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173 lines
4.1 KiB
173 lines
4.1 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* |
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* INET An implementation of the TCP/IP protocol suite for the LINUX |
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* operating system. INET is implemented using the BSD Socket |
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* interface as the means of communication with the user level. |
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* |
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* IP/TCP/UDP checksumming routines |
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* |
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* Authors: Jorge Cwik, <[email protected]> |
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* Arnt Gulbrandsen, <[email protected]> |
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* Tom May, <[email protected]> |
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* Andreas Schwab, <[email protected]> |
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* Lots of code moved from tcp.c and ip.c; see those files |
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* for more names. |
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* |
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* 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek: |
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* Fixed some nasty bugs, causing some horrible crashes. |
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* A: At some points, the sum (%0) was used as |
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* length-counter instead of the length counter |
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* (%1). Thanks to Roman Hodek for pointing this out. |
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* B: GCC seems to mess up if one uses too many |
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* data-registers to hold input values and one tries to |
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* specify d0 and d1 as scratch registers. Letting gcc |
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* choose these registers itself solves the problem. |
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*/ |
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/* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access |
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kills, so most of the assembly has to go. */ |
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#include <linux/export.h> |
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#include <net/checksum.h> |
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#include <asm/byteorder.h> |
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#ifndef do_csum |
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static inline unsigned short from32to16(unsigned int x) |
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{ |
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/* add up 16-bit and 16-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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static unsigned int do_csum(const unsigned char *buff, int len) |
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{ |
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int odd; |
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unsigned int result = 0; |
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if (len <= 0) |
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goto out; |
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odd = 1 & (unsigned long) buff; |
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if (odd) { |
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#ifdef __LITTLE_ENDIAN |
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result += (*buff << 8); |
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#else |
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result = *buff; |
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#endif |
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len--; |
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buff++; |
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} |
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if (len >= 2) { |
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if (2 & (unsigned long) buff) { |
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result += *(unsigned short *) buff; |
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len -= 2; |
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buff += 2; |
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} |
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if (len >= 4) { |
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const unsigned char *end = buff + ((unsigned)len & ~3); |
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unsigned int carry = 0; |
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do { |
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unsigned int w = *(unsigned int *) buff; |
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buff += 4; |
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result += carry; |
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result += w; |
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carry = (w > result); |
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} while (buff < end); |
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result += carry; |
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result = (result & 0xffff) + (result >> 16); |
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} |
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if (len & 2) { |
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result += *(unsigned short *) buff; |
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buff += 2; |
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} |
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} |
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if (len & 1) |
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#ifdef __LITTLE_ENDIAN |
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result += *buff; |
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#else |
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result += (*buff << 8); |
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#endif |
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result = from32to16(result); |
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if (odd) |
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result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); |
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out: |
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return result; |
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} |
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#endif |
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#ifndef ip_fast_csum |
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/* |
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* This is a version of ip_compute_csum() optimized for IP headers, |
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* which always checksum on 4 octet boundaries. |
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*/ |
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__sum16 ip_fast_csum(const void *iph, unsigned int ihl) |
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{ |
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return (__force __sum16)~do_csum(iph, ihl*4); |
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} |
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EXPORT_SYMBOL(ip_fast_csum); |
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#endif |
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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 wsum) |
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{ |
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unsigned int sum = (__force unsigned int)wsum; |
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unsigned int result = do_csum(buff, len); |
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/* add in old sum, and carry.. */ |
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result += sum; |
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if (sum > result) |
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result += 1; |
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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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#ifndef csum_tcpudp_nofold |
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static inline u32 from64to32(u64 x) |
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{ |
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/* add up 32-bit and 32-bit for 32+c bit */ |
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x = (x & 0xffffffff) + (x >> 32); |
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/* add up carry.. */ |
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x = (x & 0xffffffff) + (x >> 32); |
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return (u32)x; |
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} |
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__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, |
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__u32 len, __u8 proto, __wsum sum) |
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{ |
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unsigned long long s = (__force u32)sum; |
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s += (__force u32)saddr; |
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s += (__force u32)daddr; |
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#ifdef __BIG_ENDIAN |
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s += proto + len; |
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#else |
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s += (proto + len) << 8; |
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#endif |
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return (__force __wsum)from64to32(s); |
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} |
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EXPORT_SYMBOL(csum_tcpudp_nofold); |
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#endif
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