Author: ehuelsmann Date: Sun Feb 5 15:46:10 2006 New Revision: 44 Modified: usocket/trunk/doc/design.txt Log: Extend design document. Modified: usocket/trunk/doc/design.txt ============================================================================== --- usocket/trunk/doc/design.txt (original) +++ usocket/trunk/doc/design.txt Sun Feb 5 15:46:10 2006 @@ -66,11 +66,6 @@ to write a DNS client library: (which in the end may work better, because in this respect all implementations are different...) - retrieve IP addresses/ports for both sides of the connection ---- later addition -I don't think it's a good idea to implement name lookup in the -very first of steps: we'll see if this is required to get the -package accepted; not all implementations support it. ---- later addition; end Several relevant support functionalities will have to be provided too: - long <-> quad-vector operators @@ -86,3 +81,40 @@ - Allegro - LispWorks - OpenMCL + + +Comments on the design above +============================ + +I don't think it's a good idea to implement name lookup in the +very first of steps: we'll see if this is required to get the +package accepted; not all implementations support it. + +Name resolution errors ... +Since there is no name resolution library (yet), nor standardized +hooks into the standard C library to do it the same way on +all platforms, name resolution errors can manifest themselves +in a lot of different ways. How to marshall these to the +library users? + +Several solutions come to mind: + +1) Map them to 'unknown-error +2) Give them their own errors and map to those +3) ... + +Given that the library doesn't now, but may in the future, +include name resolution officially, I tend to think (1) is the +right answer: it leaves it all undecided. + +These errors can be raised by the nameresolution service +(netdb.h) as values for 'int h_errno': + +- HOST_NOT_FOUND (1) +- TRY_AGAIN (2) /* Server fail or non-authoritive Host not found */ +- NO_RECOVERY (3) /* Failed permanently */ +- NO_DATA (4) /* Valid address, no data for requested record */ + +int *__h_errno_location(void) points to thread local h_errno on +threaded glibc2 systems. +