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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165// SPDX-License-Identifier: GPL-2.0-or-later/* * * INET An implementation of the TCP/IP protocol suite for the LINUX * operating system. INET is implemented using the BSD Socket * interface as the means of communication with the user level. * * IP/TCP/UDP checksumming routines * * Authors: Jorge Cwik, <jorge@laser.satlink.net> * Arnt Gulbrandsen, <agulbra@nvg.unit.no> * Tom May, <ftom@netcom.com> * Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de> * Lots of code moved from tcp.c and ip.c; see those files * for more names. * * 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek: * Fixed some nasty bugs, causing some horrible crashes. * A: At some points, the sum (%0) was used as * length-counter instead of the length counter * (%1). Thanks to Roman Hodek for pointing this out. * B: GCC seems to mess up if one uses too many * data-registers to hold input values and one tries to * specify d0 and d1 as scratch registers. Letting gcc * choose these registers itself solves the problem. */
/* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access kills, so most of the assembly has to go. */
#include <linux/export.h>#include <net/checksum.h>
#include <asm/byteorder.h>
#ifndef do_csumstatic unsigned int do_csum(const unsigned char *buff, int len){ int odd; unsigned int result = 0;
if (len <= 0) goto out; odd = 1 & (unsigned long) buff; if (odd) {#ifdef __LITTLE_ENDIAN result += (*buff << 8);#else result = *buff;#endif len--; buff++; } if (len >= 2) { if (2 & (unsigned long) buff) { result += *(unsigned short *) buff; len -= 2; buff += 2; } if (len >= 4) { const unsigned char *end = buff + ((unsigned)len & ~3); unsigned int carry = 0; do { unsigned int w = *(unsigned int *) buff; buff += 4; result += carry; result += w; carry = (w > result); } while (buff < end); result += carry; result = (result & 0xffff) + (result >> 16); } if (len & 2) { result += *(unsigned short *) buff; buff += 2; } } if (len & 1)#ifdef __LITTLE_ENDIAN result += *buff;#else result += (*buff << 8);#endif result = csum_from32to16(result); if (odd) result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);out: return result;}#endif
#ifndef ip_fast_csum/* * This is a version of ip_compute_csum() optimized for IP headers, * which always checksum on 4 octet boundaries. */__sum16 ip_fast_csum(const void *iph, unsigned int ihl){ return (__force __sum16)~do_csum(iph, ihl*4);}EXPORT_SYMBOL(ip_fast_csum);#endif
/* * computes the checksum of a memory block at buff, length len, * and adds in "sum" (32-bit) * * returns a 32-bit number suitable for feeding into itself * or csum_tcpudp_magic * * this function must be called with even lengths, except * for the last fragment, which may be odd * * it's best to have buff aligned on a 32-bit boundary */__wsum csum_partial(const void *buff, int len, __wsum wsum){ unsigned int sum = (__force unsigned int)wsum; unsigned int result = do_csum(buff, len);
/* add in old sum, and carry.. */ result += sum; if (sum > result) result += 1; return (__force __wsum)result;}EXPORT_SYMBOL(csum_partial);
/* * this routine is used for miscellaneous IP-like checksums, mainly * in icmp.c */__sum16 ip_compute_csum(const void *buff, int len){ return (__force __sum16)~do_csum(buff, len);}EXPORT_SYMBOL(ip_compute_csum);
#ifndef csum_tcpudp_nofoldstatic inline u32 from64to32(u64 x){ /* add up 32-bit and 32-bit for 32+c bit */ x = (x & 0xffffffff) + (x >> 32); /* add up carry.. */ x = (x & 0xffffffff) + (x >> 32); return (u32)x;}
__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 proto, __wsum sum){ unsigned long long s = (__force u32)sum;
s += (__force u32)saddr; s += (__force u32)daddr;#ifdef __BIG_ENDIAN s += proto + len;#else s += (proto + len) << 8;#endif return (__force __wsum)from64to32(s);}EXPORT_SYMBOL(csum_tcpudp_nofold);#endif