/* * 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. * * Checksumming functions for IP, TCP, UDP and so on * * Authors: Jorge Cwik, <jorge@laser.satlink.net> * Arnt Gulbrandsen, <agulbra@nvg.unit.no> * Borrows very liberally from tcp.c and ip.c, see those * files for more names. * * 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. */ #ifndef _CHECKSUM_H #define _CHECKSUM_H #include <linux/errno.h> #include <asm/types.h> #include <asm/byteorder.h> #include <linux/uaccess.h> #include <asm/checksum.h> #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER static inline __wsum csum_and_copy_from_user (const void __user *src, void *dst, int len, __wsum sum, int *err_ptr) { if (access_ok(VERIFY_READ, src, len)) return csum_partial_copy_from_user(src, dst, len, sum, err_ptr); if (len) *err_ptr = -EFAULT; return sum; } #endif #ifndef HAVE_CSUM_COPY_USER static __inline__ __wsum csum_and_copy_to_user (const void *src, void __user *dst, int len, __wsum sum, int *err_ptr) { sum = csum_partial(src, len, sum); if (access_ok(VERIFY_WRITE, dst, len)) { if (copy_to_user(dst, src, len) == 0) return sum; } if (len) *err_ptr = -EFAULT; return (__force __wsum)-1; /* invalid checksum */ } #endif #ifndef HAVE_ARCH_CSUM_ADD static inline __wsum csum_add(__wsum csum, __wsum addend) { u32 res = (__force u32)csum; res += (__force u32)addend; return (__force __wsum)(res + (res < (__force u32)addend)); } #endif static inline __wsum csum_sub(__wsum csum, __wsum addend) { return csum_add(csum, ~addend); } static inline __sum16 csum16_add(__sum16 csum, __be16 addend) { u16 res = (__force u16)csum; res += (__force u16)addend; return (__force __sum16)(res + (res < (__force u16)addend)); } static inline __sum16 csum16_sub(__sum16 csum, __be16 addend) { return csum16_add(csum, ~addend); } static inline __wsum csum_block_add(__wsum csum, __wsum csum2, int offset) { u32 sum = (__force u32)csum2; /* rotate sum to align it with a 16b boundary */ if (offset & 1) sum = ror32(sum, 8); return csum_add(csum, (__force __wsum)sum); } static inline __wsum csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len) { return csum_block_add(csum, csum2, offset); } static inline __wsum csum_block_sub(__wsum csum, __wsum csum2, int offset) { return csum_block_add(csum, ~csum2, offset); } static inline __wsum csum_unfold(__sum16 n) { return (__force __wsum)n; } static inline __wsum csum_partial_ext(const void *buff, int len, __wsum sum) { return csum_partial(buff, len, sum); } #define CSUM_MANGLED_0 ((__force __sum16)0xffff) static inline void csum_replace_by_diff(__sum16 *sum, __wsum diff) { *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum))); } static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to) { __wsum tmp = csum_sub(~csum_unfold(*sum), (__force __wsum)from); *sum = csum_fold(csum_add(tmp, (__force __wsum)to)); } /* Implements RFC 1624 (Incremental Internet Checksum) * 3. Discussion states : * HC' = ~(~HC + ~m + m') * m : old value of a 16bit field * m' : new value of a 16bit field */ static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new) { *sum = ~csum16_add(csum16_sub(~(*sum), old), new); } struct sk_buff; void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, __be32 from, __be32 to, bool pseudohdr); void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb, const __be32 *from, const __be32 *to, bool pseudohdr); void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb, __wsum diff, bool pseudohdr); static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb, __be16 from, __be16 to, bool pseudohdr) { inet_proto_csum_replace4(sum, skb, (__force __be32)from, (__force __be32)to, pseudohdr); } static inline __wsum remcsum_adjust(void *ptr, __wsum csum, int start, int offset) { __sum16 *psum = (__sum16 *)(ptr + offset); __wsum delta; /* Subtract out checksum up to start */ csum = csum_sub(csum, csum_partial(ptr, start, 0)); /* Set derived checksum in packet */ delta = csum_sub((__force __wsum)csum_fold(csum), (__force __wsum)*psum); *psum = csum_fold(csum); return delta; } static inline void remcsum_unadjust(__sum16 *psum, __wsum delta) { *psum = csum_fold(csum_sub(delta, (__force __wsum)*psum)); } #endif