contrib/sb-bsd-sockets/name-service.lisp

   1 (in-package :sb-bsd-sockets)
   2 #|| <a name="name-service"><h2>Name Service</h2></a>
   3
   4 <p>Presently name service is implemented by calling whatever
   5 gethostbyname(2) uses.  This may be any or all of /etc/hosts, NIS, DNS,
   6 or something completely different.  Typically it's controlled by
   7 /etc/nsswitch.conf
   8
   9 <p> Direct links to the asynchronous resolver(3) routines would be nice to have
  10 eventually, so that we can do DNS lookups in parallel with other things
  11 |#
  12
  13 (defclass host-ent ()
  14   ((name :initarg :name :accessor host-ent-name)
  15    (aliases :initarg :aliases :accessor host-ent-aliases)
  16    (address-type :initarg :type :accessor host-ent-address-type)
  17                                         ; presently always AF_INET
  18    (addresses :initarg :addresses :accessor host-ent-addresses)))
  19
  20 (defmethod host-ent-address ((host-ent host-ent))
  21   (car (host-ent-addresses host-ent)))
  22
  23 ;(define-condition host-not-found-error (socket-error)) ; host unknown
  24 ;(define-condition no-address-error (socket-error)) ; valid name but no IP address
  25 ;(define-condition no-recovery-error (socket-error)) ; name server error
  26 ;(define-condition try-again-error (socket-error)) ; temporary
  27
  28 (defun get-host-by-name (host-name)
  29   "Returns a HOST-ENT instance for HOST-NAME or throws some kind of condition.
  30 HOST-NAME may also be an IP address in dotted quad notation or some other
  31 weird stuff - see gethostbyname(3) for grisly details."
  32   (let ((h (sockint::gethostbyname host-name)))
  33     (make-host-ent h)))
  34
  35 (defun get-host-by-address (address)
  36   "Returns a HOST-ENT instance for ADDRESS, which should be a vector of
  37 (integer 0 255), or throws some kind of error.  See gethostbyaddr(3) for
  38 grisly details."
  39   (let ((packed-addr (sockint::allocate-in-addr)))
  40     (loop for i from 0 to 3
  41           do (setf (sockint::in-addr-addr packed-addr i) (elt address i)))
  42     (make-host-ent
  43      (sb-sys:without-gcing
  44       (sockint::gethostbyaddr (sockint::array-data-address packed-addr)
  45                               4
  46                               sockint::af-inet)))))
  47
  48 (defun make-host-ent (h)
  49   (if (sockint::foreign-nullp h) (name-service-error "gethostbyname"))
  50   (let* ((local-h (sockint::foreign-vector h 1 sockint::size-of-hostent))
  51          (length (sockint::hostent-length local-h))
  52          (aliases
  53           (loop for i = 0 then (1+ i)
  54                 for al = (sb-sys:sap-ref-sap
  55                           (sb-sys:int-sap (sockint::hostent-aliases local-h))
  56                           (* i 4))
  57                 until (= (sb-sys:sap-int al) 0)
  58                 collect (sb-c-call::%naturalize-c-string al)))
  59          (address0 (sb-sys:sap-ref-sap (sb-sys:int-sap (sockint::hostent-addresses local-h)) 0))
  60          (addresses
  61           (loop for i = 0 then (+ length i)
  62                 for ad = (sb-sys:sap-ref-32 address0 i)
  63                 while (> ad 0)
  64                 collect
  65                 (sockint::foreign-vector (sb-sys:sap+ address0 i) 1 length))))
  66     (make-instance 'host-ent
  67                    :name (sb-c-call::%naturalize-c-string
  68                           (sb-sys:int-sap (sockint::hostent-name local-h)))
  69                    :type (sockint::hostent-type local-h)
  70                    :aliases aliases
  71                    :addresses addresses)))
  72
  73 ;;; The remainder is my fault - gw
  74
  75 (defvar *name-service-errno* 0
  76   "The value of h_errno, after it's been fetched from Unix-land by calling
  77 GET-NAME-SERVICE-ERRNO")
  78
  79 (defun name-service-error (where)
  80   (get-name-service-errno)
  81   ;; Comment next to NETDB_INTERNAL in netdb.h says "See errno.".
  82   ;; This special case treatment hasn't actually been tested yet.
  83   (if (= *name-service-errno* sockint::NETDB-INTERNAL)
  84       (socket-error where)
  85     (let ((condition
  86            (condition-for-name-service-errno *name-service-errno*)))
  87       (error condition :errno *name-service-errno* :syscall where))))
  88
  89 (define-condition name-service-error (condition)
  90   ((errno :initform nil
  91           :initarg :errno
  92           :reader name-service-error-errno)
  93    (symbol :initform nil :initarg :symbol :reader name-service-error-symbol)
  94    (syscall :initform "an unknown location" :initarg :syscall :reader name-service-error-syscall))
  95   (:report (lambda (c s)
  96              (let ((num (name-service-error-errno c)))
  97                (format s "Name service error in \"~A\": ~A (~A)"
  98                        (name-service-error-syscall c)
  99                        (or (name-service-error-symbol c)
 100                            (name-service-error-errno c))
 101                        (get-name-service-error-message num))))))
 102
 103 (defmacro define-name-service-condition (symbol name)
 104   `(progn
 105      (define-condition ,name (name-service-error)
 106        ((symbol :reader name-service-error-symbol :initform (quote ,symbol))))
 107      (push (cons ,symbol (quote ,name)) *conditions-for-name-service-errno*)))
 108
 109 (defparameter *conditions-for-name-service-errno* nil)
 110
 111 (define-name-service-condition sockint::NETDB-INTERNAL netdb-internal-error)
 112 (define-name-service-condition sockint::NETDB-SUCCESS netdb-success-error)
 113 (define-name-service-condition sockint::HOST-NOT-FOUND host-not-found-error)
 114 (define-name-service-condition sockint::TRY-AGAIN try-again-error)
 115 (define-name-service-condition sockint::NO-RECOVERY no-recovery-error)
 116 ;; this is the same as the next one
 117 ;;(define-name-service-condition sockint::NO-DATA no-data-error)
 118 (define-name-service-condition sockint::NO-ADDRESS no-address-error)
 119
 120 (defun condition-for-name-service-errno (err)
 121   (or (cdr (assoc err *conditions-for-name-service-errno* :test #'eql))
 122       'name-service))
 123
 124
 125
 126 (defun get-name-service-errno ()
 127   (setf *name-service-errno*
 128         (sb-alien:alien-funcall
 129          (sb-alien:extern-alien "get_h_errno" (function integer)))))
 130
 131 #-solaris
 132 (progn
 133   #+sbcl
 134   (sb-alien:define-alien-routine "hstrerror"
 135       sb-c-call:c-string
 136     (errno integer))
 137   #+cmu
 138   (alien:def-alien-routine "hstrerror"
 139       sb-c-call:c-string
 140     (errno integer))
 141   (defun get-name-service-error-message (num)
 142   (hstrerror num))
 143 )
 144