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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 | /* * 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> * Lots of code moved from tcp.c and ip.c; see those files * for more names. * * Adapted for PowerPC by Gary Thomas <gdt@mc.com> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <net/checksum.h> /* * 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 */ unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum) { unsigned long result = ~_csum_partial(buff, len, sum); #if 0 printk("Csum partial(%x, %d, %x) = %x\n", buff, len, sum, result); dump_buf(buff, len); #endif return result; } /* * the same as csum_partial, but copies from src while it * checksums * * here even more important to align src and dst on a 32-bit boundary */ unsigned int csum_partial_copy(const char *src, char *dst, int len, int sum) { /* * The whole idea is to do the copy and the checksum at * the same time, but we do it the easy way now. * * At least csum on the source, not destination, for cache * reasons.. */ sum = csum_partial(src, len, sum); memcpy(dst, src, len); return sum; } extern unsigned short _ip_fast_csum(unsigned char *buf); unsigned short ip_fast_csum(unsigned char *buf, unsigned int len) { unsigned short _val; _val = _ip_fast_csum(buf); #if 0 printk("IP CKSUM(%x, %d) = %x\n", buf, len, _val); dump_buf(buf, len*4); #endif return (_val); } extern unsigned short _ip_compute_csum(unsigned char *buf, int len); unsigned short ip_compute_csum(unsigned char *buf, int len) { unsigned short _val; _val = _ip_compute_csum(buf, len); #if 0 printk("Compute IP CKSUM(%x, %d) = %x\n", buf, len, _val); dump_buf(buf, len); #endif return (_val); } unsigned short _udp_check(unsigned char *buf, int len, int saddr, int daddr, int hdr); unsigned short udp_check(unsigned char *buf, int len, int saddr, int daddr) { unsigned short _val; int hdr; hdr = (len << 16) + IPPROTO_UDP; _val = _udp_check(buf, len, saddr, daddr, hdr); #if 0 printk("UDP CSUM(%x,%d,%x,%x) = %x\n", buf, len, saddr, daddr, _val); dump_buf(buf, len); #endif return (_val); } unsigned short _tcp_check(unsigned char *buf, int len, int saddr, int daddr, int hdr); unsigned short csum_tcpudp_magic(unsigned long saddr, unsigned long daddr, unsigned short len, unsigned short proto, unsigned int sum) { unsigned short _val; _val = _csum_tcpudp_magic(saddr, daddr, sum, (len<<16)+proto); #if 0 printk("TCP Magic(%x, %x, %x, %x) = %x\n", saddr, daddr, (len<<16)+proto, sum, _val); #endif return (_val); } /* * Fold a partial checksum without adding pseudo headers */ unsigned short csum_fold(unsigned int sum) { sum = (sum & 0xffff) + (sum >> 16); sum = (sum & 0xffff) + (sum >> 16); return ~sum; } |