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checksum() accesses data[0] and calculates an invalid last_byte pointer when processing an empty fragment with odd state set. Return early when len is zero to preserve the checksum state and avoid accessing data from an empty fragment. Assisted by: GitHub Copilot Signed-off-by: Megha Rajput <i.meghar.2408@gmail.com>
323 lines
8.7 KiB
C
323 lines
8.7 KiB
C
/****************************************************************************
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* net/utils/net_chksum.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#ifdef CONFIG_NET
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#include "utils/utils.h"
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: checksum
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*
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* Description:
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* Calculate the raw change sum over the memory region described by
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* data and len.
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*
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* Input Parameters:
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* sum - Partial calculations carried over from a previous call to
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* chksum(). This should be zero on the first time that check
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* sum is called.
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* data - Beginning of the data to include in the checksum.
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* len - Length of the data to include in the checksum.
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* odd - the flag of the Calculated data sum
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*
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* Returned Value:
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* The updated checksum value.
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*
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****************************************************************************/
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#ifndef CONFIG_NET_ARCH_CHKSUM
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uint16_t checksum(uint16_t sum, FAR const uint8_t *data,
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uint16_t len, bool *odd)
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{
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FAR const uint8_t *dataptr;
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FAR const uint8_t *last_byte;
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uint16_t t;
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if (len == 0)
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{
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return sum;
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}
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dataptr = data;
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last_byte = data + len - 1;
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if (*odd == true)
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{
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t = dataptr[0];
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sum += t;
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if (sum < t)
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{
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sum++; /* carry */
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}
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dataptr += 1;
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}
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while (dataptr < last_byte)
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{
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/* At least two more bytes */
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t = ((uint16_t)dataptr[0] << 8) + dataptr[1];
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sum += t;
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if (sum < t)
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{
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sum++; /* carry */
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}
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dataptr += 2;
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}
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*odd = false;
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if (dataptr == last_byte)
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{
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t = (dataptr[0] << 8) + 0;
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sum += t;
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if (sum < t)
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{
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sum++; /* carry */
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}
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*odd = true;
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}
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/* Return sum in host byte order. */
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return sum;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: chksum
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*
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* Description:
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* Calculate the raw change sum over the memory region described by
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* data and len.
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*
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* Input Parameters:
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* sum - Partial calculations carried over from a previous call to
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* chksum(). This should be zero on the first time that check
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* sum is called.
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* data - Beginning of the data to include in the checksum.
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* len - Length of the data to include in the checksum.
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*
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* Returned Value:
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* The updated checksum value.
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*
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****************************************************************************/
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uint16_t chksum(uint16_t sum, FAR const uint8_t *data, uint16_t len)
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{
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bool odd = false;
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return checksum(sum, data, len, &odd);
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}
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#endif /* CONFIG_NET_ARCH_CHKSUM */
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/****************************************************************************
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* Name: chksum_iob
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*
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* Description:
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* Calculate the Internet checksum over an iob chain buffer.
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*
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* Input Parameters:
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* sum - Partial calculations carried over from a previous call to
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* chksum(). This should be zero on the first time that check
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* sum is called.
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* iob - An iob chain buffer over which the checksum is to be computed.
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* offset - Specifies the byte offset of the start of valid data.
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*
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* Returned Value:
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* The updated checksum value.
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*
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****************************************************************************/
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#ifdef CONFIG_MM_IOB
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uint16_t chksum_iob(uint16_t sum, FAR struct iob_s *iob, uint16_t offset)
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{
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/* Skip to the I/O buffer containing the data offset */
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bool odd = false;
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while (iob != NULL && offset > iob->io_len)
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{
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offset -= iob->io_len;
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iob = iob->io_flink;
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}
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/* If the link pointer is not empty, loop to walk through all I/O buffer
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* and accumulate the sum
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*/
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while (iob != NULL)
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{
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sum = checksum(sum, iob->io_data + iob->io_offset + offset,
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iob->io_len - offset, &odd);
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iob = iob->io_flink;
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offset = 0;
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}
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return sum;
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}
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#endif /* CONFIG_MM_IOB */
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/****************************************************************************
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* Name: net_chksum
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*
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* Description:
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* Calculate the Internet checksum over a buffer.
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*
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* The Internet checksum is the one's complement of the one's complement
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* sum of all 16-bit words in the buffer.
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*
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* See RFC1071.
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*
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* If CONFIG_NET_ARCH_CHKSUM is defined, then this function must be
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* provided by architecture-specific logic.
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*
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* Input Parameters:
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*
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* buf - A pointer to the buffer over which the checksum is to be computed.
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*
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* len - The length of the buffer over which the checksum is to be
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* computed.
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*
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* Returned Value:
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* The Internet checksum of the buffer.
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*
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****************************************************************************/
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#ifndef CONFIG_NET_ARCH_CHKSUM
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uint16_t net_chksum(FAR uint16_t *data, uint16_t len)
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{
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return HTONS(chksum(0, (uint8_t *)data, len));
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}
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#endif /* CONFIG_NET_ARCH_CHKSUM */
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/****************************************************************************
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* Name: net_chksum_iob
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*
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* Description:
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* Calculate the Internet checksum over an iob chain buffer.
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*
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* The Internet checksum is the one's complement of the one's complement
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* sum of all 16-bit words in the buffer.
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*
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* See RFC1071.
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*
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* If CONFIG_NET_ARCH_CHKSUM is defined, then this function must be
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* provided by architecture-specific logic.
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*
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* Input Parameters:
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* sum - Partial calculations carried over from a previous call to
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* chksum(). This should be zero on the first time that check
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* sum is called.
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* iob - An iob chain buffer over which the checksum is to be computed.
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* offset - Specifies the byte offset of the start of valid data.
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*
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* Returned Value:
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* The Internet checksum of the given iob chain buffer.
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*
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****************************************************************************/
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#ifdef CONFIG_MM_IOB
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uint16_t net_chksum_iob(uint16_t sum, FAR struct iob_s *iob, uint16_t offset)
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{
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return HTONS(chksum_iob(sum, iob, offset));
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}
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#endif /* CONFIG_MM_IOB */
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/****************************************************************************
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* Name: net_chksum_adjust
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*
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* Description:
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* Adjusts the checksum of a packet without having to completely
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* recalculate it, as described in RFC 3022, Section 4.2, Page 9.
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*
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* Input Parameters:
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* chksum - points to the chksum in the packet
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* optr - points to the old data in the packet
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* olen - length of old data
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* nptr - points to the new data in the packet
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* nlen - length of new data
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*
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* Limitations:
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* The algorithm is applicable only for even offsets and even lengths.
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****************************************************************************/
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void net_chksum_adjust(FAR uint16_t *chksum,
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FAR const uint16_t *optr, ssize_t olen,
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FAR const uint16_t *nptr, ssize_t nlen)
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{
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int32_t x;
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int32_t oldval;
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int32_t newval;
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x = NTOHS(*chksum);
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x = ~x & 0xffff;
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while (olen > 0)
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{
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oldval = NTOHS(*optr);
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x -= oldval & 0xffff;
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if (x <= 0)
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{
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x--;
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x &= 0xffff;
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}
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optr++;
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olen -= 2;
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}
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while (nlen > 0)
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{
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newval = NTOHS(*nptr);
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x += newval & 0xffff;
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if ((x & 0x10000) != 0)
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{
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x++;
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x &= 0xffff;
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}
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nptr++;
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nlen -= 2;
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}
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x = ~x & 0xffff;
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*chksum = HTONS(x);
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}
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#endif /* CONFIG_NET */
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