proxy: add support for basic authorization (#445)

Fixes #444 where the UI with api keys did not work. The choice to use
http basic authorization is for simple, automatic browser support. No
changes to the UI were necessary. Just use an API key as the password,
no user name is required.

proxy/proxymanager.go

@@ -3,6 +3,7 @@ package proxy
 import (
 	"bytes"
 	"context"
+	"encoding/base64"
 	"fmt"
 	"io"
 	"mime/multipart"
@@ -825,23 +826,30 @@ func (pm *ProxyManager) apiKeyAuth() gin.HandlerFunc {
 		xApiKey := c.GetHeader("x-api-key")
 
 		var bearerKey string
+		var basicKey string
 		if auth := c.GetHeader("Authorization"); auth != "" {
 			if strings.HasPrefix(auth, "Bearer ") {
 				bearerKey = strings.TrimPrefix(auth, "Bearer ")
+			} else if strings.HasPrefix(auth, "Basic ") {
+				// Basic Auth: base64(username:password), password is the API key
+				encoded := strings.TrimPrefix(auth, "Basic ")
+				if decoded, err := base64.StdEncoding.DecodeString(encoded); err == nil {
+					parts := strings.SplitN(string(decoded), ":", 2)
+					if len(parts) == 2 {
+						basicKey = parts[1] // password is the API key
+					}
+				}
 			}
 		}
 
-		// If both headers present, they must match
-		if xApiKey != "" && bearerKey != "" && xApiKey != bearerKey {
-			pm.sendErrorResponse(c, http.StatusBadRequest, "x-api-key and Authorization header values do not match")
-			c.Abort()
-			return
-		}
-
-		// Use x-api-key first, then Authorization
-		providedKey := xApiKey
-		if providedKey == "" {
+		// Use first key found: Basic, then Bearer, then x-api-key
+		var providedKey string
+		if basicKey != "" {
+			providedKey = basicKey
+		} else if bearerKey != "" {
 			providedKey = bearerKey
+		} else {
+			providedKey = xApiKey
 		}
 
 		// Validate key
@@ -854,6 +862,7 @@ func (pm *ProxyManager) apiKeyAuth() gin.HandlerFunc {
 		}
 
 		if !valid {
+			c.Header("WWW-Authenticate", `Basic realm="llama-swap"`)
 			pm.sendErrorResponse(c, http.StatusUnauthorized, "unauthorized: invalid or missing API key")
 			c.Abort()
 			return