db: introduce gnutls_db_set_add_function

This adds a way to store an entry if it is not found in the database,
so that the implementation can provide atomic test-and-set.

Signed-off-by: Daiki Ueno <dueno@redhat.com>

5 files changed, 31 insertions, 0 deletions

diff --git a/lib/db.c b/lib/db.c
index e01e5b94c5..414816fcc8 100644
--- a/lib/db.c
+++ b/lib/db.c
@@ -56,6 +56,29 @@ gnutls_db_set_retrieve_function(gnutls_session_t session,
 }
 
 /**
+ * gnutls_db_set_add_function:
+ * @session: is a #gnutls_session_t type.
+ * @add_func: is the function.
+ *
+ * Sets the function that will be used to store an entry if it is not
+ * already present in the resumed sessions database.  This function returns 0
+ * if the entry is successfully stored, and a negative error code
+ * otherwise.  In particular, if the entry is found in the database,
+ * it returns %GNUTLS_E_DB_ENTRY_EXISTS.
+ *
+ * The first argument to @add_func will be null unless
+ * gnutls_db_set_ptr() has been called.
+ *
+ * Since: 3.6.5
+ **/
+void
+gnutls_db_set_add_function(gnutls_session_t session,
+			   gnutls_db_add_func add_func)
+{
+	session->internals.db_add_func = add_func;
+}
+
+/**
  * gnutls_db_set_remove_function:
  * @session: is a #gnutls_session_t type.
  * @rem_func: is the function.
diff --git a/lib/errors.c b/lib/errors.c
index e579f46852..a83a49eeab 100644
--- a/lib/errors.c
+++ b/lib/errors.c
@@ -193,6 +193,7 @@ static const gnutls_error_entry error_entries[] = {
 		    ("TLS Application data were received, while expecting handshake data."),
 		    GNUTLS_E_GOT_APPLICATION_DATA),
 	ERROR_ENTRY(N_("Error in Database backend."), GNUTLS_E_DB_ERROR),
+	ERROR_ENTRY(N_("The Database entry already exists."), GNUTLS_E_DB_ENTRY_EXISTS),
 	ERROR_ENTRY(N_("The certificate type is not supported."),
 		    GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE),
 	ERROR_ENTRY(N_
diff --git a/lib/gnutls_int.h b/lib/gnutls_int.h
index 73fcfcc9c8..42d68d4398 100644
--- a/lib/gnutls_int.h
+++ b/lib/gnutls_int.h
@@ -1216,6 +1216,7 @@ typedef struct {
 	gnutls_db_store_func db_store_func;
 	gnutls_db_retr_func db_retrieve_func;
 	gnutls_db_remove_func db_remove_func;
+	gnutls_db_add_func db_add_func;
 	void *db_ptr;
 
 	/* post client hello callback (server side only)
diff --git a/lib/includes/gnutls/gnutls.h.in b/lib/includes/gnutls/gnutls.h.in
index 1c07ff33a5..3a4d01d442 100644
--- a/lib/includes/gnutls/gnutls.h.in
+++ b/lib/includes/gnutls/gnutls.h.in
@@ -1783,6 +1783,8 @@ typedef int (*gnutls_db_store_func) (void *, gnutls_datum_t key,
 				     gnutls_datum_t data);
 typedef int (*gnutls_db_remove_func) (void *, gnutls_datum_t key);
 typedef gnutls_datum_t(*gnutls_db_retr_func) (void *, gnutls_datum_t key);
+typedef int (*gnutls_db_add_func) (void *, gnutls_datum_t key,
+				   gnutls_datum_t data);
 
 void gnutls_db_set_cache_expiration(gnutls_session_t session, int seconds);
 unsigned gnutls_db_get_default_cache_expiration(void);
@@ -1794,6 +1796,8 @@ void gnutls_db_set_remove_function(gnutls_session_t session,
 				   gnutls_db_remove_func rem_func);
 void gnutls_db_set_store_function(gnutls_session_t session,
 				  gnutls_db_store_func store_func);
+void gnutls_db_set_add_function(gnutls_session_t session,
+				gnutls_db_add_func add_func);
 void gnutls_db_set_ptr(gnutls_session_t session, void *ptr);
 void *gnutls_db_get_ptr(gnutls_session_t session);
 int gnutls_db_check_entry(gnutls_session_t session,
@@ -3265,6 +3269,7 @@ void gnutls_fips140_set_mode(gnutls_fips_mode_t mode, unsigned flags);
 #define GNUTLS_E_TOO_MANY_MATCHES -425
 #define GNUTLS_E_CRL_VERIFICATION_ERROR -426
 #define GNUTLS_E_MISSING_EXTENSION -427
+#define GNUTLS_E_DB_ENTRY_EXISTS -428
 
 #define GNUTLS_E_UNIMPLEMENTED_FEATURE -1250
 
diff --git a/lib/libgnutls.map b/lib/libgnutls.map
index cfa87a6b26..a4aaf11ca1 100644
--- a/lib/libgnutls.map
+++ b/lib/libgnutls.map
@@ -1255,6 +1255,7 @@ GNUTLS_3_6_5
 	gnutls_record_send_early_data;
 	gnutls_record_recv_early_data;
 	gnutls_db_check_entry_expire_time;
+	gnutls_db_set_add_function;
 } GNUTLS_3_6_4;
 
 GNUTLS_FIPS140_3_4 {