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102 lines
2.5 KiB
102 lines
2.5 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Network checksum routines |
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* |
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* Copyright (C) 1999, 2003 Hewlett-Packard Co |
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* Stephane Eranian <[email protected]> |
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* |
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* Most of the code coming from arch/alpha/lib/checksum.c |
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* |
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* This file contains network checksum routines that are better done |
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* in an architecture-specific manner due to speed.. |
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*/ |
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#include <linux/module.h> |
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#include <linux/string.h> |
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#include <asm/byteorder.h> |
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static inline unsigned short |
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from64to16 (unsigned long x) |
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{ |
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/* add up 32-bit words for 33 bits */ |
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x = (x & 0xffffffff) + (x >> 32); |
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/* add up 16-bit and 17-bit words for 17+c bits */ |
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x = (x & 0xffff) + (x >> 16); |
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/* add up 16-bit and 2-bit for 16+c bit */ |
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x = (x & 0xffff) + (x >> 16); |
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/* add up carry.. */ |
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x = (x & 0xffff) + (x >> 16); |
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return x; |
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} |
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/* |
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* computes the checksum of the TCP/UDP pseudo-header |
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* returns a 16-bit checksum, already complemented. |
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*/ |
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__sum16 |
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csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, |
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__u8 proto, __wsum sum) |
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{ |
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return (__force __sum16)~from64to16( |
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(__force u64)saddr + (__force u64)daddr + |
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(__force u64)sum + ((len + proto) << 8)); |
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} |
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EXPORT_SYMBOL(csum_tcpudp_magic); |
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__wsum |
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csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, |
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__u8 proto, __wsum sum) |
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{ |
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unsigned long result; |
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result = (__force u64)saddr + (__force u64)daddr + |
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(__force u64)sum + ((len + proto) << 8); |
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/* Fold down to 32-bits so we don't lose in the typedef-less network stack. */ |
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/* 64 to 33 */ |
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result = (result & 0xffffffff) + (result >> 32); |
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/* 33 to 32 */ |
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result = (result & 0xffffffff) + (result >> 32); |
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return (__force __wsum)result; |
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} |
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EXPORT_SYMBOL(csum_tcpudp_nofold); |
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extern unsigned long do_csum (const unsigned char *, long); |
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/* |
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* computes the checksum of a memory block at buff, length len, |
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* and adds in "sum" (32-bit) |
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* |
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* returns a 32-bit number suitable for feeding into itself |
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* or csum_tcpudp_magic |
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* |
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* this function must be called with even lengths, except |
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* for the last fragment, which may be odd |
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* |
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* it's best to have buff aligned on a 32-bit boundary |
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*/ |
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__wsum csum_partial(const void *buff, int len, __wsum sum) |
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{ |
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u64 result = do_csum(buff, len); |
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/* add in old sum, and carry.. */ |
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result += (__force u32)sum; |
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/* 32+c bits -> 32 bits */ |
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result = (result & 0xffffffff) + (result >> 32); |
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return (__force __wsum)result; |
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} |
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EXPORT_SYMBOL(csum_partial); |
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/* |
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* this routine is used for miscellaneous IP-like checksums, mainly |
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* in icmp.c |
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*/ |
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__sum16 ip_compute_csum (const void *buff, int len) |
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{ |
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return (__force __sum16)~do_csum(buff,len); |
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} |
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EXPORT_SYMBOL(ip_compute_csum);
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