added md5 checksum generation and salt generation

Makefile

@@ -2,9 +2,9 @@ VERSION=1.1.9
 
 CFLAGS+= -O2 -Wall -Wextra -Wshadow -rdynamic\
 	-D_FILE_OFFSET_BITS=64 -DVERSION=\"$(VERSION)\" \
-	`pkg-config --cflags-only-I gumbo libcurl fuse`
-LIBS = -pthread -lgumbo -lcurl -lfuse -lcrypto
-COBJS = main.o network.o fuse_local.o link.o cache.o util.o
+	`pkg-config --cflags-only-I gumbo libcurl fuse uuid`
+LIBS = -pthread -lgumbo -lcurl -lfuse -lcrypto -luuid
+COBJS = network.o fuse_local.o link.o cache.o util.o sonic.o
 
 prefix ?= /usr/local
 

src/link.c

@@ -172,7 +172,7 @@ void Link_req_file_stat(Link *this_link)
      *
      * It gets freed in curl_multi_perform_once();
      */
-    TransferStruct *transfer = malloc(sizeof(TransferStruct));
+    TransferStruct *transfer = calloc(1, sizeof(TransferStruct));
     if (!transfer) {
         fprintf(stderr, "Link_get_size(): malloc failed!\n");
         exit_failure();

src/sonic.c

@@ -0,0 +1,57 @@
+#include "util.h"
+
+#include <openssl/md5.h>
+#include <uuid/uuid.h>
+
+#include <string.h>
+#include <stdlib.h>
+
+#define MD5_HASH_LEN 32
+#define SALT_LEN 36
+/**
+ * \brief generate the salt for authentication string
+ * \details this effectively generates a UUID string, which we use as the salt
+ * \return a pointer to a 37-char array with the salt.
+ */
+char *generate_salt()
+{
+    char *out;
+    out = calloc(SALT_LEN + 1, sizeof(char));
+    uuid_t uu;
+    uuid_generate(uu);
+    uuid_unparse(uu, out);
+    return out;
+}
+
+/**
+ * \brief generate the md5sum of a string
+ * \param[in] str a character array for the input string
+ * \return a pointer to a 33-char array with the salt
+ */
+char *generate_md5sum(const char *str)
+{
+    MD5_CTX c;
+    unsigned char md5[MD5_DIGEST_LENGTH];
+    size_t len = strnlen(str, MAX_PATH_LEN);
+    char *out = calloc(MD5_HASH_LEN + 1, sizeof(char));
+
+    MD5_Init(&c);
+    MD5_Update(&c, str, len);
+    MD5_Final(md5, &c);
+
+    for(int i = 0; i < MD5_DIGEST_LENGTH; i++) {
+        sprintf(out + 2 * i, "%02x", md5[i]);
+    }
+    return out;
+}
+
+int main(int argc, char **argv)
+{
+    (void) argc;
+    (void) argv;
+
+    char *salt = generate_salt();
+    char *md5sum = generate_md5sum(salt);
+
+    printf("%s\n%s\n", salt, md5sum);
+}

src/sonic.h

@@ -0,0 +1,4 @@
+#ifndef SONIC_H
+#define SONIC_H
+
+#endif

src/util.h

@@ -15,7 +15,10 @@
  */
 #define MAX_PATH_LEN        4096
 
-/** \brief the maximum length of a filename. */
+/**
+ * \brief the maximum length of a filename.
+ * \details This corresponds the filename length under Ext4.
+ */
 #define MAX_FILENAME_LEN    255
 
 /**