From eba0cfa6b0bef4f2e73c8630a7efa3944df8b0f8 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Fri, 19 Apr 2024 04:56:35 +0200
Subject: Adding upstream version 1:2.0.27.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 util_lib/compute_ip_checksum.c | 102 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)
 create mode 100644 util_lib/compute_ip_checksum.c

(limited to 'util_lib/compute_ip_checksum.c')

diff --git a/util_lib/compute_ip_checksum.c b/util_lib/compute_ip_checksum.c
new file mode 100644
index 0000000..39a371b
--- /dev/null
+++ b/util_lib/compute_ip_checksum.c
@@ -0,0 +1,102 @@
+/*
+ * kexec: Linux boots Linux
+ *
+ * Copyright (C) 2003,2004  Eric Biederman (ebiederm@xmission.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (version 2 of the License).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <stdint.h>
+#include <ip_checksum.h>
+#include <string.h>
+
+unsigned long compute_ip_checksum(void *addr, unsigned long length)
+{
+	uint16_t *ptr;
+	unsigned long sum;
+	unsigned long len;
+	unsigned long laddr;
+	/* compute an ip style checksum */
+	laddr = (unsigned long )addr;
+	sum = 0;
+	if (laddr & 1) {
+		uint16_t buffer;
+		unsigned char *ptr;
+		/* copy the first byte into a 2 byte buffer.
+		 * This way automatically handles the endian question
+		 * of which byte (low or high) the last byte goes in.
+		 */
+		buffer = 0;
+		ptr = addr;
+		memcpy(&buffer, ptr, 1);
+		sum += buffer;
+		if (sum > 0xFFFF)
+			sum -= 0xFFFF;
+		length -= 1;
+		addr = ptr +1;
+		
+	}
+	len = length >> 1;
+	ptr = addr;
+	while (len--) {
+		sum += *(ptr++);
+		if (sum > 0xFFFF)
+			sum -= 0xFFFF;
+	}
+	addr = ptr;
+	if (length & 1) {
+		uint16_t buffer;
+		unsigned char *ptr;
+		/* copy the last byte into a 2 byte buffer.
+		 * This way automatically handles the endian question
+		 * of which byte (low or high) the last byte goes in.
+		 */
+		buffer = 0;
+		ptr = addr;
+		memcpy(&buffer, ptr, 1);
+		sum += buffer;
+		if (sum > 0xFFFF)
+			sum -= 0xFFFF;
+	}
+	return (~sum) & 0xFFFF;
+	
+}
+
+unsigned long add_ip_checksums(unsigned long offset, unsigned long sum, unsigned long 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;
+}
+
+unsigned long negate_ip_checksum(unsigned long sum)
+{
+	sum = ~sum & 0xFFFF;
+
+	sum = 0xFFFF - sum;
+
+	return ~sum & 0xFFFF;
+}
-- 
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