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.Dd April 16, 2003
.Dt KRB5_PRINCIPAL 3
.Os HEIMDAL
.Sh NAME
.Nm krb5_principal ,
.Nm krb5_build_principal ,
.Nm krb5_build_principal_ext ,
.Nm krb5_build_principal_va ,
.Nm krb5_build_principal_va_ext ,
.Nm krb5_copy_principal ,
.Nm krb5_free_principal ,
.Nm krb5_make_principal ,
.Nm krb5_parse_name ,
.Nm krb5_princ_realm ,
.Nm krb5_princ_set_realm ,
.Nm krb5_principal_compare ,
.Nm krb5_principal_compare_any_realm ,
.Nm krb5_principal_get_realm ,
.Nm krb5_principal_get_comp_string ,
.Nm krb5_principal_match ,
.Nm krb5_realm_compare ,
.Nm krb5_sname_to_principal ,
.Nm krb5_sock_to_principal ,
.Nm krb5_unparse_name ,
.Nm krb5_unparse_name_fixed ,
.Nm krb5_unparse_name_fixed_short ,
.Nm krb5_unparse_name_short
.Nd Kerberos 5 principal handling functions
.Sh LIBRARY
Kerberos 5 Library (libkrb5, -lkrb5)
.Sh SYNOPSIS
.In krb5.h
.Pp
.Li krb5_principal ;
.Ft void
.Fn krb5_free_principal "krb5_context context" "krb5_principal principal"
.Ft krb5_error_code
.Fn krb5_parse_name "krb5_context context" "const char *name" "krb5_principal *principal"
.Ft krb5_error_code
.Fn "krb5_unparse_name" "krb5_context context" "krb5_const_principal principal" "char **name"
.Ft krb5_error_code
.Fn krb5_unparse_name_fixed "krb5_context context" "krb5_const_principal principal" "char *name" "size_t len"
.Ft krb5_error_code
.Fn "krb5_unparse_name_short" "krb5_context context" "krb5_const_principal principal" "char **name"
.Ft krb5_error_code
.Fn krb5_unparse_name_fixed_short "krb5_context context" "krb5_const_principal principal" "char *name" "size_t len"
.Ft krb5_realm *
.Fn krb5_princ_realm "krb5_context context" "krb5_principal principal"
.Ft void
.Fn krb5_princ_set_realm "krb5_context context" "krb5_principal principal" "krb5_realm *realm"
.Ft krb5_error_code
.Fn krb5_build_principal "krb5_context context" "krb5_principal *principal" "int rlen" "krb5_const_realm realm" "..."
.Ft krb5_error_code
.Fn krb5_build_principal_va "krb5_context context" "krb5_principal *principal" "int rlen" "krb5_const_realm realm" "va_list ap"
.Ft krb5_error_code
.Fn "krb5_build_principal_ext" "krb5_context context", "krb5_principal *principal" "int rlen" "krb5_const_realm realm" "..."
.Ft krb5_error_code
.Fn krb5_build_principal_va_ext "krb5_context context" "krb5_principal *principal" "int rlen" "krb5_const_realm realm" "va_list ap"
.Ft krb5_error_code
.Fn krb5_make_principal "krb5_context context" "krb5_principal *principal" "krb5_const_realm realm" "..."
.Ft krb5_error_code
.Fn krb5_copy_principal "krb5_context context" "krb5_const_principal inprinc" "krb5_principal *outprinc"
.Ft krb5_boolean
.Fn krb5_principal_compare "krb5_context context" "krb5_const_principal princ1" "krb5_const_principal princ2"
.Ft krb5_boolean
.Fn krb5_principal_compare_any_realm "krb5_context context" "krb5_const_principal princ1 "krb5_const_principal princ2"
.Ft "const char *"
.Fn krb5_principal_get_realm "krb5_context context" "krb5_principal principal"
.Ft "const char *"
.Fn krb5_principal_get_comp_string "krb5_context context" "krb5_principal principal" "unsigned int component"
.Ft krb5_boolean
.Fn krb5_principal_match "krb5_context context" "krb5_const_principal principal" "krb5_const_principal pattern"
.Ft krb5_boolean
.Fn krb5_realm_compare "krb5_context context" "krb5_const_principal princ1" "krb5_const_principal princ2"
.Ft krb5_error_code
.Fn krb5_sname_to_principal  "krb5_context context" "const char *hostname" "const char *sname" "int32_t type" "krb5_principal *ret_princ"
.Ft krb5_error_code
.Fn krb5_sock_to_principal "krb5_context context" "int socket" "const char *sname" "int32_t type" "krb5_principal *principal"
.Sh DESCRIPTION
.Li krb5_principal
holds the name of a user or service in Kerberos.
.Pp
A principal have two parts, a
.Li PrincipalName
and a
.Li realm .
The PrincipalName consists of one or more components, in printed form,
each components are separated by /.
The PrincipalName also have a name-type.
.Pp
Examples of a principal are
.Li nisse/root@EXAMPLE.COM
and
.Li host/datan.kth.se@KTH.SE .
.Fn krb5_parse_name
passes a principal name in
.Fa name
to the kerberos pricpal structure.
.Pp
.Fn krb5_unparse_name
prints the principal
.Fa princ
to the string
.Fa name .
.Fa name
should be freed with
.Xr free 3 .
.Fn krb5_unparse_name_fixed
behavies just like
.Fn krb5_unparse ,
but instead unparses the principal into a fixed size buffer.
.Pp
.Fn krb5_unparse_name_short
just return the principal without the realm if the principal is with
in in the default realm. If the principal isn't, the full name is
returned.
.Fn krb5_unparse_name_fixed_short
works just like
.Fn krb5_unparse_name_short
but on a fixed size buffer.
.Pp
.Fn krb5_build_principal
builds a principal from the realm
.Fa realm
that have the length
.Fa rlen .
each following arguments forms the each component of the principal.
The list of components is terminated with
.Dv NULL .
.Pp
.Fn krb5_build_principal_va
works like
.Fn krb5_build_principal
using vargs.
.Pp
The
.Fn krb5_build_principal_ext
and
.Fn krb5_build_principal_va_ext
takes a list of length-value pairs, the list is terminated with a zero
length.
.Pp
.Fn krb5_make_principal
works the same way as
.Fn krb5_build_principal ,
except it figures out the length of the realm itself.
.Pp
.Fn krb5_copy_principal
makes a copy of a principal.
The copy needs to be freed with
.Fn krb5_free_principal .
.Pp
.Fn krb5_principal_compare
compares the two principals, including realm of the principal and returns
.Dv TRUE
if they are the same and
.Dv FALSE
if not.
.Pp
.Fn krb5_principal_compare_any_realm
works the same way as
.Fn krb5_principal_compare
but doesn't compare the realm component of the principal.
.Pp
.Fn krb5_realm_compare
compares the realms of the two principals and returns
.Dv TRUE
is they are the same, and
.Dv FALSE
if not.
.Pp
.Fn krb5_principal_match
maches are
.Fa principal
with a
.Fa pattern .
The patttern is a globbing expression, where each component (separated
by /) of the principal is matched with each other.
.Pp
.Fn krb5_principal_get_realm
and
.Fn krb5_principal_get_comp_string
functions return parts of the
.Fa principal ,
either the realm or a specific component.
Both functions returned string points to data inside the principal, so
they are valid only as long as the principal exists.
.Pp
The
.Fa component
argument to
.Fn krb5_principal_get_comp_string
is the component number to return, from zero to the total number of
components minus one. If a the requested component number is out of range,
.Dv NULL
is returned.
.Pp
.Fn krb5_principal_get_realm
and
.Fn krb5_principal_get_comp_string
can be seen as a replacement for the
.Fn krb5_princ_realm ,
.Fn krb5_princ_component
and related macros, described as intermal in the MIT API
specification.
A difference is that these functions return strings, not
.Dv krb5_data .
A reason to return
.Dv krb5_data
was that it was believed that principal components could contain
binary data, but this belief was unfounded, and it has been decided
that principal components are infact UTF8, so it's safe to use zero
terminated strings.
.Pp
It's generally not necessary to look at the components of a principal.
.Pp
.Fn krb5_princ_realm
returns the realm component of the principal.
Caller must not free realm unless
.Fn krb5_princ_set_realm
is called to set a new realm after freeing the realm.
.Fn krb5_princ_set_realm
sets the realm component of a principal. Old realm is not freed.
.Pp
There are two functions
.Fn krb5_sname_to_principal
and
.Fn krb5_sock_to_principal
that are for easy creation of
.Dq service
principals that can, for instance, be used to lookup a key in a keytab.
For both functions the
.Fa sname
parameter will be used for the first component of the created principal.
If
.Fa sname
is
.Dv NULL ,
.Dq host
will be used instead.
.Pp
.Fn krb5_sname_to_principal
will use the passed
.Fa hostname
for the second component.
If type
.Dv KRB5_NT_SRV_HST
this name will be looked up with
.Fn gethostbyname .
If
.Fa hostname is
.Dv NULL ,
the local hostname will be used.
.Pp
.Fn krb5_sock_to_principal
will use the
.Dq sockname
of the passed
.Fa socket ,
which should be a bound
.Dv AF_INET
or
.Dv AF_INET6
socket.
This function require there is a mapping between the address
.Fq sockname .
This function might try to resolve the name in DNS.
.\" .Sh EXAMPLES
.Sh SEE ALSO
.Xr krb5_425_conv_principal 3 ,
.Xr krb5_config 3 ,
.Xr krb5.conf 5
.Sh BUGS
You can not have a NUL in a component in some of the variable argument function above.
Until someone can give a good example of where it would be a good idea
to have NUL's in a component, this will not be fixed.