Factor PSK pms computation to ssl_tls.c
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index d3b4ce3..e4ae682 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -825,6 +825,96 @@
#endif /* POLARSSL_SHA512_C */
#endif /* POLARSSL_SSL_PROTO_TLS1_2 */
+#if defined(POLARSSL_KEY_EXCHANGE_PSK_ENABLED) || \
+ defined(POLARSSL_KEY_EXCHANGE_DHE_PSK_ENABLED) || \
+ defined(POLARSSL_KEY_EXCHANGE_ECDHE_PSK_ENABLED)
+int ssl_psk_derive_premaster( ssl_context *ssl, key_exchange_type_t key_ex )
+{
+ int ret;
+ unsigned char *p = ssl->handshake->premaster;
+ unsigned char *end = p + sizeof( ssl->handshake->premaster );
+
+ /*
+ * PMS = struct {
+ * opaque other_secret<0..2^16-1>;
+ * opaque psk<0..2^16-1>;
+ * };
+ * with "other_secret" depending on the particular key exchange
+ */
+#if defined(POLARSSL_KEY_EXCHANGE_PSK_ENABLED)
+ if( key_ex == POLARSSL_KEY_EXCHANGE_PSK )
+ {
+ if( end - p < 2 + (int) ssl->psk_len )
+ return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
+
+ *(p++) = (unsigned char)( ssl->psk_len >> 8 );
+ *(p++) = (unsigned char)( ssl->psk_len );
+ p += ssl->psk_len;
+ }
+ else
+#endif /* POLARSSL_KEY_EXCHANGE_PSK_ENABLED */
+#if defined(POLARSSL_KEY_EXCHANGE_DHE_PSK_ENABLED)
+ if( key_ex == POLARSSL_KEY_EXCHANGE_DHE_PSK )
+ {
+ size_t len = ssl->handshake->dhm_ctx.len;
+
+ if( end - p < 2 + (int) len )
+ return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
+
+ *(p++) = (unsigned char)( len >> 8 );
+ *(p++) = (unsigned char)( len );
+ if( ( ret = dhm_calc_secret( &ssl->handshake->dhm_ctx,
+ p, &len, ssl->f_rng, ssl->p_rng ) ) != 0 )
+ {
+ SSL_DEBUG_RET( 1, "dhm_calc_secret", ret );
+ return( ret );
+ }
+ p += len;
+
+ SSL_DEBUG_MPI( 3, "DHM: K ", &ssl->handshake->dhm_ctx.K );
+ }
+ else
+#endif /* POLARSSL_KEY_EXCHANGE_DHE_PSK_ENABLED */
+#if defined(POLARSSL_KEY_EXCHANGE_ECDHE_PSK_ENABLED)
+ if( key_ex == POLARSSL_KEY_EXCHANGE_ECDHE_PSK )
+ {
+ size_t zlen;
+
+ if( ( ret = ecdh_calc_secret( &ssl->handshake->ecdh_ctx, &zlen,
+ p + 2, end - (p + 2),
+ ssl->f_rng, ssl->p_rng ) ) != 0 )
+ {
+ SSL_DEBUG_RET( 1, "ecdh_calc_secret", ret );
+ return( ret );
+ }
+
+ *(p++) = (unsigned char)( zlen >> 8 );
+ *(p++) = (unsigned char)( zlen );
+ p += zlen;
+
+ SSL_DEBUG_MPI( 3, "ECDH: z", &ssl->handshake->ecdh_ctx.z );
+ }
+ else
+#endif /* POLARSSL_KEY_EXCHANGE_ECDHE_PSK_ENABLED */
+ {
+ SSL_DEBUG_MSG( 1, ( "should never happen" ) );
+ return( POLARSSL_ERR_SSL_FEATURE_UNAVAILABLE );
+ }
+
+ /* opaque psk<0..2^16-1>; */
+ *(p++) = (unsigned char)( ssl->psk_len >> 8 );
+ *(p++) = (unsigned char)( ssl->psk_len );
+ memcpy( p, ssl->psk, ssl->psk_len );
+ p += ssl->psk_len;
+
+ ssl->handshake->pmslen = p - ssl->handshake->premaster;
+
+ return( 0 );
+}
+#endif /* POLARSSL_KEY_EXCHANGE_PSK_ENABLED ||
+ POLARSSL_KEY_EXCHANGE_DHE_PSK_ENABLED ||
+ POLARSSL_KEY_EXCHANGE_ECDHE_PSK_ENABLED */
+
#if defined(POLARSSL_SSL_PROTO_SSL3)
/*
* SSLv3.0 MAC functions