Some things are mentioned here to help any potential gnutls coder.
The rules here are not always used, although we try to stick to them.


*** File names:
  All file names are usually prefixed with "gnutls_", "auth_", or
 "x509_", or something else that indicates the part of gnutls
 where this file refers to. The suffix should be more
 specific. I.e., "gnutls_record.c" refers to the TLS library
 and, more specifically, to the TLS record protocol. "auth_rsa.c"
 is the implementation of the RSA certificate authentication
 method.

 Another way to distinguish files might be using different
 subdirectories. Use the lib/x509/ directory, which contains
 all the X.509 certificate and crl stuff.


*** Function names:
  All the function names use underscore "_", to separate words,
 functions like gnutlsDoThat are not used. The function names
 usually start with "gnutls_" prefix, and the words that follow
 specify the exact part of gnutls that this function refers to.
 E.g. "gnutls_x509_crt_get_dn", refers to the X.509
 certificate parsing part of gnutls. Currently used prefixes are:
 "gnutls_x509_crt_" for the X.509 certificate part
 "gnutls_openpgp_key_" for the openpgp key part
 "gnutls_session_" for the TLS session part (but this may be omited)
 "gnutls_handshake_" for the TLS handshake part
 "gnutls_record_" for the TLS record protocol part
 "gnutls_alert_" for the TLS alert protocol part
 "gnutls_credentials_" for the credentials structures
 "gnutls_global_" for the global structures handling
 and probably more.

 Internal functions -- that are not exported in the API -- should
 be prefixed with an underscore. E.g. _gnutls_handshake_begin()

 All exported functions must be listed in gnutls.sym and gnutls-extra.sym
 in order to be exported. [this is not true for now]

*** Constructed types:
  The constructed types in gnutls always have the "gnutls_" prefix.
 Definitions, value defaults and enumerated values should be in
 capitals. E.g. GNUTLS_CIPHER_3DES_CBC

 Structures should have the '_st' suffix in their name even
 if they are a typedef. One can use the sizeof() on types with 
 '_st' as suffix.

 Other constructed types should have the '_t' suffix. A pointer
 to a structure also has the '_t' suffix.

*** Function parameters:
  The gnutls functions accept parameters in the order:
  1. Input parameters
  2. Output parameters

  When data and size is expected, a gnutls_datum structure should be
  used (or more precisely a pointer to the structure).

*** Callback function parameters:
  Callback functions should be avoided, if this is possible. 
 Callbacks that refer to a TLS session should include the
 current session as a parameter, in order for the called function to
 be able to retrieve the data associated with the session.
 This is not always done though -- see the push/pull callbacks.

*** Return values:
  Functions in gnutls return an int type, when possible. In that
 case 0 should be returned in case of success, or maybe a positive
 value, if some other indication is needed.
 
 A negative value always indicates failure. All the available
 error codes are defined in gnutls.h and a description
 is available in gnutls_errors.c

*** Indentation style:
  In general, use the GNU Coding Standard.  You may indent the source
  using GNU indent, e.g. "indent *.c".