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-rw-r--r--src/eyetil.cc29
-rw-r--r--src/eyetil.h3
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 @@
4#include <iostream> 4#include <iostream>
5#include <cassert> 5#include <cassert>
6#include <stdexcept> 6#include <stdexcept>
7#include <algorithm>
8#include <numeric>
7#include <openssl/md5.h> 9#include <openssl/md5.h>
8#include "eyetil.h" 10#include "eyetil.h"
9 11
10binary_t& binary_t::from_hex(const std::string& h) { 12binary_t& binary_t::from_hex(const std::string& h) {
11 /* TODO: algorithmize */
12 std::string::size_type hs = h.length(); 13 std::string::size_type hs = h.length();
13 if(hs&1) 14 if(hs&1)
14 throw std::runtime_error("odd number of characters in hexadecimal number"); 15 throw std::runtime_error("odd number of characters in hexadecimal number");
@@ -117,3 +118,29 @@ bool tarchive_t::read_data_into_fd(int fd) {
117 assert(a); 118 assert(a);
118 return archive_read_data_into_fd(a,fd)==ARCHIVE_OK; 119 return archive_read_data_into_fd(a,fd)==ARCHIVE_OK;
119} 120}
121
122#pragma pack(1)
123struct block512_t {
124 enum { words = 512 / sizeof(uint16_t) };
125 uint16_t data[words];
126
127 static uint16_t tcpcksum(block512_t& data) {
128 uint32_t sum = std::accumulate(data.data,data.data+words,0);
129 while(uint32_t hw = sum>>16) sum = (sum&0xffff)+hw;
130 return ~sum;
131 }
132
133};
134#pragma pack()
135
136binary_t integrity_digest(const void *ptr,size_t size,const std::string& ukey) {
137 binary_t key; key.from_hex(ukey);
138 std::vector<uint16_t> blksums; blksums.reserve(size/sizeof(block512_t));
139 block512_t *db = (block512_t*)ptr,
140 *de = db + size/sizeof(block512_t);
141 std::transform( db, de, std::back_inserter(blksums), block512_t::tcpcksum );
142 binary_t subject;
143 subject.from_data((void*)&(blksums.front()),blksums.size()*sizeof(uint16_t));
144 std::copy( key.begin(), key.end(), std::back_inserter(subject) );
145 return subject.md5();
146}
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 {
45 bool read_data_into_fd(int fd); 45 bool read_data_into_fd(int fd);
46}; 46};
47 47
48binary_t integrity_digest(const void *ptr,size_t size,
49 const std::string& ukey);
50
48#endif /* __EYETIL_H */ 51#endif /* __EYETIL_H */