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, 12 insertions, 4 deletions

diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index 76cf1cd62e29..0e85238bdf48 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -1007,16 +1007,24 @@ int iscsit_accept_np(struct iscsi_np *np, struct iscsi_conn *conn)
 		rc = conn->sock->ops->getname(conn->sock,
 				(struct sockaddr *)&sock_in6, &err, 1);
 		if (!rc) {
-			snprintf(conn->login_ip, sizeof(conn->login_ip), "%pI6c",
-				&sock_in6.sin6_addr.in6_u);
+			if (!ipv6_addr_v4mapped(&sock_in6.sin6_addr))
+				snprintf(conn->login_ip, sizeof(conn->login_ip), "[%pI6c]",
+					&sock_in6.sin6_addr.in6_u);
+			else
+				snprintf(conn->login_ip, sizeof(conn->login_ip), "%pI4",
+					&sock_in6.sin6_addr.s6_addr32[3]);
 			conn->login_port = ntohs(sock_in6.sin6_port);
 		}
 
 		rc = conn->sock->ops->getname(conn->sock,
 				(struct sockaddr *)&sock_in6, &err, 0);
 		if (!rc) {
-			snprintf(conn->local_ip, sizeof(conn->local_ip), "%pI6c",
-				&sock_in6.sin6_addr.in6_u);
+			if (!ipv6_addr_v4mapped(&sock_in6.sin6_addr))
+				snprintf(conn->local_ip, sizeof(conn->local_ip), "[%pI6c]",
+					&sock_in6.sin6_addr.in6_u);
+			else
+				snprintf(conn->local_ip, sizeof(conn->local_ip), "%pI4",
+					&sock_in6.sin6_addr.s6_addr32[3]);
 			conn->local_port = ntohs(sock_in6.sin6_port);
 		}
 	} else {