feat(functions): add libnet_build_lldp_end function

1 files changed, 46 insertions, 0 deletions

diff --git a/src/libnet_build_lldp.c b/src/libnet_build_lldp.c
index b0ee5fa..c49fb8f 100644
--- a/src/libnet_build_lldp.c
+++ b/src/libnet_build_lldp.c
@@ -211,6 +211,52 @@ bad:
   return (-1);
 }
 
+
+LIBNET_API
+libnet_ptag_t libnet_build_lldp_end(libnet_t *l, libnet_ptag_t ptag)
+{
+  assert(LIBNET_LLDP_TLV_HDR_SIZE == 0x02 && "TLV header size must be a 2 bytes");
+  assert(LIBNET_LLDP_SUBTYPE_SIZE == 0x01 && "Subtype field size must be 1 byte");
+
+  uint32_t n, h;
+  libnet_pblock_t *p;
+  struct libnet_lldp_hdr hdr;
+  memset(&hdr, 0, sizeof(struct libnet_lldp_hdr));
+
+  if (l == NULL)
+  {
+    return (-1);
+  }
+
+  /* size of memory block */
+  n = h =  LIBNET_LLDP_TLV_HDR_SIZE; /* TLV Header size */
+
+  LIBNET_LLDP_TLV_SET_TYPE(hdr.tlv_info, LIBNET_LLDP_END_LLDPDU);
+  LIBNET_LLDP_TLV_SET_LEN(hdr.tlv_info, 0);
+
+  /*
+   *  Find the existing protocol block if a ptag is specified, or create
+   *  a new one.
+   */
+  p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_LLDP_TTL_H);
+  if (p == NULL)
+  {
+    return (-1);
+  }
+
+  const uint16_t type_and_len = htons(hdr.tlv_info);
+  if (libnet_pblock_append(l, p, &type_and_len, sizeof(type_and_len)) == -1)
+  {
+    goto bad;
+  }
+
+  return (ptag ? ptag
+               : libnet_pblock_update(l, p, h, LIBNET_PBLOCK_LLDP_TTL_H));
+bad:
+  libnet_pblock_delete(l, p);
+  return (-1);
+}
+
 /**
  * Local Variables:
  *  indent-tabs-mode: nil