Samba comes with its own asynchronous DNS parser framework developed for the internal DNS server. Basic calls have been implemented for a client-side library as well, but a more fleshed out implementation would be needed. The goal of this project is to implement more high-level calls handling DNS requests, such as UDP/TCP switchover and client-side GSS-TSIG cryptography. A test suite excercising all the functions is required and can be used to cross-check and complement the existing DNS server tests already shipped by Samba. This testsuite should use cmocka.
- Difficulty: Medium
- Language(s): C
- Mentors: Kai Blin, David Disseldorp
- Student: Dimitris Gravanis
Client-side DNS call handling with GSS-TSIG
Unix SMB/CIFS implementation
Dimitrios Gravanis (C) 2017
Based on the existing work by Samba Team
For the Samba AD DC, libcli/dns is a library that allows the handling of DNS calls (send/receive requests) and generates GSS-TSIG type encryption signature for signed packets, to accomodate encrypted client-server communication.
It consists of its respective function and structure libraries, that provide definitions for client-side functionality.
Test suites are also available, that inspect individual features of cli_dns.c
For more information on the project goals, read the GSoC proposal here.
The project timeline and development journal is documented in its dedicated blogspot.
- Stand-alone repository (requires Samba source code for integration): link
- Personal samba-team/samba fork: link
- Samba GitHub mirror: link
DNS Client (with wrapper support)
Handles TCP and UDP requests.
The client may use either TCP or UDP protocols to send a DNS name request to the server, then handle the reception of the appropriate server response.
- UDP request send/receive
- TCP request send/receive
- GSS-TSIG generation
- DNS name packet parsing and signing
The library consists of cli_dns.c, that includes functions, and dns.h, libtcp.h, libtsig.h, libudp.h, that provide declarations, definitions and structures.
wrap_cli.c provides multiple wrapping of the above functionality, to hide buffer creation, DNS packet parsing and signature generation. Definitions of the wrapped functions are provided in libwrap.h.
cli_tests.c provides a test suite for all client-side functionality, as defined by the functions in libcli/dns/cli_dns.c. The API used for unit testing is Cmocka.