[SCTP] Add a generic csum_copy for sctp.

Do the sctp checksum while copying. 

include/net/sctp/sctp.h

@@ -153,6 +153,7 @@ extern int sctp_primitive_REQUESTHEARTBEAT(struct sctp_association *, void *arg)
 extern __u32 sctp_start_cksum(__u8 *ptr, __u16 count);
 extern __u32 sctp_update_cksum(__u8 *ptr, __u16 count, __u32 cksum);
 extern __u32 sctp_end_cksum(__u32 cksum);
+extern __u32 sctp_update_copy_cksum(__u8 *, __u8 *, __u16 count, __u32 cksum);
 
 /*
  * sctp/input.c

net/sctp/adler32.c

@@ -156,6 +156,15 @@ __u32 sctp_update_cksum(__u8 *ptr, __u16 count, __u32 adler)
 	return adler;
 }
 
+__u32 sctp_update_copy_cksum(__u8 *to, __u8 *from, __u16 count, __u32 adler)
+{
+	/* Its not worth it to try harder.  Adler32 is obsolescent. */
+	adler = update_adler32(adler, from, count);
+	memcpy(to, from, count);
+
+	return adler;
+}
+
 __u32 sctp_end_cksum(__u32 adler)
 {
 	return adler;

net/sctp/crc32c.c

@@ -170,6 +170,23 @@ __u32 sctp_update_cksum(__u8 *buffer, __u16 length, __u32 crc32)
 	return crc32;
 }
 
+__u32 sctp_update_copy_cksum(__u8 *to, __u8 *from, __u16 length, __u32 crc32)
+{
+	__u32 i;
+	__u32 *_to = (__u32 *)to;
+	__u32 *_from = (__u32 *)from;
+	
+	for (i = 0; i < (length/4); i++) {
+		_to[i] = _from[i];
+		CRC32C(crc32, from[i*4]);
+		CRC32C(crc32, from[i*4+1]);
+		CRC32C(crc32, from[i*4+2]);
+		CRC32C(crc32, from[i*4+3]);	
+	}
+
+	return crc32;
+}
+
 __u32 sctp_end_cksum(__u32 crc32)
 {
 	__u32 result;

net/sctp/output.c

@@ -276,8 +276,8 @@ sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet,
  */
 int sctp_packet_transmit(struct sctp_packet *packet)
 {
-	struct sctp_transport *transport = packet->transport;
-	struct sctp_association *asoc = transport->asoc;
+	struct sctp_transport *tp = packet->transport;
+	struct sctp_association *asoc = tp->asoc;
 	struct sctphdr *sh;
 	__u32 crc32;
 	struct sk_buff *nskb;
@@ -311,6 +311,32 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 	 */
 	skb_set_owner_w(nskb, sk);
 
+	/* Build the SCTP header.  */
+	sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr));
+	sh->source = htons(packet->source_port);
+	sh->dest   = htons(packet->destination_port);
+
+	/* From 6.8 Adler-32 Checksum Calculation:
+	 * After the packet is constructed (containing the SCTP common
+	 * header and one or more control or DATA chunks), the
+	 * transmitter shall:
+	 *
+	 * 1) Fill in the proper Verification Tag in the SCTP common
+	 *    header and initialize the checksum field to 0's.
+	 */
+	sh->vtag     = htonl(packet->vtag);
+	sh->checksum = 0;
+
+
+	/* 2) Calculate the Adler-32 checksum of the whole packet,
+	 *    including the SCTP common header and all the
+	 *    chunks.
+	 *
+	 * Note: Adler-32 is no longer applicable, as has been replaced
+	 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
+	 */
+	crc32 = sctp_start_cksum((__u8 *)sh, sizeof(struct sctphdr));
+
 	/**
 	 * 6.10 Bundling
 	 *
@@ -344,16 +370,20 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 			 * for a given destination transport address.
 			 */
 			if ((1 == chunk->num_times_sent) &&
-			    (!transport->rto_pending)) {
+			    (!tp->rto_pending)) {
 				chunk->rtt_in_progress = 1;
-				transport->rto_pending = 1;
+				tp->rto_pending = 1;
 			}
 			has_data = 1;
 		}
-		memcpy(skb_put(nskb, chunk->skb->len),
-		       chunk->skb->data, chunk->skb->len);
 		padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len;
-		memset(skb_put(nskb, padding), 0, padding);
+		if (padding)
+			memset(skb_put(chunk->skb, padding), 0, padding);      
+
+		crc32 = sctp_update_copy_cksum(skb_put(nskb, chunk->skb->len),
+					       chunk->skb->data, 
+					       chunk->skb->len, crc32);
+		
 		SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d, "
 				  "%s %d\n",
 				  "*** Chunk", chunk,
@@ -376,30 +406,7 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 			sctp_free_chunk(chunk);
 	}
 
-	/* Build the SCTP header.  */
-	sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr));
-	sh->source = htons(packet->source_port);
-	sh->dest   = htons(packet->destination_port);
-
-	/* From 6.8 Adler-32 Checksum Calculation:
-	 * After the packet is constructed (containing the SCTP common
-	 * header and one or more control or DATA chunks), the
-	 * transmitter shall:
-	 *
-	 * 1) Fill in the proper Verification Tag in the SCTP common
-	 *    header and initialize the checksum field to 0's.
-	 */
-	sh->vtag     = htonl(packet->vtag);
-	sh->checksum = 0;
-
-	/* 2) Calculate the Adler-32 checksum of the whole packet,
-	 *    including the SCTP common header and all the
-	 *    chunks.
-	 *
-	 * Note: Adler-32 is no longer applicable, as has been replaced
-	 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
-	 */
-	crc32 = sctp_start_cksum((__u8 *)sh, nskb->len);
+	/* Perform final transformation on checksum. */
 	crc32 = sctp_end_cksum(crc32);
 
 	/* 3) Put the resultant value into the checksum field in the
@@ -431,18 +438,18 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 	 */
 
 	/* Dump that on IP!  */
-	if (asoc && asoc->peer.last_sent_to != transport) {
+	if (asoc && asoc->peer.last_sent_to != tp) {
 		/* Considering the multiple CPU scenario, this is a
 		 * "correcter" place for last_sent_to.  --xguo
 		 */
-		asoc->peer.last_sent_to = transport;
+		asoc->peer.last_sent_to = tp;
 	}
 
 	if (has_data) {
 		struct timer_list *timer;
 		unsigned long timeout;
 
-		transport->last_time_used = jiffies;
+		tp->last_time_used = jiffies;
 
 		/* Restart the AUTOCLOSE timer when sending data. */
 		if ((SCTP_STATE_ESTABLISHED == asoc->state) &&
@@ -455,21 +462,21 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 		}
 	}
 
-	dst = transport->dst;
+	dst = tp->dst;
 	/* The 'obsolete' field of dst is set to 2 when a dst is freed. */
 	if (!dst || (dst->obsolete > 1)) {
 		dst_release(dst);
-		sctp_transport_route(transport, NULL, sctp_sk(sk));
+		sctp_transport_route(tp, NULL, sctp_sk(sk));
 		sctp_assoc_sync_pmtu(asoc);
 	}
 
-	nskb->dst = dst_clone(transport->dst);
+	nskb->dst = dst_clone(tp->dst);
 	if (!nskb->dst)
 		goto no_route;
 
 	SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb length %d\n",
 			  nskb->len);
-	(*transport->af_specific->sctp_xmit)(nskb, transport, packet->ipfragok);
+	(*tp->af_specific->sctp_xmit)(nskb, tp, packet->ipfragok);
 out:
 	packet->size = SCTP_IP_OVERHEAD;
 	return err;