branch master updated: ftp-client: Before 'PASV', try 'EPSV' first for IPv6.

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iyzsong pushed a commit to branch master
in repository guix.

The following commit(s) were added to refs/heads/master by this push:
     new 858898e  ftp-client: Before 'PASV', try 'EPSV' first for IPv6.
858898e is described below

commit 858898e348eb300a94b74115328ee39191829bda
Author: 宋文武 <iyzsong@member.fsf.org>
AuthorDate: Sun Feb 14 12:02:57 2021 +0800

    ftp-client: Before 'PASV', try 'EPSV' first for IPv6.
    
    This fixes <https://bugs.gnu.org/46481>.
    
    * guix/ftp-client.scm (ftp-epsv, ftp-passive): New procedures.
    (ftp-list, ftp-retr): Replace call to 'ftp-pasv' with 'ftp-passive'.
---
 guix/ftp-client.scm | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/guix/ftp-client.scm b/guix/ftp-client.scm
index 8d5adcb..9cc34cc 100644
--- a/guix/ftp-client.scm
+++ b/guix/ftp-client.scm
@@ -216,6 +216,17 @@ TIMEOUT, an ETIMEDOUT error is raised."
           (else
            (throw 'ftp-error conn "PASV" 227 message)))))
 
+(define (ftp-epsv conn)
+  (let* ((message (%ftp-command "EPSV" 229 (ftp-connection-socket conn))))
+    (string->number
+     (match:substring (string-match "\\(...([0-9]+).\\)" message) 1))))
+
+(define (ftp-passive conn)
+  "Enter passive mode using EPSV or PASV, return a data connection port on
+success."
+  ;; IPv6 only works with EPSV, so try it first.
+  (or (false-if-exception (ftp-epsv conn)) (ftp-pasv conn)))
+
 (define (address-with-port sa port)
   "Return a socket-address object based on SA, but with PORT."
   (let ((fam  (sockaddr:fam sa))
@@ -232,7 +243,7 @@ TIMEOUT, an ETIMEDOUT error is raised."
   (if directory
       (ftp-chdir conn directory))
 
-  (let* ((port (ftp-pasv conn))
+  (let* ((port (ftp-passive conn))
          (ai   (ftp-connection-addrinfo conn))
          (s    (socket (addrinfo:fam ai) (addrinfo:socktype ai)
                        (addrinfo:protocol ai))))
@@ -281,7 +292,7 @@ must be closed before CONN can be used for other purposes."
   ;; Ask for "binary mode".
   (%ftp-command "TYPE I" 200 (ftp-connection-socket conn))
 
-  (let* ((port (ftp-pasv conn))
+  (let* ((port (ftp-passive conn))
          (ai   (ftp-connection-addrinfo conn))
          (s    (with-fluids ((%default-port-encoding #f))
                  (socket (addrinfo:fam ai) (addrinfo:socktype ai)