iscsi-target: ST response on IN6ADDR_ANY socket

Odd little issue, found that if you create an IPv6 portal bound to the
IN6ADDR_ANY wildcard address it will accept IPv4 connections (as long as
bindv6only isn't set globally) but respond to SendTargets requests with
an IPv4-mapped IPv6 address.

Example over loopback:

 In targetcli create a wildcard IPv6 portal
   /iscsi/iqn.../portals/> create ::
 Which should create a portal [::]:3260

 Initiate SendTargets discovery to the portal using an IPv4 address
   # iscsiadm -m discovery -t st -p 127.0.0.1
 The response formats TargetAddress as [::ffff:127.0.0.1]:3260,1

This still works and uses v4 on the network between two v6 sockets, but
only if the initiator supports IPv6 with v4-mapped addresses.

This change detects v4-mapped address on v6 sockets for the wildcard
case, and instead formats the TargetAddress response as an IPv4 address.

In order to not further complicate iscsit_build_sendtargets_response,
I've actually simplified it by moving the bracket wrapping of IPv6
address into iscsit_accept_np where local_ip and login_ip strings are
set.  That also simplifies iscsi_stat_tgt_attr_show_attr_fail_intr_addr.

Side effect of the string format change is that
lio_target_nacl_show_info will now print login_ip bracket wrapped for
IPv6 connections, as will a few debug prints.

Signed-off-by: Chris Leech <cleech@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 3 insertions, 5 deletions

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index f73da43cdf9..c4aeac314b2 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -3444,12 +3444,10 @@ static int iscsit_build_sendtargets_response(struct iscsi_cmd *cmd)
 				bool inaddr_any = iscsit_check_inaddr_any(np);
 
 				len = sprintf(buf, "TargetAddress="
-					"%s%s%s:%hu,%hu",
-					(np->np_sockaddr.ss_family == AF_INET6) ?
-					"[" : "", (inaddr_any == false) ?
+					"%s:%hu,%hu",
+					(inaddr_any == false) ?
 						np->np_ip : conn->local_ip,
-					(np->np_sockaddr.ss_family == AF_INET6) ?
-					"]" : "", (inaddr_any == false) ?
+					(inaddr_any == false) ?
 						np->np_port : conn->local_port,
 					tpg->tpgt);
 				len += 1;