system-linux: enable by default ignore encaplimit for grev6 tunnels

Similar as for ip6 tunnels ignore encaplimit by default as not all ISPs
support the destination option header containing the tunnel encapsulation
limit resulting into broken connectivity

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

3 files changed, 27 insertions, 5 deletions

diff --git a/system-linux.c b/system-linux.c
index 8cfad3c..60f55ee 100644
--- a/system-linux.c
+++ b/system-linux.c
@@ -2456,10 +2456,11 @@ static int system_add_gre_tunnel(const char *name, const char *kind,
 	struct nl_msg *nlm;
 	struct ifinfomsg ifi = { .ifi_family = AF_UNSPEC, };
 	struct blob_attr *cur;
-	uint32_t ikey = 0, okey = 0, flags = 0, flowinfo = 0;
+	uint32_t ikey = 0, okey = 0, flowinfo = 0, flags6 = IP6_TNL_F_IGN_ENCAP_LIMIT;
 	uint16_t iflags = 0, oflags = 0;
 	uint8_t tos = 0;
 	int ret = 0, ttl = 0;
+	unsigned encap_limit = 0;
 
 	nlm = nlmsg_alloc_simple(RTM_NEWLINK, NLM_F_REQUEST | NLM_F_REPLACE | NLM_F_CREATE);
 	if (!nlm)
@@ -2503,7 +2504,7 @@ static int system_add_gre_tunnel(const char *name, const char *kind,
 				tos = uval;
 		} else {
 			if (v6)
-				flags |= IP6_TNL_F_USE_ORIG_TCLASS;
+				flags6 |= IP6_TNL_F_USE_ORIG_TCLASS;
 			else
 				tos = 1;
 		}
@@ -2544,6 +2545,23 @@ static int system_add_gre_tunnel(const char *name, const char *kind,
 			if (blobmsg_get_bool(cur))
 				oflags |= GRE_SEQ;
 		}
+
+		if ((cur = tb_data[GRE_DATA_ENCAPLIMIT])) {
+			char *str = blobmsg_get_string(cur);
+
+			if (strcmp(str, "ignore")) {
+				char *e;
+
+				encap_limit = strtoul(str, &e, 0);
+
+				if (e == str || *e || encap_limit > 255) {
+					ret = -EINVAL;
+					goto failure;
+				}
+
+				flags6 &= ~IP6_TNL_F_IGN_ENCAP_LIMIT;
+			}
+		}
 	}
 
 	if (v6) {
@@ -2563,13 +2581,15 @@ static int system_add_gre_tunnel(const char *name, const char *kind,
 			}
 			nla_put(nlm, IFLA_GRE_REMOTE, sizeof(in6buf), &in6buf);
 		}
-		nla_put_u8(nlm, IFLA_GRE_ENCAP_LIMIT, 4);
+
+		if (!(flags6 & IP6_TNL_F_IGN_ENCAP_LIMIT))
+			nla_put_u8(nlm, IFLA_GRE_ENCAP_LIMIT, encap_limit);
 
 		if (flowinfo)
 			nla_put_u32(nlm, IFLA_GRE_FLOWINFO, flowinfo);
 
-		if (flags)
-			nla_put_u32(nlm, IFLA_GRE_FLAGS, flags);
+		if (flags6)
+			nla_put_u32(nlm, IFLA_GRE_FLAGS, flags6);
 
 		if (!ttl)
 			ttl = 64;
diff --git a/system.c b/system.c
index f96708d..dd9ab50 100644
--- a/system.c
+++ b/system.c
@@ -52,6 +52,7 @@ static const struct blobmsg_policy gre_data_attrs[__GRE_DATA_ATTR_MAX] = {
 	[GRE_DATA_OCSUM] = { .name = "ocsum", .type = BLOBMSG_TYPE_BOOL },
 	[GRE_DATA_ISEQNO] = { .name = "iseqno", .type = BLOBMSG_TYPE_BOOL },
 	[GRE_DATA_OSEQNO] = { .name = "oseqno", .type = BLOBMSG_TYPE_BOOL },
+	[GRE_DATA_ENCAPLIMIT] = { .name = "encaplimit", .type = BLOBMSG_TYPE_STRING },
 };
 
 const struct uci_blob_param_list gre_data_attr_list = {
diff --git a/system.h b/system.h
index 683dc18..4d4cf6e 100644
--- a/system.h
+++ b/system.h
@@ -53,6 +53,7 @@ enum gre_data {
 	GRE_DATA_OCSUM,
 	GRE_DATA_ISEQNO,
 	GRE_DATA_OSEQNO,
+	GRE_DATA_ENCAPLIMIT,
 	__GRE_DATA_ATTR_MAX
 };