string: Use the struct and array for allocating the struct.

include/libssh/string.h

@@ -29,7 +29,7 @@
 #endif
 struct ssh_string_struct {
 	uint32_t size;
-	unsigned char string[MAX_PACKET_LEN];
+	unsigned char data[1];
 }
 #if !defined(__SUNPRO_C) && !defined(_MSC_VER)
 __attribute__ ((packed))

src/dh.c

@@ -356,19 +356,19 @@ ssh_string make_bignum_string(bignum num) {
   fprintf(stderr, "%d bits, %d bytes, %d padding\n", bits, len, pad);
 #endif /* DEBUG_CRYPTO */
 /* TODO: fix that crap !! */
-  ptr = malloc(4 + len + pad);
+  ptr = malloc(sizeof(struct ssh_string_struct) + len + pad);
   if (ptr == NULL) {
     return NULL;
   }
   ptr->size = htonl(len + pad);
   if (pad) {
-    ptr->string[0] = 0;
+    ptr->data[0] = 0;
   }
 
 #ifdef HAVE_LIBGCRYPT
-  bignum_bn2bin(num, len, ptr->string + pad);
+  bignum_bn2bin(num, len, ptr->data + pad);
 #elif HAVE_LIBCRYPTO
-  bignum_bn2bin(num, ptr->string + pad);
+  bignum_bn2bin(num, ptr->data + pad);
 #endif
 
   return ptr;
@@ -384,9 +384,9 @@ bignum make_string_bn(ssh_string string){
 #endif /* DEBUG_CRYPTO */
 
 #ifdef HAVE_LIBGCRYPT
-  bignum_bin2bn(string->string, len, &bn);
+  bignum_bin2bn(string->data, len, &bn);
 #elif defined HAVE_LIBCRYPTO
-  bn = bignum_bin2bn(string->string, len, NULL);
+  bn = bignum_bin2bn(string->data, len, NULL);
 #endif
 
   return bn;
@@ -985,7 +985,7 @@ int ssh_get_pubkey_hash(ssh_session session, unsigned char **hash) {
 
   pubkey = session->current_crypto->server_pubkey;
 
-  md5_update(ctx, pubkey->string, ssh_string_len(pubkey));
+  md5_update(ctx, ssh_string_data(pubkey), ssh_string_len(pubkey));
   md5_final(h, ctx);
 
   *hash = h;

src/known_hosts.c

@@ -241,9 +241,9 @@ static int check_public_key(ssh_session session, char **tokens) {
       /* TODO: fix the hardcoding */
       tmpstring->size = htonl(len);
 #ifdef HAVE_LIBGCRYPT
-      bignum_bn2bin(tmpbn, len, tmpstring->string);
+      bignum_bn2bin(tmpbn, len, string_data(tmpstring));
 #elif defined HAVE_LIBCRYPTO
-      bignum_bn2bin(tmpbn, tmpstring->string);
+      bignum_bn2bin(tmpbn, string_data(tmpstring));
 #endif
       bignum_free(tmpbn);
       if (buffer_add_ssh_string(pubkey_buffer, tmpstring) < 0) {
@@ -272,7 +272,7 @@ static int check_public_key(ssh_session session, char **tokens) {
   }
 
   /* now test that they are identical */
-  if (memcmp(buffer_get_rest(pubkey_buffer), pubkey->string,
+  if (memcmp(buffer_get_rest(pubkey_buffer), ssh_string_data(pubkey),
         buffer_get_rest_len(pubkey_buffer)) != 0) {
     ssh_buffer_free(pubkey_buffer);
     return 0;

src/string.c

@@ -51,12 +51,14 @@
 struct ssh_string_struct *ssh_string_new(size_t size) {
   struct ssh_string_struct *str = NULL;
 
-  str = malloc(size + 4);
+  str = malloc(sizeof(struct ssh_string_struct) + size);
   if (str == NULL) {
     return NULL;
   }
 
   str->size = htonl(size);
+  str->data[0] = 0;
+
   return str;
 }
 
@@ -77,7 +79,8 @@ int ssh_string_fill(struct ssh_string_struct *s, const void *data, size_t len) {
     return -1;
   }
 
-  memcpy(s->string, data, len);
+  memcpy(s->data, data, len);
+
   return 0;
 }
 
@@ -102,12 +105,12 @@ struct ssh_string_struct *ssh_string_from_char(const char *what) {
 
   len = strlen(what);
 
-  ptr = malloc(4 + len);
+  ptr = ssh_string_new(len);
   if (ptr == NULL) {
     return NULL;
   }
-  ptr->size = htonl(len);
+
-  memcpy(ptr->string, what, len);
+  memcpy(ptr->data, what, len);
 
   return ptr;
 }
@@ -141,7 +144,7 @@ size_t ssh_string_len(struct ssh_string_struct *s) {
 char *ssh_string_to_char(struct ssh_string_struct *s) {
 	size_t len;
 	char *new;
-	if(s==NULL || s->string == NULL)
+    if (s == NULL || s->data == NULL)
 		return NULL;
   len = ntohl(s->size) + 1;
   new = malloc(len);
@@ -149,7 +152,7 @@ char *ssh_string_to_char(struct ssh_string_struct *s) {
   if (new == NULL) {
     return NULL;
   }
-  memcpy(new, s->string, len - 1);
+  memcpy(new, s->data, len - 1);
   new[len - 1] = '\0';
   return new;
 }
@@ -174,16 +177,16 @@ void ssh_string_free_char(char *s) {
 struct ssh_string_struct *ssh_string_copy(struct ssh_string_struct *s) {
   struct ssh_string_struct *new;
 
-  if(s == NULL || s->string == NULL) {
+  if (s == NULL || s->data == NULL) {
       return NULL;
   }
-  new = malloc(ntohl(s->size) + 4);
 
+  new = ssh_string_new(s->size);
   if (new == NULL) {
     return NULL;
   }
   new->size = s->size;
-  memcpy(new->string, s->string, ntohl(s->size));
+  memcpy(new->data, s->data, ntohl(s->size));
 
   return new;
 }
@@ -197,7 +200,7 @@ void ssh_string_burn(struct ssh_string_struct *s) {
   if (s == NULL) {
     return;
   }
-  memset(s->string, 'X', ssh_string_len(s));
+  memset(s->data, 'X', ssh_string_len(s));
 }
 
 /**
@@ -212,7 +215,7 @@ void *ssh_string_data(struct ssh_string_struct *s) {
     return NULL;
   }
 
-  return s->string;
+  return s->data;
 }
 
 /**