From dafe5227d4449bfd898c12b713ffb802686c65ee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Manuel=20P=C3=A9gouri=C3=A9-Gonnard?=
 <manuel.pegourie-gonnard@arm.com>
Date: Fri, 3 May 2019 09:16:16 +0200
Subject: [PATCH] Reduce indentation in ssl_compute_master()

Exit earlier when there's noting to do.

For a small diff, review with 'git show -w'.
---
 library/ssl_tls.c | 91 +++++++++++++++++++++--------------------------
 1 file changed, 41 insertions(+), 50 deletions(-)

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 87e3c7b96..bdfb34d64 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1094,7 +1094,7 @@ static int ssl_set_handshake_prfs( mbedtls_ssl_handshake_params *handshake,
 }
 
 /*
- * Compute master secret
+ * Compute master secret if needed
  */
 static int ssl_compute_master( mbedtls_ssl_context *ssl )
 {
@@ -1103,65 +1103,46 @@ static int ssl_compute_master( mbedtls_ssl_context *ssl )
     const mbedtls_ssl_ciphersuite_t *ciphersuite_info = handshake->ciphersuite_info;
     mbedtls_ssl_session *session = ssl->session_negotiate;
 
-    /*
-     * SSLv3:
-     *   master =
-     *     MD5( premaster + SHA1( 'A'   + premaster + randbytes ) ) +
-     *     MD5( premaster + SHA1( 'BB'  + premaster + randbytes ) ) +
-     *     MD5( premaster + SHA1( 'CCC' + premaster + randbytes ) )
-     *
-     * TLSv1+:
-     *   master = PRF( premaster, "master secret", randbytes )[0..47]
-     */
-    if( handshake->resume == 0 )
+    if( handshake->resume != 0 )
     {
-        MBEDTLS_SSL_DEBUG_BUF( 3, "premaster secret", handshake->premaster,
-                       handshake->pmslen );
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "no premaster (session resumed)" ) );
+        return( 0 );
+    }
+
+    MBEDTLS_SSL_DEBUG_BUF( 3, "premaster secret", handshake->premaster,
+                                                  handshake->pmslen );
 
 #if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
-        if( ssl->handshake->extended_ms == MBEDTLS_SSL_EXTENDED_MS_ENABLED )
-        {
-            unsigned char session_hash[48];
-            size_t hash_len;
+    if( ssl->handshake->extended_ms == MBEDTLS_SSL_EXTENDED_MS_ENABLED )
+    {
+        unsigned char session_hash[48];
+        size_t hash_len;
 
-            MBEDTLS_SSL_DEBUG_MSG( 3, ( "using extended master secret" ) );
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "using extended master secret" ) );
 
-            ssl->handshake->calc_verify( ssl, session_hash );
+        ssl->handshake->calc_verify( ssl, session_hash );
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
-            if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
-            {
+        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
+        {
 #if defined(MBEDTLS_SHA512_C)
-                if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
-                {
-                    hash_len = 48;
-                }
-                else
-#endif
-                    hash_len = 32;
+            if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
+            {
+                hash_len = 48;
             }
             else
-#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
-                hash_len = 36;
-
-            MBEDTLS_SSL_DEBUG_BUF( 3, "session hash", session_hash, hash_len );
-
-            ret = handshake->tls_prf( handshake->premaster, handshake->pmslen,
-                                      "extended master secret",
-                                      session_hash, hash_len,
-                                      session->master, 48 );
-            if( ret != 0 )
-            {
-                MBEDTLS_SSL_DEBUG_RET( 1, "prf", ret );
-                return( ret );
-            }
-
+#endif
+                hash_len = 32;
         }
         else
-#endif
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+            hash_len = 36;
+
+        MBEDTLS_SSL_DEBUG_BUF( 3, "session hash", session_hash, hash_len );
+
         ret = handshake->tls_prf( handshake->premaster, handshake->pmslen,
-                                  "master secret",
-                                  handshake->randbytes, 64,
+                                  "extended master secret",
+                                  session_hash, hash_len,
                                   session->master, 48 );
         if( ret != 0 )
         {
@@ -1169,11 +1150,21 @@ static int ssl_compute_master( mbedtls_ssl_context *ssl )
             return( ret );
         }
 
-        mbedtls_platform_zeroize( handshake->premaster,
-                                  sizeof(handshake->premaster) );
     }
     else
-        MBEDTLS_SSL_DEBUG_MSG( 3, ( "no premaster (session resumed)" ) );
+#endif
+    ret = handshake->tls_prf( handshake->premaster, handshake->pmslen,
+                              "master secret",
+                              handshake->randbytes, 64,
+                              session->master, 48 );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "prf", ret );
+        return( ret );
+    }
+
+    mbedtls_platform_zeroize( handshake->premaster,
+                              sizeof(handshake->premaster) );
 
     return( 0 );
 }