From b7e63b5408aba603d12c9e2c3ae5f32b2620bcc7 Mon Sep 17 00:00:00 2001
From: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Date: Thu, 4 Sep 2008 07:30:19 +0200
Subject: [PATCH] --- yaml --- r: 111463 b: refs/heads/master c:
 20f41eee82864e308a5499308a1722dc3181cc3a h: refs/heads/master i:   111461:
 a7197dce6b02981b2f4bb73ed9f25b6c4ca12200   111459:
 fb5773c7a96965accf19d7dc79d8cbe46d04dc7e   111455:
 1b4c33f075cac75e45c02ce33c10b6562fb8f46a v: v3

---
 [refs]                     |  2 +-
 trunk/include/linux/dccp.h |  4 +--
 trunk/net/dccp/proto.c     | 53 ++++++++++++++++++++++++++++----------
 3 files changed, 43 insertions(+), 16 deletions(-)

diff --git a/[refs] b/[refs]
index 5862a020934c..5199cad884fb 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 668144f7b41716a9efe1b398e15ead32a26cd101
+refs/heads/master: 20f41eee82864e308a5499308a1722dc3181cc3a
diff --git a/trunk/include/linux/dccp.h b/trunk/include/linux/dccp.h
index 6eaaca9b037a..5a5a89935dbc 100644
--- a/trunk/include/linux/dccp.h
+++ b/trunk/include/linux/dccp.h
@@ -527,8 +527,8 @@ struct dccp_sock {
 	__u32				dccps_timestamp_time;
 	__u16				dccps_l_ack_ratio;
 	__u16				dccps_r_ack_ratio;
-	__u16				dccps_pcslen;
-	__u16				dccps_pcrlen;
+	__u8				dccps_pcslen:4;
+	__u8				dccps_pcrlen:4;
 	__u64				dccps_ndp_count:48;
 	unsigned long			dccps_rate_last;
 	struct dccp_minisock		dccps_minisock;
diff --git a/trunk/net/dccp/proto.c b/trunk/net/dccp/proto.c
index 108d56bd25c5..47b137a3feaf 100644
--- a/trunk/net/dccp/proto.c
+++ b/trunk/net/dccp/proto.c
@@ -470,6 +470,42 @@ static int dccp_setsockopt_service(struct sock *sk, const __be32 service,
 	return 0;
 }
 
+static int dccp_setsockopt_cscov(struct sock *sk, int cscov, bool rx)
+{
+	u8 *list, len;
+	int i, rc;
+
+	if (cscov < 0 || cscov > 15)
+		return -EINVAL;
+	/*
+	 * Populate a list of permissible values, in the range cscov...15. This
+	 * is necessary since feature negotiation of single values only works if
+	 * both sides incidentally choose the same value. Since the list starts
+	 * lowest-value first, negotiation will pick the smallest shared value.
+	 */
+	if (cscov == 0)
+		return 0;
+	len = 16 - cscov;
+
+	list = kmalloc(len, GFP_KERNEL);
+	if (list == NULL)
+		return -ENOBUFS;
+
+	for (i = 0; i < len; i++)
+		list[i] = cscov++;
+
+	rc = dccp_feat_register_sp(sk, DCCPF_MIN_CSUM_COVER, rx, list, len);
+
+	if (rc == 0) {
+		if (rx)
+			dccp_sk(sk)->dccps_pcrlen = cscov;
+		else
+			dccp_sk(sk)->dccps_pcslen = cscov;
+	}
+	kfree(list);
+	return rc;
+}
+
 static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
 		char __user *optval, int optlen)
 {
@@ -502,20 +538,11 @@ static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
 		else
 			dp->dccps_server_timewait = (val != 0);
 		break;
-	case DCCP_SOCKOPT_SEND_CSCOV:	/* sender side, RFC 4340, sec. 9.2 */
-		if (val < 0 || val > 15)
-			err = -EINVAL;
-		else
-			dp->dccps_pcslen = val;
+	case DCCP_SOCKOPT_SEND_CSCOV:
+		err = dccp_setsockopt_cscov(sk, val, false);
 		break;
-	case DCCP_SOCKOPT_RECV_CSCOV:	/* receiver side, RFC 4340 sec. 9.2.1 */
-		if (val < 0 || val > 15)
-			err = -EINVAL;
-		else {
-			dp->dccps_pcrlen = val;
-			/* FIXME: add feature negotiation,
-			 * ChangeL(MinimumChecksumCoverage, val) */
-		}
+	case DCCP_SOCKOPT_RECV_CSCOV:
+		err = dccp_setsockopt_cscov(sk, val, true);
 		break;
 	default:
 		err = -ENOPROTOOPT;