sss_client: Use SAFEALIGN_COPY_<type> macros where appropriate. resolves: https://fedorahosted.org/sssd/ticket/1359

NSS: Add sss_readrep_copy_string There were many places in the client code where we were duplicating a loop to copy data in from the response buffer. This patch turns those loops into a function for easier maintenance and easier-to-read *readrep() routines.

NSS: Validate input string lengths Also fixes a return value bug where we were returning errno error codes instead of nss_status codes. Fixes https://fedorahosted.org/sssd/ticket/1135

sss_client: make code thread-safe Add mutexes around nss operations and serialize them. This is necessary because nss operations may have global state. For pam it is sufficient to protect socket operations instead. As pam functions use only the provided pam handler. Fixes: https://fedorahosted.org/sssd/ticket/640

Avoid a global variable in netgroup client. The structure which is used to store the result also provides elements to store a context for the netgroup enumeration call.

Add handling of nested netgroups to nss client

Return NSS_STATUS_RETURN instead of NSS_STATUS_NOTFOUND NSS_STATUS_RETURN needs to be returned to glibc otherwise nested groups are not resolved by glibc.

Add support for netgroups to NSS sss_client