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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 | // 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_csum static inline unsigned short from32to16(unsigned int x) { /* add up 16-bit and 16-bit for 16+c bit */ x = (x & 0xffff) + (x >> 16); /* add up carry.. */ x = (x & 0xffff) + (x >> 16); return x; } static 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 = 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); /* * copy from ds while checksumming, otherwise like csum_partial */ __wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum) { memcpy(dst, src, len); return csum_partial(dst, len, sum); } EXPORT_SYMBOL(csum_partial_copy); #ifndef csum_tcpudp_nofold static 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 |