Add simple IP/UDP fragmentation support

From: Frank Haverkamp <[email protected]>

http://tools.ietf.org/html/rfc2348 describes the TFTP block size option which allows larger packtes than the 512 byte default. This reduces the number of TFTP ACKs significantly and improves performance.

To get the most benefit out of the tftp block size option the support of defragementation of IP/UDP packet is helpful. The current implemenation should work even with packets received out of order. To enable the large packet size the user should set "tftp_block_size" so a value like 16352.

We experimented with different packet sizes and found that more than those 16KiB do not contribute much to the performance anymore. Therefor I limited the defragmentation buffer to 16KiB no too waste memory.

Signed-off-by Frank Haverkamp <[email protected]>

Signed-off-by Josh Boyer <[email protected]>

---

From: Frank Haverkamp <[email protected]>

http://tools.ietf.org/html/rfc2348 describes the TFTP block size option which allows larger packtes than the 512 byte default. This reduces the

number of TFTP ACKs significantly and improves performance.

To get the most benefit out of the tftp block size option the support of defragementation of IP/UDP packet is helpful. The current implemenation

should work even with packets received out of order. To enable the large packet size the user should set "tftp_block_size" so a value like 16352.

We experimented with different packet sizes and found that more than those 16KiB do not contribute much to the performance anymore. Therefor I limited

the defragmentation buffer to 16KiB no too waste memory.

Signed-off-by Frank Haverkamp <[email protected]>

Signed-off-by Josh Boyer <[email protected]>

---
 include/net.h |   17 ++++++
 net/net.c     |  156 ++++++++++++++++++++++++++++++++++++++++++++++++++--------
 net/tftp.c    |   22 ++++++++
 net/tftp.h    |   10 +++
 4 files changed, 185 insertions(+), 20 deletions(-)

include/net.h +0 -0

@@ -200,6 +200,13 @@ typedef struct {
 	ushort		udp_xsum;	/* Checksum			*/

include/net.h +10 -0

 #define IP_HDR_SIZE_NO_UDP	(sizeof (IP_t) - 8)
 #define IP_HDR_SIZE		(sizeof (IP_t))

@@ -282,6 +289,16 @@ typedef struct icmphdr {
 #define PKTSIZE_ALIGN		1536
 /*#define PKTSIZE		608*/
 
+ /*
+  * IP/UDP Fragmentation support
+  * See: http://en.wikipedia.org/wiki/IPv4#Fragmentation_and_reassembly
+  * MAX possible UDP packet size is 64 KiB, if there is memory available.
+  */
+#define NET_ETH_MTU		1500
+#define NET_FRAG_BUF_SIZE	(16 * 1024) /* MAX is 64 KiB */
+#define NET_UDP_FRAG_SIZE	(NET_ETH_MTU - IP_HDR_SIZE_NO_UDP) /* 1480 */
+#define NET_FRAG_BUF_USED	(NET_FRAG_BUF_SIZE / NET_UDP_FRAG_SIZE + 1)
+
 /*
  * Maximum receive ring size; that is, the number of packets
  * we can buffer before overflow happens. Basically, this just

net/net.c +16 -0

@@ -192,6 +192,15 @@ volatile uchar	PktBuf[(PKTBUFSRX+1) * PK
 
 volatile uchar *NetRxPackets[PKTBUFSRX]; /* Receive packets			*/
 
+/* Packet fragmentation support */
+static uint16_t ip_id = 0; /* sequence number */
+static uint16_t udp_len = 0;
+static uint16_t udp_src = 0;
+static uint16_t udp_dst = 0;
+static int max_idx = 0;
+static uchar NetFragBuf[NET_FRAG_BUF_SIZE];
+static char NetFragBufUsed[NET_FRAG_BUF_USED] = { 0, };
+
 static rxhand_f *packetHandler;		/* Current RX packet handler		*/
 static thand_f *timeHandler;		/* Current timeout handler		*/
 static ulong	timeStart;		/* Time base value			*/

@@ -288,6 +297,13 @@ NetLoop(proto_t protocol)
 {
 	bd_t *bd = gd->bd;
 
+	/* Packet fragmentation support */
+	ip_id = udp_len = udp_src = udp_dst = max_idx = 0;
+	memset(NetFragBuf, 0xFF, sizeof(NetFragBuf));
+	memset(NetFragBufUsed, 0, sizeof(NetFragBufUsed));
+	printf("NetFragBuf @ %08x max tftp_block_size=%d udp_frag_size=%d\n",
+	       NetFragBuf, TFTP_BLOCK_SIZE_MAX, NET_UDP_FRAG_SIZE);
+
 #ifdef CONFIG_NET_MULTI
 	NetRestarted = 0;
 	NetDevExists = 0;

@@ -1150,6 +1166,39 @@ static void CDPStart(void)
 }

net/net.c +26 -0

+ */
+static int udp_checksum(ushort *sumptr, ushort sumlen, ulong xsum)
+{
+       while (sumlen > 1) {
+	       ushort sumdata;
+
+	       sumdata = *sumptr++;
+	       xsum += ntohs(sumdata);
+	       sumlen -= 2;
+       }
+       if (sumlen > 0) {
+	       ushort sumdata;
+
+	       sumdata = *(unsigned char *) sumptr;
+	       sumdata = (sumdata << 8) & 0xff00;
+	       xsum += sumdata;
+       }
+       while ((xsum >> 16) != 0) {
+	       xsum = (xsum & 0x0000ffff) + ((xsum >> 16) & 0x0000ffff);
+       }
+       if ((xsum != 0x00000000) && (xsum != 0x0000ffff))
+	       return 1;
+
+       return 0;
+}
+#endif /* CONFIG_UDP_CHECKSUM */
 
 void

NetReceive(volatile uchar * inpkt, int len)

net/net.c +0 -0

 		/* can't deal with headers > 20 bytes */
 		if ((ip->ip_hl_v & 0x0f) > 0x05) {

net/net.c +30 -0

 			return;

@@ -1422,6 +1474,88 @@ NetReceive(volatile uchar * inpkt, int l
 #endif
 			return;
 		}
+
+		/*
+		 * Fragmentation support. We need to check the ip_id
+		 * and if all fragments were received correctly.
+		 */
+		off = (ntohs(ip->ip_off) & IP_OFFS) << IP_OFFS_SHIFT;
+		if ((off != 0) || (ip->ip_off & htons(IP_FLAGS_MFRAG))) {
+			int size, idx, complete;
+			char *start;
+
+			/* New fragmented packet arrived, clear data. */
+			if (ntohs(ip->ip_id) != ip_id) {
+				ip_id = ntohs(ip->ip_id);
+				memset(NetFragBufUsed, 0, sizeof(NetFragBufUsed));
+				udp_len = udp_src = udp_dst = max_idx = 0;
+			}
+
+			idx = off / NET_UDP_FRAG_SIZE;
+
+			/* Packet does not fit into IP/UDP fragmentation buf */
+			if (idx >= NET_FRAG_BUF_USED) {
+				return;
+			}
+
+			NetFragBufUsed[idx] = 1;
+
+			/* Copy the UDP hdr with the data for 1st
+			   fragment, else copy just payload */
+			if (off == 0) {
+				udp_len = ntohs(ip->udp_len);

net/net.c +31 -0

+			 * know the number of fragments we expect. If
+			 * all have arrived we process the packet.
+			 */
+			if (((off != 0) && !(ip->ip_off & htons(IP_FLAGS_MFRAG))))
+				max_idx = idx;
+
+			if (max_idx == 0)
+				return;
+
+			complete = 1;
+			for (idx = 0; idx < max_idx; idx++) {
+				if (NetFragBufUsed[idx] == 0) {
+					complete = 0;
+					break;
+				}
+			}
+			if (!complete)
+				return;
+#ifdef CONFIG_UDP_CHECKSUM
+			if (ip->udp_xsum != 0) {
+				ulong xsum = ip->ip_p;
+				uint16_t *sumptr;
+
+				xsum += udp_len;
+				xsum += (ntohl(ip->ip_src) >> 16) & 0xffff;
+				xsum += (ntohl(ip->ip_src) >>  0) & 0xffff;
+				xsum += (ntohl(ip->ip_dst) >> 16) & 0xffff;
+				xsum += (ntohl(ip->ip_dst) >>  0) & 0xffff;
+				sumptr = (ushort *)NetFragBuf;
+
+				if (udp_checksum(sumptr, udp_len, xsum)) {

net/net.c +3 -0

+			return;
+		}
+
 		/*

net/net.c +2 -20

 		 * watch for ICMP host redirects
 		 *

@@ -1502,26 +1636,8 @@ NetReceive(volatile uchar * inpkt, int l
 			sumlen = ntohs(ip->udp_len);
 			sumptr = (ushort *) &(ip->udp_src);
 
-			while (sumlen > 1) {
-				ushort sumdata;
-
-				sumdata = *sumptr++;
-				xsum += ntohs(sumdata);
-				sumlen -= 2;
-			}
-			if (sumlen > 0) {
-				ushort sumdata;
-
-				sumdata = *(unsigned char *) sumptr;
-				sumdata = (sumdata << 8) & 0xff00;
-				xsum += sumdata;
-			}
-			while ((xsum >> 16) != 0) {
-				xsum = (xsum & 0x0000ffff) + ((xsum >> 16) & 0x0000ffff);
-			}
-			if ((xsum != 0x00000000) && (xsum != 0x0000ffff)) {
-				printf(" UDP wrong checksum %08lx %08x\n",
-					xsum, ntohs(ip->udp_xsum));
+			if (udp_checksum(sumptr, sumlen, xsum)) {
+				putc('U');
 				return;
 			}
 		}

net/tftp.c +1 -0

@@ -456,6 +456,7 @@ TftpTimeout (void)
 void
 TftpStart (void)
 {
+	char *s, *err;
 #ifdef CONFIG_TFTP_PORT
 	char *ep;             /* Environment pointer */
 #endif

net/tftp.c +19 -0

+		err = NULL;
+
+		TftpBlkSizeOption = simple_strtoul(s, &err, 10);
+		if (*err) {
+			printf("ERR: \"tftp_block_size\" is not a number\n");
+			TftpBlkSizeOption = TFTP_BLOCK_SIZE;
+		}
+		/*
+		 * Reject values which require extensive handling.
+		 * block size of 1428 octets (Ethernet MTU, less
+		 * the TFTP, UDP and IP header lengths).
+		 */
+		if (TftpBlkSizeOption > TFTP_BLOCK_SIZE_MAX) {
+			printf("ERR: tftp_block_sizes larger than %d not "
+			       "supported\n", TFTP_BLOCK_SIZE_MAX);
+			TftpBlkSizeOption = TFTP_BLOCK_SIZE;
+		}
+	}
+
 	NetSetTimeout (TIMEOUT * CFG_HZ, TftpTimeout);
 	NetSetHandler (TftpHandler);

net/tftp.h +3 -0

@@ -8,11 +8,21 @@
 #ifndef __TFTP_H__
 #define __TFTP_H__
 
+#include <net.h>
+
 /**********************************************************************/
 /*
  *	Global functions and variables.
  */
 
+/*

Subject: U-Boot: Add simple IP/UDP fragmentation support
From: Frank Haverkamp <[email protected]>

Dear Ben,

Quoted 3 lines · In message <1220460631.17453.3.camel@august> Frank Haverkamp wrote:

Subject: U-Boot: Add simple IP/UDP fragmentation support
From: Frank Haverkamp <[email protected]>

You replied:

| I know you guys posted this one a couple of months ago and I apologize 
| for not being more active.  I've put this in the net/testing repo with 
| the hope that people will smack it around a bit.

What to do with this now?

Best regards,

Wolfgang Denk

From: Frank Haverkamp <[email protected]>

http://tools.ietf.org/html/rfc2348 describes the TFTP block size option which allows larger packtes than the 512 byte default. This reduces the number of TFTP ACKs significantly and improves performance.

To get the most benefit out of the tftp block size option the support of defragementation of IP/UDP packet is helpful. The current implemenation should work even with packets received out of order. To enable the large packet size the user should set "tftp_block_size" so a value like 16352.

We experimented with different packet sizes and found that more than those 16KiB do not contribute much to the performance anymore. Therefor I limited the defragmentation buffer to 16KiB no too waste memory.

Signed-off-by Frank Haverkamp <[email protected]>

Signed-off-by Josh Boyer <[email protected]>

From: Frank Haverkamp <[email protected]>

http://tools.ietf.org/html/rfc2348 describes the TFTP block size option which allows larger packtes than the 512 byte default. This reduces the number of TFTP ACKs significantly and improves performance.

To get the most benefit out of the tftp block size option the support of defragementation of IP/UDP packet is helpful. The current implemenation should work even with packets received out of order. To enable the large packet size the user should set "tftp_block_size" so a value like 16352.

We experimented with different packet sizes and found that more than those 16KiB do not contribute much to the performance anymore. Therefor I limited the defragmentation buffer to 16KiB no too waste memory.

Signed-off-by Frank Haverkamp <[email protected]>

Signed-off-by Josh Boyer <[email protected]>

---
 include/net.h |   17 ++++++
 net/net.c     |  156 ++++++++++++++++++++++++++++++++++++++++++++++++++--------
 net/tftp.c    |   22 ++++++++
 net/tftp.h    |   10 +++
 4 files changed, 185 insertions(+), 20 deletions(-)

include/net.h +17 -0

@@ -200,6 +200,13 @@ typedef struct {
 	ushort		udp_xsum;	/* Checksum			*/
 } IP_t;
 
+#define IP_OFFS			 0x1FFF	/* ip offset *= 8 */
+#define	  IP_OFFS_SHIFT	  3	/* in 8 byte steps */
+#define IP_FLAGS	 0xE000	/* first 3 bits */
+#define		 IP_FLAGS_RES	 0x8000	/* reserved */
+#define		 IP_FLAGS_DFRAG	 0x4000	/* don't fragments */
+#define		 IP_FLAGS_MFRAG	 0x2000	/* more fragments */
+
 #define IP_HDR_SIZE_NO_UDP	(sizeof (IP_t) - 8)
 #define IP_HDR_SIZE		(sizeof (IP_t))
 

@@ -282,6 +289,16 @@ typedef struct icmphdr {
 #define PKTSIZE_ALIGN		1536
 /*#define PKTSIZE		608*/
 
+ /*
+  * IP/UDP Fragmentation support
+  * See: http://en.wikipedia.org/wiki/IPv4#Fragmentation_and_reassembly
+  * MAX possible UDP packet size is 64 KiB, if there is memory available.
+  */
+#define NET_ETH_MTU		1500
+#define NET_FRAG_BUF_SIZE	(16 * 1024) /* MAX is 64 KiB */
+#define NET_UDP_FRAG_SIZE	(NET_ETH_MTU - IP_HDR_SIZE_NO_UDP) /* 1480 */
+#define NET_FRAG_BUF_USED	(NET_FRAG_BUF_SIZE / NET_UDP_FRAG_SIZE + 1)
+
 /*
  * Maximum receive ring size; that is, the number of packets
  * we can buffer before overflow happens. Basically, this just

net/net.c +0 -0

@@ -192,6 +192,15 @@ volatile uchar	PktBuf[(PKTBUFSRX+1) * PK
 

net/net.c +2 -0

+static char NetFragBufUsed[NET_FRAG_BUF_USED] = { 0, };
+
 static rxhand_f *packetHandler;		/* Current RX packet handler		*/
 static thand_f *timeHandler;		/* Current timeout handler		*/

static ulong timeStart; /* Time base value */