| -rw-r--r-- | src/eyetil.cc | 29 | ||||
| -rw-r--r-- | src/eyetil.h | 3 |
2 files changed, 31 insertions, 1 deletions
diff --git a/src/eyetil.cc b/src/eyetil.cc index 2fbd687..fe816a6 100644 --- a/src/eyetil.cc +++ b/src/eyetil.cc @@ -4,11 +4,12 @@ #include <iostream> #include <cassert> #include <stdexcept> +#include <algorithm> +#include <numeric> #include <openssl/md5.h> #include "eyetil.h" binary_t& binary_t::from_hex(const std::string& h) { - /* TODO: algorithmize */ std::string::size_type hs = h.length(); if(hs&1) throw std::runtime_error("odd number of characters in hexadecimal number"); @@ -117,3 +118,29 @@ bool tarchive_t::read_data_into_fd(int fd) { assert(a); return archive_read_data_into_fd(a,fd)==ARCHIVE_OK; } + +#pragma pack(1) +struct block512_t { + enum { words = 512 / sizeof(uint16_t) }; + uint16_t data[words]; + + static uint16_t tcpcksum(block512_t& data) { + uint32_t sum = std::accumulate(data.data,data.data+words,0); + while(uint32_t hw = sum>>16) sum = (sum&0xffff)+hw; + return ~sum; + } + +}; +#pragma pack() + +binary_t integrity_digest(const void *ptr,size_t size,const std::string& ukey) { + binary_t key; key.from_hex(ukey); + std::vector<uint16_t> blksums; blksums.reserve(size/sizeof(block512_t)); + block512_t *db = (block512_t*)ptr, + *de = db + size/sizeof(block512_t); + std::transform( db, de, std::back_inserter(blksums), block512_t::tcpcksum ); + binary_t subject; + subject.from_data((void*)&(blksums.front()),blksums.size()*sizeof(uint16_t)); + std::copy( key.begin(), key.end(), std::back_inserter(subject) ); + return subject.md5(); +} diff --git a/src/eyetil.h b/src/eyetil.h index 195d24f..378f703 100644 --- a/src/eyetil.h +++ b/src/eyetil.h @@ -45,4 +45,7 @@ class tarchive_t { bool read_data_into_fd(int fd); }; +binary_t integrity_digest(const void *ptr,size_t size, + const std::string& ukey); + #endif /* __EYETIL_H */ |