On 2023-04-01, at 12:43:04 +0100, Jeremy Sowden wrote: > On 2023-03-31, at 22:36:01 +0000, Alyssa Ross wrote: > > If building statically, with libpcap built with libnl support, linking > > will fail, as the compiler won't be able to find the libnl symbols > > since static libraries don't contain dependency information. To fix > > this, use pkg-config to find the flags for linking libpcap, since the > > pkg-config files contain the neccesary dependency information. > ^^^^^^^^^ > "necessary" > > > Signed-off-by: Alyssa Ross <hi@xxxxxxxxx> > > LGTM. Actually, there is a problem. See below. > The only thing I would say is that pkg-config support was added > to libpcap comparatively recently (2018). When I made similar changes > to ulogd2 last year, I added a fall-back to pcap-config: > > https://git.netfilter.org/ulogd2/commit/?id=be4df8f66eb843dc19c7d1fed7c33fd7a40c2e21 > > > --- > > configure.ac | 3 ++- > > utils/Makefile.am | 6 +++--- > > 2 files changed, 5 insertions(+), 4 deletions(-) > > > > diff --git a/configure.ac b/configure.ac > > index bc2ed47b..e0bb26aa 100644 > > --- a/configure.ac > > +++ b/configure.ac > > @@ -114,7 +114,8 @@ AM_CONDITIONAL([ENABLE_NFTABLES], [test "$enable_nftables" = "yes"]) > > AM_CONDITIONAL([ENABLE_CONNLABEL], [test "$enable_connlabel" = "yes"]) > > > > if test "x$enable_bpfc" = "xyes" || test "x$enable_nfsynproxy" = "xyes"; then > > - AC_CHECK_LIB(pcap, pcap_compile,, AC_MSG_ERROR(missing libpcap library required by bpf compiler or nfsynproxy tool)) > > + PKG_CHECK_MODULES([libpcap], [libpcap], [], [ > > + AC_MSG_ERROR(missing libpcap library required by bpf compiler or nfsynproxy tool)]) > > fi When autoconf first encounters `PKG_CHECK_MODULES`, if `$PKG_CONFIG` is not already defined it will execute `PKG_PROG_PKG_CONFIG` to find it. However, because you are calling `PKG_CHECK_MODULES` in a conditional, if `$enable_bpfc` and `$enable_nfsynproxy` are not `yes`, the expansion of `PKG_PROG_PKG_CONFIG` will not be executed and so the following pkg-config checks will fail: checking for libnfnetlink >= 1.0... no checking for libmnl >= 1.0... no *** Error: No suitable libmnl found. *** Please install the 'libmnl' package Or consider --disable-nftables to skip iptables-compat over nftables support. Something like this will fix it: @@ -14,6 +14,7 @@ AC_PROG_CC AM_PROG_CC_C_O m4_ifdef([AM_PROG_AR], [AM_PROG_AR]) LT_INIT([disable-static]) +PKG_PROG_PKG_CONFIG AC_ARG_WITH([kernel], AS_HELP_STRING([--with-kernel=PATH], > > PKG_CHECK_MODULES([libnfnetlink], [libnfnetlink >= 1.0], > > diff --git a/utils/Makefile.am b/utils/Makefile.am > > index e9eec48f..34056514 100644 > > --- a/utils/Makefile.am > > +++ b/utils/Makefile.am > > @@ -2,7 +2,7 @@ > > > > AM_CFLAGS = ${regular_CFLAGS} > > AM_CPPFLAGS = ${regular_CPPFLAGS} -I${top_builddir}/include \ > > - -I${top_srcdir}/include ${libnfnetlink_CFLAGS} > > + -I${top_srcdir}/include ${libnfnetlink_CFLAGS} ${libpcap_CFLAGS} > > AM_LDFLAGS = ${regular_LDFLAGS} > > > > sbin_PROGRAMS = > > @@ -25,12 +25,12 @@ endif > > if ENABLE_BPFC > > man_MANS += nfbpf_compile.8 > > sbin_PROGRAMS += nfbpf_compile > > -nfbpf_compile_LDADD = -lpcap > > +nfbpf_compile_LDADD = ${libpcap_LIBS} > > endif > > > > if ENABLE_SYNCONF > > sbin_PROGRAMS += nfsynproxy > > -nfsynproxy_LDADD = -lpcap > > +nfsynproxy_LDADD = ${libpcap_LIBS} > > endif > > > > CLEANFILES = nfnl_osf.8 nfbpf_compile.8 > > > > base-commit: 09f0bfe2032454d21e3650e7ac75c4dc53f3c881 > > -- > > 2.37.1 > > > > J.
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