Require config.h to be from the tcpdump build.

This way the build will reliably fail if it happened to include the
header from some other build (e.g. libpcap).  See GitHub bug report
#1313.

Author: infrastation

CHANGES

@@ -80,6 +80,7 @@ DayOfTheWeek, Month DD, YYYY / The Tcpdump Group
       autogen.sh: Allow to configure Autoconf warnings.
       autogen.sh: Delete all trailing blank lines at end of configure.
       Reimplement the tests similarly to libpcap.
+      Require config.h to be from the tcpdump build.
     Documentation:
       man: Clarify the "any" pseudo-interface further.
 

cmakeconfig.h.in

@@ -1,5 +1,8 @@
 /* cmakeconfig.h.in */
 
+#ifndef TCPDUMP_CONFIG_H_
+#define TCPDUMP_CONFIG_H_
+
 /* Define to 1 if arpa/inet.h declares `ether_ntohost' */
 #cmakedefine ARPA_INET_H_DECLARES_ETHER_NTOHOST 1
 
@@ -185,3 +188,5 @@
 
 /* Define to `uint8_t' if u_int8_t not defined. */
 #cmakedefine u_int8_t 1
+
+#endif // TCPDUMP_CONFIG_H_

configure.ac

@@ -1121,6 +1121,13 @@ AC_SUBST(MAN_MISC_INFO)
 AC_PROG_INSTALL
 
 AC_CONFIG_HEADERS([config.h])
+AH_TOP([
+#ifndef TCPDUMP_CONFIG_H_
+#define TCPDUMP_CONFIG_H_
+])
+AH_BOTTOM([
+#endif // TCPDUMP_CONFIG_H_
+])
 
 AC_CONFIG_COMMANDS([.devel],[[if test -f .devel; then
 	echo timestamp > stamp-h

tcpdump.c

@@ -34,6 +34,9 @@
  */
 
 #include <config.h>
+#ifndef TCPDUMP_CONFIG_H_
+#error "The included config.h header is not from the tcpdump build."
+#endif
 
 #include "netdissect-stdinc.h"