added lib/fko_util.c with basic length checking functions

lib/Makefile.am

@@ -6,9 +6,9 @@ libfko_source_files = \
     fko_decode.c fko_encryption.c fko_error.c fko_funcs.c fko_message.c \
     fko_message.h fko_nat_access.c fko_rand_value.c fko_server_auth.c \
     fko.h fko_limits.h fko_timestamp.c fko_hmac.c hmac.c hmac.h \
-    fko_user.c fko_util.h md5.c md5.h rijndael.c rijndael.h sha1.c sha1.h \
-    sha2.c sha2.h strlcat.c strlcpy.c fko_state.h fko_context.h \
-    gpgme_funcs.c gpgme_funcs.h
+    fko_user.c fko_util.c fko_util.h md5.c md5.h rijndael.c rijndael.h \
+    sha1.c sha1.h  sha2.c sha2.h strlcat.c strlcpy.c fko_state.h \
+    fko_context.h gpgme_funcs.c gpgme_funcs.h
 
 libfko_la_SOURCES   = $(libfko_source_files)
 

lib/fko_decode.c

@@ -42,8 +42,7 @@ fko_decode_spa_data(fko_ctx_t ctx)
     char       *tbuf, *ndx, *tmp;
     int         t_size, i;
 
-    if (ctx->encoded_msg_len < MIN_SPA_ENCODED_MSG_SIZE
-            || ctx->encoded_msg_len > MAX_SPA_ENCODED_MSG_SIZE)
+    if (! is_valid_encoded_msg_len(ctx->encoded_msg_len))
         return(FKO_ERROR_INVALID_DATA);
 
     /* Make sure there are enough fields in the SPA packet

lib/fko_encode.c

@@ -197,7 +197,7 @@ fko_encode_spa_data(fko_ctx_t ctx)
 
     ctx->encoded_msg_len = strnlen(ctx->encoded_msg, MAX_SPA_ENCODED_MSG_SIZE);
 
-    if(ctx->encoded_msg_len == MAX_SPA_ENCODED_MSG_SIZE)
+    if(! is_valid_encoded_msg_len(ctx->encoded_msg_len));
         return(FKO_ERROR_INVALID_DATA);
 
     /* At this point we can compute the digest for this SPA data.

lib/fko_encryption.c

@@ -50,6 +50,12 @@ _rijndael_encrypt(fko_ctx_t ctx, const char *enc_key, const int enc_key_len)
     unsigned char  *ciphertext;
     int             cipher_len;
 
+    if (! is_valid_encoded_msg_len(ctx->encoded_msg_len))
+        return(FKO_ERROR_INVALID_DATA);
+
+    if (! is_valid_digest_len(ctx->digest_len))
+        return(FKO_ERROR_INVALID_DATA);
+
     /* Make a bucket big enough to hold the enc msg + digest (plaintext)
      * and populate it appropriately.
     */
@@ -170,10 +176,10 @@ _rijndael_decrypt(fko_ctx_t ctx,
     if(pt_len < (cipher_len - 32))
         return(FKO_ERROR_DECRYPTION_SIZE);
 
-    if(ctx->encoded_msg == NULL || pt_len < MIN_SPA_ENCODED_MSG_SIZE)
+    if(ctx->encoded_msg == NULL)
         return(FKO_ERROR_INVALID_DATA);
 
-    if(pt_len == MAX_SPA_ENCODED_MSG_SIZE)
+    if(! is_valid_encoded_msg_len(pt_len))
         return(FKO_ERROR_INVALID_DATA);
 
     ctx->encoded_msg_len = pt_len;
@@ -211,6 +217,12 @@ gpg_encrypt(fko_ctx_t ctx, const char *enc_key)
     size_t          cipher_len;
     char           *empty_key = "";
 
+    if (! is_valid_encoded_msg_len(ctx->encoded_msg_len))
+        return(FKO_ERROR_INVALID_DATA);
+
+    if (! is_valid_digest_len(ctx->digest_len))
+        return(FKO_ERROR_INVALID_DATA);
+
     /* First make sure we have a recipient key set.
     */
     if(ctx->gpg_recipient == NULL)
@@ -342,10 +354,10 @@ gpg_decrypt(fko_ctx_t ctx, const char *dec_key)
 
     pt_len = strnlen(ctx->encoded_msg, MAX_SPA_ENCODED_MSG_SIZE);
 
-    if(ctx->encoded_msg == NULL || pt_len < MIN_SPA_ENCODED_MSG_SIZE)
+    if(ctx->encoded_msg == NULL)
         return(FKO_ERROR_INVALID_DATA);
 
-    if(pt_len == MAX_SPA_ENCODED_MSG_SIZE)
+    if(! is_valid_encoded_msg_len(pt_len))
         return(FKO_ERROR_INVALID_DATA);
 
     ctx->encoded_msg_len = pt_len;
@@ -454,7 +466,7 @@ fko_encrypt_spa_data(fko_ctx_t ctx, const char *enc_key, const int enc_key_len)
      * check for a somewhat arbitrary minimum length for the encoded
      * data.
     */
-    if(ctx->encoded_msg_len < MIN_SPA_ENCODED_MSG_SIZE)
+    if (! is_valid_encoded_msg_len(ctx->encoded_msg_len))
         return(FKO_ERROR_MISSING_ENCODED_DATA);
 
     /* Encrypt according to type and return...

lib/fko_util.c

@@ -0,0 +1,67 @@
+/*
+ *****************************************************************************
+ *
+ * File:    fko_util.c
+ *
+ * Author:  Michael Rash
+ *
+ * Purpose: Set/Get the current username.
+ *
+ * Copyright 2012 Michael Rash (mbr@cipherdyne.org)
+ *
+ *  License (GNU Public License):
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License
+ *  as published by the Free Software Foundation; either version 2
+ *  of the License, or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
+ *  USA
+ *
+ *****************************************************************************
+*/
+#include "fko_common.h"
+#include "fko.h"
+
+/* Validate encoded message length
+*/
+int
+is_valid_encoded_msg_len(const int len)
+{
+    if(len < MIN_SPA_ENCODED_MSG_SIZE || len >= MAX_SPA_ENCODED_MSG_SIZE)
+        return(0);
+
+    return(1);
+}
+
+/* Validate digest length
+*/
+int
+is_valid_digest_len(const int len)
+{
+    switch(len)
+    {
+        case MD5_B64_LENGTH:
+            break;
+        case SHA1_B64_LENGTH:
+            break;
+        case SHA256_B64_LENGTH:
+            break;
+        case SHA384_B64_LENGTH:
+            break;
+        case SHA512_B64_LENGTH:
+            break;
+        default:
+            return(0);
+    }
+
+    return(1);
+}

lib/fko_util.h

@@ -35,6 +35,9 @@
 
 /* Function prototypes
 */
+int is_valid_encoded_msg_len(const int len);
+int is_valid_digest_len(const int len);
+
 size_t strlcat(char *dst, const char *src, size_t siz);
 size_t strlcpy(char *dst, const char *src, size_t siz);