From ab458eae56be4c2bd0291ab6b4d8fb518fa836eb Mon Sep 17 00:00:00 2001
From: Edward Hervey <edward@centricular.com>
Date: Wed, 19 Apr 2023 09:55:14 +0200
Subject: [PATCH] pcapparse: Add support for Linux "cooked" capture
 encapsulation v2

See https://www.tcpdump.org/linktypes/LINKTYPE_LINUX_SLL2.html

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4451>
---
 .../gst-plugins-bad/gst/pcapparse/gstpcapparse.c     | 12 ++++++++++--
 .../gst-plugins-bad/gst/pcapparse/gstpcapparse.h     |  3 ++-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/subprojects/gst-plugins-bad/gst/pcapparse/gstpcapparse.c b/subprojects/gst-plugins-bad/gst/pcapparse/gstpcapparse.c
index a4922053d0..53e7ef6fc2 100644
--- a/subprojects/gst-plugins-bad/gst/pcapparse/gstpcapparse.c
+++ b/subprojects/gst-plugins-bad/gst/pcapparse/gstpcapparse.c
@@ -351,6 +351,7 @@ gst_pcap_parse_read_uint32 (GstPcapParse * self, const guint8 * p)
 #define ETH_HEADER_LEN    14
 #define ETH_VLAN_HEADER_LEN    4
 #define SLL_HEADER_LEN    16
+#define SLL2_HEADER_LEN    20
 #define IP_HEADER_MIN_LEN 20
 #define UDP_HEADER_LEN     8
 
@@ -404,6 +405,13 @@ gst_pcap_parse_scan_frame (GstPcapParse * self,
       eth_type = GUINT16_FROM_BE (*((guint16 *) (buf + 14)));
       buf_ip = buf + SLL_HEADER_LEN;
       break;
+    case LINKTYPE_SLL2:
+      if (buf_size < SLL2_HEADER_LEN + IP_HEADER_MIN_LEN + UDP_HEADER_LEN)
+        return FALSE;
+
+      eth_type = GUINT16_FROM_BE (*((guint16 *) (buf)));
+      buf_ip = buf + SLL2_HEADER_LEN;
+      break;
     case LINKTYPE_RAW:
       if (buf_size < IP_HEADER_MIN_LEN + UDP_HEADER_LEN)
         return FALSE;
@@ -641,9 +649,9 @@ gst_pcap_parse_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer)
       }
 
       if (linktype != LINKTYPE_ETHER && linktype != LINKTYPE_SLL &&
-          linktype != LINKTYPE_RAW) {
+          linktype != LINKTYPE_RAW && linktype != LINKTYPE_SLL2) {
         GST_ELEMENT_ERROR (self, STREAM, WRONG_TYPE, (NULL),
-            ("Only dumps of type Ethernet, raw IP or Linux Cooked (SLL) "
+            ("Only dumps of type Ethernet, raw IP or Linux Cooked (SLL/SLL2) "
                 "understood; type %d unknown", linktype));
         ret = GST_FLOW_ERROR;
         goto out;
diff --git a/subprojects/gst-plugins-bad/gst/pcapparse/gstpcapparse.h b/subprojects/gst-plugins-bad/gst/pcapparse/gstpcapparse.h
index 29e2188c72..9547ce4003 100644
--- a/subprojects/gst-plugins-bad/gst/pcapparse/gstpcapparse.h
+++ b/subprojects/gst-plugins-bad/gst/pcapparse/gstpcapparse.h
@@ -49,7 +49,8 @@ typedef enum
 {
   LINKTYPE_ETHER  = 1,
   LINKTYPE_RAW = 101,
-  LINKTYPE_SLL = 113
+  LINKTYPE_SLL = 113,
+  LINKTYPE_SLL2 = 276
 } GstPcapParseLinktype;
 
 /**