mobilebackup: add internal mobilebackup_receive_message() for cleaner code

This does not clean up too much for now, but when completing the rest of
the mobilebackup API it will help to provide nice and clean code.

1 files changed, 69 insertions, 21 deletions

diff --git a/src/mobilebackup.c b/src/mobilebackup.c
index 0005284..234ad8f 100644
--- a/src/mobilebackup.c
+++ b/src/mobilebackup.c
@@ -152,6 +152,72 @@ mobilebackup_error_t mobilebackup_send(mobilebackup_client_t client, plist_t pli
 }
 
 /**
+ * Receives a plist from the device and checks if the value for the
+ * BackupMessageTypeKey matches the value passed in the message parameter.
+ *
+ * @param client The connected MobileBackup client to use.
+ * @param message The expected message to check.
+ * @param result Pointer to a plist_t that will be set to the received plist
+ *    for further processing. The caller has to free it using plist_free().
+ *    Note that it will be set to NULL if the operation itself fails due to
+ *    a communication or plist error.
+ *    If this parameter is NULL, it will be ignored.
+ *
+ * @return MOBILEBACKUP_E_SUCCESS on success, MOBILEBACKUP_E_INVALID_ARG if
+ *    client or message is invalid, MOBILEBACKUP_E_REPLY_NOT_OK if the
+ *    expected message could not be received, MOBILEBACKUP_E_PLIST_ERROR if
+ *    the received message is not a valid backup message plist (i.e. the
+ *    BackupMessageTypeKey is not present), or MOBILEBACKUP_E_MUX_ERROR
+ *    if a communication error occurs.
+ */
+static mobilebackup_error_t mobilebackup_receive_message(mobilebackup_client_t client, const char *message, plist_t *result)
+{
+        if (!client || !client->parent || !message)
+                return MOBILEBACKUP_E_INVALID_ARG;
+
+        if (result)
+                *result = NULL;
+        mobilebackup_error_t err;
+
+        plist_t dict = NULL;
+
+        /* receive DLMessageProcessMessage */
+        err = mobilebackup_error(device_link_service_receive_process_message(client->parent, &dict));
+        if (err != MOBILEBACKUP_E_SUCCESS) {
+                goto leave;
+        }
+
+        plist_t node = plist_dict_get_item(dict, "BackupMessageTypeKey");
+        if (!node) {
+                debug_info("ERROR: BackupMessageTypeKey not found in plist!");
+                err = MOBILEBACKUP_E_PLIST_ERROR;
+                goto leave;
+        }
+
+        char *str = NULL;
+        plist_get_string_val(node, &str);
+        if (str && (strcmp(str, message) == 0)) {
+                err = MOBILEBACKUP_E_SUCCESS;
+        } else {
+                debug_info("ERROR: BackupMessageTypeKey value does not match '%s'!", message);
+                err = MOBILEBACKUP_E_REPLY_NOT_OK;
+        }
+        if (str)
+                free(str);
+
+        if (result) {
+                *result = dict;
+                dict = NULL;
+        }
+leave:
+        if (dict) {
+                plist_free(dict);
+        }
+
+        return err;
+}
+
+/**
  * Request a backup from the connected device.
  *
  * @param client The connected MobileBackup client to use.
@@ -196,33 +262,15 @@ mobilebackup_error_t mobilebackup_request_backup(mobilebackup_client_t client, p
         }
 
         /* now receive and hopefully get a BackupMessageBackupReplyOK */
-        err = mobilebackup_error(device_link_service_receive_process_message(client->parent, &dict));
+        err = mobilebackup_receive_message(client, "BackupMessageBackupReplyOK", &dict);
         if (err != MOBILEBACKUP_E_SUCCESS) {
                 debug_info("ERROR: Could not receive BackupReplyOK message (%d)!", err);
                 goto leave;
         }
 
-        plist_t node = plist_dict_get_item(dict, "BackupMessageTypeKey");
-        if (!node) {
-                debug_info("ERROR: BackupMessageTypeKey not found in BackupReplyOK message!");
-                err = MOBILEBACKUP_E_PLIST_ERROR;
-                goto leave;
-        }
-
-        char *str = NULL;
-        plist_get_string_val(node, &str);
-        if (!str || (strcmp(str, "BackupMessageBackupReplyOK") != 0)) {
-                debug_info("ERROR: BackupMessageTypeKey value does not match 'BackupMessageBackupReplyOK'");
-                err = MOBILEBACKUP_E_REPLY_NOT_OK;
-                if (str)
-                        free(str);
-                goto leave;
-        }
-        free(str);
-        str = NULL;
-
-        node = plist_dict_get_item(dict, "BackupProtocolVersion");
+        plist_t node = plist_dict_get_item(dict, "BackupProtocolVersion");
         if (node) {
+                char *str = NULL;
                 plist_get_string_val(node, &str);
                 if (str) {
                         if (strcmp(str, proto_version) != 0) {