Add new error code for SSL cache entry not found

There was no good error to return in this case.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index cc9a270..3ec558b 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -193,6 +193,8 @@
 #define MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS                -0x7000
 /** Invalid value in SSL config */
 #define MBEDTLS_ERR_SSL_BAD_CONFIG                        -0x5E80
+/** Cache entry not found */
+#define MBEDTLS_ERR_SSL_CACHE_ENTRY_NOT_FOUND             -0x5E00
 
 /*
  * Various constants
diff --git a/library/error.c b/library/error.c
index f4826c8..6aa4b92 100644
--- a/library/error.c
+++ b/library/error.c
@@ -518,6 +518,8 @@
             return( "SSL - A cryptographic operation is in progress. Try again later" );
         case -(MBEDTLS_ERR_SSL_BAD_CONFIG):
             return( "SSL - Invalid value in SSL config" );
+        case -(MBEDTLS_ERR_SSL_CACHE_ENTRY_NOT_FOUND):
+            return( "SSL - Cache entry not found" );
 #endif /* MBEDTLS_SSL_TLS_C */
 
 #if defined(MBEDTLS_X509_USE_C) || defined(MBEDTLS_X509_CREATE_C)