hash

src/Notes.md

@@ -1 +1,4 @@
 # Notes et recherches sur le projet
+
+Telecharger la librarie OpenSSl avec 'sudo apt-get install libssl-dev'
+Utiliser 'gcc -o {exec} {fichier.c} -lssl -lcrypto' pour utiliser la librarie OpenSSL

src/hash.c

@@ -0,0 +1,60 @@
+#include "hash.h"
+
+// Hash a single data
+void hash_data(pub_data *data, unsigned char *buf) {
+	// All three fields are concatenated into a single buffer
+	int totlen = data->length + 10;
+	unsigned char concat[totlen];
+	concat_data(data, concat);
+
+	// The resulting buf is hashed and put into a buffer
+	unsigned char hash[SHA256_DIGEST_LENGTH];
+	SHA256(concat, totlen, hash);
+
+	// Put truncated hash into buf 
+	hash_trunc(hash, buf);
+}
+
+// Hash every data contained in data_list then return a network hash
+void hash_network(list *data_list, unsigned char *buf) {
+	unsigned char *concat = (unsigned char*) malloc(0);
+	unsigned char hash[SHA256_DIGEST_LENGTH];
+	int totlen = 0;
+	list *tmp = data_list;
+
+	// Hash every known data and concatenate it to buffer concat
+	while(tmp != NULL) {
+		hash_data((pub_data*) tmp->data, hash);
+		concat_hash(concat, hash, totlen);
+		totlen += 16;
+		tmp = tmp->next;
+	}
+
+	// Hash all of concat to obtain the network hash
+	SHA256(concat, totlen, hash);
+
+	// Put truncated hash into buf 
+	hash_trunc(hash, buf);
+
+	// Get rid of concat
+	free(concat);
+}
+
+// Truncate 32 octet hash to 16 octets
+void hash_trunc(unsigned char *hash32oct, unsigned char *buf) {
+	// Copy the first 16 octets from hash32oct
+	memcpy(buf, hash32oct, 16);
+}
+
+// Concat all fields of data and put them in buf
+void concat_data(pub_data *data, unsigned char *buf) {
+	memcpy(buf, &(data->id), 8);
+	memcpy(buf+8, &(data->seqno), 2);
+	memcpy(buf+10, data->data, data->length);
+}
+
+// Concat hash2 to hash1 (hash1 is modified)
+void concat_hash(unsigned char *hash1, unsigned char *hash2, size_t size) {
+	hash1 = (unsigned char*) realloc(hash1, size + 16);
+	memcpy(hash1+size, hash2, 16);
+}

src/hash.h

@@ -0,0 +1,23 @@
+#ifndef HASH_H
+#define HASH_H
+
+#include <openssl/sha.h>
+#include "node.h"
+#include "tlv.h"
+
+// Hash a single data
+void hash_data(pub_data *data, unsigned char *buf);
+
+// Hash every data contained in data_list then return a network hash
+void hash_network(list *data_list, unsigned char *buf);
+
+// Truncate 32 octet hash to 16 octets
+void hash_trunc(unsigned char *hash256bit, unsigned char *buf);
+
+// Concat all fields of data and put them in buf
+void concat_data(pub_data *data, unsigned char *buf);
+
+// Concat hash2 to hash1 (hash1 is modified)
+void concat_hash(unsigned char *hash1, unsigned char *hash2, size_t size);
+
+#endif

src/node.c

@@ -1,13 +1,5 @@
 // This is the main file of the Dazibao project. It represents the node, and
 // handles all of the main logic, including the network connexions.
-#include <stdlib.h>
-#include <stdio.h>
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netinet/in.h>
-#include <string.h>
-
-#include "tlv.h"
 #include "node.h"
 
 // For every packet recivied,

src/node.h

@@ -3,8 +3,15 @@
 #ifndef NODE_H
 #define NODE_H
 
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <string.h>
+
 #include "tlv.h"
-#include "misc.h"
+#include "hash.h"
 
 // On which port do we listen to
 #define LISTEN_PORT 1212
@@ -42,6 +49,12 @@ typedef struct pub_data {
     char *data;
 } pub_data;
 
+// General list
+typedef struct list {
+	void *data;
+	void *next;	
+} list;
+
 // static lists
 static list *data_list; 
 static list *neighbour_list;