sctp: delete the obsolete code for the host name address param

In the latest RFC9260, the Host Name Address param has been deprecated.
For INIT chunk:

  Note 3: An INIT chunk MUST NOT contain the Host Name Address
  parameter.  The receiver of an INIT chunk containing a Host Name
  Address parameter MUST send an ABORT chunk and MAY include an
  "Unresolvable Address" error cause.

For Supported Address Types:

  The value indicating the Host Name Address parameter MUST NOT be
  used when sending this parameter and MUST be ignored when receiving
  this parameter.

Currently Linux SCTP doesn't really support Host Name Address param,
but only saves some flag and print debug info, which actually won't
even be triggered due to the verification in sctp_verify_param().
This patch is to delete those dead code.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/structs.h

@@ -1711,7 +1711,6 @@ struct sctp_association {
 		__u16	ecn_capable:1,      /* Can peer do ECN? */
 			ipv4_address:1,     /* Peer understands IPv4 addresses? */
 			ipv6_address:1,     /* Peer understands IPv6 addresses? */
-			hostname_address:1, /* Peer understands DNS addresses? */
 			asconf_capable:1,   /* Does peer support ADDIP? */
 			prsctp_capable:1,   /* Can peer do PR-SCTP? */
 			reconf_capable:1,   /* Can peer do RE-CONFIG? */

net/sctp/sm_make_chunk.c

@@ -2207,7 +2207,7 @@ static enum sctp_ierror sctp_verify_param(struct net *net,
 		break;
 
 	case SCTP_PARAM_HOST_NAME_ADDRESS:
-		/* Tell the peer, we won't support this param.  */
+		/* This param has been Deprecated, send ABORT.  */
 		sctp_process_hn_param(asoc, param, chunk, err_chunk);
 		retval = SCTP_IERROR_ABORT;
 		break;
@@ -2589,10 +2589,6 @@ static int sctp_process_param(struct sctp_association *asoc,
 		asoc->cookie_life = ktime_add_ms(asoc->cookie_life, stale);
 		break;
 
-	case SCTP_PARAM_HOST_NAME_ADDRESS:
-		pr_debug("%s: unimplemented SCTP_HOST_NAME_ADDRESS\n", __func__);
-		break;
-
 	case SCTP_PARAM_SUPPORTED_ADDRESS_TYPES:
 		/* Turn off the default values first so we'll know which
 		 * ones are really set by the peer.
@@ -2624,10 +2620,6 @@ static int sctp_process_param(struct sctp_association *asoc,
 					asoc->peer.ipv6_address = 1;
 				break;
 
-			case SCTP_PARAM_HOST_NAME_ADDRESS:
-				asoc->peer.hostname_address = 1;
-				break;
-
 			default: /* Just ignore anything else.  */
 				break;
 			}

net/sctp/socket.c

@@ -5195,7 +5195,7 @@ int sctp_get_sctp_info(struct sock *sk, struct sctp_association *asoc,
 	mask = asoc->peer.ecn_capable << 1;
 	mask = (mask | asoc->peer.ipv4_address) << 1;
 	mask = (mask | asoc->peer.ipv6_address) << 1;
-	mask = (mask | asoc->peer.hostname_address) << 1;
+	mask = mask << 1;
 	mask = (mask | asoc->peer.asconf_capable) << 1;
 	mask = (mask | asoc->peer.prsctp_capable) << 1;
 	mask = (mask | asoc->peer.auth_capable);