FETCH(3)                NetBSD Library Functions Manual               FETCH(3)

NAME
     fetchMakeURL, fetchParseURL, fetchCopyURL, fetchFreeURL, fetchXGetURL,
     fetchGetURL, fetchPutURL, fetchStatURL, fetchListURL, fetchXGet,
     fetchGet, fetchPut, fetchStat, fetchList, fetchXGetFile, fetchGetFile,
     fetchPutFile, fetchStatFile, fetchListFile, fetchXGetHTTP, fetchGetHTTP,
     fetchPutHTTP, fetchStatHTTP, fetchListHTTP, fetchXGetFTP, fetchGetFTP,
     fetchPutFTP, fetchStatFTP, fetchListFTP fetchInitURLList,
     fetchFreeURLList, fetchUnquotePath, fetchUnquoteFilename,
     fetchStringifyURL, fetchConnectionCacheInit, fetchConnectionCacheClose,
     fetch -- file transfer functions

LIBRARY
     File Transfer Library for URLs (libfetch, -lfetch)

SYNOPSIS
     #include <stdio.h>
     #include <fetch.h>

     struct url *
     fetchMakeURL(const char *scheme, const char *host, int port,
         const char *doc, const char *user, const char *pwd);

     struct url *
     fetchParseURL(const char *URL);

     struct url *
     fetchCopyURL(const struct url *u);

     void
     fetchFreeURL(struct url *u);

     fetchIO *
     fetchXGetURL(const char *URL, struct url_stat *us, const char *flags);

     fetchIO *
     fetchGetURL(const char *URL, const char *flags);

     fetchIO *
     fetchPutURL(const char *URL, const char *flags);

     int
     fetchStatURL(const char *URL, struct url_stat *us, const char *flags);

     int
     fetchListURL(struct url_list *list, const char *URL, const char *pattern,
         const char *flags);

     fetchIO *
     fetchXGet(struct url *u, struct url_stat *us, const char *flags);

     fetchIO *
     fetchGet(struct url *u, const char *flags);

     fetchIO *
     fetchPut(struct url *u, const char *flags);

     int
     fetchStat(struct url *u, struct url_stat *us, const char *flags);

     int
     fetchList(struct url_list *list, struct url *u, const char *pattern,
         const char *flags);

     fetchIO *
     fetchXGetFile(struct url *u, struct url_stat *us, const char *flags);

     fetchIO *
     fetchGetFile(struct url *u, const char *flags);

     fetchIO *
     fetchPutFile(struct url *u, const char *flags);

     int
     fetchStatFile(struct url *u, struct url_stat *us, const char *flags);

     int
     fetchListFile(struct url_list *list, struct url *u, const char *pattern,
         const char *flags);

     fetchIO *
     fetchXGetHTTP(struct url *u, struct url_stat *us, const char *flags);

     fetchIO *
     fetchGetHTTP(struct url *u, const char *flags);

     fetchIO *
     fetchPutHTTP(struct url *u, const char *flags);

     int
     fetchStatHTTP(struct url *u, struct url_stat *us, const char *flags);

     int
     fetchListHTTP(struct url_list *list, struct url *u, const char *pattern,
         const char *flags);

     fetchIO *
     fetchXGetFTP(struct url *u, struct url_stat *us, const char *flags);

     fetchIO *
     fetchGetFTP(struct url *u, const char *flags);

     fetchIO *
     fetchPutFTP(struct url *u, const char *flags);

     int
     fetchStatFTP(struct url *u, struct url_stat *us, const char *flags);

     int
     fetchListFTP(struct url_list *list, struct url *u, const char *pattern,
         const char *flags);

     void
     fetchInitURLList(struct url_list *ul);

     int
     fetchAppendURLList(struct url_list *dst, const struct url_list *src);

     void
     fetchFreeURLList(struct url_list *ul);

     char *
     fetchUnquotePath(struct url *u);

     char *
     fetchUnquoteFilename(struct url *u);

     char *
     fetchStringifyURL(const struct url *u);

     void
     fetchConnectionCacheInit(int global, int per_host);

     void
     fetchConnectionCacheClose(void);

DESCRIPTION
     These functions implement a high-level library for retrieving and upload-
     ing files using Uniform Resource Locators (URLs).

     fetchParseURL() takes a URL in the form of a null-terminated string and
     splits it into its components function according to the Common Internet
     Scheme Syntax detailed in RFC 1738.  A regular expression which produces
     this syntax is:

           <scheme>:(//(<user>(:<pwd>)?@)?<host>(:<port>)?)?/(<doc>)?

     If the URL does not seem to begin with a scheme name, it is assumed to be
     a local path.  Only absolute path names are accepted.

     Note that some components of the URL are not necessarily relevant to all
     URL schemes.  For instance, the file scheme only needs the <scheme> and
     <doc> components.  fetchParseURL() quotes any unsafe character in the URL
     automatically.  This is not done by fetchMakeURL().  fetchCopyURL()
     copies an existing url structure.

     fetchMakeURL(), fetchParseURL(), and fetchCopyURL() return a pointer to a
     url structure, which is defined as follows in <fetch.h>:

     #define URL_SCHEMELEN 16
     #define URL_USERLEN 256
     #define URL_PWDLEN 256
     #define URL_HOSTLEN 255

     struct url {
         char         scheme[URL_SCHEMELEN + 1];
         char         user[URL_USERLEN + 1];
         char         pwd[URL_PWDLEN + 1];
         char         host[URL_HOSTLEN + 1];
         int          port;
         char        *doc;
         off_t        offset;
         size_t       length;
         time_t       last_modified;
     };

     The pointer returned by fetchMakeURL(), fetchCopyURL(), and
     fetchParseURL() should be freed using fetchFreeURL().  The size of struct
     URL is not part of the ABI.

     fetchXGetURL(), fetchGetURL(), and fetchPutURL() constitute the recom-
     mended interface to the fetch library.  They examine the URL passed to
     them to determine the transfer method, and call the appropriate lower-
     level functions to perform the actual transfer.  fetchXGetURL() also
     returns the remote document's metadata in the url_stat structure pointed
     to by the us argument.

     The flags argument is a string of characters which specify transfer
     options.  The meaning of the individual flags is scheme-dependent, and is
     detailed in the appropriate section below.

     fetchStatURL() attempts to obtain the requested document's metadata and
     fill in the structure pointed to by its second argument.  The url_stat
     structure is defined as follows in <fetch.h>:

     struct url_stat {
         off_t        size;
         time_t       atime;
         time_t       mtime;
     };

     If the size could not be obtained from the server, the size field is set
     to -1.  If the modification time could not be obtained from the server,
     the mtime field is set to the epoch.  If the access time could not be
     obtained from the server, the atime field is set to the modification
     time.

     fetchListURL() attempts to list the contents of the directory pointed to
     by the URL provided.  The pattern can be a simple glob-like expression as
     hint.  Callers should not depend on the server to filter names.  If suc-
     cessful, it appends the list of entries to the url_list structure.  The
     url_list structure is defined as follows in <fetch.h>:

     struct url_list {
         size_t      length;
         size_t      alloc_size;
         struct url  *urls;
     };

     The list should be initialized by calling fetchInitURLList() and the
     entries be freed by calling fetchFreeURLList().  The function
     fetchAppendURLList() can be used to append one URL lists to another.  If
     the `c' (cache result) flag is specified, the library is allowed to
     internally cache the result.

     fetchStringifyURL() returns the URL as string.  fetchUnquotePath()
     returns the path name part of the URL with any quoting undone.  Query
     arguments and fragment identifiers are not included.
     fetchUnquoteFilename() returns the last component of the path name as
     returned by fetchUnquotePath().  fetchStringifyURL(), fetchUnquotePath(),
     and fetchUnquoteFilename() return a string that should be deallocated
     with free() after use.

     fetchConnectionCacheInit() enables the connection cache.  The first argu-
     ment specifies the global limit on cached connections.  The second argu-
     ment specifies the host limit.  Entries are considered to specify the
     same host, if the host name from the URL is identical, indepent of the
     address or address family.  fetchConnectionCacheClose() flushed the con-
     nection cache and closes all cached connections.

     fetchXGet(), fetchGet(), fetchPut(), and fetchStat() are similar to
     fetchXGetURL(), fetchGetURL(), fetchPutURL(), and fetchStatURL(), except
     that they expect a pre-parsed URL in the form of a pointer to a struct
     url rather than a string.

     All of the fetchXGetXXX(), fetchGetXXX(), and fetchPutXXX() functions
     return a pointer to a stream which can be used to read or write data from
     or to the requested document, respectively.  Note that although the
     implementation details of the individual access methods vary, it can gen-
     erally be assumed that a stream returned by one of the fetchXGetXXX() or
     fetchGetXXX() functions is read-only, and that a stream returned by one
     of the fetchPutXXX() functions is write-only.

PROTOCOL INDEPENDENT FLAGS
     If the `i' (if-modified-since) flag is specified, the library will try to
     fetch the content only if it is newer than last_modified.  For HTTP an
     If-Modified-Since HTTP header is sent.  For FTP a MTDM command is sent
     first and compared locally.  For FILE the source file is compared.

FILE SCHEME
     fetchXGetFile(), fetchGetFile(), and fetchPutFile() provide access to
     documents which are files in a locally mounted file system.  Only the
     <document> component of the URL is used.

     fetchXGetFile() and fetchGetFile() do not accept any flags.

     fetchPutFile() accepts the `a' (append to file) flag.  If that flag is
     specified, the data written to the stream returned by fetchPutFile() will
     be appended to the previous contents of the file, instead of replacing
     them.

FTP SCHEME
     fetchXGetFTP(), fetchGetFTP(), and fetchPutFTP() implement the FTP proto-
     col as described in RFC 959.

     By default libfetch will attempt to use passive mode first and only fall-
     back to active mode if the server reports a syntax error.  If the `a'
     (active) flag is specified, a passive connection is not tried and active
     mode is used directly.

     If the `l' (low) flag is specified, data sockets will be allocated in the
     low (or default) port range instead of the high port range (see ip(4)).

     If the `d' (direct) flag is specified, fetchXGetFTP(), fetchGetFTP(), and
     fetchPutFTP() will use a direct connection even if a proxy server is
     defined.

     If no user name or password is given, the fetch library will attempt an
     anonymous login, with user name "anonymous" and password "anony-
     mous@<hostname>".

HTTP SCHEME
     The fetchXGetHTTP(), fetchGetHTTP(), and fetchPutHTTP() functions imple-
     ment the HTTP/1.1 protocol.  With a little luck, there is even a chance
     that they comply with RFC 2616 and RFC 2617.

     If the `d' (direct) flag is specified, fetchXGetHTTP(), fetchGetHTTP(),
     and fetchPutHTTP() will use a direct connection even if a proxy server is
     defined.

     Since there seems to be no good way of implementing the HTTP PUT method
     in a manner consistent with the rest of the fetch library, fetchPutHTTP()
     is currently unimplemented.

AUTHENTICATION
     Apart from setting the appropriate environment variables and specifying
     the user name and password in the URL or the struct url, the calling pro-
     gram has the option of defining an authentication function with the fol-
     lowing prototype:

     int myAuthMethod(struct url *u)

     The callback function should fill in the user and pwd fields in the pro-
     vided struct url and return 0 on success, or any other value to indicate
     failure.

     To register the authentication callback, simply set fetchAuthMethod to
     point at it.  The callback will be used whenever a site requires authen-
     tication and the appropriate environment variables are not set.

     This interface is experimental and may be subject to change.

RETURN VALUES
     fetchParseURL() returns a pointer to a struct url containing the individ-
     ual components of the URL.  If it is unable to allocate memory, or the
     URL is syntactically incorrect, fetchParseURL() returns a NULL pointer.

     The fetchStat() functions return 0 on success and -1 on failure.

     All other functions return a stream pointer which may be used to access
     the requested document, or NULL if an error occurred.

     The following error codes are defined in <fetch.h>:

     [FETCH_ABORT]       Operation aborted

     [FETCH_AUTH]        Authentication failed

     [FETCH_DOWN]        Service unavailable

     [FETCH_EXISTS]      File exists

     [FETCH_FULL]        File system full

     [FETCH_INFO]        Informational response

     [FETCH_MEMORY]      Insufficient memory

     [FETCH_MOVED]       File has moved

     [FETCH_NETWORK]     Network error

     [FETCH_OK]          No error

     [FETCH_PROTO]       Protocol error

     [FETCH_RESOLV]      Resolver error

     [FETCH_SERVER]      Server error

     [FETCH_TEMP]        Temporary error

     [FETCH_TIMEOUT]     Operation timed out

     [FETCH_UNAVAIL]     File is not available

     [FETCH_UNKNOWN]     Unknown error

     [FETCH_URL]         Invalid URL

     The accompanying error message includes a protocol-specific error code
     and message, e.g. "File is not available (404 Not Found)"

ENVIRONMENT
     FETCH_BIND_ADDRESS  Specifies a host name or IP address to which sockets
                         used for outgoing connections will be bound.

     FTP_LOGIN           Default FTP login if none was provided in the URL.

     FTP_PASSIVE_MODE    If set to anything but `no', forces the FTP code to
                         use passive mode.

     FTP_PASSWORD        Default FTP password if the remote server requests
                         one and none was provided in the URL.

     FTP_PROXY           URL of the proxy to use for FTP requests.  The docu-
                         ment part is ignored.  FTP and HTTP proxies are sup-
                         ported; if no scheme is specified, FTP is assumed.
                         If the proxy is an FTP proxy, libfetch will send
                         `user@host' as user name to the proxy, where `user'
                         is the real user name, and `host' is the name of the
                         FTP server.

                         If this variable is set to an empty string, no proxy
                         will be used for FTP requests, even if the HTTP_PROXY
                         variable is set.

     ftp_proxy           Same as FTP_PROXY, for compatibility.

     HTTP_AUTH           Specifies HTTP authorization parameters as a colon-
                         separated list of items.  The first and second item
                         are the authorization scheme and realm respectively;
                         further items are scheme-dependent.  Currently, only
                         basic authorization is supported.

                         Basic authorization requires two parameters: the user
                         name and password, in that order.

                         This variable is only used if the server requires
                         authorization and no user name or password was speci-
                         fied in the URL.

     HTTP_PROXY          URL of the proxy to use for HTTP requests.  The docu-
                         ment part is ignored.  Only HTTP proxies are sup-
                         ported for HTTP requests.  If no port number is spec-
                         ified, the default is 3128.

                         Note that this proxy will also be used for FTP docu-
                         ments, unless the FTP_PROXY variable is set.

     http_proxy          Same as HTTP_PROXY, for compatibility.

     HTTP_PROXY_AUTH     Specifies authorization parameters for the HTTP proxy
                         in the same format as the HTTP_AUTH variable.

                         This variable is used if and only if connected to an
                         HTTP proxy, and is ignored if a user and/or a pass-
                         word were specified in the proxy URL.

     HTTP_REFERER        Specifies the referrer URL to use for HTTP requests.
                         If set to ``auto'', the document URL will be used as
                         referrer URL.

     HTTP_USER_AGENT     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.

     NETRC               Specifies a file to use instead of ~/.netrc to look
                         up login names and passwords for FTP sites.  See
                         ftp(1) for a description of the file format.  This
                         feature is experimental.

     NO_PROXY            Either a single asterisk, which disables the use of
                         proxies altogether, or a comma- or whitespace-sepa-
                         rated list of hosts for which proxies should not be
                         used.

     no_proxy            Same as NO_PROXY, for compatibility.

EXAMPLES
     To access a proxy server on proxy.example.com port 8080, set the
     HTTP_PROXY environment variable in a manner similar to this:

           HTTP_PROXY=http://proxy.example.com:8080

     If the proxy server requires authentication, there are two options avail-
     able for passing the authentication data.  The first method is by using
     the proxy URL:

           HTTP_PROXY=http://<user>:<pwd>@proxy.example.com:8080

     The second method is by using the HTTP_PROXY_AUTH environment variable:

           HTTP_PROXY=http://proxy.example.com:8080
           HTTP_PROXY_AUTH=basic:*:<user>:<pwd>

     To disable the use of a proxy for an HTTP server running on the local
     host, define NO_PROXY as follows:

           NO_PROXY=localhost,127.0.0.1

SEE ALSO
     ftp(1), ip(4)

     J. Postel and J. K. Reynolds, File Transfer Protocol, October 1985, RFC
     959.

     P. Deutsch, A. Emtage, and A. Marine, How to Use Anonymous FTP, May 1994,
     RFC 1635.

     T. Berners-Lee, L. Masinter, and M. McCahill, Uniform Resource Locators
     (URL), December 1994, RFC 1738.

     R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P. Leach, and
     T. Berners-Lee, Hypertext Transfer Protocol -- HTTP/1.1, January 1999,
     RFC 2616.

     J. Franks, P. Hallam-Baker, J. Hostetler, S. Lawrence, P. Leach, A.
     Luotonen, and L. Stewart, HTTP Authentication: Basic and Digest Access
     Authentication, June 1999, RFC 2617.

HISTORY
     The fetch library first appeared in FreeBSD 3.0.

AUTHORS
     The fetch library was mostly written by Dag-Erling Smørgrav
     <des@FreeBSD.org> with numerous suggestions from Jordan K. Hubbard
     <jkh@FreeBSD.org>, Eugene Skepner <eu@qub.com> and other FreeBSD develop-
     ers.  It replaces the older ftpio library written by Poul-Henning Kamp
     <phk@FreeBSD.org> and Jordan K. Hubbard <jkh@FreeBSD.org>.

     This manual page was written by Dag-Erling Smørgrav <des@FreeBSD.org>.

BUGS
     Some parts of the library are not yet implemented.  The most notable
     examples of this are fetchPutHTTP() and FTP proxy support.

     There is no way to select a proxy at run-time other than setting the
     HTTP_PROXY or FTP_PROXY environment variables as appropriate.

     libfetch does not understand or obey 305 (Use Proxy) replies.

     Error numbers are unique only within a certain context; the error codes
     used for FTP and HTTP overlap, as do those used for resolver and system
     errors.  For instance, error code 202 means "Command not implemented,
     superfluous at this site" in an FTP context and "Accepted" in an HTTP
     context.

     fetchStatFTP() does not check that the result of an MDTM command is a
     valid date.

     The man page is incomplete, poorly written and produces badly formatted
     text.

     The error reporting mechanism is unsatisfactory.

     Some parts of the code are not fully reentrant.

NetBSD 7.0                     January 22, 2010                     NetBSD 7.0

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