2 .\" Copyright (c) 1998-2013 Dag-Erling Smørgrav
3 .\" Copyright (c) 2013 Michael Gmelin <freebsd@grem.de>
4 .\" All rights reserved.
6 .\" Redistribution and use in source and binary forms, with or without
7 .\" modification, are permitted provided that the following conditions
9 .\" 1. Redistributions of source code must retain the above copyright
10 .\" notice, this list of conditions and the following disclaimer.
11 .\" 2. Redistributions in binary form must reproduce the above copyright
12 .\" notice, this list of conditions and the following disclaimer in the
13 .\" documentation and/or other materials provided with the distribution.
15 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
61 .Nd file transfer functions
69 .Fn fetchMakeURL "const char *scheme" "const char *host" "int port" "const char *doc" "const char *user" "const char *pwd"
71 .Fn fetchParseURL "const char *URL"
73 .Fn fetchFreeURL "struct url *u"
75 .Fn fetchXGetURL "const char *URL" "struct url_stat *us" "const char *flags"
77 .Fn fetchGetURL "const char *URL" "const char *flags"
79 .Fn fetchPutURL "const char *URL" "const char *flags"
81 .Fn fetchStatURL "const char *URL" "struct url_stat *us" "const char *flags"
83 .Fn fetchListURL "const char *URL" "const char *flags"
85 .Fn fetchXGet "struct url *u" "struct url_stat *us" "const char *flags"
87 .Fn fetchGet "struct url *u" "const char *flags"
89 .Fn fetchPut "struct url *u" "const char *flags"
91 .Fn fetchStat "struct url *u" "struct url_stat *us" "const char *flags"
93 .Fn fetchList "struct url *u" "const char *flags"
95 .Fn fetchXGetFile "struct url *u" "struct url_stat *us" "const char *flags"
97 .Fn fetchGetFile "struct url *u" "const char *flags"
99 .Fn fetchPutFile "struct url *u" "const char *flags"
101 .Fn fetchStatFile "struct url *u" "struct url_stat *us" "const char *flags"
103 .Fn fetchListFile "struct url *u" "const char *flags"
105 .Fn fetchXGetHTTP "struct url *u" "struct url_stat *us" "const char *flags"
107 .Fn fetchGetHTTP "struct url *u" "const char *flags"
109 .Fn fetchPutHTTP "struct url *u" "const char *flags"
111 .Fn fetchStatHTTP "struct url *u" "struct url_stat *us" "const char *flags"
113 .Fn fetchListHTTP "struct url *u" "const char *flags"
115 .Fn fetchXGetFTP "struct url *u" "struct url_stat *us" "const char *flags"
117 .Fn fetchGetFTP "struct url *u" "const char *flags"
119 .Fn fetchPutFTP "struct url *u" "const char *flags"
121 .Fn fetchStatFTP "struct url *u" "struct url_stat *us" "const char *flags"
123 .Fn fetchListFTP "struct url *u" "const char *flags"
125 These functions implement a high-level library for retrieving and
126 uploading files using Uniform Resource Locators (URLs).
129 takes a URL in the form of a null-terminated string and splits it into
130 its components function according to the Common Internet Scheme Syntax
132 A regular expression which produces this syntax is:
134 <scheme>:(//(<user>(:<pwd>)?@)?<host>(:<port>)?)?/(<document>)?
137 If the URL does not seem to begin with a scheme name, the following
140 ((<user>(:<pwd>)?@)?<host>(:<port>)?)?/(<document>)?
143 Note that some components of the URL are not necessarily relevant to
145 For instance, the file scheme only needs the <scheme> and <document>
151 return a pointer to a
153 structure, which is defined as follows in
156 #define URL_SCHEMELEN 16
157 #define URL_USERLEN 256
158 #define URL_PWDLEN 256
161 char scheme[URL_SCHEMELEN+1];
162 char user[URL_USERLEN+1];
163 char pwd[URL_PWDLEN+1];
164 char host[MAXHOSTNAMELEN+1];
175 field stores the time value for
176 .Li If-Modified-Since
179 The pointer returned by
183 should be freed using
190 constitute the recommended interface to the
193 They examine the URL passed to them to determine the transfer
194 method, and call the appropriate lower-level functions to perform the
197 also returns the remote document's metadata in the
199 structure pointed to by the
205 argument is a string of characters which specify transfer options.
207 meaning of the individual flags is scheme-dependent, and is detailed
208 in the appropriate section below.
211 attempts to obtain the requested document's metadata and fill in the
212 structure pointed to by its second argument.
215 structure is defined as follows in
225 If the size could not be obtained from the server, the
228 If the modification time could not be obtained from the server, the
230 field is set to the epoch.
231 If the access time could not be obtained from the server, the
233 field is set to the modification time.
236 attempts to list the contents of the directory pointed to by the URL
238 If successful, it returns a malloced array of
243 structure is defined as follows in
248 struct url_stat stat;
252 The list is terminated by an entry with an empty name.
254 The pointer returned by
256 should be freed using
270 except that they expect a pre-parsed URL in the form of a pointer to
273 rather than a string.
280 functions return a pointer to a stream which can be used to read or
281 write data from or to the requested document, respectively.
283 although the implementation details of the individual access methods
284 vary, it can generally be assumed that a stream returned by one of the
288 functions is read-only, and that a stream returned by one of the
290 functions is write-only.
296 provide access to documents which are files in a locally mounted file
298 Only the <document> component of the URL is used.
303 do not accept any flags.
308 (append to file) flag.
309 If that flag is specified, the data written to
310 the stream returned by
312 will be appended to the previous contents of the file, instead of
319 implement the FTP protocol as described in RFC959.
323 (not passive) flag is specified, an active (rather than passive)
324 connection will be attempted.
328 flag is supported for compatibility with earlier versions where active
329 connections were the default.
330 It has precedence over the
332 flag, so if both are specified,
334 will use a passive connection.
338 (low) flag is specified, data sockets will be allocated in the low (or
339 default) port range instead of the high port range (see
344 (direct) flag is specified,
349 will use a direct connection even if a proxy server is defined.
351 If no user name or password is given, the
353 library will attempt an anonymous login, with user name "anonymous"
354 and password "anonymous@<hostname>".
361 functions implement the HTTP/1.1 protocol.
362 With a little luck, there is
363 even a chance that they comply with RFC2616 and RFC2617.
367 (direct) flag is specified,
372 will use a direct connection even if a proxy server is defined.
376 (if-modified-since) flag is specified, and
385 will send a conditional
386 .Li If-Modified-Since
387 HTTP header to only fetch the content if it is newer than
390 Since there seems to be no good way of implementing the HTTP PUT
391 method in a manner consistent with the rest of the
395 is currently unimplemented.
397 Based on HTTP SCHEME.
398 By default the peer is verified using the CA bundle located in
399 .Pa /etc/ssl/cert.pem .
400 The file may contain multiple CA certificates.
401 A common source of a current CA bundle is
402 .Pa \%security/ca_root_nss .
404 The CA bundle used for peer verification can be changed by setting the
405 environment variables
407 to point to a concatenated bundle of trusted certificates and
409 to point to a directory containing hashes of trusted CAs (see
412 A certificate revocation list (CRL) can be used by setting the
418 Peer verification can be disabled by setting the environment variable
419 .Ev SSL_NO_VERIFY_PEER .
420 Note that this also disables CRL checking.
422 By default the service identity is verified according to the rules
423 detailed in RFC6125 (also known as hostname verification).
424 This feature can be disabled by setting the environment variable
425 .Ev SSL_NO_VERIFY_HOSTNAME .
427 Client certificate based authentication is supported.
428 The environment variable
429 .Ev SSL_CLIENT_CERT_FILE
430 should be set to point to a file containing key and client certificate
431 to be used in PEM format. In case the key is stored in a separate
432 file, the environment variable
433 .Ev SSL_CLIENT_KEY_FILE
434 can be set to point to the key in PEM format.
435 In case the key uses a password, the user will be prompted on standard
441 allows TLSv1 when negotiating the connecting with the remote
443 You can change this behavior by setting the
445 environment variable to allow SSLv3 and
449 Apart from setting the appropriate environment variables and
450 specifying the user name and password in the URL or the
452 the calling program has the option of defining an authentication
453 function with the following prototype:
456 .Fn myAuthMethod "struct url *u"
458 The callback function should fill in the
462 fields in the provided
464 and return 0 on success, or any other value to indicate failure.
466 To register the authentication callback, simply set
469 The callback will be used whenever a site requires authentication and
470 the appropriate environment variables are not set.
472 This interface is experimental and may be subject to change.
475 returns a pointer to a
477 containing the individual components of the URL.
479 unable to allocate memory, or the URL is syntactically incorrect,
481 returns a NULL pointer.
485 functions return 0 on success and -1 on failure.
487 All other functions return a stream pointer which may be used to
488 access the requested document, or NULL if an error occurred.
490 The following error codes are defined in
493 .It Bq Er FETCH_ABORT
496 Authentication failed
499 .It Bq Er FETCH_EXISTS
504 Informational response
505 .It Bq Er FETCH_MEMORY
507 .It Bq Er FETCH_MOVED
509 .It Bq Er FETCH_NETWORK
513 .It Bq Er FETCH_PROTO
515 .It Bq Er FETCH_RESOLV
517 .It Bq Er FETCH_SERVER
521 .It Bq Er FETCH_TIMEOUT
523 .It Bq Er FETCH_UNAVAIL
524 File is not available
525 .It Bq Er FETCH_UNKNOWN
531 The accompanying error message includes a protocol-specific error code
532 and message, e.g.\& "File is not available (404 Not Found)"
534 .Bl -tag -width ".Ev FETCH_BIND_ADDRESS"
535 .It Ev FETCH_BIND_ADDRESS
536 Specifies a hostname or IP address to which sockets used for outgoing
537 connections will be bound.
539 Default FTP login if none was provided in the URL.
540 .It Ev FTP_PASSIVE_MODE
543 forces the FTP code to use active mode.
544 If set to any other value, forces passive mode even if the application
545 requested active mode.
547 Default FTP password if the remote server requests one and none was
550 URL of the proxy to use for FTP requests.
551 The document part is ignored.
552 FTP and HTTP proxies are supported; if no scheme is specified, FTP is
554 If the proxy is an FTP proxy,
558 as user name to the proxy, where
560 is the real user name, and
562 is the name of the FTP server.
564 If this variable is set to an empty string, no proxy will be used for
565 FTP requests, even if the
573 Specifies the value of the
575 header for HTTP requests.
582 Specifies HTTP authorization parameters as a colon-separated list of
584 The first and second item are the authorization scheme and realm
585 respectively; further items are scheme-dependent.
590 authorization methods are supported.
592 Both methods require two parameters: the user name and
593 password, in that order.
595 This variable is only used if the server requires authorization and
596 no user name or password was specified in the URL.
598 URL of the proxy to use for HTTP requests.
599 The document part is ignored.
600 Only HTTP proxies are supported for HTTP requests.
601 If no port number is specified, the default is 3128.
603 Note that this proxy will also be used for FTP documents, unless the
610 .It Ev HTTP_PROXY_AUTH
611 Specifies authorization parameters for the HTTP proxy in the same
616 This variable is used if and only if connected to an HTTP proxy, and
617 is ignored if a user and/or a password were specified in the proxy
620 Specifies the referrer URL to use for HTTP requests.
623 the document URL will be used as referrer URL.
624 .It Ev HTTP_USER_AGENT
625 Specifies the User-Agent string to use for HTTP requests.
626 This can be useful when working with HTTP origin or proxy servers that
627 differentiate between user agents.
628 If defined but empty, no User-Agent header is sent.
630 Specifies a file to use instead of
632 to look up login names and passwords for FTP and HTTP sites as well as
636 for a description of the file format.
638 Either a single asterisk, which disables the use of proxies
639 altogether, or a comma- or whitespace-separated list of hosts for
640 which proxies should not be used.
645 .It Ev SSL_ALLOW_SSL3
646 Allow SSL version 3 when negotiating the connection (not recommended).
647 .It Ev SSL_CA_CERT_FILE
648 CA certificate bundle containing trusted CA certificates.
650 .Pa /etc/ssl/cert.pem .
651 .It Ev SSL_CA_CERT_PATH
652 Path containing trusted CA hashes.
653 .It Ev SSL_CLIENT_CERT_FILE
654 PEM encoded client certificate/key which will be used in
655 client certificate authentication.
656 .It Ev SSL_CLIENT_KEY_FILE
657 PEM encoded client key in case key and client certificate
658 are stored separately.
660 File containing certificate revocation list.
662 Do not allow TLS version 1.0 when negotiating the connection.
664 Do not allow TLS version 1.1 when negotiating the connection.
666 Do not allow TLS version 1.2 when negotiating the connection.
667 .It Ev SSL_NO_VERIFY_HOSTNAME
668 If set, do not verify that the hostname matches the subject of the
669 certificate presented by the server.
670 .It Ev SSL_NO_VERIFY_PEER
671 If set, do not verify the peer certificate against trusted CAs.
674 To access a proxy server on
675 .Pa proxy.example.com
678 environment variable in a manner similar to this:
680 .Dl HTTP_PROXY=http://proxy.example.com:8080
682 If the proxy server requires authentication, there are
683 two options available for passing the authentication data.
684 The first method is by using the proxy URL:
686 .Dl HTTP_PROXY=http://<user>:<pwd>@proxy.example.com:8080
688 The second method is by using the
690 environment variable:
691 .Bd -literal -offset indent
692 HTTP_PROXY=http://proxy.example.com:8080
693 HTTP_PROXY_AUTH=basic:*:<user>:<pwd>
696 To disable the use of a proxy for an HTTP server running on the local
700 .Bd -literal -offset indent
701 NO_PROXY=localhost,127.0.0.1
704 Access HTTPS website without any certificate verification whatsoever:
705 .Bd -literal -offset indent
707 SSL_NO_VERIFY_HOSTNAME=1
710 Access HTTPS website using client certificate based authentication
712 .Bd -literal -offset indent
713 SSL_CLIENT_CERT_FILE=/path/to/client.pem
714 SSL_CA_CERT_FILE=/path/to/myca.pem
724 .%B File Transfer Protocol
732 .%T How to Use Anonymous FTP
740 .%T Uniform Resource Locators (URL)
752 .%B Hypertext Transfer Protocol -- HTTP/1.1
764 .%B HTTP Authentication: Basic and Digest Access Authentication
770 library first appeared in
776 library was mostly written by
777 .An Dag-Erling Sm\(/orgrav Aq des@FreeBSD.org
778 with numerous suggestions and contributions from
779 .An Jordan K. Hubbard Aq jkh@FreeBSD.org ,
780 .An Eugene Skepner Aq eu@qub.com ,
781 .An Hajimu Umemoto Aq ume@FreeBSD.org ,
782 .An Henry Whincup Aq henry@techiebod.com ,
783 .An Jukka A. Ukkonen Aq jau@iki.fi ,
784 .An Jean-Fran\(,cois Dockes Aq jf@dockes.org ,
785 .An Michael Gmelin Aq freebsd@grem.de
787 It replaces the older
790 .An Poul-Henning Kamp Aq phk@FreeBSD.org
792 .An Jordan K. Hubbard Aq jkh@FreeBSD.org .
794 This manual page was written by
795 .An Dag-Erling Sm\(/orgrav Aq des@FreeBSD.org
797 .An Michael Gmelin Aq freebsd@grem.de .
799 Some parts of the library are not yet implemented.
805 and FTP proxy support.
807 There is no way to select a proxy at run-time other than setting the
811 environment variables as appropriate.
814 does not understand or obey 305 (Use Proxy) replies.
816 Error numbers are unique only within a certain context; the error
817 codes used for FTP and HTTP overlap, as do those used for resolver and
819 For instance, error code 202 means "Command not
820 implemented, superfluous at this site" in an FTP context and
821 "Accepted" in an HTTP context.
824 does not check that the result of an MDTM command is a valid date.
826 In case password protected keys are used for client certificate based
827 authentication the user is prompted for the password on each and every
830 The man page is incomplete, poorly written and produces badly
833 The error reporting mechanism is unsatisfactory.
835 Some parts of the code are not fully reentrant.