http/ftp: Tweak to avoid depending on libc's NSS.

* guix/build/http.scm (open-connection-for-uri): New procedure.
  (http-fetch): Use it.  Pass the result as a #:port argument to
  `http-get'.
  Add hack to modify the `set-port-encoding!' binding in (web response).

* guix/ftp-client.scm (ftp-open): Add optional `port' parameter,
  defaulting to 21.  When calling `getaddrinfo', convert PORT to a
  string and pass AI_NUMERICSERV when PORT is a number.

guix/build/http.scm

@@ -29,13 +29,61 @@
 ;;;
 ;;; Code:
 
+(define (open-connection-for-uri uri)
+  "Return an open input/output port for a connection to URI.
+
+This is the same as Guile's `open-socket-for-uri', except that we always
+use a numeric port argument, to avoid the need to go through libc's NSS,
+which is not available during bootstrap."
+  (define addresses
+    (let ((port (or (uri-port uri)
+                    (case (uri-scheme uri)
+                      ((http) 80)           ; /etc/services, not for me!
+                      (else
+                       (error "unsupported URI scheme" uri))))))
+      (getaddrinfo (uri-host uri)
+                   (number->string port)
+                   AI_NUMERICSERV)))
+
+  (let loop ((addresses addresses))
+    (let* ((ai (car addresses))
+           (s  (with-fluids ((%default-port-encoding #f))
+                 (socket (addrinfo:fam ai) (addrinfo:socktype ai)
+                         (addrinfo:protocol ai)))))
+      (catch 'system-error
+        (lambda ()
+          (connect s (addrinfo:addr ai))
+
+          ;; Buffer input and output on this port.
+          (setvbuf s _IOFBF)
+          ;; Enlarge the receive buffer.
+          (setsockopt s SOL_SOCKET SO_RCVBUF (* 12 1024))
+          s)
+        (lambda args
+          ;; Connection failed, so try one of the other addresses.
+          (close s)
+          (if (null? addresses)
+              (apply throw args)
+              (loop (cdr addresses))))))))
+
+;; XXX: This is an awful hack to make sure the (set-port-encoding! p
+;; "ISO-8859-1") call in `read-response' passes, even during bootstrap
+;; where iconv is not available.
+(module-define! (resolve-module '(web response))
+                'set-port-encoding!
+                (lambda (p e) #f))
+
 (define (http-fetch url file)
   "Fetch data from URL and write it to FILE.  Return FILE on success."
 
   ;; FIXME: Use a variant of `http-get' that returns a port instead of
   ;; loading everything in memory.
-  (let-values (((resp bv)
-                (http-get (string->uri url) #:decode-body? #f)))
+  (let*-values (((uri)
+                 (string->uri url))
+                ((connection)
+                 (open-connection-for-uri uri))
+                ((resp bv)
+                 (http-get uri #:port connection #:decode-body? #f)))
     (call-with-output-file file
       (lambda (p)
         (put-bytevector p bv))))

guix/ftp-client.scm

@@ -80,12 +80,18 @@
         ((331) (%ftp-command (string-append "PASS " pass) 230 port))
         (else  (throw 'ftp-error port command code message))))))
 
-(define (ftp-open host)
-  "Open an FTP connection to HOST, and return it."
+(define* (ftp-open host #:optional (port 21))
+  "Open an FTP connection to HOST on PORT (a service-identifying string,
+or a TCP port number), and return it."
+  ;; Use 21 as the default PORT instead of "ftp", to avoid depending on
+  ;; libc's NSS, which is not available during bootstrap.
+
   (catch 'getaddrinfo-error
     (lambda ()
       (define addresses
-        (getaddrinfo host "ftp"))
+        (getaddrinfo host
+                     (if (number? port) (number->string port) port)
+                     (if (number? port) AI_NUMERICSERV 0)))
 
       (let loop ((addresses addresses))
         (let* ((ai (car addresses))