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-rw-r--r--util-print.c20
1 files changed, 16 insertions, 4 deletions
diff --git a/util-print.c b/util-print.c
index 90e11b9f3b80..0e30d7900d41 100644
--- a/util-print.c
+++ b/util-print.c
@@ -120,10 +120,21 @@ fn_print(netdissect_options *ndo,
/*
* Print out a null-terminated filename (or other ascii string) from
- * a fixed-length buffer.
- * If ep is NULL, assume no truncation check is needed.
+ * a fixed-length field in the packet buffer, or from what remains of
+ * the packet.
+ *
+ * n is the length of the fixed-length field, or the number of bytes
+ * remaining in the packet based on its on-the-network length.
+ *
+ * If ep is non-null, it should point just past the last captured byte
+ * of the packet, e.g. ndo->ndo_snapend. If ep is NULL, we assume no
+ * truncation check, other than the checks of the field length/remaining
+ * packet data length, is needed.
+ *
* Return the number of bytes of string processed, including the
- * terminating null, if not truncated. Return 0 if truncated.
+ * terminating null, if not truncated; as the terminating null is
+ * included in the count, and as there must be a terminating null,
+ * this will always be non-zero. Return 0 if truncated.
*/
u_int
fn_printztn(netdissect_options *ndo,
@@ -137,7 +148,8 @@ fn_printztn(netdissect_options *ndo,
if (n == 0 || (ep != NULL && s >= ep)) {
/*
* Truncated. This includes "no null before we
- * got to the end of the fixed-length buffer".
+ * got to the end of the fixed-length buffer or
+ * the end of the packet".
*
* XXX - BOOTP says "null-terminated", which
* means the maximum length of the string, in