329 lines
12 KiB
Scheme
329 lines
12 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2019 Ludovic Courtès <ludo@gnu.org>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (guix ftp-client)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-9)
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#:use-module (srfi srfi-11)
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#:use-module (srfi srfi-26)
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#:use-module (srfi srfi-31)
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#:use-module (ice-9 binary-ports)
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#:use-module (rnrs bytevectors)
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#:use-module (ice-9 match)
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#:use-module (ice-9 regex)
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#:use-module (ice-9 rdelim)
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#:export (ftp-connection?
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ftp-connection-addrinfo
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connect*
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ftp-open
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ftp-close
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ftp-chdir
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ftp-size
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ftp-list
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ftp-retr))
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;;; Commentary:
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;;;
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;;; Simple FTP client (RFC 959).
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;;;
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;;; Code:
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;; TODO: Use SRFI-3{4,5} error conditions.
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(define-record-type <ftp-connection>
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(%make-ftp-connection socket addrinfo)
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ftp-connection?
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(socket ftp-connection-socket)
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(addrinfo ftp-connection-addrinfo))
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(define %ftp-ready-rx
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(make-regexp "^([0-9]{3}) (.+)$"))
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(define (%ftp-listen port)
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(let loop ((line (read-line port)))
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(cond ((eof-object? line) (values line #f))
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((regexp-exec %ftp-ready-rx line)
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=>
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(lambda (match)
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(values (string->number (match:substring match 1))
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(match:substring match 2))))
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(else
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(loop (read-line port))))))
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(define (%ftp-command command expected-code port)
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(format port "~A~A~A" command (string #\return) (string #\newline))
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(let-values (((code message) (%ftp-listen port)))
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(if (eqv? code expected-code)
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message
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(throw 'ftp-error port command code message))))
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(define (%ftp-login user pass port)
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(let ((command (string-append "USER " user
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(string #\return) (string #\newline))))
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(display command port)
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(let-values (((code message) (%ftp-listen port)))
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(case code
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((230) #t)
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((331) (%ftp-command (string-append "PASS " pass) 230 port))
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(else (throw 'ftp-error port command code message))))))
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(define-syntax-rule (catch-EINPROGRESS body ...)
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(catch 'system-error
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(lambda ()
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body ...)
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(lambda args
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(unless (= (system-error-errno args) EINPROGRESS)
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(apply throw args)))))
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;; XXX: For lack of a better place.
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(define* (connect* s sockaddr #:optional timeout)
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"When TIMEOUT is omitted or #f, this procedure is equivalent to 'connect'.
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When TIMEOUT is a number, it is the (possibly inexact) maximum number of
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seconds to wait for the connection to succeed."
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(define (raise-error errno)
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(throw 'system-error 'connect* "~A"
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(list (strerror errno))
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(list errno)))
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(if timeout
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(let ((flags (fcntl s F_GETFL)))
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(fcntl s F_SETFL (logior flags O_NONBLOCK))
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(catch-EINPROGRESS (connect s sockaddr))
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(match (select '() (list s) (list s) timeout)
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((() () ())
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;; Time is up!
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(raise-error ETIMEDOUT))
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((() (write) ())
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;; Check for ECONNREFUSED and the likes.
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(fcntl s F_SETFL flags)
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(let ((errno (getsockopt s SOL_SOCKET SO_ERROR)))
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(unless (zero? errno)
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(raise-error errno))))
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((() () (except))
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;; Seems like this cannot really happen, but who knows.
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(let ((errno (getsockopt s SOL_SOCKET SO_ERROR)))
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(raise-error errno)))))
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(connect s sockaddr)))
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(define* (ftp-open host #:optional (port "ftp")
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#:key timeout
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(username "anonymous")
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(password "guix@example.com"))
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"Open an FTP connection to HOST on PORT (a service-identifying string,
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or a TCP port number), and return it.
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When TIMEOUT is not #f, it must be a (possibly inexact) number denoting the
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maximum duration in seconds to wait for the connection to complete; passed
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TIMEOUT, an ETIMEDOUT error is raised."
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;; Using "ftp" for PORT instead of 21 allows 'getaddrinfo' to return only
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;; TCP/IP addresses (otherwise it would return SOCK_DGRAM and SOCK_RAW
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;; addresses as well.) With our bootstrap Guile, which includes a
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;; statically-linked NSS, resolving "ftp" works well, as long as
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;; /etc/services is available.
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(define addresses
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(getaddrinfo host
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(if (number? port) (number->string port) port)
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(if (number? port)
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(logior AI_ADDRCONFIG AI_NUMERICSERV)
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AI_ADDRCONFIG)))
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(let loop ((addresses addresses))
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(match addresses
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((ai rest ...)
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(let ((s (socket (addrinfo:fam ai)
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;; TCP/IP only
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SOCK_STREAM IPPROTO_IP)))
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(catch 'system-error
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(lambda ()
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(connect* s (addrinfo:addr ai) timeout)
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(setvbuf s 'line)
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(let-values (((code message) (%ftp-listen s)))
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(if (eqv? code 220)
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(begin
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;;(%ftp-command "OPTS UTF8 ON" 200 s)
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(%ftp-login username password s)
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(%make-ftp-connection s ai))
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(begin
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(close s)
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(throw 'ftp-error s "log-in" code message)))))
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(lambda args
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;; Connection failed, so try one of the other addresses.
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(close s)
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(if (null? rest)
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(apply throw args)
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(loop rest)))))))))
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(define (ftp-close conn)
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(close (ftp-connection-socket conn)))
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(define %char-set:not-slash
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(char-set-complement (char-set #\/)))
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(define (ftp-chdir conn dir)
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"Change to directory DIR."
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;; On ftp.gnupg.org, "PASV" right after "CWD /gcrypt/gnupg" hangs. Doing
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;; CWD in two steps works, so just do this.
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(let ((components (string-tokenize dir %char-set:not-slash)))
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(fold (lambda (dir result)
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(%ftp-command (string-append "CWD " dir) 250
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(ftp-connection-socket conn)))
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#f
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(if (string-prefix? "/" dir)
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(cons "/" components)
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components))))
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(define (ftp-size conn file)
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"Return the size in bytes of FILE."
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;; Ask for "binary mode", otherwise some servers, such as sourceware.org,
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;; fail with 550 ("SIZE not allowed in ASCII mode").
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(%ftp-command "TYPE I" 200 (ftp-connection-socket conn))
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(let ((message (%ftp-command (string-append "SIZE " file) 213
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(ftp-connection-socket conn))))
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(string->number (string-trim-both message))))
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(define (ftp-pasv conn)
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(define %pasv-rx
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(make-regexp "([0-9]+),([0-9]+),([0-9]+),([0-9]+),([0-9]+),([0-9]+)"))
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(let ((message (%ftp-command "PASV" 227 (ftp-connection-socket conn))))
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(cond ((regexp-exec %pasv-rx message)
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=>
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(lambda (match)
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(+ (* (string->number (match:substring match 5)) 256)
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(string->number (match:substring match 6)))))
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(else
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(throw 'ftp-error conn "PASV" 227 message)))))
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(define (ftp-epsv conn)
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(let* ((message (%ftp-command "EPSV" 229 (ftp-connection-socket conn))))
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(string->number
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(match:substring (string-match "\\(...([0-9]+).\\)" message) 1))))
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(define (ftp-passive conn)
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"Enter passive mode using EPSV or PASV, return a data connection port on
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success."
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;; IPv6 only works with EPSV, so try it first.
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(or (false-if-exception (ftp-epsv conn)) (ftp-pasv conn)))
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(define (address-with-port sa port)
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"Return a socket-address object based on SA, but with PORT."
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(let ((fam (sockaddr:fam sa))
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(addr (sockaddr:addr sa)))
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(cond ((= fam AF_INET)
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(make-socket-address fam addr port))
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((= fam AF_INET6)
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(make-socket-address fam addr port
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(sockaddr:flowinfo sa)
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(sockaddr:scopeid sa)))
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(else #f))))
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(define* (ftp-list conn #:optional directory #:key timeout)
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(if directory
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(ftp-chdir conn directory))
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(let* ((port (ftp-passive conn))
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(ai (ftp-connection-addrinfo conn))
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(s (socket (addrinfo:fam ai) (addrinfo:socktype ai)
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(addrinfo:protocol ai))))
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(connect* s (address-with-port (addrinfo:addr ai) port) timeout)
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(setvbuf s 'line)
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(dynamic-wind
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(lambda () #t)
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(lambda ()
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(%ftp-command "LIST" 150 (ftp-connection-socket conn))
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(let loop ((line (read-line s))
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(result '()))
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(cond ((eof-object? line) (reverse result))
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((regexp-exec %ftp-ready-rx line)
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=>
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(lambda (match)
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(let ((code (string->number (match:substring match 1))))
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(if (= 126 code)
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(reverse result)
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(throw 'ftp-error conn "LIST" code)))))
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(else
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(loop (read-line s)
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(match (reverse (string-tokenize line))
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((file _ ... permissions)
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(let ((type (case (string-ref permissions 0)
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((#\d) 'directory)
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(else 'file))))
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(cons (list file type) result)))
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((file _ ...)
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(cons (cons file 'file) result))))))))
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(lambda ()
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(close s)
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(let-values (((code message) (%ftp-listen (ftp-connection-socket conn))))
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(or (eqv? code 226)
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(throw 'ftp-error conn "LIST" code message)))))))
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(define* (ftp-retr conn file #:optional directory
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#:key timeout)
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"Retrieve FILE from DIRECTORY (or, if omitted, the current directory) from
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FTP connection CONN. Return a binary port to that file. The returned port
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must be closed before CONN can be used for other purposes."
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(if directory
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(ftp-chdir conn directory))
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;; Ask for "binary mode".
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(%ftp-command "TYPE I" 200 (ftp-connection-socket conn))
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(let* ((port (ftp-passive conn))
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(ai (ftp-connection-addrinfo conn))
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(s (with-fluids ((%default-port-encoding #f))
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(socket (addrinfo:fam ai) (addrinfo:socktype ai)
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(addrinfo:protocol ai)))))
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(define (terminate)
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(close s)
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(let-values (((code message) (%ftp-listen (ftp-connection-socket conn))))
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(or (eqv? code 226)
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(throw 'ftp-error conn "LIST" code message))))
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(connect* s (address-with-port (addrinfo:addr ai) port) timeout)
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(setvbuf s 'line)
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(%ftp-command (string-append "RETR " file)
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150 (ftp-connection-socket conn))
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(make-custom-binary-input-port "FTP RETR port"
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(rec (read! bv start count)
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(match (get-bytevector-n! s bv
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start count)
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((? eof-object?) 0)
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(0
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;; Nothing available yet, so try
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;; again. This is important because
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;; the return value of `read!' makes
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;; it impossible to distinguish
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;; between "not yet" and "EOF".
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(read! bv start count))
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(read read)))
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#f #f ; no get/set position
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terminate)))
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;;; ftp-client.scm ends here
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