[DCCP]: Introduce DCCP_SOCKOPT_PACKET_SIZE

So that applications can set dccp_sock->dccps_pkt_size, that in turn
is used in the CCID3 half connection init routines to set
ccid3hc[tr]x_s and use it in its rate calculations.

Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/dccp.h

···
 	DCCPF_MAX_CCID_SPECIFIC = 255,
 };
 
+/* DCCP socket options */
+#define DCCP_SOCKOPT_PACKET_SIZE	1
+
 #ifdef __KERNEL__
 
 #include <linux/in.h>
···
  * @dccps_timestamp_echo - latest timestamp received on a TIMESTAMP option
  * @dccps_ext_header_len - network protocol overhead (IP/IPv6 options)
  * @dccps_pmtu_cookie - Last pmtu seen by socket
- * @dccps_avg_packet_size - FIXME: has to be set by the app thru some setsockopt or ioctl, CCID3 uses it
+ * @dccps_packet_size - Set thru setsockopt
  * @dccps_role - Role of this sock, one of %dccp_role
  * @dccps_ndp_count - number of Non Data Packets since last data packet
  * @dccps_hc_rx_ackpkts - receiver half connection acked packets
···
 	unsigned long			dccps_service;
 	struct timeval			dccps_timestamp_time;
 	__u32				dccps_timestamp_echo;
-	__u32				dccps_avg_packet_size;
+	__u32				dccps_packet_size;
 	unsigned long			dccps_ndp_count;
 	__u16				dccps_ext_header_len;
 	__u32				dccps_pmtu_cookie;

net/dccp/ccids/ccid3.c

···
 
 	memset(hctx, 0, sizeof(*hctx));
 
-	if (dp->dccps_avg_packet_size >= TFRC_MIN_PACKET_SIZE &&
-	    dp->dccps_avg_packet_size <= TFRC_MAX_PACKET_SIZE)
-		hctx->ccid3hctx_s = (u16)dp->dccps_avg_packet_size;
+	if (dp->dccps_packet_size >= TFRC_MIN_PACKET_SIZE &&
+	    dp->dccps_packet_size <= TFRC_MAX_PACKET_SIZE)
+		hctx->ccid3hctx_s = dp->dccps_packet_size;
 	else
 		hctx->ccid3hctx_s = TFRC_STD_PACKET_SIZE;
 
···
 
 	memset(hcrx, 0, sizeof(*hcrx));
 
-	if (dp->dccps_avg_packet_size >= TFRC_MIN_PACKET_SIZE &&
-	    dp->dccps_avg_packet_size <= TFRC_MAX_PACKET_SIZE)
-		hcrx->ccid3hcrx_s = (u16)dp->dccps_avg_packet_size;
+	if (dp->dccps_packet_size >= TFRC_MIN_PACKET_SIZE &&
+	    dp->dccps_packet_size <= TFRC_MAX_PACKET_SIZE)
+		hcrx->ccid3hcrx_s = dp->dccps_packet_size;
 	else
 		hcrx->ccid3hcrx_s = TFRC_STD_PACKET_SIZE;
 

net/dccp/proto.c

···
 int dccp_setsockopt(struct sock *sk, int level, int optname,
 		    char __user *optval, int optlen)
 {
-	dccp_pr_debug("entry\n");
+	struct dccp_sock *dp;
+	int err;
+	int val;
 
 	if (level != SOL_DCCP)
 		return ip_setsockopt(sk, level, optname, optval, optlen);
 
-	return -EOPNOTSUPP;
+	if (optlen < sizeof(int))
+		return -EINVAL;
+
+	if (get_user(val, (int __user *)optval))
+		return -EFAULT;
+
+	lock_sock(sk);
+
+	dp = dccp_sk(sk);
+	err = 0;
+
+	switch (optname) {
+	case DCCP_SOCKOPT_PACKET_SIZE:
+		dp->dccps_packet_size = val;
+		break;
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+	
+	release_sock(sk);
+	return err;
 }
 
 int dccp_getsockopt(struct sock *sk, int level, int optname,
 		    char __user *optval, int __user *optlen)
 {
-	dccp_pr_debug("entry\n");
+	struct dccp_sock *dp;
+	int val, len;
 
 	if (level != SOL_DCCP)
 		return ip_getsockopt(sk, level, optname, optval, optlen);
 
-	return -EOPNOTSUPP;
+	if (get_user(len, optlen))
+		return -EFAULT;
+
+	len = min_t(unsigned int, len, sizeof(int));
+	if (len < 0)
+		return -EINVAL;
+
+	dp = dccp_sk(sk);
+
+	switch (optname) {
+	case DCCP_SOCKOPT_PACKET_SIZE:
+		val = dp->dccps_packet_size;
+		break;
+	default:
+		return -ENOPROTOOPT;
+	}
+
+	if (put_user(len, optlen) || copy_to_user(optval, &val, len))
+		return -EFAULT;
+
+	return 0;
 }
 
 int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,