213 lines
7.2 KiB
C
213 lines
7.2 KiB
C
/*
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* pibs - Passive Identification of BackScatter
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*
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* Copyright (C) 2019 Gerard Wagener
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* Copyright (C) 2019 CIRCL Computer Incident Response Center Luxembourg
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* (SMILE gie).
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "pibs.h"
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//TODO when attaching the next_item must be recovered if results
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//of previous runs need to be increased
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/*
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* Returns -1 if not found
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* returns last timestamp if found
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*/
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int_fast64_t get_last_timestamp(pibs_t* pibs, uint32_t ip)
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{
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uint32_t idx;
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uint32_t i;
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//TODO explore alternative hashing functions
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//https://stackoverflow.com/questions/664014/what-integer-hash-function-are-good-that-accepts-an-integer-hash-key/12996028#12996028
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idx = ip % NBINS;
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HDBG("[TS] Checking for IP %x at index = %d\n", ip, idx);
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i = pibs->bin_table[idx];
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while (i){
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if (pibs->items[i].ipaddr == ip) {
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HDBG("[TS] Found item %x at position %d\n", ip , i);
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return pibs->items[i].timestamp;
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}
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i = pibs->items[i].next_item;
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}
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HDBG("[TS] IP: %x was not found return -1\n",ip);
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return -1;
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}
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void insert_ip(pibs_t* pibs, uint32_t ip, uint32_t ts)
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{
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uint32_t idx;
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uint32_t i;
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uint32_t parent;
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idx = ip % NBINS;
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HDBG("[INS] Lookup IP address %x. Hashed value: %d\n", ip, idx);
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parent = 0;
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if (pibs->bin_table[idx]){
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// There is already someone in the bin
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i = pibs->bin_table[idx];
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HDBG("[INS] Starting searching at position %d\n", i);
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do {
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HDBG("[INS] Iterating items at index %d. Current position: %d.\
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Next position = %d\n",
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idx,i,pibs->items[i].next_item);
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HDBG("[INS] Checking IP at address %p\n",&pibs->items[i]);
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if (pibs->items[i].ipaddr == ip) {
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HDBG("[INS] Found item %x at position %d\n", ip , i);
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HDBG("[INS] New timestamp for ip %x is %d\n",ip,ts);
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pibs->items[i].timestamp = ts;
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return;
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}
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parent = i;
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i = pibs->items[i].next_item;
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} while (i != 0 );
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HDBG("[INS] The IP %x was not found in the item list, last parent %d\n",
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ip, parent);
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}
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// The IP was not found in an item list or the hashed value wsa not present
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// in the bin table, so create a new item
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pibs->next_item++;
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if (pibs->next_item > pibs->max_item) {
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printf("FIXME run out of memory. Do something better than abort\n");
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//Go through old timestamps and keep linked list of stuff that can be
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//reused or do kind of defragmentation
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abort();
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}
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if (pibs->bin_table[idx] == 0) {
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pibs->bin_table[idx] = pibs->next_item;
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}
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HDBG("[INS] Insert ip %x at position %d, parent = %d\n", ip,
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pibs->next_item,parent);
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pibs->items[pibs->next_item].ipaddr = ip;
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pibs->items[pibs->next_item].timestamp = ts;
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if (parent) {
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pibs->items[parent].next_item = pibs->next_item;
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}
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}
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void pibs_dump_raw(pibs_t* pibs)
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{
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int i;
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printf("#RAW table dump\n");
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printf("#Index next_item\n");
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printf("#BINs\n");
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for (i=0; i< NBINS; i++) {
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printf("%d %d\n", i, pibs->bin_table[i]);
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}
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printf("#ITEMS\n");
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printf("#Index next_item, timestamp, ipaddr\n");
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for (i=0; i < NBINITEMS * NBINS; i++) {
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printf("%d %d %d %x\n", i, pibs->items[i].next_item,
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pibs->items[i].timestamp,
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pibs->items[i].ipaddr);
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}
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}
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void pibs_dump_stats(pibs_t* pibs)
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{
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int i;
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int j;
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int cnt;
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uint64_t sum;
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sum = 0;
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printf("#Bin table\n");
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printf("#Bin number, Item offset, number of items\n");
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for (i=0; i < NBINS; i++) {
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j= pibs->bin_table[i];
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cnt = 0;
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while (j) {
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cnt++;
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j=pibs->items[j].next_item;
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}
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sum+=cnt;
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printf("%d %d %d\n", i, pibs->bin_table[i], cnt);
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}
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printf("#Number of unique IP addresses: %ld\n", sum);
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}
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void synseen_process_frame(pibs_t *pibs, wtap *wth, uint8_t* eth,
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struct ip* ipv4, struct tcphdr* tcp)
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{
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synseen_callback_t synseen_callback;
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int_fast64_t lastseen;
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uint32_t ip;
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struct pcap_pkthdr pchdr;
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memcpy(&ip, &ipv4->ip_src, 4);
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if (!pibs->bypass) {
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// Record only source ips where syn flag is set
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// TODO check other connection establishment alternatives
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if (tcp->th_flags == 2 ){
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insert_ip(pibs, ip, wth->rec.ts.secs);
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return;
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}
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lastseen = get_last_timestamp(pibs, ip);
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if (lastseen > 0){
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HDBG("IP %x %s was already seen before at %ld. Time difference %ld.\n"
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, ip, inet_ntoa(ipv4->ip_src), lastseen, wth->rec.ts.secs-lastseen);
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return;
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}
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// TODO keep these IPs in a hashtable and rank them
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if (pibs->show_backscatter) {
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printf("%ld,%s,%d,%d\n",
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wth->rec.ts.secs, inet_ntoa(ipv4->ip_src), tcp->th_flags,
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ntohs(tcp->th_sport));
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}
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//TODO relative time
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//Purge old ips?
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if (pibs->should_writepcap) {
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pchdr.ts.tv_sec = wth->rec.ts.secs;
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//TODO other part of the timestamp
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pchdr.ts.tv_usec = wth->rec.ts.nsecs / 1000;
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pchdr.caplen = wth->rec.rec_header.packet_header.caplen;
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pchdr.len = wth->rec.rec_header.packet_header.len;
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pcap_dump((u_char*)pibs->dumper, &pchdr, eth);
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}
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}
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if (pibs->synseen_callback) {
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synseen_callback = pibs->synseen_callback;
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synseen_callback(pibs, wth, eth, ipv4, tcp);
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}
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}
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int synseen_init(pibs_t* pibs)
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{
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pibs->data_size = sizeof(pibs_header_t) + NBINSCALE * NBINS * SZBIN * NBINITEMS * sizeof(item_t);
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pibs->data = calloc(pibs->data_size,1);
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printf("#Internal look up structure size in bytes: %ld\n", pibs->data_size);
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// Build header
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pibs->data[0]='P';
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pibs->data[1] = 'I';
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pibs->data[2] = 'B';
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pibs->data[3] = 'S';
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pibs->data[4] = 1; //version 1
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pibs->next_block = sizeof(pibs_header_t);
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pibs->bin_offset = pibs->next_block;
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printf("#data address is %p\n",pibs->data);
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pibs->bin_table = (uint32_t*)(pibs->data+pibs->bin_offset);
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printf("#bin_table address is %p\n", pibs->bin_table);
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// Create bins
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pibs->next_block+=SZBIN * NBINS;
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printf("#next block %d\n", pibs->next_block);
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pibs->items = (item_t*)(pibs->data+pibs->next_block);
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pibs->next_item = 0;
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printf("#items are address %p\n", pibs->items);
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pibs->max_item = NBINS * NBINITEMS;
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printf("#max_item: %d\n", pibs->max_item);
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return 1;
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}
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