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28 .Dd September 27, 2011
60 .Nd file transfer functions
68 .Fn fetchMakeURL "const char *scheme" "const char *host" "int port" "const char *doc" "const char *user" "const char *pwd"
70 .Fn fetchParseURL "const char *URL"
72 .Fn fetchFreeURL "struct url *u"
74 .Fn fetchXGetURL "const char *URL" "struct url_stat *us" "const char *flags"
76 .Fn fetchGetURL "const char *URL" "const char *flags"
78 .Fn fetchPutURL "const char *URL" "const char *flags"
80 .Fn fetchStatURL "const char *URL" "struct url_stat *us" "const char *flags"
82 .Fn fetchListURL "const char *URL" "const char *flags"
84 .Fn fetchXGet "struct url *u" "struct url_stat *us" "const char *flags"
86 .Fn fetchGet "struct url *u" "const char *flags"
88 .Fn fetchPut "struct url *u" "const char *flags"
90 .Fn fetchStat "struct url *u" "struct url_stat *us" "const char *flags"
92 .Fn fetchList "struct url *u" "const char *flags"
94 .Fn fetchXGetFile "struct url *u" "struct url_stat *us" "const char *flags"
96 .Fn fetchGetFile "struct url *u" "const char *flags"
98 .Fn fetchPutFile "struct url *u" "const char *flags"
100 .Fn fetchStatFile "struct url *u" "struct url_stat *us" "const char *flags"
102 .Fn fetchListFile "struct url *u" "const char *flags"
104 .Fn fetchXGetHTTP "struct url *u" "struct url_stat *us" "const char *flags"
106 .Fn fetchGetHTTP "struct url *u" "const char *flags"
108 .Fn fetchPutHTTP "struct url *u" "const char *flags"
110 .Fn fetchStatHTTP "struct url *u" "struct url_stat *us" "const char *flags"
112 .Fn fetchListHTTP "struct url *u" "const char *flags"
114 .Fn fetchXGetFTP "struct url *u" "struct url_stat *us" "const char *flags"
116 .Fn fetchGetFTP "struct url *u" "const char *flags"
118 .Fn fetchPutFTP "struct url *u" "const char *flags"
120 .Fn fetchStatFTP "struct url *u" "struct url_stat *us" "const char *flags"
122 .Fn fetchListFTP "struct url *u" "const char *flags"
124 These functions implement a high-level library for retrieving and
125 uploading files using Uniform Resource Locators (URLs).
128 takes a URL in the form of a null-terminated string and splits it into
129 its components function according to the Common Internet Scheme Syntax
131 A regular expression which produces this syntax is:
133 <scheme>:(//(<user>(:<pwd>)?@)?<host>(:<port>)?)?/(<document>)?
136 If the URL does not seem to begin with a scheme name, the following
139 ((<user>(:<pwd>)?@)?<host>(:<port>)?)?/(<document>)?
142 Note that some components of the URL are not necessarily relevant to
144 For instance, the file scheme only needs the <scheme> and <document>
150 return a pointer to a
152 structure, which is defined as follows in
155 #define URL_SCHEMELEN 16
156 #define URL_USERLEN 256
157 #define URL_PWDLEN 256
160 char scheme[URL_SCHEMELEN+1];
161 char user[URL_USERLEN+1];
162 char pwd[URL_PWDLEN+1];
163 char host[MAXHOSTNAMELEN+1];
174 field stores the time value for
175 .Li If-Modified-Since
178 The pointer returned by
182 should be freed using
189 constitute the recommended interface to the
192 They examine the URL passed to them to determine the transfer
193 method, and call the appropriate lower-level functions to perform the
196 also returns the remote document's metadata in the
198 structure pointed to by the
204 argument is a string of characters which specify transfer options.
206 meaning of the individual flags is scheme-dependent, and is detailed
207 in the appropriate section below.
210 attempts to obtain the requested document's metadata and fill in the
211 structure pointed to by its second argument.
214 structure is defined as follows in
224 If the size could not be obtained from the server, the
227 If the modification time could not be obtained from the server, the
229 field is set to the epoch.
230 If the access time could not be obtained from the server, the
232 field is set to the modification time.
235 attempts to list the contents of the directory pointed to by the URL
237 If successful, it returns a malloced array of
242 structure is defined as follows in
247 struct url_stat stat;
251 The list is terminated by an entry with an empty name.
253 The pointer returned by
255 should be freed using
269 except that they expect a pre-parsed URL in the form of a pointer to
272 rather than a string.
279 functions return a pointer to a stream which can be used to read or
280 write data from or to the requested document, respectively.
282 although the implementation details of the individual access methods
283 vary, it can generally be assumed that a stream returned by one of the
287 functions is read-only, and that a stream returned by one of the
289 functions is write-only.
295 provide access to documents which are files in a locally mounted file
297 Only the <document> component of the URL is used.
302 do not accept any flags.
307 (append to file) flag.
308 If that flag is specified, the data written to
309 the stream returned by
311 will be appended to the previous contents of the file, instead of
318 implement the FTP protocol as described in RFC959.
322 (passive) flag is specified, a passive (rather than active) connection
327 (low) flag is specified, data sockets will be allocated in the low (or
328 default) port range instead of the high port range (see
333 (direct) flag is specified,
338 will use a direct connection even if a proxy server is defined.
340 If no user name or password is given, the
342 library will attempt an anonymous login, with user name "anonymous"
343 and password "anonymous@<hostname>".
350 functions implement the HTTP/1.1 protocol.
351 With a little luck, there is
352 even a chance that they comply with RFC2616 and RFC2617.
356 (direct) flag is specified,
361 will use a direct connection even if a proxy server is defined.
365 (if-modified-since) flag is specified, and
374 will send a conditional
375 .Li If-Modified-Since
376 HTTP header to only fetch the content if it is newer than
379 Since there seems to be no good way of implementing the HTTP PUT
380 method in a manner consistent with the rest of the
384 is currently unimplemented.
386 Apart from setting the appropriate environment variables and
387 specifying the user name and password in the URL or the
389 the calling program has the option of defining an authentication
390 function with the following prototype:
393 .Fn myAuthMethod "struct url *u"
395 The callback function should fill in the
399 fields in the provided
401 and return 0 on success, or any other value to indicate failure.
403 To register the authentication callback, simply set
406 The callback will be used whenever a site requires authentication and
407 the appropriate environment variables are not set.
409 This interface is experimental and may be subject to change.
412 returns a pointer to a
414 containing the individual components of the URL.
416 unable to allocate memory, or the URL is syntactically incorrect,
418 returns a NULL pointer.
422 functions return 0 on success and -1 on failure.
424 All other functions return a stream pointer which may be used to
425 access the requested document, or NULL if an error occurred.
427 The following error codes are defined in
430 .It Bq Er FETCH_ABORT
433 Authentication failed
436 .It Bq Er FETCH_EXISTS
441 Informational response
442 .It Bq Er FETCH_MEMORY
444 .It Bq Er FETCH_MOVED
446 .It Bq Er FETCH_NETWORK
450 .It Bq Er FETCH_PROTO
452 .It Bq Er FETCH_RESOLV
454 .It Bq Er FETCH_SERVER
458 .It Bq Er FETCH_TIMEOUT
460 .It Bq Er FETCH_UNAVAIL
461 File is not available
462 .It Bq Er FETCH_UNKNOWN
468 The accompanying error message includes a protocol-specific error code
469 and message, e.g.\& "File is not available (404 Not Found)"
471 .Bl -tag -width ".Ev FETCH_BIND_ADDRESS"
472 .It Ev FETCH_BIND_ADDRESS
473 Specifies a hostname or IP address to which sockets used for outgoing
474 connections will be bound.
476 Default FTP login if none was provided in the URL.
477 .It Ev FTP_PASSIVE_MODE
478 If set to anything but
480 forces the FTP code to use passive mode.
482 Default FTP password if the remote server requests one and none was
485 URL of the proxy to use for FTP requests.
486 The document part is ignored.
487 FTP and HTTP proxies are supported; if no scheme is specified, FTP is
489 If the proxy is an FTP proxy,
493 as user name to the proxy, where
495 is the real user name, and
497 is the name of the FTP server.
499 If this variable is set to an empty string, no proxy will be used for
500 FTP requests, even if the
508 Specifies HTTP authorization parameters as a colon-separated list of
510 The first and second item are the authorization scheme and realm
511 respectively; further items are scheme-dependent.
516 authorization methods are supported.
518 Both methods require two parameters: the user name and
519 password, in that order.
521 This variable is only used if the server requires authorization and
522 no user name or password was specified in the URL.
524 URL of the proxy to use for HTTP requests.
525 The document part is ignored.
526 Only HTTP proxies are supported for HTTP requests.
527 If no port number is specified, the default is 3128.
529 Note that this proxy will also be used for FTP documents, unless the
536 .It Ev HTTP_PROXY_AUTH
537 Specifies authorization parameters for the HTTP proxy in the same
542 This variable is used if and only if connected to an HTTP proxy, and
543 is ignored if a user and/or a password were specified in the proxy
546 Specifies the referrer URL to use for HTTP requests.
549 the document URL will be used as referrer URL.
550 .It Ev HTTP_USER_AGENT
551 Specifies the User-Agent string to use for HTTP requests.
552 This can be useful when working with HTTP origin or proxy servers that
553 differentiate between user agents.
555 Specifies a file to use instead of
557 to look up login names and passwords for FTP sites.
560 for a description of the file format.
561 This feature is experimental.
563 Either a single asterisk, which disables the use of proxies
564 altogether, or a comma- or whitespace-separated list of hosts for
565 which proxies should not be used.
572 To access a proxy server on
573 .Pa proxy.example.com
576 environment variable in a manner similar to this:
578 .Dl HTTP_PROXY=http://proxy.example.com:8080
580 If the proxy server requires authentication, there are
581 two options available for passing the authentication data.
582 The first method is by using the proxy URL:
584 .Dl HTTP_PROXY=http://<user>:<pwd>@proxy.example.com:8080
586 The second method is by using the
588 environment variable:
589 .Bd -literal -offset indent
590 HTTP_PROXY=http://proxy.example.com:8080
591 HTTP_PROXY_AUTH=basic:*:<user>:<pwd>
594 To disable the use of a proxy for an HTTP server running on the local
598 .Bd -literal -offset indent
599 NO_PROXY=localhost,127.0.0.1
609 .%B File Transfer Protocol
617 .%T How to Use Anonymous FTP
625 .%T Uniform Resource Locators (URL)
637 .%B Hypertext Transfer Protocol -- HTTP/1.1
649 .%B HTTP Authentication: Basic and Digest Access Authentication
655 library first appeared in
661 library was mostly written by
662 .An Dag-Erling Sm\(/orgrav Aq des@FreeBSD.org
663 with numerous suggestions and contributions from
664 .An Jordan K. Hubbard Aq jkh@FreeBSD.org ,
665 .An Eugene Skepner Aq eu@qub.com ,
666 .An Hajimu Umemoto Aq ume@FreeBSD.org ,
667 .An Henry Whincup Aq henry@techiebod.com ,
668 .An Jukka A. Ukkonen Aq jau@iki.fi ,
669 .An Jean-Fran\(,cois Dockes Aq jf@dockes.org
671 It replaces the older
674 .An Poul-Henning Kamp Aq phk@FreeBSD.org
676 .An Jordan K. Hubbard Aq jkh@FreeBSD.org .
678 This manual page was written by
679 .An Dag-Erling Sm\(/orgrav Aq des@FreeBSD.org .
681 Some parts of the library are not yet implemented.
687 and FTP proxy support.
689 There is no way to select a proxy at run-time other than setting the
693 environment variables as appropriate.
696 does not understand or obey 305 (Use Proxy) replies.
698 Error numbers are unique only within a certain context; the error
699 codes used for FTP and HTTP overlap, as do those used for resolver and
701 For instance, error code 202 means "Command not
702 implemented, superfluous at this site" in an FTP context and
703 "Accepted" in an HTTP context.
706 does not check that the result of an MDTM command is a valid date.
708 The man page is incomplete, poorly written and produces badly
711 The error reporting mechanism is unsatisfactory.
713 Some parts of the code are not fully reentrant.