The Tcpdump Group git mirrors - tcpdump/blob - CONTRIBUTING

   1 Some Information for Contributors
   2 ---------------------------------
   3 You want to contribute to Tcpdump, Thanks!
   4 Please, read these lines.
   5
   6 1) Fork the Tcpdump repository on GitHub from
   7    https://github.com/the-tcpdump-group/tcpdump
   8    (See https://help.github.com/articles/fork-a-repo/)
   9
  10 2) Setup an optional Travis-CI build
  11    You can setup a travis build for your fork. So, you can test your changes
  12    on Linux and OSX before sending pull requests.
  13    (See http://docs.travis-ci.com/user/getting-started/)
  14
  15 3) Clone your repository
  16    git clone https://github.com/<username>/tcpdump.git
  17
  18 4) Do a 'touch .devel' in your working directory.
  19    Currently, the effect is
  20    a) add (via configure, in Makefile) some warnings options ( -Wall
  21    -Wmissing-prototypes -Wstrict-prototypes, ...) to the compiler if it
  22    supports these options,
  23    b) have the Makefile support "make depend" and the configure script run it.
  24
  25 5) Configure and build
  26    ./configure && make -s && make check
  27
  28 6) Add/update sample.pcap files
  29    We use tests directory to do regression tests on the dissection of captured
  30    packets, by running tcpdump against a savefile sample.pcap, created with -w
  31    option and comparing the results with a text file sample.out giving the
  32    expected results.
  33
  34    Any new/updated fields in a dissector must be present in a sample.pcap file
  35    and the corresponding output file.
  36
  37    Configuration is set in tests/TESTLIST.
  38    Each line in this file has the following format:
  39    test-name   sample.pcap   sample.out   tcpdump-options
  40
  41    the sample.out file can be build by:
  42    (cd tests && ../tcpdump -n -r sample.pcap tcpdump-options > sample.out)
  43
  44    It is often useful to have test outputs with different verbosity levels
  45    (none, -v, -vv, -vvv, etc.) depending on the code.
  46
  47 7) Test with 'make check'
  48    Don't send a pull request if 'make check' gives failed tests.
  49
  50 8) Rebase your commits against upstream/master
  51    (To keep linearity)
  52
  53 9) Initiate and send a pull request
  54    (See https://help.github.com/articles/using-pull-requests/)
  55
  56 Some remarks
  57 ------------
  58 a) A thorough reading of some other printers code is useful.
  59
  60 b) Put the normative reference if any as comments (RFC, etc.).
  61
  62 c) Put the format of packets/headers/options as comments.
  63
  64 d) The printer may receive incomplete packet in the buffer, truncated at any
  65    random position, for example by capturing with '-s size' option.
  66    Thus use ND_TTEST, ND_TTEST2, ND_TCHECK or ND_TCHECK2 for bound checking.
  67    For ND_TCHECK2:
  68      Define : static const char tstr[] = " [|protocol]";
  69      Define a label: trunc
  70      Print with: ND_PRINT((ndo, "%s", tstr));
  71    You can test the code via:
  72      sudo ./tcpdump -s snaplen [-v][v][...] -i lo # in a terminal
  73      sudo tcpreplay -i lo sample.pcap             # in another terminal
  74    You should try several values for snaplen to do various truncation.
  75
  76 e) Do invalid packet checks in code: Think that your code can receive in input
  77    not only a valid packet but any arbitrary random sequence of octets (packet
  78    - built malformed originally by the sender or by a fuzz tester,
  79    - became corrupted in transit).
  80    Print with: ND_PRINT((ndo, "%s", istr));     /* to print " (invalid)" */
  81
  82 f) Use 'struct tok' for indexed strings and print them with
  83    tok2str() or bittok2str() (for flags).
  84
  85 g) Avoid empty lines in output of printers.
  86
  87 h) A commit message must have:
  88    First line: Capitalized short summary in the imperative (70 chars or less)
  89
  90    Body: Detailed explanatory text, if necessary. Fold it to approximately
  91    72 characters. There must be an empty line separating the summary from
  92    the body.
  93
  94 i) Avoid non-ASCII characters in code and commit messages.
  95
  96 j) Use the style of the modified sources.
  97
  98 k) Don't mix declarations and code
  99
 100 l) Don't use // for comments
 101    Not all C compilers accept C++/C99 comments by default.
 102
 103 m) Avoid trailing tabs/spaces