From f4f5cba43dc1ed11bb97329cd2a6bc43e5e35d43 Mon Sep 17 00:00:00 2001
From: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Fri, 11 Apr 2025 21:45:17 +0000
Subject: [PATCH] Avoid copying link-layer header; point instead

---
 libnetutil/netutil.h | 2 +-
 tcpip.cc             | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/libnetutil/netutil.h b/libnetutil/netutil.h
index c34f986ed..3b15c922f 100644
--- a/libnetutil/netutil.h
+++ b/libnetutil/netutil.h
@@ -237,7 +237,7 @@ typedef enum { devt_ethernet, devt_loopback, devt_p2p, devt_other  } devtype;
 struct link_header {
   int datalinktype; /* pcap_datalink(), such as DLT_EN10MB */
   int headerlen; /* 0 if header was too big or unavailaable */
-  u8 header[MAX_LINK_HEADERSZ];
+  const u8 *header;
 };
 
 /* Relevant (to Nmap) information about an interface */
diff --git a/tcpip.cc b/tcpip.cc
index f704dcf72..e38d20c15 100644
--- a/tcpip.cc
+++ b/tcpip.cc
@@ -1554,8 +1554,7 @@ const u8 *readip_pcap(pcap_t *pd, unsigned int *len, long to_usec,
   if (offset && linknfo) {
     linknfo->datalinktype = datalink;
     linknfo->headerlen = offset;
-    assert(offset <= MAX_LINK_HEADERSZ);
-    memcpy(linknfo->header, p - offset, MIN(sizeof(linknfo->header), offset));
+    linknfo->header = p;
   }
   if (rcvdtime)
     PacketTrace::trace(PacketTrace::RCVD, (u8 *) p, *len,