diff options
Diffstat (limited to 'manual/nss.texi')
| -rw-r--r-- | manual/nss.texi | 45 |
1 files changed, 34 insertions, 11 deletions
diff --git a/manual/nss.texi b/manual/nss.texi index b2dc886..6d9d831 100644 --- a/manual/nss.texi +++ b/manual/nss.texi @@ -57,6 +57,7 @@ The databases available in the NSS are @cindex ethers @cindex group @cindex hosts +@cindex netgroup @cindex network @cindex protocols @cindex passwd @@ -71,6 +72,8 @@ Ethernet numbers, Groups of users, @pxref{Group Database}. @item hosts Host names and numbers, @pxref{Host Names}. +@item netgroup +Network wide list of host and users, @pxref{Netgroup Database}. @item network Network names and numbers, @pxref{Networks Database}. @item protocols @@ -89,8 +92,7 @@ Shadow user passwords, @noindent There will be some more added later (@code{aliases}, @code{automount}, -@code{bootparams}, @code{netgroup}, @code{netmasks}, and -@code{publickey}). +@code{bootparams}, @code{netmasks}, and @code{publickey}). @node NSS Configuration File, NSS Module Internals, NSS Basics, Name Service Switch @section The NSS Configuration File @@ -122,7 +124,7 @@ the reaction on lookup result line @code{[NOTFOUND=return]}. @end itemize @menu -* Services in the NSS configuration:: Service names in the NSS configuratin. +* Services in the NSS configuration:: Service names in the NSS configuration. * Actions in the NSS configuration:: React approprite on the lookup result. * Notes on NSS Configuration File:: Things to take care about while configuring NSS. @@ -256,6 +258,20 @@ all supported databases there is a default value so it should normally be possible to get the system running even if the file is corrupted or missing. +@cindex default value, and NSS +For the @code{hosts} and @code{network} databases the default value is +@code{dns [!UNAVAIL=return] files}. I.e., the system is prepared for +the DNS service not to be available but if it is available the answer it +returns is ultimative. + +For all other databases the default value is +@code{compat [NOTFOUND=return] files}. This solution give the best +chance to be correct since NIS and file based lookup is used. The +@code{compat} service is available in a separate add-on to GNU C +library, available in the same place you got the GNU C library source +from. + +@cindex optimizing NSS A second point is that the user should try to optimize the lookup process. The different service have different response times. A simple file look up on a local file could be fast, but if the file is long and the @@ -365,17 +381,19 @@ struct hostent *gethostbyname_r (const char *name, @end smallexample @noindent -The actual prototype of the function is the NSS modules in this case is +The actual prototype of the function in the NSS modules in this case is @smallexample -int _nss_files_gethostbyname_r (const char *name, - struct hostent *result_buf, char *buf, - int buflen, int *h_errnop) +enum nss_status _nss_files_gethostbyname_r (const char *name, + struct hostent *result_buf, + char *buf, int buflen, + int *h_errnop) @end smallexample -I.e., the interface function is in fact the reentrant function with -the change of the return value. While the user-level function returns a -pointer to the result the reentrant function return an @code{int} value: +I.e., the interface function is in fact the reentrant function with the +change of the return value. While the user-level function returns a +pointer to the result the reentrant function return an @code{enum +nss_status} value: @cindex NSS_STATUS_TRYAGAIN @cindex NSS_STATUS_UNAVAIL @@ -399,7 +417,12 @@ numeric value @code{1} Now you see where the action items of the @file{/etc/nsswitch.conf} file are used. -The above function has somthing special which is missing for almost all +If you study the source code you will find there is a fifth value: +@code{NSS_STATUS_RETURN}. This is an internal use only value, used by a +few functions in places where none of the above value can be used. If +necessary the source code should be examined to learn about the details. + +The above function has something special which is missing for almost all the other module functions. There is an argument @var{h_errnop}. This points to a variable which will be filled with the error code in case the execution of the function fails for some reason. The reentrant |