1 /* 2 * INET An implementation of the TCP/IP protocol suite for the LINUX 3 * operating system. INET is implemented using the BSD Socket 4 * interface as the means of communication with the user level. 5 * 6 * Checksumming functions for IP, TCP, UDP and so on 7 * 8 * Authors: Jorge Cwik, <jorge@laser.satlink.net> 9 * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 10 * Borrows very liberally from tcp.c and ip.c, see those 11 * files for more names. 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License 15 * as published by the Free Software Foundation; either version 16 * 2 of the License, or (at your option) any later version. 17 */ 18 19 #ifndef _CHECKSUM_H 20 #define _CHECKSUM_H 21 22 #include <linux/errno.h> 23 #include <asm/types.h> 24 #include <asm/byteorder.h> 25 #include <asm/uaccess.h> 26 #include <asm/checksum.h> 27 28 #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER 29 static inline 30 unsigned int csum_and_copy_from_user (const unsigned char __user *src, unsigned char *dst, 31 int len, int sum, int *err_ptr) 32 { 33 if (access_ok(VERIFY_READ, src, len)) 34 return csum_partial_copy_from_user(src, dst, len, sum, err_ptr); 35 36 if (len) 37 *err_ptr = -EFAULT; 38 39 return sum; 40 } 41 #endif 42 43 #ifndef HAVE_CSUM_COPY_USER 44 static __inline__ unsigned int csum_and_copy_to_user 45 (const unsigned char *src, unsigned char __user *dst, int len, unsigned int sum, int *err_ptr) 46 { 47 sum = csum_partial(src, len, sum); 48 49 if (access_ok(VERIFY_WRITE, dst, len)) { 50 if (copy_to_user(dst, src, len) == 0) 51 return sum; 52 } 53 if (len) 54 *err_ptr = -EFAULT; 55 56 return -1; /* invalid checksum */ 57 } 58 #endif 59 60 static inline unsigned int csum_add(unsigned int csum, unsigned int addend) 61 { 62 csum += addend; 63 return csum + (csum < addend); 64 } 65 66 static inline unsigned int csum_sub(unsigned int csum, unsigned int addend) 67 { 68 return csum_add(csum, ~addend); 69 } 70 71 static inline unsigned int 72 csum_block_add(unsigned int csum, unsigned int csum2, int offset) 73 { 74 if (offset&1) 75 csum2 = ((csum2&0xFF00FF)<<8)+((csum2>>8)&0xFF00FF); 76 return csum_add(csum, csum2); 77 } 78 79 static inline unsigned int 80 csum_block_sub(unsigned int csum, unsigned int csum2, int offset) 81 { 82 if (offset&1) 83 csum2 = ((csum2&0xFF00FF)<<8)+((csum2>>8)&0xFF00FF); 84 return csum_sub(csum, csum2); 85 } 86 87 #endif 88