From 5a6c54aeb95fcfdc70bef20e4a24a0bceed9ba45 Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Mon, 15 Dec 2008 21:18:19 +0000
Subject: Implement lengths in thandy objects, mostly: Accept them, and when
 they're present, don't fetch more bytes than specified, since that would be
 dangerous.  Include lengths in every generated object type except for the
 timestamp, since that would break exising code.

git-svn-id: file:///home/or/svnrepo/updater/trunk@17629 55e972cd-5a19-0410-ae62-a4d7a52db4cd
---
 specs/thandy-spec.txt | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

(limited to 'specs')

diff --git a/specs/thandy-spec.txt b/specs/thandy-spec.txt
index 3726c94..5cc4fa6 100644
--- a/specs/thandy-spec.txt
+++ b/specs/thandy-spec.txt
@@ -397,10 +397,10 @@
 
     { "_type" : Timestamp,
       "at" : TIME,
-      "m" : [ TIME, HASH ],
-      "k" : [ TIME, HASH ],
+      "m" : [ TIME, HASH, LENGTH ],
+      "k" : [ TIME, HASH, LENGTH ],
       "b" : { NAME :
-                 [ [ Version, Path, Time, Hash ] ] }
+                 [ [ Version, Path, Time, Hash, (Length) ] ] }
     }
 
   TIME is when the timestamp was signed.  MIRRORLISTHASH is the digest
@@ -409,6 +409,8 @@
   bundles and their locations and hashes.  The "name" of a bundle (in
   this context) is the directory component of the bundle's path.
 
+  The LENGTH field may be absent on very old timestamp files.
+
 3.6. File formats: bundle files
 
      { "_type" : "Bundle",
@@ -423,6 +425,7 @@
               "version" : VERSION,
               "path" : PATH,
               "hash" : HASH,
+              ("length" : LENGTH),
               "order" : [ INST, UPDATE, REMOVE ],
               ("optional : BOOL, )
               "gloss" : { LANG : TEXT },
@@ -446,6 +449,9 @@
   language. The UI should display the must appropriate language to the
   user.
 
+  The LENGTH field is required on all new bundles, but may be absent
+  on very old ones.
+
 3.7. File formats: package files
 
    { "_type" : "Package",
@@ -454,13 +460,14 @@
      "version" : VERSION,
      "format" : FMT,
      "ts" : TIME,
-     "files" : [  [ PATH, HASH, INFO ], ... ],
+     "files" : [  [ PATH, HASH, INFO, (LENGTH) ], ... ],
      "shortdesc" : { LANG : DESC, ... },
      "longdesc" : { LANG : DESC, ... },
    }
 
   Most elements are self-explanatory.  To interpret the 'INFO' entry
-  for each installable file, see section 6.
+  for each installable file, see section 6.  The LENGTH field is
+  required on all new packages, but may be absent on very old ones.
 
   No two package files in the same repository should have the same
   name and version.  If a package needs to be changed, the version
@@ -508,6 +515,10 @@
   Clients SHOULD cache at least the latest versions they have received
   of all files.
 
+  When dowloading a file, if the client knows what that file's length
+  should be, it SHOULD NOT accept a longer file, and SHOULD NOT
+  continue the download past the file length.
+
 4.1.1. Download preferences
 
   Users should be able to specify that packages must be only
-- 
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