Date: Wed, 4 Dec 2013 23:57:38 GMT From: Jan Beich <jbeich@tormail.org> To: freebsd-gnats-submit@FreeBSD.org Subject: bin/184507: [patch] libfetch: allow hiding User-Agent with empty string Message-ID: <201312042357.rB4NvcpN003567@oldred.freebsd.org> Resent-Message-ID: <201312050000.rB5000JB022498@freefall.freebsd.org>
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>Number: 184507 >Category: bin >Synopsis: [patch] libfetch: allow hiding User-Agent with empty string >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: change-request >Submitter-Id: current-users >Arrival-Date: Thu Dec 05 00:00:00 UTC 2013 >Closed-Date: >Last-Modified: >Originator: Jan Beich >Release: >Organization: >Environment: >Description: In some situations it may be desirable to completely hide User-Agent field when fetching a file e.g., when using over Tor. >How-To-Repeat: $ sudo nc -kl 0 80 & # before $ HTTP_USER_AGENT= fetch http://0 GET / HTTP/1.1 Host: 0 Accept: */* User-Agent: fetch libfetch/2.0 Connection: close ^C # after $ HTTP_USER_AGENT= fetch http://0 GET / HTTP/1.1 Host: 0 Accept: */* Connection: close ^C # other download tools $ curl -A "" http://0 GET / HTTP/1.1 Host: 0 Accept: */* ^C $ wget -U "" http://0 2>/dev/null GET / HTTP/1.1 Accept: */* Host: 0 Connection: Keep-Alive ^C >Fix: --- noua.diff begins here --- Index: lib/libfetch/fetch.3 =================================================================== --- lib/libfetch/fetch.3 (revision 258921) +++ lib/libfetch/fetch.3 (working copy) @@ -627,6 +627,7 @@ the document URL will be used as referrer URL. Specifies the User-Agent string to use for HTTP requests. This can be useful when working with HTTP origin or proxy servers that differentiate between user agents. +If used with an empty string no User-Agent is sent. .It Ev NETRC Specifies a file to use instead of .Pa ~/.netrc Index: lib/libfetch/http.c =================================================================== --- lib/libfetch/http.c (revision 258921) +++ lib/libfetch/http.c (working copy) @@ -1679,9 +1679,10 @@ http_request(struct url *URL, const char *op, stru else http_cmd(conn, "Referer: %s", p); } - if ((p = getenv("HTTP_USER_AGENT")) != NULL && *p != '\0') - http_cmd(conn, "User-Agent: %s", p); - else + if ((p = getenv("HTTP_USER_AGENT")) != NULL) { + if (*p != '\0') + http_cmd(conn, "User-Agent: %s", p); + } else http_cmd(conn, "User-Agent: %s " _LIBFETCH_VER, getprogname()); if (url->offset > 0) http_cmd(conn, "Range: bytes=%lld-", (long long)url->offset); --- noua.diff ends here --- >Release-Note: >Audit-Trail: >Unformatted:help
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