[PATCH] ppp-manager: Enable IPV6CP

[Tore Anderson <tore fud no>]

This patch lets pppd negotiate IPv6 parameters using IPV6CP. It allows
dual-stack mobile broadband to work correctly.

Due to the fact that ModemManager hard-codes use of IPv4-only PDP type,
the PDP context must manually be defined first using for example
AT+CGDCONT=1,"IPV4V6","apn". (ModemManager does not overwrite an
already-defined PDP context with the correct APN.)

IPV6CP is not considered essential, so when connecting using an IPv4-
only PDP context, pppd gives up after a retransmitting a few IPV6CP
ConfReqs. The retransmissions happen asynchronously, pppd nor NM waits
for them to finish before activating the IPv4 part of the connections.

The patch also makes pppd support IPv6-only connections (because IPCP
isn't considered essential by pppd either), however NM will currently
fail the entire connection if IPCP/IPv4 doesn't succeed.
---
 src/ppp-manager/nm-ppp-manager.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/src/ppp-manager/nm-ppp-manager.c b/src/ppp-manager/nm-ppp-manager.c
index 243d2e1..c1acea1 100644
--- a/src/ppp-manager/nm-ppp-manager.c
+++ b/src/ppp-manager/nm-ppp-manager.c
@@ -821,6 +821,10 @@ create_pppd_cmd_line (NMPPPManager *self,
 	/* NM handles setting the default route */
 	nm_cmd_line_add_string (cmd, "nodefaultroute");
 
+	/* Allow IPv6 to be configured by IPV6CP */
+	nm_cmd_line_add_string (cmd, "ipv6");
+	nm_cmd_line_add_string (cmd, ",");
+
 	ppp_debug = !!getenv ("NM_PPP_DEBUG");
 	if (   nm_logging_level_enabled (LOGL_DEBUG)
 	    && nm_logging_domain_enabled (LOGD_PPP))
-- 
1.7.7.6