From 1776de0140fb663777d4590fbb849c1d0a0c7885 Mon Sep 17 00:00:00 2001
From: Stefano Brivio <sbrivio@redhat.com>
Date: Tue, 25 Jan 2022 19:55:54 +0100
Subject: tcp, netlink, HAS{BYTES_ACKED,MIN_RTT,GETRANDOM} and
 NETLINK_GET_STRICT_CHK

tcpi_bytes_acked and tcpi_min_rtt are only available on recent
kernel versions: provide fall-back paths (incurring some grade of
performance penalty).

Support for getrandom() was introduced in Linux 3.17 and glibc 2.25:
provide an alternate mechanism for that as well, reading from
/dev/random.

Also check if NETLINK_GET_STRICT_CHK is defined before using it:
it's not strictly needed, we'll filter out irrelevant results from
netlink anyway.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 Makefile | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'Makefile')

diff --git a/Makefile b/Makefile
index 4647210..443c39d 100644
--- a/Makefile
+++ b/Makefile
@@ -45,6 +45,21 @@ ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
 	CFLAGS += -DHAS_SND_WND
 endif
 
+C := \#include <linux/tcp.h>\nstruct tcp_info x = { .tcpi_bytes_acked = 0 };
+ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
+	CFLAGS += -DHAS_BYTES_ACKED
+endif
+
+C := \#include <linux/tcp.h>\nstruct tcp_info x = { .tcpi_min_rtt = 0 };
+ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
+	CFLAGS += -DHAS_MIN_RTT
+endif
+
+C := \#include <sys/random.h>\nint main(){int a=getrandom(0, 0, 0);}
+ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
+	CFLAGS += -DHAS_GETRANDOM
+endif
+
 prefix ?= /usr/local
 
 all: passt pasta passt4netns qrap
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