Merge branch 'jk/reduce-malloc-in-v2-servers'

Code cleanup to limit memory consumption and tighten protocol
message parsing.

* jk/reduce-malloc-in-v2-servers:
  ls-refs: reject unknown arguments
  serve: reject commands used as capabilities
  serve: reject bogus v2 "command=ls-refs=foo"
  docs/protocol-v2: clarify some ls-refs ref-prefix details
  ls-refs: ignore very long ref-prefix counts
  serve: drop "keys" strvec
  serve: provide "receive" function for session-id capability
  serve: provide "receive" function for object-format capability
  serve: add "receive" method for v2 capabilities table
  serve: return capability "value" from get_capability()
  serve: rename is_command() to parse_command()

1 files changed, 20 insertions, 2 deletions

diff --git a/ls-refs.c b/ls-refs.c
index be09568910..73eb7da528 100644
--- a/ls-refs.c
+++ b/ls-refs.c
@@ -41,6 +41,12 @@ static void ensure_config_read(void)
 }
 
 /*
+ * If we see this many or more "ref-prefix" lines from the client, we consider
+ * it "too many" and will avoid using the prefix feature entirely.
+ */
+#define TOO_MANY_PREFIXES 65536
+
+/*
  * Check if one of the prefixes is a prefix of the ref.
  * If no prefixes were provided, all refs match.
  */
@@ -158,15 +164,27 @@ int ls_refs(struct repository *r, struct packet_reader *request)
 			data.peel = 1;
 		else if (!strcmp("symrefs", arg))
 			data.symrefs = 1;
-		else if (skip_prefix(arg, "ref-prefix ", &out))
-			strvec_push(&data.prefixes, out);
+		else if (skip_prefix(arg, "ref-prefix ", &out)) {
+			if (data.prefixes.nr < TOO_MANY_PREFIXES)
+				strvec_push(&data.prefixes, out);
+		}
 		else if (!strcmp("unborn", arg))
 			data.unborn = allow_unborn;
+		else
+			die(_("unexpected line: '%s'"), arg);
 	}
 
 	if (request->status != PACKET_READ_FLUSH)
 		die(_("expected flush after ls-refs arguments"));
 
+	/*
+	 * If we saw too many prefixes, we must avoid using them at all; as
+	 * soon as we have any prefix, they are meant to form a comprehensive
+	 * list.
+	 */
+	if (data.prefixes.nr >= TOO_MANY_PREFIXES)
+		strvec_clear(&data.prefixes);
+
 	send_possibly_unborn_head(&data);
 	if (!data.prefixes.nr)
 		strvec_push(&data.prefixes, "");