Use octet_string_from_mpi in oaep_decode.

This is to remove duplicated code.  I had to move
octet_string_from_mpi more to the top of the file.

1 files changed, 62 insertions, 82 deletions

diff --git a/cipher/pubkey.c b/cipher/pubkey.c
index 830f5150..a8da7343 100644
--- a/cipher/pubkey.c
+++ b/cipher/pubkey.c
@@ -784,6 +784,64 @@ pubkey_verify (int algorithm, gcry_mpi_t hash, gcry_mpi_t *data,
 }
 
 
+/* Turn VALUE into an octet string and store it in an allocated buffer
+   at R_FRAME or - if R_RAME is NULL - copy it into the caller
+   provided buffer SPACE; either SPACE or R_FRAME may be used.  If
+   SPACE if not NULL, the caller must provide a buffer of at least
+   NBYTES.  If the resulting octet string is shorter than NBYTES pad
+   it to the left with zeroes.  If VALUE does not fit into NBYTES
+   return an error code.  */
+static gpg_err_code_t
+octet_string_from_mpi (unsigned char **r_frame, void *space,
+                       gcry_mpi_t value, size_t nbytes)
+{
+  gpg_err_code_t rc;
+  size_t nframe, noff, n;
+  unsigned char *frame;
+
+  if (!r_frame == !space)
+    return GPG_ERR_INV_ARG;  /* Only one may be used.  */
+
+  if (r_frame)
+    *r_frame = NULL;
+
+  rc = gcry_err_code (gcry_mpi_print (GCRYMPI_FMT_USG,
+                                      NULL, 0, &nframe, value));
+  if (rc)
+    return rc;
+  if (nframe > nbytes)
+    return GPG_ERR_TOO_LARGE; /* Value too long to fit into NBYTES.  */
+
+  noff = (nframe < nbytes)? nbytes - nframe : 0;
+  n = nframe + noff;
+  if (space)
+    frame = space;
+  else
+    {
+      frame = mpi_is_secure (value)? gcry_malloc_secure (n) : gcry_malloc (n);
+      if (!frame)
+        {
+          rc = gpg_err_code_from_syserror ();
+          return rc;
+        }
+    }
+  if (noff)
+    memset (frame, 0, noff);
+  nframe += noff;
+  rc = gcry_err_code (gcry_mpi_print (GCRYMPI_FMT_USG,
+                                      frame+noff, nframe-noff, NULL, value));
+  if (rc)
+    {
+      gcry_free (frame);
+      return rc;
+    }
+
+  if (r_frame)
+    *r_frame = frame;
+  return 0;
+}
+
+
 /* Encode {VALUE,VALUELEN} for an NBITS keys using the pkcs#1 block
    type 2 padding.  On sucess the result is stored as a new MPI at
    R_RESULT.  On error the value at R_RESULT is undefined.
@@ -1268,7 +1326,7 @@ oaep_decode (unsigned char **r_result, size_t *r_resultlen,
   size_t db_len;               /* Length of DB and masked_db.  */
   size_t nkey = (nbits+7)/8;   /* Length of the key in bytes.  */
   int failed = 0;              /* Error indicator.  */
-  size_t noff, n;
+  size_t n;
 
   *r_result = NULL;
 
@@ -1297,33 +1355,13 @@ oaep_decode (unsigned char **r_result, size_t *r_resultlen,
      bytes.  This all is needed to cope with our leading zeroes
      suppressing MPI implementation.  The code implictly implements
      Step 1b (bail out if NFRAME != N).  */
-  rc = gcry_err_code (gcry_mpi_print (GCRYMPI_FMT_USG,
-                                      NULL, 0, &nframe, value));
-  if (rc || nframe > nkey)
-    {
-      gcry_free (lhash);
-      return GPG_ERR_ENCODING_PROBLEM;
-    }
-  noff = (nframe < nkey)? nkey - nframe : 0;
-  n = nframe + noff;
-  frame = mpi_is_secure (value)? gcry_malloc_secure (n) : gcry_malloc (n);
-  if (!frame)
-    {
-      rc = gpg_error_from_syserror ();
-      gcry_free (lhash);
-      return rc;
-    }
-  if (noff)
-    memset (frame, 0, noff);
-  nframe += noff;
-  rc = gcry_err_code (gcry_mpi_print (GCRYMPI_FMT_USG,
-                                      frame+noff, nframe-noff, NULL, value));
+  rc = octet_string_from_mpi (&frame, NULL, value, nkey);
   if (rc)
     {
-      gcry_free (frame);
       gcry_free (lhash);
-      return rc;
+      return GPG_ERR_ENCODING_PROBLEM;
     }
+  nframe = nkey;
 
   /* Step 1c: Check that the key is long enough.  */
   if ( nframe < 2 * hlen + 2 )
@@ -1571,64 +1609,6 @@ pss_encode (gcry_mpi_t *r_result, unsigned int nbits, int algo,
 }
 
 
-/* Turn VALUE into an octet string and store it in an allocated buffer
-   at R_FRAME or - if R_RAME is NULL - copy it into the caller
-   provided buffer SPACE; either SPACE or R_FRAME may be used.  If
-   SPACE if not NULL, the caller must provide a buffer of at least
-   NBYTES.  If the resulting octet string is shorter than NBYTES pad
-   it to the left with zeroes.  If VALUE does not fit into NBYTES
-   return an error code.  */
-static gpg_err_code_t
-octet_string_from_mpi (unsigned char **r_frame, void *space,
-                       gcry_mpi_t value, size_t nbytes)
-{
-  gpg_err_code_t rc;
-  size_t nframe, noff, n;
-  unsigned char *frame;
-
-  if (!r_frame == !space)
-    return GPG_ERR_INV_ARG;  /* Only one may be used.  */
-
-  if (r_frame)
-    *r_frame = NULL;
-
-  rc = gcry_err_code (gcry_mpi_print (GCRYMPI_FMT_USG,
-                                      NULL, 0, &nframe, value));
-  if (rc)
-    return rc;
-  if (nframe > nbytes)
-    return GPG_ERR_TOO_LARGE; /* Value too long to fit into NBYTES.  */
-
-  noff = (nframe < nbytes)? nbytes - nframe : 0;
-  n = nframe + noff;
-  if (space)
-    frame = space;
-  else
-    {
-      frame = mpi_is_secure (value)? gcry_malloc_secure (n) : gcry_malloc (n);
-      if (!frame)
-        {
-          rc = gpg_err_code_from_syserror ();
-          return rc;
-        }
-    }
-  if (noff)
-    memset (frame, 0, noff);
-  nframe += noff;
-  rc = gcry_err_code (gcry_mpi_print (GCRYMPI_FMT_USG,
-                                      frame+noff, nframe-noff, NULL, value));
-  if (rc)
-    {
-      gcry_free (frame);
-      return rc;
-    }
-
-  if (r_frame)
-    *r_frame = frame;
-  return 0;
-}
-
-
 /* Verify a signature assuming PSS padding.  VALUE is the hash of the
    message (mHash) encoded as an MPI; its length must match the digest
    length of ALGO.  ENCODED is the output of the RSA public key