gateway: add path prefix for directory listings

License: MIT
Signed-off-by: Lars Gierth <larsg@systemli.org>

core/corehttp/gateway_handler.go

@@ -92,16 +92,24 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 
 	urlPath := r.URL.Path
 
+	// If the gateway is behind a reverse proxy and mounted at a sub-path,
+	// the prefix header can be set to signal this sub-path.
+	// It will be prepended to links in directory listings and the index.html redirect.
+	prefix := ""
+	if prefixHdr := r.Header["X-Ipfs-Gateway-Prefix"]; len(prefixHdr) > 0 {
+		log.Debugf("X-Ipfs-Gateway-Prefix: %s", prefixHdr[0])
+		prefix = prefixHdr[0]
+	}
+
 	// IPNSHostnameOption might have constructed an IPNS path using the Host header.
 	// In this case, we need the original path for constructing redirects
 	// 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 := urlPath
+	originalUrlPath := prefix + urlPath
 	ipnsHostname := false
-	hdr := r.Header["X-IPNS-Original-Path"]
-	if len(hdr) > 0 {
-		originalUrlPath = hdr[0]
+	if hdr := r.Header["X-Ipns-Original-Path"]; len(hdr) > 0 {
+		originalUrlPath = prefix + hdr[0]
 		ipnsHostname = true
 	}
 
@@ -211,7 +219,7 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 		if r.Method != "HEAD" {
 			// construct the correct back link
 			// https://github.com/ipfs/go-ipfs/issues/1365
-			var backLink string = urlPath
+			var backLink string = prefix + urlPath
 
 			// don't go further up than /ipfs/$hash/
 			pathSplit := strings.Split(backLink, "/")
@@ -233,7 +241,7 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 
 			// strip /ipfs/$hash from backlink if IPNSHostnameOption touched the path.
 			if ipnsHostname {
-				backLink = "/"
+				backLink = prefix + "/"
 				if len(pathSplit) > 5 {
 					// also strip the trailing segment, because it's a backlink
 					backLinkParts := pathSplit[3 : len(pathSplit)-2]

core/corehttp/gateway_test.go

@@ -213,6 +213,30 @@ func TestIPNSHostnameRedirect(t *testing.T) {
 	} else if hdr[0] != "/foo/" {
 		t.Errorf("location header is %v, expected /foo/", hdr[0])
 	}
+
+	// make request with prefix to directory containing index.html
+	req, err = http.NewRequest("GET", ts.URL+"/foo", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Host = "example.net"
+	req.Header.Set("X-Ipfs-Gateway-Prefix", "/prefix")
+
+	res, err = doWithoutRedirect(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// expect 302 redirect to same path, but with prefix and trailing slash
+	if res.StatusCode != 302 {
+		t.Errorf("status is %d, expected 302", res.StatusCode)
+	}
+	hdr = res.Header["Location"]
+	if len(hdr) < 1 {
+		t.Errorf("location header not present")
+	} else if hdr[0] != "/prefix/foo/" {
+		t.Errorf("location header is %v, expected /prefix/foo/", hdr[0])
+	}
 }
 
 func TestIPNSHostnameBacklinks(t *testing.T) {
@@ -282,7 +306,7 @@ func TestIPNSHostnameBacklinks(t *testing.T) {
 		t.Fatalf("expected file in directory listing")
 	}
 
-	// make request to directory listing
+	// make request to directory listing at root
 	req, err = http.NewRequest("GET", ts.URL, nil)
 	if err != nil {
 		t.Fatal(err)
@@ -294,7 +318,7 @@ func TestIPNSHostnameBacklinks(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	// expect correct backlinks
+	// expect correct backlinks at root
 	body, err = ioutil.ReadAll(res.Body)
 	if err != nil {
 		t.Fatalf("error reading response: %s", err)
@@ -341,4 +365,35 @@ func TestIPNSHostnameBacklinks(t *testing.T) {
 	if !strings.Contains(s, "<a href=\"/foo/bar/file.txt\">") {
 		t.Fatalf("expected file in directory listing")
 	}
+
+	// make request to directory listing with prefix
+	req, err = http.NewRequest("GET", ts.URL, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.Host = "example.net"
+	req.Header.Set("X-Ipfs-Gateway-Prefix", "/prefix")
+
+	res, err = doWithoutRedirect(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// expect correct backlinks with prefix
+	body, err = ioutil.ReadAll(res.Body)
+	if err != nil {
+		t.Fatalf("error reading response: %s", err)
+	}
+	s = string(body)
+	t.Logf("body: %s\n", string(body))
+
+	if !strings.Contains(s, "Index of /prefix") {
+		t.Fatalf("expected a path in directory listing")
+	}
+	if !strings.Contains(s, "<a href=\"/prefix/\">") {
+		t.Fatalf("expected backlink in directory listing")
+	}
+	if !strings.Contains(s, "<a href=\"/prefix/file.txt\">") {
+		t.Fatalf("expected file in directory listing")
+	}
 }

core/corehttp/ipns_hostname.go

@@ -24,7 +24,7 @@ func IPNSHostnameOption() ServeOption {
 			if len(host) > 0 && isd.IsDomain(host) {
 				name := "/ipns/" + host
 				if _, err := n.Namesys.Resolve(ctx, name); err == nil {
-					r.Header["X-IPNS-Original-Path"] = []string{r.URL.Path}
+					r.Header["X-Ipns-Original-Path"] = []string{r.URL.Path}
 					r.URL.Path = name + r.URL.Path
 				}
 			}