118 lines
5.2 KiB
Scheme
118 lines
5.2 KiB
Scheme
(module dispatch-passwords mzscheme
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(require "dispatch.ss"
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"util.ss"
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"servlet-helpers.ss"
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"connection-manager.ss"
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"response.ss")
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(provide interface-version
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gen-dispatcher)
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(define interface-version 'v1)
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(define (gen-dispatcher password-file password-connection-timeout authentication-responder passwords-refresh-responder)
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(let* ([password-cache (box #f)]
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[reset-password-cache!
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(lambda ()
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; more here - a malformed password file will kill the connection
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(set-box! password-cache (read-passwords password-file)))]
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[read-password-cache
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(lambda ()
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(unbox password-cache))])
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(reset-password-cache!)
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(lambda (conn req)
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(let-values ([(uri method path) (decompose-request req)])
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(cond
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[(access-denied? method path (request-headers req) (read-password-cache))
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=> (lambda (realm)
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(adjust-connection-timeout! conn password-connection-timeout)
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(request-authentication conn method uri
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authentication-responder
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realm))]
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[(string=? "/conf/refresh-passwords" path)
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;; more here - send a nice error page
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(reset-password-cache!)
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(output-response/method
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conn
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(passwords-refresh-responder)
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method)]
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[else
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(next-dispatcher)])))))
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;; ****************************************
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;; ****************************************
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;; ACCESS CONTROL
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;; pass-entry = (make-pass-entry str regexp (list sym str))
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(define-struct pass-entry (domain pattern users))
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;; access-denied? : Method string x-table denied? -> (or/c false str)
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;; denied?: str sym str -> (or/c str #f)
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;; the return string is the prompt for authentication
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(define (access-denied? method uri-str headers denied?)
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(let ([user-pass (extract-user-pass headers)])
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(if user-pass
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(denied? uri-str (lowercase-symbol! (car user-pass)) (cdr user-pass))
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(denied? uri-str fake-user ""))))
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(define-struct (exn:password-file exn) ())
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;; : host -> (str sym str -> (or/c str #f))
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;; to produce a function that checks if a given url path is accessible by a given user with a given
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;; password. If not, the produced function returns a string, prompting for the password.
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;; If the password file does not exist, all accesses are allowed. If the file is malformed, an
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;; exn:password-file is raised.
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(define (read-passwords password-path)
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(with-handlers ([void (lambda (exn)
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(raise (make-exn:password-file (string->immutable-string
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(format "could not load password file ~a" password-path))
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(current-continuation-marks))))])
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(if (and (file-exists? password-path) (memq 'read (file-or-directory-permissions password-path)))
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(let ([passwords
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(let ([raw (load password-path)])
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(unless (password-list? raw)
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(raise "malformed passwords"))
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(map (lambda (x) (make-pass-entry (car x) (regexp (cadr x)) (cddr x)))
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raw))])
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;; string symbol bytes -> (or/c #f string)
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(lambda (request-path user-name password)
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(ormap (lambda (x)
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(and (regexp-match (pass-entry-pattern x) request-path)
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(let ([name-pass (assq user-name (pass-entry-users x))])
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(if (and name-pass
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(string=?
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(cadr name-pass)
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(bytes->string/utf-8 password)))
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#f
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(pass-entry-domain x)))))
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passwords)))
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(lambda (req user pass) #f))))
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(define fake-user (gensym))
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;; password-list? : TST -> bool
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;; Note: andmap fails for dotted pairs at end.
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;; This is okay, since #f ends up raising a caught exception anyway.
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(define (password-list? passwords)
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(and (list? passwords)
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(andmap (lambda (domain)
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(and (pair? domain) (pair? (cdr domain)) (list (cddr domain))
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(string? (car domain))
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(string? (cadr domain))
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(andmap (lambda (x)
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(and (pair? x) (pair? (cdr x)) (null? (cddr x))
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(symbol? (car x)) (string? (cadr x))))
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(cddr domain))))
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passwords)))
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;; request-authentication : connection Method URL iport oport host str bool -> bool
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;; GregP: at first look, it seems that this gets called when the user
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;; has supplied bad authentication credentials.
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(define (request-authentication conn method uri authentication-responder realm)
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(output-response/method
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conn
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(authentication-responder
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uri
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`(WWW-Authenticate . ,(format " Basic realm=\"~a\"" realm)))
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method))) |