From 268044ea400658de92cd0272f6928c35d8d6d916 Mon Sep 17 00:00:00 2001
From: Simon Arlott <sa.me.uk>
Date: Thu, 24 Aug 2017 00:21:02 +0100
Subject: [PATCH] Add workaround for Linux SCTP_I_WANT_MAPPED_V4_ADDR bug on
 older kernels

---
 librb/src/commio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/librb/src/commio.c b/librb/src/commio.c
index a994d5bc..3fda4bca 100644
--- a/librb/src/commio.c
+++ b/librb/src/commio.c
@@ -361,6 +361,9 @@ rb_setsockopt_sctp(rb_fde_t *F)
 {
 	int opt_zero = 0;
 	int opt_one = 1;
+	/* workaround for https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/sctp?id=299ee123e19889d511092347f5fc14db0f10e3a6 */
+	char *env_mapped = getenv("SCTP_I_WANT_MAPPED_V4_ADDR");
+	int opt_mapped = env_mapped != NULL ? atoi(env_mapped) : opt_zero;
 	int ret;
 	struct sctp_initmsg initmsg;
 	struct sctp_rtoinfo rtoinfo;
@@ -374,7 +377,7 @@ rb_setsockopt_sctp(rb_fde_t *F)
 		return ret;
 	}
 
-	ret = setsockopt(F->fd, SOL_SCTP, SCTP_I_WANT_MAPPED_V4_ADDR, &opt_zero, sizeof(opt_zero));
+	ret = setsockopt(F->fd, SOL_SCTP, SCTP_I_WANT_MAPPED_V4_ADDR, &opt_mapped, sizeof(opt_mapped));
 	if (ret) {
 		rb_lib_log("rb_setsockopt_sctp: Cannot unset SCTP_I_WANT_MAPPED_V4_ADDR for fd %d: %s",
 				F->fd, strerror(rb_get_sockerr(F)));