libnftables-dotnet/docs/low-level-bindings-reference.md

Low-Level Binding Reference (LibNftables.Bindings.Generated)

This document describes the generated low-level .NET bindings for libnftables.

Generation policy

• Source of truth: /usr/include/nftables/libnftables.h
• Generator: SWIG C# (./eng/regen-bindings.sh)
• Generated files are under src/LibNftables.Bindings/Generated/.
• Do not manually edit generated files. Regenerate instead.

Primary generated types

• libnftables: static entrypoint for native calls and exported constants.
• SWIGTYPE_p_nft_ctx: opaque native context pointer wrapper.
• nft_debug_level: generated native debug enum.
• nft_optimize_flags: generated native optimize enum.

API groups

1) Context lifecycle

• nft_ctx_new(uint flags)
• nft_ctx_free(SWIGTYPE_p_nft_ctx ctx)

These allocate/free the native nft_ctx handle.

2) Context behavior flags

• Dry-run:
  • nft_ctx_get_dry_run(...)
  • nft_ctx_set_dry_run(...)
• Optimize:
  • nft_ctx_get_optimize(...)
  • nft_ctx_set_optimize(...)
• Input flags:
  • nft_ctx_input_get_flags(...)
  • nft_ctx_input_set_flags(...)
• Output flags:
  • nft_ctx_output_get_flags(...)
  • nft_ctx_output_set_flags(...)
• Debug flags:
  • nft_ctx_output_get_debug(...)
  • nft_ctx_output_set_debug(...)

3) Buffered output/error capture

• Output buffer:
  • nft_ctx_buffer_output(...)
  • nft_ctx_unbuffer_output(...)
  • nft_ctx_get_output_buffer(...)
• Error buffer:
  • nft_ctx_buffer_error(...)
  • nft_ctx_unbuffer_error(...)
  • nft_ctx_get_error_buffer(...)

4) Include paths and variables

• Include paths:
  • nft_ctx_add_include_path(...)
  • nft_ctx_clear_include_paths(...)
• Variables:
  • nft_ctx_add_var(...)
  • nft_ctx_clear_vars(...)

5) Command execution

• nft_run_cmd_from_buffer(...)
• nft_run_cmd_from_filename(...)

These are the low-level command execution entrypoints.

Constants exposed via generated class

libnftables exposes native constants as static readonly fields, including:

• NFT_CTX_DEFAULT
• NFT_CTX_INPUT_*
• NFT_CTX_OUTPUT_*

Use the high-level enums in LibNftables when possible.

Relation to high-level API

Use low-level generated bindings only when you need direct native semantics.

For application code, prefer:

• NftablesClient / INftablesClient for workflow operations (validate/apply/snapshot/restore)
• NftContext for advanced managed control over native context settings