net: Add a separate file for IP checksumming

Move the checksum code out into its own file so it can be used elsewhere. Also use a new version which supports a length which is not a multiple of 2 and add a new function to add two checksums. Signed-off-by: Simon Glass <sjg@chromium.org>

net: Add a separate file for IP checksumming
Move the checksum code out into its own file so it can be used elsewhere. Also use a new version which supports a length which is not a multiple of 2 and add a new function to add two checksums. Signed-off-by: Simon Glass <sjg@chromium.org>
Simon Glass
1 parent 5da38086bd
Showing 3 changed files with 91 additions and 0 deletions Side-by-side Diff
include/net.h
net/Makefile
net/checksum.c
@@ -482,6 +482,36 @@
 extern void net_set_udp_header(uchar *pkt, IPaddr_t dest, int dport,
 				int sport, int len);
  
+/**
+ * compute_ip_checksum() - Compute IP checksum
+ *
+ * @addr:	Address to check (must be 16-bit aligned)
+ * @nbytes:	Number of bytes to check (normally a multiple of 2)
+ * @return 16-bit IP checksum
+ */
+unsigned compute_ip_checksum(const void *addr, unsigned nbytes);
+
+/**
+ * add_ip_checksums() - add two IP checksums
+ *
+ * @offset:	Offset of first sum (if odd we do a byte-swap)
+ * @sum:	First checksum
+ * @new_sum:	New checksum to add
+ * @return updated 16-bit IP checksum
+ */
+unsigned add_ip_checksums(unsigned offset, unsigned sum, unsigned new_sum);
+
+/**
+ * ip_checksum_ok() - check if a checksum is correct
+ *
+ * This works by making sure the checksum sums to 0
+ *
+ * @addr:	Address to check (must be 16-bit aligned)
+ * @nbytes:	Number of bytes to check (normally a multiple of 2)
+ * @return true if the checksum matches, false if not
+ */
+int ip_checksum_ok(const void *addr, unsigned nbytes);
+
 /* Checksum */
 extern int	NetCksumOk(uchar *, int);	/* Return true if cksum OK */
 extern uint	NetCksum(uchar *, int);		/* Calculate the checksum */
@@ -7,6 +7,7 @@
  
 #ccflags-y += -DDEBUG
  
+obj-y += checksum.o
 obj-$(CONFIG_CMD_NET)  += arp.o
 obj-$(CONFIG_CMD_NET)  += bootp.o
 obj-$(CONFIG_CMD_CDP)  += cdp.o
+/*
+ * This file was originally taken from the FreeBSD project.
+ *
+ * Copyright (c) 2001 Charles Mott <cm@linktel.net>
+ * Copyright (c) 2008 coresystems GmbH
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier:	BSD-2-Clause
+ */
+
+#include <common.h>
+#include <net.h>
+
+unsigned compute_ip_checksum(const void *vptr, unsigned nbytes)
+{
+	int sum, oddbyte;
+	const unsigned short *ptr = vptr;
+
+	sum = 0;
+	while (nbytes > 1) {
+		sum += *ptr++;
+		nbytes -= 2;
+	}
+	if (nbytes == 1) {
+		oddbyte = 0;
+		((u8 *)&oddbyte)[0] = *(u8 *)ptr;
+		((u8 *)&oddbyte)[1] = 0;
+		sum += oddbyte;
+	}
+	sum = (sum >> 16) + (sum & 0xffff);
+	sum += (sum >> 16);
+	sum = ~sum & 0xffff;
+
+	return sum;
+}
+
+unsigned add_ip_checksums(unsigned offset, unsigned sum, unsigned new)
+{
+	unsigned long checksum;
+
+	sum = ~sum & 0xffff;
+	new = ~new & 0xffff;
+	if (offset & 1) {
+		/*
+		 * byte-swap the sum if it came from an odd offset; since the
+		 * computation is endian independant this works.
+		 */
+		new = ((new >> 8) & 0xff) | ((new << 8) & 0xff00);
+	}
+	checksum = sum + new;
+	if (checksum > 0xffff)
+		checksum -= 0xffff;
+
+	return (~checksum) & 0xffff;
+}
+
+int ip_checksum_ok(const void *addr, unsigned nbytes)
+{
+	return !(compute_ip_checksum(addr, nbytes) & 0xfffe);
+}
...	...	@@ -482,6 +482,36 @@
482	482	extern void net_set_udp_header(uchar *pkt, IPaddr_t dest, int dport,
483	483	int sport, int len);
484	484
	485	+/**
	486	+ * compute_ip_checksum() - Compute IP checksum
	487	+ *
	488	+ * @addr: Address to check (must be 16-bit aligned)
	489	+ * @nbytes: Number of bytes to check (normally a multiple of 2)
	490	+ * @return 16-bit IP checksum
	491	+ */
	492	+unsigned compute_ip_checksum(const void *addr, unsigned nbytes);
	493	+
	494	+/**
	495	+ * add_ip_checksums() - add two IP checksums
	496	+ *
	497	+ * @offset: Offset of first sum (if odd we do a byte-swap)
	498	+ * @sum: First checksum
	499	+ * @new_sum: New checksum to add
	500	+ * @return updated 16-bit IP checksum
	501	+ */
	502	+unsigned add_ip_checksums(unsigned offset, unsigned sum, unsigned new_sum);
	503	+
	504	+/**
	505	+ * ip_checksum_ok() - check if a checksum is correct
	506	+ *
	507	+ * This works by making sure the checksum sums to 0
	508	+ *
	509	+ * @addr: Address to check (must be 16-bit aligned)
	510	+ * @nbytes: Number of bytes to check (normally a multiple of 2)
	511	+ * @return true if the checksum matches, false if not
	512	+ */
	513	+int ip_checksum_ok(const void *addr, unsigned nbytes);
	514	+
485	515	/* Checksum */
486	516	extern int NetCksumOk(uchar , int); / Return true if cksum OK */
487	517	extern uint NetCksum(uchar , int); / Calculate the checksum */
...	...	@@ -7,6 +7,7 @@
7	7
8	8	#ccflags-y += -DDEBUG
9	9
	10	+obj-y += checksum.o
10	11	obj-$(CONFIG_CMD_NET) += arp.o
11	12	obj-$(CONFIG_CMD_NET) += bootp.o
12	13	obj-$(CONFIG_CMD_CDP) += cdp.o
	1	+/*
	2	+ * This file was originally taken from the FreeBSD project.
	3	+ *
	4	+ * Copyright (c) 2001 Charles Mott <cm@linktel.net>
	5	+ * Copyright (c) 2008 coresystems GmbH
	6	+ * All rights reserved.
	7	+ *
	8	+ * SPDX-License-Identifier: BSD-2-Clause
	9	+ */
	10	+
	11	+#include <common.h>
	12	+#include <net.h>
	13	+
	14	+unsigned compute_ip_checksum(const void *vptr, unsigned nbytes)
	15	+{
	16	+ int sum, oddbyte;
	17	+ const unsigned short *ptr = vptr;
	18	+
	19	+ sum = 0;
	20	+ while (nbytes > 1) {
	21	+ sum += *ptr++;
	22	+ nbytes -= 2;
	23	+ }
	24	+ if (nbytes == 1) {
	25	+ oddbyte = 0;
	26	+ ((u8 )&oddbyte)[0] = (u8 *)ptr;
	27	+ ((u8 *)&oddbyte)[1] = 0;
	28	+ sum += oddbyte;
	29	+ }
	30	+ sum = (sum >> 16) + (sum & 0xffff);
	31	+ sum += (sum >> 16);
	32	+ sum = ~sum & 0xffff;
	33	+
	34	+ return sum;
	35	+}
	36	+
	37	+unsigned add_ip_checksums(unsigned offset, unsigned sum, unsigned new)
	38	+{
	39	+ unsigned long checksum;
	40	+
	41	+ sum = ~sum & 0xffff;
	42	+ new = ~new & 0xffff;
	43	+ if (offset & 1) {
	44	+ /*
	45	+ * byte-swap the sum if it came from an odd offset; since the
	46	+ * computation is endian independant this works.
	47	+ */
	48	+ new = ((new >> 8) & 0xff) \| ((new << 8) & 0xff00);
	49	+ }
	50	+ checksum = sum + new;
	51	+ if (checksum > 0xffff)
	52	+ checksum -= 0xffff;
	53	+
	54	+ return (~checksum) & 0xffff;
	55	+}
	56	+
	57	+int ip_checksum_ok(const void *addr, unsigned nbytes)
	58	+{
	59	+ return !(compute_ip_checksum(addr, nbytes) & 0xfffe);
	60	+}