From a0bcbdcb04d52c3ca71045f90aac33d9dd7965bf Mon Sep 17 00:00:00 2001
From: Lukas Tribus <luky-37@hotmail.com>
Date: Mon, 12 Sep 2016 21:42:20 +0000
Subject: [PATCH] MEDIUM: make SO_REUSEPORT configurable

With Linux officially introducing SO_REUSEPORT support in 3.9 and
its mainstream adoption we have seen more people running into strange
SO_REUSEPORT related issues (a process management issue turning into
hard to diagnose problems because the kernel load-balances between the
new and an obsolete haproxy instance).

Also some people simply want the guarantee that the bind fails when
the old process is still bound.

This change makes SO_REUSEPORT configurable, introducing the command
line argument "-dR" and the noreuseport configuration directive.

A backport to 1.6 should be considered.
---
 doc/configuration.txt  |  5 +++++
 include/types/global.h |  1 +
 src/cfgparse.c         |  5 +++++
 src/haproxy.c          | 10 ++++++++++
 src/proto_tcp.c        |  6 +++---
 5 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/doc/configuration.txt b/doc/configuration.txt
index 1a7114e4b..52e6cf44b 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -578,6 +578,7 @@ The following keywords are supported in the "global" section :
    - nopoll
    - nosplice
    - nogetaddrinfo
+   - noreuseport
    - spread-checks
    - server-state-base
    - server-state-file
@@ -1130,6 +1131,10 @@ nogetaddrinfo
   Disables the use of getaddrinfo(3) for name resolving. It is equivalent to
   the command line argument "-dG". Deprecated gethostbyname(3) will be used.
 
+noreuseport
+  Disables the use of SO_REUSEPORT - see socket(7). It is equivalent to the
+  command line argument "-dR".
+
 spread-checks <0..50, in percent>
   Sometimes it is desirable to avoid sending agent and health checks to
   servers at exact intervals, for instance when many logical servers are
diff --git a/include/types/global.h b/include/types/global.h
index 71eacf296..2a9bf5636 100644
--- a/include/types/global.h
+++ b/include/types/global.h
@@ -63,6 +63,7 @@
 /* platform-specific options */
 #define GTUNE_USE_SPLICE         (1<<4)
 #define GTUNE_USE_GAI            (1<<5)
+#define GTUNE_USE_REUSEPORT      (1<<6)
 
 /* Access level for a stats socket */
 #define ACCESS_LVL_NONE     0
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 09077d8ce..7b58ef6bb 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -664,6 +664,11 @@ int cfg_parse_global(const char *file, int linenum, char **args, int kwm)
 			goto out;
 		global.tune.options &= ~GTUNE_USE_GAI;
 	}
+	else if (!strcmp(args[0], "noreuseport")) {
+		if (alertif_too_many_args(0, file, linenum, args, &err_code))
+			goto out;
+		global.tune.options &= ~GTUNE_USE_REUSEPORT;
+	}
 	else if (!strcmp(args[0], "quiet")) {
 		if (alertif_too_many_args(0, file, linenum, args, &err_code))
 			goto out;
diff --git a/src/haproxy.c b/src/haproxy.c
index 96ecd0db6..b1c10b66d 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -458,6 +458,9 @@ void usage(char *name)
 #endif
 #if defined(USE_GETADDRINFO)
 		"        -dG disables getaddrinfo() usage\n"
+#endif
+#if defined(SO_REUSEPORT)
+		"        -dR disables SO_REUSEPORT usage\n"
 #endif
 		"        -dV disables SSL verify on servers side\n"
 		"        -sf/-st [pid ]* finishes/terminates old pids.\n"
@@ -726,6 +729,9 @@ void init(int argc, char **argv)
 #if defined(USE_GETADDRINFO)
 	global.tune.options |= GTUNE_USE_GAI;
 #endif
+#if defined(SO_REUSEPORT)
+	global.tune.options |= GTUNE_USE_REUSEPORT;
+#endif
 
 	pid = getpid();
 	progname = *argv;
@@ -768,6 +774,10 @@ void init(int argc, char **argv)
 #if defined(USE_GETADDRINFO)
 			else if (*flag == 'd' && flag[1] == 'G')
 				global.tune.options &= ~GTUNE_USE_GAI;
+#endif
+#if defined(SO_REUSEPORT)
+			else if (*flag == 'd' && flag[1] == 'R')
+				global.tune.options &= ~GTUNE_USE_REUSEPORT;
 #endif
 			else if (*flag == 'd' && flag[1] == 'V')
 				global.ssl_server_verify = SSL_SERVER_VERIFY_NONE;
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index b614e6b59..91d66881a 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -823,10 +823,10 @@ int tcp_bind_listener(struct listener *listener, char *errmsg, int errlen)
 		setsockopt(fd, SOL_SOCKET, SO_LINGER, &nolinger, sizeof(struct linger));
 
 #ifdef SO_REUSEPORT
-	/* OpenBSD supports this. As it's present in old libc versions of Linux,
-	 * it might return an error that we will silently ignore.
+	/* OpenBSD and Linux 3.9 support this. As it's present in old libc versions of
+	 * Linux, it might return an error that we will silently ignore.
 	 */
-	if (!ext)
+	if (!ext && (global.tune.options & GTUNE_USE_REUSEPORT))
 		setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
 #endif