[feature] request blocking by http headers (#2409)

internal/middleware/useragent.go

@@ -18,21 +18,22 @@
 package middleware
 
 import (
-	"errors"
 	"net/http"
 
 	"github.com/gin-gonic/gin"
+	apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
 )
 
 // UserAgent returns a gin middleware which aborts requests with
 // empty user agent strings, returning code 418 - I'm a teapot.
 func UserAgent() gin.HandlerFunc {
 	// todo: make this configurable
+	var rsp = []byte(`{"error": "I'm a teapot: no user-agent sent with request"}`)
 	return func(c *gin.Context) {
 		if ua := c.Request.UserAgent(); ua == "" {
-			code := http.StatusTeapot
-			err := errors.New(http.StatusText(code) + ": no user-agent sent with request")
-			c.AbortWithStatusJSON(code, gin.H{"error": err.Error()})
+			apiutil.Data(c,
+				http.StatusTeapot, apiutil.AppJSON, rsp)
+			c.Abort()
 		}
 	}
 }