implement arbitrary HTTP header support

this commit adds the ability to specify arbitrary HTTP headers
for either the Gateway or the API. simply set the desired headers
on the config:

    ipfs config --json API.HTTPHeaders.X-MyHdr '["meow :)"]'
    ipfs config --json Gateway.HTTPHeaders.X-MyHdr '["meow :)"]'

License: MIT
Signed-off-by: Juan Batiz-Benet <juan@benet.ai>


This commit was moved from ipfs/kubo@4a571b0

gateway/core/corehttp/commands.go

@@ -39,7 +39,7 @@ func addCORSFromEnv(c *cmdsHttp.ServerConfig) {
 	}
 }
 
-func addCORSFromConfig(c *cmdsHttp.ServerConfig, nc *config.Config) {
+func addHeadersFromConfig(c *cmdsHttp.ServerConfig, nc *config.Config) {
 	log.Info("Using API.HTTPHeaders:", nc.API.HTTPHeaders)
 
 	if acao := nc.API.HTTPHeaders["Access-Control-Allow-Origin"]; acao != nil {
@@ -53,6 +53,8 @@ func addCORSFromConfig(c *cmdsHttp.ServerConfig, nc *config.Config) {
 			c.CORSOpts.AllowCredentials = (strings.ToLower(v) == "true")
 		}
 	}
+
+	c.Headers = nc.API.HTTPHeaders
 }
 
 func CommandsOption(cctx commands.Context) ServeOption {
@@ -64,7 +66,7 @@ func CommandsOption(cctx commands.Context) ServeOption {
 			},
 		}
 
-		addCORSFromConfig(cfg, n.Repo.Config())
+		addHeadersFromConfig(cfg, n.Repo.Config())
 		addCORSFromEnv(cfg)
 
 		cmdHandler := cmdsHttp.NewHandler(cctx, corecommands.Root, cfg)

gateway/core/corehttp/gateway.go

@@ -15,6 +15,7 @@ type Gateway struct {
 }
 
 type GatewayConfig struct {
+	Headers   map[string][]string
 	BlockList *BlockList
 	Writable  bool
 }
@@ -27,6 +28,9 @@ func NewGateway(conf GatewayConfig) *Gateway {
 
 func (g *Gateway) ServeOption() ServeOption {
 	return func(n *core.IpfsNode, mux *http.ServeMux) (*http.ServeMux, error) {
+		// pass user's HTTP headers
+		g.Config.Headers = n.Repo.Config().Gateway.HTTPHeaders
+
 		gateway, err := newGatewayHandler(n, g.Config)
 		if err != nil {
 			return nil, err

gateway/core/corehttp/gateway_handler.go

@@ -106,6 +106,7 @@ func (i *gatewayHandler) getOrHeadHandler(w http.ResponseWriter, r *http.Request
 		return
 	}
 
+	i.addUserHeaders(w) // ok, _now_ write user's headers.
 	w.Header().Set("X-IPFS-Path", urlPath)
 
 	// Suborigin header, sandboxes apps from each other in the browser (even
@@ -229,6 +230,7 @@ func (i *gatewayHandler) postHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	i.addUserHeaders(w) // ok, _now_ write user's headers.
 	w.Header().Set("IPFS-Hash", k.String())
 	http.Redirect(w, r, ipfsPathPrefix+k.String(), http.StatusCreated)
 }
@@ -242,6 +244,7 @@ func (i *gatewayHandler) putEmptyDirHandler(w http.ResponseWriter, r *http.Reque
 		return
 	}
 
+	i.addUserHeaders(w) // ok, _now_ write user's headers.
 	w.Header().Set("IPFS-Hash", key.String())
 	http.Redirect(w, r, ipfsPathPrefix+key.String()+"/", http.StatusCreated)
 }
@@ -340,6 +343,7 @@ func (i *gatewayHandler) putHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	i.addUserHeaders(w) // ok, _now_ write user's headers.
 	w.Header().Set("IPFS-Hash", key.String())
 	http.Redirect(w, r, ipfsPathPrefix+key.String()+"/"+strings.Join(components, "/"), http.StatusCreated)
 }
@@ -411,10 +415,17 @@ func (i *gatewayHandler) deleteHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	i.addUserHeaders(w) // ok, _now_ write user's headers.
 	w.Header().Set("IPFS-Hash", key.String())
 	http.Redirect(w, r, ipfsPathPrefix+key.String()+"/"+strings.Join(components[:len(components)-1], "/"), http.StatusCreated)
 }
 
+func (i *gatewayHandler) addUserHeaders(w http.ResponseWriter) {
+	for k, v := range i.config.Headers {
+		w.Header()[k] = v
+	}
+}
+
 func webError(w http.ResponseWriter, message string, err error, defaultCode int) {
 	if _, ok := err.(path.ErrNoLink); ok {
 		webErrorWithCode(w, message, err, http.StatusNotFound)