lib: add hook for preprocessing commands

This patch adds a hook point intended to allow subscribers to modify the
raw text of a CLI command before it is passed to the rest of the CLI
pipeline. To give access to the raw text of the command, a new function
for executing CLI has been defined whose only difference from
`cmd_execute_command` is that it accepts the command to execute as a
string rather than as a string vector.

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/lib/command.c b/lib/command.c
index 6aae4a074c..97e60a5929 100644
--- a/lib/command.c
+++ b/lib/command.c
@@ -44,6 +44,7 @@
 #include "defaults.h"
 #include "libfrr.h"
 #include "jhash.h"
+#include "hook.h"
 
 DEFINE_MTYPE(LIB, HOST, "Host config")
 DEFINE_MTYPE(LIB, COMPLETION, "Completion item")
@@ -1140,6 +1141,68 @@ int cmd_execute_command_strict(vector vline, struct vty *vty,
 	return cmd_execute_command_real(vline, FILTER_STRICT, vty, cmd);
 }
 
+/*
+ * Hook for preprocessing command string before executing.
+ *
+ * All subscribers are called with the raw command string that is to be
+ * executed. If any changes are to be made, a new string should be allocated
+ * with MTYPE_TMP and *cmd_out updated to point to this new string. The caller
+ * is then responsible for freeing this string.
+ *
+ * All processing functions must be mutually exclusive in their action, i.e. if
+ * one subscriber decides to modify the command, all others must not modify it
+ * when called. Feeding the output of one processing command into a subsequent
+ * one is not supported.
+ *
+ * This hook is intentionally internal to the command processing system.
+ *
+ * cmd_in
+ *    The raw command string.
+ *
+ * cmd_out
+ *    The result of any processing.
+ */
+DECLARE_HOOK(cmd_execute,
+	     (struct vty * vty, const char *cmd_in, char **cmd_out),
+	     (vty, cmd_in, cmd_out));
+DEFINE_HOOK(cmd_execute, (struct vty * vty, const char *cmd_in, char **cmd_out),
+	    (vty, cmd_in, cmd_out));
+
+/* Hook executed after a CLI command. */
+DECLARE_KOOH(cmd_execute_done, (struct vty * vty, const char *cmd_exec),
+	     (vty, cmd_exec));
+DEFINE_KOOH(cmd_execute_done, (struct vty * vty, const char *cmd_exec),
+	    (vty, cmd_exec));
+
+int cmd_execute(struct vty *vty, const char *cmd,
+		const struct cmd_element **matched, int vtysh)
+{
+	int ret;
+	char *cmd_out = NULL;
+	const char *cmd_exec;
+	vector vline;
+
+	hook_call(cmd_execute, vty, cmd, &cmd_out);
+	cmd_exec = cmd_out ? (const char *)cmd_out : cmd;
+
+	vline = cmd_make_strvec(cmd_exec);
+
+	if (vline) {
+		ret = cmd_execute_command(vline, vty, matched, vtysh);
+		cmd_free_strvec(vline);
+	} else {
+		ret = CMD_SUCCESS;
+	}
+
+	hook_call(cmd_execute_done, vty, cmd_exec);
+
+	if (cmd_out)
+		XFREE(MTYPE_TMP, cmd_out);
+
+	return ret;
+}
+
+
 /**
  * Parse one line of config, walking up the parse tree attempting to find a
  * match