--- /dev/null
+From b3c61360a93b7f08fc9c33526056211408301ea9 Mon Sep 17 00:00:00 2001
+From: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+Date: Mon, 23 Nov 2020 21:16:38 +0100
+Subject: [PATCH] configure.ac: use pkg-config to find netfilter_conntrack
+
+Use pkg-config to retrieve the dependencies of netfilter_conntrack
+and avoid the following build failure when building statically:
+
+configure:13096: /data/buildroot-test/instance-1/output-1/host/bin/x86_64-linux-gcc -o conftest -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -static -I/data/buildroot-test/instance-1/output-1/host/x86_64-buildroot-linux-uclibc/sysroot/usr/include -DPCRE_STATIC -pthread -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -static -L/data/buildroot-test/instance-1/output-1/host/x86_64-buildroot-linux-uclibc/sysroot/usr/lib conftest.c -lnetfilter_conntrack -lnfnetlink -lev -lcares -lsodium -lmbedcrypto -lpcre >&5
+/data/buildroot-test/instance-1/output-1/host/opt/ext-toolchain/bin/../lib/gcc/x86_64-buildroot-linux-uclibc/8.3.0/../../../../x86_64-buildroot-linux-uclibc/bin/ld: /data/buildroot-test/instance-1/output-1/host/x86_64-buildroot-linux-uclibc/sysroot/usr/lib/libnetfilter_conntrack.a(api.o): in function `nfct_fill_hdr.constprop.4':
+api.c:(.text+0x3f): undefined reference to `mnl_nlmsg_put_header'
+
+Fixes:
+ - http://autobuild.buildroot.org/results/6cad497a7ab941a0ee3fd7007defc81e30cdcbe0
+
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+[Upstream status:
+https://github.com/shadowsocks/shadowsocks-libev/pull/2773]
+---
+ configure.ac | 5 +++--
+ src/Makefile.am | 2 +-
+ 2 files changed, 4 insertions(+), 3 deletions(-)
+
+diff --git a/configure.ac b/configure.ac
+index 9787bc2..207c041 100755
+--- a/configure.ac
++++ b/configure.ac
+@@ -252,7 +252,8 @@ AC_ARG_ENABLE(connmarktos,
+ if test x"$enable_connmarktos" = "xyes" ; then
+ AC_MSG_NOTICE([Linux Netfilter Conntrack support requested by --enable-connmarktos: ${enable_connmarktos}])
+ if test "x$enable_connmarktos" != "xno"; then
+- AC_SEARCH_LIBS([nfct_query], [netfilter_conntrack],,[
++ PKG_CHECK_MODULES([NETFILTER_CONNTRACK], [libnetfilter_conntrack],,
++ [AC_SEARCH_LIBS([nfct_query], [netfilter_conntrack],,[
+ if test x"$enable_connmarktos" = "xyes"; then
+ AC_MSG_ERROR([--enable-connmarktos specified but libnetfilter-conntrack library not found])
+ fi
+@@ -262,7 +263,7 @@ if test x"$enable_connmarktos" = "xyes" ; then
+ if test x"$enable_connmarktos" = "xyes"; then
+ AC_MSG_ERROR([--enable-connmarktos specified but libnetfilter-conntrack headers not found])
+ fi
+- with_netfilter_conntrack=no])
++ with_netfilter_conntrack=no])])
+ # If nothing is broken; enable the libraries usage.
+ if test "x$with_netfilter_conntrack" != "xno"; then
+ with_netfilter_conntrack=yes
+diff --git a/src/Makefile.am b/src/Makefile.am
+index c261ed0..b81ced7 100644
+--- a/src/Makefile.am
++++ b/src/Makefile.am
+@@ -9,7 +9,7 @@ AM_CFLAGS += -I$(top_srcdir)/libcork/include
+ endif
+ AM_CFLAGS += $(LIBPCRE_CFLAGS)
+
+-SS_COMMON_LIBS = $(INET_NTOP_LIB) $(LIBPCRE_LIBS)
++SS_COMMON_LIBS = $(INET_NTOP_LIB) $(LIBPCRE_LIBS) $(NETFILTER_CONNTRACK_LIBS)
+ if !USE_SYSTEM_SHARED_LIB
+ SS_COMMON_LIBS += $(top_builddir)/libbloom/libbloom.la \
+ $(top_builddir)/libipset/libipset.la \
+--
+2.29.2
+