From db1775332c83a8d0943bea4b69c49ea5b47cc2a6 Mon Sep 17 00:00:00 2001
From: Christopher Baines <mail@cbaines.net>
Date: Mon, 22 May 2023 11:34:32 +0100
Subject: Better handle invalid GET /nar/ requests

---
 nar-herder/server.scm | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/nar-herder/server.scm b/nar-herder/server.scm
index 07cb1c4..f07cb9d 100644
--- a/nar-herder/server.scm
+++ b/nar-herder/server.scm
@@ -283,20 +283,24 @@
              (values (build-response #:code 404)
                      "404"))))
       (('GET "nar" compression filename)
-       (let* ((hash (string-take filename 32))
+       (let* ((hash (and (>= (string-length filename) 32)
+                         (string-take filename 32)))
               (narinfo
-               (database-select-narinfo-by-hash
-                database
-                hash))
+               (and hash
+                    (database-select-narinfo-by-hash
+                     database
+                     hash)))
               (narinfo-files
-               (database-select-narinfo-files-by-narinfo-id
-                database
-                (assq-ref narinfo 'id)))
+               (and=> (assq-ref narinfo 'id)
+                      (lambda (id)
+                        (database-select-narinfo-files-by-narinfo-id
+                         database
+                         id))))
               (narinfo-file-for-compression
                (find (lambda (file)
                        (string=? (assq-ref file 'compression)
                                  compression))
-                     narinfo-files))
+                     (or narinfo-files '())))
               (compression-symbol
                (if (member
                     compression
-- 
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