vty: add ctrl section for Control interface bind address

This may seem like overkill for a mere const char * config item, but it makes
the Control interface VTY commands reusable in any main() scope (inspired by
libosmo-abis' VTY config).

Add API functions ctrl_vty_init() and ctrl_vty_get_bind_addr(), in new files
src/ctrl/control_vty.c and include/osmocom/ctrl/control_vty.h, compiled and/or
installed dependent on ENABLE_VTY.

Using these functions allows configuring a static const char* with the VTY
commands

    ctrl
     bind A.B.C.D

which callers shall subsequently use to bind the Control interface to a
specific local interface address, by passing the return value of
ctrl_vty_get_bind_addr() to control_interface_setup().

Add CTRL_NODE to enum node_type, "eating" RESERVED4_NODE to heed that comment
on avoiding ABI changes.

1 files changed, 9 insertions, 0 deletions

diff --git a/include/osmocom/ctrl/control_vty.h b/include/osmocom/ctrl/control_vty.h
new file mode 100644
index 00000000..d0ef69f4
--- /dev/null
+++ b/include/osmocom/ctrl/control_vty.h
@@ -0,0 +1,9 @@
+#pragma once
+
+/* Add the 'ctrl' section to VTY, containing the 'bind' command. */
+int ctrl_vty_init(void *ctx);
+
+/* Obtain the IP address configured by the 'ctrl'/'bind A.B.C.D' VTY command.
+ * This should be fed to ctrl_interface_setup() once the configuration has been
+ * read. */
+const char *ctrl_vty_get_bind_addr(void);