gpg: Change --show-session-key to print the session key earlier.

* g10/cpr.c (write_status_strings): New.
(write_status_text): Replace code by a call to write_status_strings.
* g10/mainproc.c (proc_encrypted): Remove show_session_key code.
* g10/decrypt-data.c (decrypt_data): Add new show_session_key code.
--

This feature can be used to return the session key for just a part of
a file.  For example to downloading just the first 32k of a huge file,
decrypting that incomplete part and while ignoring all the errors
break out the session key.  The session key may then be used on the
server to decrypt the entire file without the need to have the private
key on the server.

GnuPG-bug-id: 1389
Signed-off-by: Werner Koch <wk@gnupg.org>
(cherry picked from commit 101a54add3)

Resolved Conflicts:
	doc/DETAILS    - removed
	g10/cpr.c      - replace estream fucntion by stdio.
	g10/mainproc.c - Adjust for changed calling convention.

g10/cpr.c

@@ -132,31 +132,53 @@ write_status ( int no )
     write_status_text( no, NULL );
 }
 
+
+/* Write a status line with code NO followed by the string TEXT and
+   directly followed by the remaining strings up to a NULL. */
 void
-write_status_text ( int no, const char *text)
+write_status_strings (int no, const char *text, ...)
 {
-    if( !statusfp || !status_currently_allowed (no) )
+  va_list arg_ptr;
+  const char *s;
+
+  if (!statusfp || !status_currently_allowed (no) )
     return;  /* Not enabled or allowed. */
 
-    fputs ( "[GNUPG:] ", statusfp );
+  fputs ("[GNUPG:] ", statusfp);
-    fputs ( get_status_string (no), statusfp );
+  fputs (get_status_string (no), statusfp);
-    if( text ) {
+  if ( text )
-        putc ( ' ', statusfp );
+    {
-        for (; *text; text++) {
+      putc ( ' ', statusfp);
-            if (*text == '\n')
+      va_start (arg_ptr, text);
-                fputs ( "\\n", statusfp );
+      s = text;
-            else if (*text == '\r')
+      do
-                fputs ( "\\r", statusfp );
+        {
+          for (; *s; s++)
+            {
+              if (*s == '\n')
+                fputs ("\\n", statusfp);
+              else if (*s == '\r')
+                fputs ("\\r", statusfp);
               else
-                putc ( *(const byte *)text,  statusfp );
+                fputc (*(const byte *)s, statusfp);
             }
         }
-    putc ('\n',statusfp);
+      while ((s = va_arg (arg_ptr, const char*)));
-    if ( fflush (statusfp) && opt.exit_on_status_write_error )
+      va_end (arg_ptr);
+    }
+  putc ('\n', statusfp);
+  if (fflush (statusfp) && opt.exit_on_status_write_error)
     g10_exit (0);
 }
 
 
+void
+write_status_text (int no, const char *text)
+{
+  write_status_strings (no, text, NULL);
+}
+
+
 void
 write_status_error (const char *where, int errcode)
 {

g10/encr-data.c

@@ -104,6 +104,23 @@ decrypt_data( void *procctx, PKT_encrypted *ed, DEK *dek )
     write_status_text (STATUS_DECRYPTION_INFO, buf);
   }
 
+  if (opt.show_session_key)
+    {
+      char numbuf[25];
+      char *hexbuf;
+
+      snprintf (numbuf, sizeof numbuf, "%d:", dek->algo);
+      hexbuf = bin2hex (dek->key, dek->keylen, NULL);
+      if (!hexbuf)
+        {
+          rc = gpg_error_from_syserror ();
+          goto leave;
+        }
+      log_info ("session key: '%s%s'\n", numbuf, hexbuf);
+      write_status_strings (STATUS_SESSION_KEY, numbuf, hexbuf, NULL);
+      xfree (hexbuf);
+    }
+
   rc = openpgp_cipher_test_algo (dek->algo);
   if (rc)
     goto leave;

g10/main.h

@@ -160,6 +160,8 @@ int  is_status_enabled ( void );
 void write_status ( int no );
 void write_status_error (const char *where, int errcode);
 void write_status_text ( int no, const char *text );
+void write_status_strings (int no, const char *text,
+                           ...) GNUPG_GCC_A_SENTINEL(0);
 void write_status_buffer ( int no,
                            const char *buffer, size_t len, int wrap );
 void write_status_text_and_buffer ( int no, const char *text,

g10/mainproc.c

@@ -569,6 +569,7 @@ proc_encrypted( CTX c, PACKET *pkt )
     }
     else if( !c->dek )
 	result = G10ERR_NO_SECKEY;
+
     if( !result )
 	result = decrypt_data( c, pkt->pkt.encrypted, c->dek );
 
@@ -583,16 +584,6 @@ proc_encrypted( CTX c, PACKET *pkt )
 	    write_status( STATUS_GOODMDC );
 	else if(!opt.no_mdc_warn)
 	    log_info (_("WARNING: message was not integrity protected\n"));
-	if(opt.show_session_key)
-	  {
-	    int i;
-	    char *buf = xmalloc ( c->dek->keylen*2 + 20 );
-	    sprintf ( buf, "%d:", c->dek->algo );
-	    for(i=0; i < c->dek->keylen; i++ )
-	      sprintf(buf+strlen(buf), "%02X", c->dek->key[i] );
-	    log_info( "session key: `%s'\n", buf );
-	    write_status_text ( STATUS_SESSION_KEY, buf );
-	  }
     }
     else if( result == G10ERR_BAD_SIGN ) {
 	log_error(_("WARNING: encrypted message has been manipulated!\n"));