Difference between revisions of "SoC/2017"

From SambaWiki
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For the Samba AD DC, libcli/dns is a library that allows the handling of DNS
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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
 
calls (send/receive requests) and generates GSS-TSIG type encryption signature
 
for signed packets, to accomodate encrypted client-server communication.
 
for signed packets, to accomodate encrypted client-server communication.
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* DNS name packet parsing and signing
 
* DNS name packet parsing and signing
   
The library consists of cli_dns.c, that includes functions, and dns.h, libtcp.h,
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The library consists of ''cli_dns.c'', that includes functions, and ''dns.h, libtcp.h,
libtsig.h, libudp.h, that provide definitions and structures.
+
libtsig.h, libudp.h,'' that provide definitions and structures.
   
 
====== Wrapping ======
 
====== Wrapping ======
 
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wrap_cli.c provides multiple wrapping of the above functionality, to hide buffer
+
''wrap_cli.c'' provides multiple wrapping of the above functionality, to hide buffer
 
creation, DNS packet parsing and signature generation. Definitions of the wrapped
 
creation, DNS packet parsing and signature generation. Definitions of the wrapped
functions are provided in libwrap.h.
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functions are provided in ''libwrap.h''.
   
   
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In cmocka-tests, cli_tests.c provides a test suite for the complete client-side functionality,
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In ''cmocka-tests, cli_tests.c'' provides a test suite for the complete client-side functionality,
as defined by the functions in libcli/dns/cli_dns.c. The API used for unit testing is
+
as defined by the functions in ''libcli/dns/cli_dns.c''. The API used for unit testing is
 
Cmocka.
 
Cmocka.
   
In cmocka-tests/test-fn, there are individual unit tests for every feature library in libcli/dns. All of these tests are incorporated in cmocka-tests/cli_tests.c These tests
+
In ''cmocka-tests/test-fn'', there are individual unit tests for every feature library in ''libcli/dns''. All of these tests are incorporated in ''cmocka-tests/cli_tests.c'' These tests
can be built by using waf-samba and the intended configuration in cmocka-tests/test-fn/wscript.
+
can be built by using waf-samba and the intended configuration in ''cmocka-tests/test-fn/wscript''.
 
The purpose of these test suites is to facilitate future additions and features in Samba
 
The purpose of these test suites is to facilitate future additions and features in Samba
client-side code, without the necessity to integrate them directly to cli_dns.c, thus
+
client-side code, without the necessity to integrate them directly to ''cli_dns.c'', thus
 
making changes easier to test and encourage future contributions.
 
making changes easier to test and encourage future contributions.

Revision as of 22:18, 26 August 2017

Improve libcli/dns

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


Project Information


Client-side DNS call handling with GSS-TSIG

Unix SMB/CIFS implementation

Dimitrios Gravanis (C) 2017

Based on the existing work by Samba Team


About

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.

The project goal was to enhance client-server communication, by implementing TCP request send/receive handling and sign client-side packets with GSS-TSIG signatures, to provide security.

It consists of its respective function and structure libraries, that provide definitions for client-side functionality.


Project libcli/dns structure:

  • cli-fn/
    • README.md
    • client_crypto.c
    • dns_tcp.c
    • dns_udp.c
  • cmocka-tests/
    • test-fn
      • cli_crypto_test.c
      • dns_tcp_test.c
      • dns_udp_test.c
      • wscript
    • README.md
    • cli_tests.c
    • wscript_build
  • README.md
  • cli_dns.c
  • dns.h
  • libtcp.h
  • libudp.h
  • libtsig.h
  • libwrap.h
  • wrap_cli.c
  • wscript_build


For more information on the project goals, read the GSoC proposal here.

The project timeline and development journal is documented in its dedicated blogspot.


Repositories

  • Individual project repository (requires Samba source code for integration - NOT STANDALONE): link
  • Samba GitHub mirror: link
  • Personal samba-team/samba fork with integrated changes in libcli/dns: 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.

Features:

  • 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 definitions and structures.

Wrapping

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.


Test suite

In cmocka-tests, cli_tests.c provides a test suite for the complete client-side functionality, as defined by the functions in libcli/dns/cli_dns.c. The API used for unit testing is Cmocka.

In cmocka-tests/test-fn, there are individual unit tests for every feature library in libcli/dns. All of these tests are incorporated in cmocka-tests/cli_tests.c These tests can be built by using waf-samba and the intended configuration in cmocka-tests/test-fn/wscript. The purpose of these test suites is to facilitate future additions and features in Samba client-side code, without the necessity to integrate them directly to cli_dns.c, thus making changes easier to test and encourage future contributions.