ftp(1): handle HTTP 308

[Lucas]

Hello tech@,

Given that ftp already deals with HTTP 307, I think we can teach it to
deal with HTTP 308 too. HTTP 308 is to HTTP 301 what HTTP 307 is to HTTP
302: Permanently Moved, but doesn't allow to change the HTTP verb.
Definition of HTTP 308 can be found in RFC 7538.

        oolong$ ftp -Mo /dev/null http://h.lgv5.net/c/308
        Trying 78.47.117.79...
        Requesting http://h.lgv5.net/c/308
        ftp: Error retrieving http://h.lgv5.net/c/308: 308 Permanent Redirect
        oolong$ ./ftp -Mo /dev/null http://h.lgv5.net/c/308
        Trying 78.47.117.79...
        Requesting http://h.lgv5.net/c/308
        Redirected to http://h.lgv5.net/c/200
        Trying 78.47.117.79...
        Requesting http://h.lgv5.net/c/200
        480 bytes received in 0.00 seconds (4.66 MB/s)

Cheers!
-Lucas

Index: fetch.c
===================================================================
RCS file: /home/cvs/src/usr.bin/ftp/fetch.c,v
retrieving revision 1.198
diff -u -p -r1.198 fetch.c
--- fetch.c     18 Oct 2020 20:35:18 -0000      1.198
+++ fetch.c     24 Dec 2020 14:03:03 -0000
@@ -843,6 +843,7 @@ noslash:
        case 302:       /* Found */
        case 303:       /* See Other */
        case 307:       /* Temporary Redirect */
+       case 308:       /* Permanent Redirect */
                isredirect++;
                if (redirect_loop++ > 10) {
                        warnx("Too many redirections requested");