Provide local definition of IPPROTO_GRE to allow iptunnel

to build under glibc 2.0.
Make it configurable whether iptunnel & ipmaddr are built,
with the default being off.  This seems to be necessary since
making them work with 2.0 looks hard.  Does it sound
reasonable?

1 files changed, 5 insertions, 0 deletions

diff --git a/iptunnel.c b/iptunnel.c
index 254e873..aa90882 100644
--- a/iptunnel.c
+++ b/iptunnel.c
@@ -47,6 +47,11 @@
 #undef GRE_VERSION
 #define GRE_VERSION	htons(0x0007)
 
+/* Old versions of glibc do not define this */
+#if __GLIBC__ == 2 && __GLIBC_MINOR__ == 0
+#define IPPROTO_GRE	47
+#endif
+
 #include "utils.h"
 
 static void usage(void) __attribute__((noreturn));