve dnslink rewrite handling

Instead of adding a new fake header (that could be spoofed by the client...),
just read the original request URI from the request object.

This also removes support for suborigins. They have never been implemented in
browsers and it looks like efforts have stalled. We can add support back if we
need it but, well, maintaining support was going to be more trouble than it was
worth.

License: MIT
Signed-off-by: Steven Allen <steven@stebalien.com>
---
 core/corehttp/gateway_handler.go | 59 ++++----------------------------
 core/corehttp/ipns_hostname.go   |  1 -
 2 files changed, 7 insertions(+), 53 deletions(-)

diff --git a/core/corehttp/gateway_handler.go b/core/corehttp/gateway_handler.go
index de8038f5306..5b1382a8655 100644
--- a/core/corehttp/gateway_handler.go
+++ b/core/corehttp/gateway_handler.go
@@ -24,7 +24,6 @@ import (
 	coreiface "github.com/ipfs/interface-go-ipfs-core"
 	ipath "github.com/ipfs/interface-go-ipfs-core/path"
 	routing "github.com/libp2p/go-libp2p-core/routing"
-	"github.com/multiformats/go-multibase"
 )
 
 const (
@@ -148,12 +147,11 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 	// and links that match the requested URL.
 	// For example, http://example.net would become /ipns/example.net, and
 	// the redirects and links would end up as http://example.net/ipns/example.net
-	originalUrlPath := prefix + urlPath
-	ipnsHostname := false
-	if hdr := r.Header.Get("X-Ipns-Original-Path"); len(hdr) > 0 {
-		originalUrlPath = prefix + hdr
-		ipnsHostname = true
+	requestURI, err := url.ParseRequestURI(r.RequestURI)
+	if err != nil {
+		webError(w, "failed to parse request path", err, http.StatusInternalServerError)
 	}
+	originalUrlPath := prefix + requestURI.Path
 
 	// Service Worker registration request
 	if r.Header.Get("Service-Worker") == "script" {
@@ -206,39 +204,6 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 	w.Header().Set("X-IPFS-Path", urlPath)
 	w.Header().Set("Etag", etag)
 
-	// Suborigin header, sandboxes apps from each other in the browser (even
-	// though they are served from the same gateway domain).
-	//
-	// Omitted if the path was treated by IPNSHostnameOption(), for example
-	// a request for http://example.net/ would be changed to /ipns/example.net/,
-	// which would turn into an incorrect Suborigin header.
-	// In this case the correct thing to do is omit the header because it is already
-	// handled correctly without a Suborigin.
-	//
-	// NOTE: This is not yet widely supported by browsers.
-	if !ipnsHostname {
-		// e.g.: 1="ipfs", 2="QmYuNaKwY...", ...
-		pathComponents := strings.SplitN(urlPath, "/", 4)
-
-		var suboriginRaw []byte
-		cidDecoded, err := cid.Decode(pathComponents[2])
-		if err != nil {
-			// component 2 doesn't decode with cid, so it must be a hostname
-			suboriginRaw = []byte(strings.ToLower(pathComponents[2]))
-		} else {
-			suboriginRaw = cidDecoded.Bytes()
-		}
-
-		base32Encoded, err := multibase.Encode(multibase.Base32, suboriginRaw)
-		if err != nil {
-			internalWebError(w, err)
-			return
-		}
-
-		suborigin := pathComponents[1] + "000" + strings.ToLower(base32Encoded)
-		w.Header().Set("Suborigin", suborigin)
-	}
-
 	// set these headers _after_ the error, for we may just not have it
 	// and dont want the client to cache a 500 response...
 	// and only if it's /ipfs!
@@ -322,10 +287,10 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 
 	// construct the correct back link
 	// https://github.com/ipfs/go-ipfs/issues/1365
-	var backLink string = prefix + urlPath
+	var backLink string = originalUrlPath
 
 	// don't go further up than /ipfs/$hash/
-	pathSplit := path.SplitList(backLink)
+	pathSplit := path.SplitList(urlPath)
 	switch {
 	// keep backlink
 	case len(pathSplit) == 3: // url: /ipfs/$hash
@@ -342,18 +307,8 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 		}
 	}
 
-	// strip /ipfs/$hash from backlink if IPNSHostnameOption touched the path.
-	if ipnsHostname {
-		backLink = prefix + "/"
-		if len(pathSplit) > 5 {
-			// also strip the trailing segment, because it's a backlink
-			backLinkParts := pathSplit[3 : len(pathSplit)-2]
-			backLink += path.Join(backLinkParts) + "/"
-		}
-	}
-
 	var hash string
-	if !strings.HasPrefix(originalUrlPath, ipfsPathPrefix) {
+	if !strings.HasPrefix(urlPath, ipfsPathPrefix) {
 		hash = resolvedPath.Cid().String()
 	}
 
diff --git a/core/corehttp/ipns_hostname.go b/core/corehttp/ipns_hostname.go
index d5512779b35..ddcd58c6129 100644
--- a/core/corehttp/ipns_hostname.go
+++ b/core/corehttp/ipns_hostname.go
@@ -28,7 +28,6 @@ func IPNSHostnameOption() ServeOption {
 				name := "/ipns/" + host
 				_, err := n.Namesys.Resolve(ctx, name, nsopts.Depth(1))
 				if err == nil || err == namesys.ErrResolveRecursion {
-					r.Header.Set("X-Ipns-Original-Path", r.URL.Path)
 					r.URL.Path = name + r.URL.Path
 				}
 			}