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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 | /* * Network checksum routines * * Copyright (C) 1999 Hewlett-Packard Co * Copyright (C) 1999 Stephane Eranian <eranian@hpl.hp.com> * * Most of the code coming from arch/alpha/lib/checksum.c * * This file contains network checksum routines that are better done * in an architecture-specific manner due to speed.. */ #include <linux/string.h> #include <asm/byteorder.h> static inline unsigned short from64to16(unsigned long x) { /* add up 32-bit words for 33 bits */ x = (x & 0xffffffff) + (x >> 32); /* add up 16-bit and 17-bit words for 17+c bits */ x = (x & 0xffff) + (x >> 16); /* add up 16-bit and 2-bit for 16+c bit */ x = (x & 0xffff) + (x >> 16); /* add up carry.. */ x = (x & 0xffff) + (x >> 16); return x; } /* * computes the checksum of the TCP/UDP pseudo-header * returns a 16-bit checksum, already complemented. */ unsigned short int csum_tcpudp_magic(unsigned long saddr, unsigned long daddr, unsigned short len, unsigned short proto, unsigned int sum) { return ~from64to16(saddr + daddr + sum + ((unsigned long) ntohs(len) << 16) + ((unsigned long) proto << 8)); } unsigned int csum_tcpudp_nofold(unsigned long saddr, unsigned long daddr, unsigned short len, unsigned short proto, unsigned int sum) { unsigned long result; result = (saddr + daddr + sum + ((unsigned long) ntohs(len) << 16) + ((unsigned long) proto << 8)); /* Fold down to 32-bits so we don't loose in the typedef-less network stack. */ /* 64 to 33 */ result = (result & 0xffffffff) + (result >> 32); /* 33 to 32 */ result = (result & 0xffffffff) + (result >> 32); return result; } extern unsigned long do_csum(const unsigned char *, unsigned int, unsigned int); extern unsigned long do_csum_c(const unsigned char *, unsigned int, unsigned int); /* * This is a version of ip_compute_csum() optimized for IP headers, * which always checksum on 4 octet boundaries. */ unsigned short ip_fast_csum(unsigned char * iph, unsigned int ihl) { return ~do_csum(iph,ihl*4,0); } /* * 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 = do_csum(buff, len, 0); /* add in old sum, and carry.. */ result += sum; /* 32+c bits -> 32 bits */ result = (result & 0xffffffff) + (result >> 32); return result; } /* * this routine is used for miscellaneous IP-like checksums, mainly * in icmp.c */ unsigned short ip_compute_csum(unsigned char * buff, int len) { return ~do_csum(buff,len, 0); } |