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.Dd May  1, 2006
.Dt KRB5_PRINCIPAL 3
.Os HEIMDAL
.Sh NAME
.Nm krb5_get_default_principal ,
.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_parse_name_flags ,
.Nm krb5_parse_nametype ,
.Nm krb5_princ_set_realm ,
.Nm krb5_principal_compare ,
.Nm krb5_principal_compare_any_realm ,
.Nm krb5_principal_get_comp_string ,
.Nm krb5_principal_get_realm ,
.Nm krb5_principal_get_type ,
.Nm krb5_principal_match ,
.Nm krb5_principal_set_type ,
.Nm krb5_realm_compare ,
.Nm krb5_sname_to_principal ,
.Nm krb5_sock_to_principal ,
.Nm krb5_unparse_name ,
.Nm krb5_unparse_name_flags ,
.Nm krb5_unparse_name_fixed ,
.Nm krb5_unparse_name_fixed_flags ,
.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_parse_name_flags "krb5_context context" "const char *name" "int flags" "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_flags" "krb5_context context" "krb5_const_principal principal" "int flags" "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_fixed_flags "krb5_context context" "krb5_const_principal principal" "int flags" "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 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_comp_string "krb5_context context" "krb5_const_principal principal" "unsigned int component"
.Ft "const char *"
.Fn krb5_principal_get_realm "krb5_context context" "krb5_const_principal principal"
.Ft int
.Fn krb5_principal_get_type "krb5_context context" "krb5_const_principal principal"
.Ft krb5_boolean
.Fn krb5_principal_match "krb5_context context" "krb5_const_principal principal" "krb5_const_principal pattern"
.Ft void
.Fn krb5_principal_set_type "krb5_context context" "krb5_principal principal" "int type"
.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"
.Ft krb5_error_code
.Fn krb5_get_default_principal "krb5_context context" "krb5_principal *princ"
.Ft krb5_error_code
.Fn krb5_parse_nametype "krb5_context context" "const char *str" "int32_t *type"
.Sh DESCRIPTION
.Li krb5_principal
holds the name of a user or service in Kerberos.
.Pp
A principal has two parts, a
.Li PrincipalName
and a
.Li realm .
The PrincipalName consists of one or more components. In printed form,
the components are separated by /.
The PrincipalName also has 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
and
.Fn krb5_parse_name_flags
passes a principal name in
.Fa name
to the kerberos principal structure.
.Fn krb5_parse_name_flags
takes an extra
.Fa flags
argument the following flags can be passed in
.Bl -tag -width Ds
.It Dv KRB5_PRINCIPAL_PARSE_NO_REALM
requires the input string to be without a realm, and no realm is
stored in the
.Fa principal
return argument.
.It Dv KRB5_PRINCIPAL_PARSE_REQUIRE_REALM
requires the input string to with a realm.
.El
.Pp
.Fn krb5_unparse_name
and
.Fn krb5_unparse_name_flags
prints the principal
.Fa princ
to the string
.Fa name .
.Fa name
should be freed with
.Xr free 3 .
To the
.Fa flags
argument the following flags can be passed in
.Bl -tag -width Ds
.It Dv KRB5_PRINCIPAL_UNPARSE_SHORT
no realm if the realm is one of the local realms.
.It Dv KRB5_PRINCIPAL_UNPARSE_NO_REALM
never include any realm in the principal name.
.It Dv KRB5_PRINCIPAL_UNPARSE_DISPLAY
don't quote
.El
On failure
.Fa name
is set to
.Dv NULL .
.Fn krb5_unparse_name_fixed
and
.Fn krb5_unparse_name_fixed_flags
behaves just like
.Fn krb5_unparse ,
but instead unparses the principal into a fixed size buffer.
.Pp
.Fn krb5_unparse_name_short
just returns the principal without the realm if the principal is
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 has the length
.Fa rlen .
The following arguments form the components 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
.Fn krb5_build_principal_ext
and
.Fn krb5_build_principal_va_ext
take 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 principals 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
matches a
.Fa principal
against a
.Fa pattern .
The pattern is a globbing expression, where each component (separated
by /) is matched against the corresponding component of the principal.
.Pp
The
.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 return string pointers 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 index of the component to return, from zero to the total number of
components minus one. If the index is out of range
.Dv NULL
is returned.
.Pp
.Fn krb5_principal_get_realm
and
.Fn krb5_principal_get_comp_string
are replacements for
.Fn krb5_princ_component
and related macros, described as internal in the MIT API
specification.
Unlike the macros, 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 in fact 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_principal_get_type
and
.Fn krb5_principal_set_type
get and sets the name type for a principal.
Name type handling is tricky and not often needed,
don't use this unless you know what you do.
.Pp
.Fn krb5_sname_to_principal
and
.Fn krb5_sock_to_principal
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
.Fa type
is
.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.
There must be a mapping between the address and
.Dq sockname .
The function may try to resolve the name in DNS.
.Pp
.Fn krb5_get_default_principal
tries to find out what's a reasonable default principal by looking at
the environment it is running in.
.Pp
.Fn krb5_parse_nametype
parses and returns the name type integer value in
.Fa type .
On failure the function returns an error code and set the error
string.
.\" .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
functions 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.