lean into examples

examples/basic-authentication/basic-authentication.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+    "encoding/base64"
+    "fmt"
+    "net/http"
+    "strings"
+)
+
+type Auth func(string, string) bool
+type handler http.HandlerFunc
+
+func testAuth(r *http.Request, auth Auth) bool {
+    header := r.Header.Get("Authorization")
+    s := strings.SplitN(header, " ", 2)
+    if len(s) != 2 || s[0] != "Basic" {
+        return false
+    }
+    b, err := base64.StdEncoding.DecodeString(s[1])
+    if err != nil {
+        return false
+    }
+    pair := strings.SplitN(string(b), ":", 2)
+    if len(pair) != 2 {
+        return false
+    }
+    return auth(pair[0], pair[1])
+}
+
+func requireAuth(w http.ResponseWriter, r *http.Request) {
+    w.Header().Set("WWW-Authenticate",
+        "Basic realm=\"private\"")
+    w.WriteHeader(401)
+    w.Write([]byte("401 Unauthorized\n"))
+}
+
+func wrapAuth(h handler, a Auth) handler {
+    return func(w http.ResponseWriter, r *http.Request) {
+        if testAuth(r, a) {
+            h(w, r)
+        } else {
+            requireAuth(w, r)
+        }
+    }
+}
+
+func hello(w http.ResponseWriter, r *http.Request) {
+    fmt.Fprintln(w, "Hello secret world!")
+}
+
+func main() {
+    checkPassword := func(_, password string) bool {
+        return password == "supersecret"
+    }
+    handler1 := http.HanderFunc(hello)
+    handler2 := wrapAuth(handler1, checkPassword)
+    http.ListenAndServe(":5000", handler2)
+}