Ensure that stomp-read-frame returns nil for incomplete frames

stomp.el

@@ -26,7 +26,7 @@
 (defun stomp-send-frame (process frame)
   "Send a message to a STOMP process"
   (process-send-string process (stomp-frame-to-string frame)))
-                       
+
 (defun stomp-filter-function (callback)
   "Filter function to be used with processes"
   (unless (functionp callback) (signal 'wrong-type-argument 'functionp))
@@ -69,10 +69,11 @@
        ((and headers-end-point)
         (map-put frame 'command (current-word))
         (map-put frame 'headers (stomp-read-headers buffer headers-end-point))
-        (map-put frame 'content
-                 (buffer-substring
-                  (+ 1 headers-end-point)
-                  (stomp-find-frame-end-point buffer frame headers-end-point))))
+
+        (let ((frame-end-point (stomp-find-frame-end-point buffer frame headers-end-point)))
+          (if frame-end-point
+              (map-put frame 'content (buffer-substring (+ 1 headers-end-point) frame-end-point))
+            nil)))
        (t nil)))))
 
 (defun stomp-read-headers (buffer end-point &optional headers)
@@ -96,16 +97,18 @@
    either by using the content-length header or by searching for
    the null octet."
   (with-current-buffer buffer
-    (let ((content-length (stomp-frame-header "content-length" frame))
-          (headers-end-point(if headers-end-point
-                                 headers-end-point
-                               (stomp-find-headers-end-point buffer))))
-      (if content-length
-          (+ headers-end-point 1 (string-to-number content-length))
-        (progn
-          (goto-char (point-min))
-          (search-forward-regexp "\u0000\\|\u0000\r")
-          (- (point) 1))))))
+    (let* ((content-length (stomp-frame-header "content-length" frame))
+           (headers-end-point
+            (if headers-end-point headers-end-point (stomp-find-headers-end-point buffer)))
+           (end-point (if content-length
+                          (+ headers-end-point 1 (string-to-number content-length))
+                        (progn
+                          (goto-char (point-min))
+                          (search-forward-regexp "\u0000\\|\u0000\r" nil t)
+                          (- (point) 1)))))
+      (if (or (> end-point (point-max)) (<= end-point 0))
+          nil
+        end-point))))
 
 (defun stomp-find-headers-end-point (buffer)
   "Find the end of the header part of a STOMP frame."

test/test.el

@@ -60,6 +60,23 @@
                     ("content-length" . "11"))))
    (should (equal (alist-get 'content recieved) "jwe\u0000jsiwli\u0000"))))
 
+(ert-deftest returns-nil-when-incomplete-frame ()
+  "When there is no complete frame at the top of a buffer, read-frame
+   should return nil"
+  (with-testing-buffer
+   "incomplete_frame.txt"
+   (setq recieved (stomp-read-frame (current-buffer)))
+
+   (should (equal recieved nil))))
+
+(ert-deftest returns-nil-when-incomplete-frame-no-headers ()
+  "When no 'end of headers' marker can be found, stomp-read-frame should return nil"
+  (with-testing-buffer
+   "incomplete_frame_no_headers.txt"
+   (setq recieved (stomp-read-frame (current-buffer)))
+
+   (should (equal nil recieved))))
+
 (ert-deftest can-delete-one-frame ()
   "Can delete the topmost frame in a buffer"
   (with-testing-buffer

test/testdata/incomplete_frame.txt

@@ -0,0 +1,3 @@
+MESSAGE
+not-complete:nope
+

test/testdata/incomplete_frame_no_headers.txt

@@ -0,0 +1 @@
+BLA