lib/http: add BasePath to the ServerOptions

The BasePath allow server to serve HTTP from custom prefix, other than
"/".

Each request that server received will remove the BasePath first
from the [http.Request.URL.Path] before passing to the handler.
Each redirect that server sent will add the BasePath as the prefix
to redirect URL.

Any trailing slash in the BasePath will be removed.

2 files changed, 26 insertions, 2 deletions

diff --git a/lib/http/server.go b/lib/http/server.go
index 64ac5c14..4501cb9f 100644
--- a/lib/http/server.go
+++ b/lib/http/server.go
@@ -1,6 +1,5 @@
-// SPDX-FileCopyrightText: 2018 M. Shulhan <ms@kilabit.info>
-//
 // SPDX-License-Identifier: BSD-3-Clause
+// SPDX-FileCopyrightText: 2018 M. Shulhan <ms@kilabit.info>
 
 package http
 
@@ -83,6 +82,11 @@ func (srv *Server) RedirectTemp(res http.ResponseWriter, redirectURL string) {
 	if len(redirectURL) == 0 {
 		redirectURL = "/"
 	}
+	endWithSlash := redirectURL[len(redirectURL)-1] == '/'
+	redirectURL = path.Join(srv.Options.BasePath, redirectURL)
+	if endWithSlash {
+		redirectURL += `/`
+	}
 	res.Header().Set(HeaderLocation, redirectURL)
 	res.WriteHeader(http.StatusTemporaryRedirect)
 }
@@ -319,6 +323,8 @@ func (srv *Server) registerPut(ep *Endpoint) (err error) {
 
 // ServeHTTP handle mapping of client request to registered endpoints.
 func (srv *Server) ServeHTTP(res http.ResponseWriter, req *http.Request) {
+	req.URL.Path = strings.TrimPrefix(req.URL.Path, srv.Options.BasePath)
+
 	switch req.Method {
 	case http.MethodDelete:
 		srv.handleDelete(res, req)
@@ -481,6 +487,11 @@ func (srv *Server) HandleFS(res http.ResponseWriter, req *http.Request) {
 		// If request path is a directory and it is not end with
 		// slash, redirect request to location with slash to allow
 		// relative links works inside the HTML content.
+		endWithSlash := redirectURL.Path[len(redirectURL.Path)-1] == '/'
+		redirectURL.Path = path.Join(srv.Options.BasePath, redirectURL.Path)
+		if endWithSlash {
+			redirectURL.Path += `/`
+		}
 		http.Redirect(res, req, redirectURL.String(), http.StatusMovedPermanently)
 		return
 	}
diff --git a/lib/http/server_options.go b/lib/http/server_options.go
index d51fe381..8e168885 100644
--- a/lib/http/server_options.go
+++ b/lib/http/server_options.go
@@ -8,6 +8,7 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"strings"
 
 	"git.sr.ht/~shulhan/pakakeh.go/lib/memfs"
 )
@@ -38,6 +39,16 @@ type ServerOptions struct {
 	// This field is optional, default to ":80".
 	Address string
 
+	// BasePath define the base path or prefix to serve the HTTP request
+	// and response.
+	// Each request that server received will remove the BasePath first
+	// from the [http.Request.URL.Path] before passing to the handler.
+	// Each redirect that server sent will add the BasePath as the prefix
+	// to redirect URL.
+	//
+	// Any trailing slash in the BasePath will be removed.
+	BasePath string
+
 	// Conn contains custom HTTP server connection.
 	// This fields is optional.
 	Conn *http.Server
@@ -64,6 +75,8 @@ func (opts *ServerOptions) init() {
 		opts.Address = ":80"
 	}
 
+	opts.BasePath = strings.TrimRight(opts.BasePath, `/`)
+
 	if opts.Conn == nil {
 		opts.Conn = &http.Server{
 			ReadTimeout:    defRWTimeout,