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-rw-r--r--src/eyetil.cc29
1 files changed, 28 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
@@ -3,13 +3,14 @@
#include <syslog.h>
#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");
int rvs = hs>>1;
@@ -116,4 +117,30 @@ std::string tarchive_t::entry_pathname() {
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();
+}