From 27fc1672d45fe2089fdcbc14459e46c30f825104 Mon Sep 17 00:00:00 2001
From: Matthew Holt <Matthew.Holt+git@gmail.com>
Date: Thu, 23 Apr 2015 14:57:07 -0600
Subject: [PATCH] Basic auth middleware

---
 config/middleware.go              |   2 +
 middleware/basicauth/basicauth.go | 101 ++++++++++++++++++++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 middleware/basicauth/basicauth.go

diff --git a/config/middleware.go b/config/middleware.go
index 4f2fe547..d144cc6a 100644
--- a/config/middleware.go
+++ b/config/middleware.go
@@ -2,6 +2,7 @@ package config
 
 import (
 	"github.com/mholt/caddy/middleware"
+	"github.com/mholt/caddy/middleware/basicauth"
 	"github.com/mholt/caddy/middleware/browse"
 	"github.com/mholt/caddy/middleware/errors"
 	"github.com/mholt/caddy/middleware/extensions"
@@ -45,6 +46,7 @@ func init() {
 	register("rewrite", rewrite.New)
 	register("redir", redirect.New)
 	register("ext", extensions.New)
+	register("basicauth", basicauth.New)
 	register("proxy", proxy.New)
 	register("fastcgi", fastcgi.New)
 	register("websocket", websockets.New)
diff --git a/middleware/basicauth/basicauth.go b/middleware/basicauth/basicauth.go
new file mode 100644
index 00000000..d81d3a2e
--- /dev/null
+++ b/middleware/basicauth/basicauth.go
@@ -0,0 +1,101 @@
+package basicauth
+
+import (
+	"net/http"
+
+	"github.com/mholt/caddy/middleware"
+)
+
+// New constructs a new BasicAuth middleware instance.
+func New(c middleware.Controller) (middleware.Middleware, error) {
+	rules, err := parse(c)
+	if err != nil {
+		return nil, err
+	}
+
+	basic := BasicAuth{
+		Rules: rules,
+	}
+
+	return func(next middleware.Handler) middleware.Handler {
+		basic.Next = next
+		return basic
+	}, nil
+}
+
+// ServeHTTP implements the middleware.Handler interface.
+func (a BasicAuth) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
+	for _, rule := range a.Rules {
+		for _, res := range rule.Resources {
+			if !middleware.Path(r.URL.Path).Matches(res) {
+				continue
+			}
+
+			// Path matches; parse auth header
+			username, password, ok := r.BasicAuth()
+
+			// Check credentials
+			if !ok || username != rule.Username || password != rule.Password {
+				w.Header().Set("WWW-Authenticate", "Basic")
+				return http.StatusUnauthorized, nil
+			}
+
+			// "It's an older code, sir, but it checks out. I was about to clear them."
+			return a.Next.ServeHTTP(w, r)
+		}
+	}
+
+	// Pass-thru when no paths match
+	return a.Next.ServeHTTP(w, r)
+}
+
+func parse(c middleware.Controller) ([]Rule, error) {
+	var rules []Rule
+
+	for c.Next() {
+		var rule Rule
+
+		args := c.RemainingArgs()
+
+		switch len(args) {
+		case 2:
+			rule.Username = args[0]
+			rule.Password = args[1]
+			for c.NextBlock() {
+				rule.Resources = append(rule.Resources, c.Val())
+				if c.NextArg() {
+					return rules, c.Err("Expecting only one resource per line (extra '" + c.Val() + "')")
+				}
+			}
+		case 3:
+			rule.Resources = append(rule.Resources, args[0])
+			rule.Username = args[1]
+			rule.Password = args[2]
+		default:
+			return rules, c.ArgErr()
+		}
+
+		rules = append(rules, rule)
+	}
+
+	return rules, nil
+}
+
+// BasicAuth is middleware to protect resources with a username and password.
+// Note that HTTP Basic Authentication is not secure by itself and should
+// not be used to protect important assets without HTTPS. Even then, the
+// security of HTTP Basic Auth is disputed. Use discretion when deciding
+// what to protect with BasicAuth.
+type BasicAuth struct {
+	Next  middleware.Handler
+	Rules []Rule
+}
+
+// Rule represents a BasicAuth rule. A username and password
+// combination protect the associated resources, which are
+// file or directory paths.
+type Rule struct {
+	Username  string
+	Password  string
+	Resources []string
+}