protover: reject unexpected commas

Consistently reject extra commas, instead of only rejecting leading
commas.

Fix on b2b2e1c7f2.
Fixes #27194; bugfix on 0.2.9.4-alpha.

changes/bug27194

@@ -0,0 +1,3 @@
+  o Minor bugfixes (protover):
+    - Consistently reject extra commas, instead of only rejecting leading commas.
+      Fixes bug 27194; bugfix on 0.2.9.4-alpha.

src/core/or/protover.c

@@ -245,7 +245,8 @@ parse_single_entry(const char *s, const char *end_of_entry)
     }
 
     s = comma;
-    while (*s == ',' && s < end_of_entry)
+    // Skip the comma separator between ranges. Don't ignore a trailing comma.
+    if (s < (end_of_entry - 1))
       ++s;
   }
 

src/test/test_protover.c

@@ -572,6 +572,10 @@ test_protover_vote_roundtrip(void *args)
     { "N-1=1,2", "N-1=1-2" },
     { "-1=4294967295", NULL },
     { "-1=3", "-1=3" },
+    { "Foo=,", NULL },
+    { "Foo=,1", NULL },
+    { "Foo=1,,3", NULL },
+    { "Foo=1,3,", NULL },
     /* junk. */
     { "!!3@*", NULL },
     /* Missing equals sign */