From a619e7a88c6b6be4d3862a936f27cecffacf9f2b Mon Sep 17 00:00:00 2001
From: Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com>
Date: Sun, 22 Aug 2021 19:49:55 +0900
Subject: [PATCH] Define UDP_SEGMENT if linux/udp.h has it

---
 configure.ac | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/configure.ac b/configure.ac
index 37256518..cc328e15 100644
--- a/configure.ac
+++ b/configure.ac
@@ -910,6 +910,31 @@ AC_CHECK_DECLS([initgroups], [], [], [[
   #include <grp.h>
 ]])
 
+have_netinet_udp_h_udp_segment=no
+AC_CHECK_DECL([UDP_SEGMENT], [have_netinet_udp_h_udp_segment=yes],
+              [have_netinet_udp_h_udp_segment=no], [[
+  #include <netinet/udp.h>
+]])
+
+if test "x$have_netinet_udp_h_udp_segment" = "xno"; then
+  have_linux_udp_h_udp_segment=no
+  AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+                     [[
+                       #include <linux/udp.h>
+                     ]],
+                     [[
+		       #if UDP_SEGMENT != 103
+		       exit(1)
+		       #endif
+                     ]])],
+		    [have_linux_udp_h_udp_segment=yes],
+		    [have_linux_udp_h_udp_segment=no])
+
+  if test "x$have_linux_udp_h_udp_segment" = "xyes"; then
+    EXTRA_DEFS="$EXTRA_DEFS -DUDP_SEGMENT=103"
+  fi
+fi
+
 save_CFLAGS=$CFLAGS
 save_CXXFLAGS=$CXXFLAGS
 
@@ -1077,6 +1102,8 @@ AC_MSG_NOTICE([summary of build options:
       CXX1XCXXFLAGS:  ${CXX1XCXXFLAGS}
       EXTRACFLAG:     ${EXTRACFLAG}
       LIBS:           ${LIBS}
+      DEFS:           ${DEFS}
+      EXTRA_DEFS:     ${EXTRA_DEFS}
     Library:
       Shared:         ${enable_shared}
       Static:         ${enable_static}