[master] Fixed unsupported vlan tag build issue

Merges in rt38677

RELNOTES

@@ -52,6 +52,14 @@ ISC DHCP is open source software maintained by Internet Systems
 Consortium.  This product includes cryptographic software written
 by Eric Young (eay@cryptsoft.com).
 
+			Changes since 4.3.2c1
+
+- Corrected a compilation error introduced by the fix for ISC-Bugs #37415.
+  The error occurs on Linux variants that do not support VLAN tag information
+  in packet auxiliary data.  The configure script now only enables inclusion
+  of the VLAN tag-based logic if it is supported by the underlying OS.
+  [ISC-Bugs #38677]
+
 			Changes since 4.3.2b1
 
 - Specifying the option, --disable-debug, on the configure script command line

common/lpf.c

@@ -398,7 +398,8 @@ ssize_t receive_packet (interface, buf, len, from, hfrom)
 	 *  NICs perform VLAN encapsulation, while drivers for PCnet series
 	 *  do not, for example. The linux kernel makes stripped vlan info
 	 *  visible to user space via CMSG/auxdata, this appears to not be
-	 *  true for BSD OSs.)
+	 *  true for BSD OSs.).  NOTE: this is only supported on linux flavors
+	 *  which define the tpacket_auxdata.tp_vlan_tci.
 	 *
 	 *  b. Determine if checksum is valid for use. It may not be if
 	 *  checksum offloading is enabled on the interface.  */
@@ -409,8 +410,11 @@ ssize_t receive_packet (interface, buf, len, from, hfrom)
 		    cmsg->cmsg_type == PACKET_AUXDATA) {
 			struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
 			/* Discard packets with stripped vlan id */
+
+#ifdef VLAN_TCI_PRESENT
 			if (aux->tp_vlan_tci != 0)
 				return 0;
+#endif
 
 			csum_ready = ((aux->tp_status & TP_STATUS_CSUMNOTREADY)
 				      ? 0 : 1);

configure

@@ -6570,6 +6570,16 @@ fi
 fi
 
 
+ac_fn_c_check_member "$LINENO" "struct tpacket_auxdata" "tp_vlan_tci" "ac_cv_member_struct_tpacket_auxdata_tp_vlan_tci" "#include <linux/if_packet.h>
+"
+if test "x$ac_cv_member_struct_tpacket_auxdata_tp_vlan_tci" = xyes; then :
+
+$as_echo "#define VLAN_TCI_PRESENT 1" >>confdefs.h
+
+
+fi
+
+
 libbind=
 
 # Check whether --with-libbind was given.

configure.ac

@@ -576,6 +576,10 @@ AC_CHECK_MEMBER(struct msghdr.msg_control,,
 #include <sys/socket.h>
 	])
 
+AC_CHECK_MEMBER(struct tpacket_auxdata.tp_vlan_tci,
+    [AC_DEFINE([VLAN_TCI_PRESENT], [1], [tpacket_auxdata.tp_vlan_tci present])]
+    ,, [#include <linux/if_packet.h>])
+
 libbind=
 AC_ARG_WITH(libbind,
 	AS_HELP_STRING([--with-libbind=PATH],[bind includes and libraries are in PATH 

includes/config.h.in

@@ -185,6 +185,9 @@
 /* Version number of package */
 #undef VERSION
 
+/* tpacket_auxdata.tp_vlan_tci present */
+#undef VLAN_TCI_PRESENT
+
 /* Define WORDS_BIGENDIAN to 1 if your processor stores words with the most
    significant byte first (like Motorola and SPARC, unlike Intel). */
 #if defined AC_APPLE_UNIVERSAL_BUILD