.\"- .\" Copyright (c) 1998-2013 Dag-Erling Smørgrav .\" Copyright (c) 2013-2016 Michael Gmelin .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .Dd October 7, 2023 .Dt FETCH 3 .Os .Sh NAME .Nm fetchMakeURL , .Nm fetchParseURL , .Nm fetchFreeURL , .Nm fetchXGetURL , .Nm fetchGetURL , .Nm fetchPutURL , .Nm fetchStatURL , .Nm fetchListURL , .Nm fetchXGet , .Nm fetchGet , .Nm fetchPut , .Nm fetchStat , .Nm fetchList , .Nm fetchXGetFile , .Nm fetchGetFile , .Nm fetchPutFile , .Nm fetchStatFile , .Nm fetchListFile , .Nm fetchXGetHTTP , .Nm fetchGetHTTP , .Nm fetchPutHTTP , .Nm fetchStatHTTP , .Nm fetchListHTTP , .Nm fetchReqHTTP , .Nm fetchXGetFTP , .Nm fetchGetFTP , .Nm fetchPutFTP , .Nm fetchStatFTP , .Nm fetchListFTP .Nd file transfer functions .Sh LIBRARY .Lb libfetch .Sh SYNOPSIS .In sys/param.h .In stdio.h .In fetch.h .Ft struct url * .Fn fetchMakeURL "const char *scheme" "const char *host" "int port" "const char *doc" "const char *user" "const char *pwd" .Ft struct url * .Fn fetchParseURL "const char *URL" .Ft void .Fn fetchFreeURL "struct url *u" .Ft FILE * .Fn fetchXGetURL "const char *URL" "struct url_stat *us" "const char *flags" .Ft FILE * .Fn fetchGetURL "const char *URL" "const char *flags" .Ft FILE * .Fn fetchPutURL "const char *URL" "const char *flags" .Ft int .Fn fetchStatURL "const char *URL" "struct url_stat *us" "const char *flags" .Ft struct url_ent * .Fn fetchListURL "const char *URL" "const char *flags" .Ft FILE * .Fn fetchXGet "struct url *u" "struct url_stat *us" "const char *flags" .Ft FILE * .Fn fetchGet "struct url *u" "const char *flags" .Ft FILE * .Fn fetchPut "struct url *u" "const char *flags" .Ft int .Fn fetchStat "struct url *u" "struct url_stat *us" "const char *flags" .Ft struct url_ent * .Fn fetchList "struct url *u" "const char *flags" .Ft FILE * .Fn fetchXGetFile "struct url *u" "struct url_stat *us" "const char *flags" .Ft FILE * .Fn fetchGetFile "struct url *u" "const char *flags" .Ft FILE * .Fn fetchPutFile "struct url *u" "const char *flags" .Ft int .Fn fetchStatFile "struct url *u" "struct url_stat *us" "const char *flags" .Ft struct url_ent * .Fn fetchListFile "struct url *u" "const char *flags" .Ft FILE * .Fn fetchXGetHTTP "struct url *u" "struct url_stat *us" "const char *flags" .Ft FILE * .Fn fetchGetHTTP "struct url *u" "const char *flags" .Ft FILE * .Fn fetchPutHTTP "struct url *u" "const char *flags" .Ft int .Fn fetchStatHTTP "struct url *u" "struct url_stat *us" "const char *flags" .Ft struct url_ent * .Fn fetchListHTTP "struct url *u" "const char *flags" .Ft FILE * .Fn fetchReqHTTP "struct url *u" "const char *method" "const char *flags" "const char *content_type" "const char *body" .Ft FILE * .Fn fetchXGetFTP "struct url *u" "struct url_stat *us" "const char *flags" .Ft FILE * .Fn fetchGetFTP "struct url *u" "const char *flags" .Ft FILE * .Fn fetchPutFTP "struct url *u" "const char *flags" .Ft int .Fn fetchStatFTP "struct url *u" "struct url_stat *us" "const char *flags" .Ft struct url_ent * .Fn fetchListFTP "struct url *u" "const char *flags" .Sh DESCRIPTION These functions implement a high-level library for retrieving and uploading files using Uniform Resource Locators (URLs). .Pp .Fn 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 RFC1738. A regular expression which produces this syntax is: .Bd -literal :(//((:)?@)?(:)?)?/()? .Ed .Pp If the URL does not seem to begin with a scheme name, the following syntax is assumed: .Bd -literal (((:)?@)?(:)?)?/()? .Ed .Pp Note that some components of the URL are not necessarily relevant to all URL schemes. For instance, the file scheme only needs the and components. .Pp .Fn fetchMakeURL and .Fn fetchParseURL return a pointer to a .Vt url structure, which is defined as follows in .In fetch.h : .Bd -literal #define URL_SCHEMELEN 16 #define URL_USERLEN 256 #define URL_PWDLEN 256 struct url { char scheme[URL_SCHEMELEN+1]; char user[URL_USERLEN+1]; char pwd[URL_PWDLEN+1]; char host[MAXHOSTNAMELEN+1]; int port; char *doc; off_t offset; size_t length; time_t ims_time; }; .Ed .Pp The .Va ims_time field stores the time value for .Li If-Modified-Since HTTP requests. .Pp The pointer returned by .Fn fetchMakeURL or .Fn fetchParseURL should be freed using .Fn fetchFreeURL . .Pp .Fn fetchXGetURL , .Fn fetchGetURL , and .Fn fetchPutURL constitute the recommended interface to the .Nm 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. .Fn fetchXGetURL also returns the remote document's metadata in the .Vt url_stat structure pointed to by the .Fa us argument. .Pp The .Fa 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. .Pp .Fn fetchStatURL attempts to obtain the requested document's metadata and fill in the structure pointed to by its second argument. The .Vt url_stat structure is defined as follows in .In fetch.h : .Bd -literal struct url_stat { off_t size; time_t atime; time_t mtime; }; .Ed .Pp If the size could not be obtained from the server, the .Fa size field is set to -1. If the modification time could not be obtained from the server, the .Fa mtime field is set to the epoch. If the access time could not be obtained from the server, the .Fa atime field is set to the modification time. .Pp .Fn fetchListURL attempts to list the contents of the directory pointed to by the URL provided. If successful, it returns a malloced array of .Vt url_ent structures. The .Vt url_ent structure is defined as follows in .In fetch.h : .Bd -literal struct url_ent { char name[PATH_MAX]; struct url_stat stat; }; .Ed .Pp The list is terminated by an entry with an empty name. .Pp The pointer returned by .Fn fetchListURL should be freed using .Fn free . .Pp .Fn fetchXGet , .Fn fetchGet , .Fn fetchPut and .Fn fetchStat are similar to .Fn fetchXGetURL , .Fn fetchGetURL , .Fn fetchPutURL and .Fn fetchStatURL , except that they expect a pre-parsed URL in the form of a pointer to a .Vt struct url rather than a string. .Pp All of the .Fn fetchXGetXXX , .Fn fetchGetXXX and .Fn 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 generally be assumed that a stream returned by one of the .Fn fetchXGetXXX or .Fn fetchGetXXX functions is read-only, and that a stream returned by one of the .Fn fetchPutXXX functions is write-only. .Sh FILE SCHEME .Fn fetchXGetFile , .Fn fetchGetFile and .Fn fetchPutFile provide access to documents which are files in a locally mounted file system. Only the component of the URL is used. .Pp .Fn fetchXGetFile and .Fn fetchGetFile do not accept any flags. .Pp .Fn fetchPutFile accepts the .Ql a (append to file) flag. If that flag is specified, the data written to the stream returned by .Fn fetchPutFile will be appended to the previous contents of the file, instead of replacing them. .Sh FTP SCHEME .Fn fetchXGetFTP , .Fn fetchGetFTP and .Fn fetchPutFTP implement the FTP protocol as described in RFC959. .Pp If the .Ql P (not passive) flag is specified, an active (rather than passive) connection will be attempted. .Pp The .Ql p flag is supported for compatibility with earlier versions where active connections were the default. It has precedence over the .Ql P flag, so if both are specified, .Nm will use a passive connection. .Pp If the .Ql l (low) flag is specified, data sockets will be allocated in the low (or default) port range instead of the high port range (see .Xr ip 4 ) . .Pp If the .Ql d (direct) flag is specified, .Fn fetchXGetFTP , .Fn fetchGetFTP and .Fn fetchPutFTP will use a direct connection even if a proxy server is defined. .Pp If no user name or password is given, the .Nm fetch library will attempt an anonymous login, with user name "anonymous" and password "anonymous@". .Sh HTTP SCHEME The .Fn fetchXGetHTTP , .Fn fetchGetHTTP , .Fn fetchPutHTTP and .Fn fetchReqHTTP functions implement the HTTP/1.1 protocol. With a little luck, there is even a chance that they comply with RFC2616 and RFC2617. .Pp If the .Ql d (direct) flag is specified, .Fn fetchXGetHTTP , .Fn fetchGetHTTP and .Fn fetchPutHTTP will use a direct connection even if a proxy server is defined. .Pp If the .Ql i (if-modified-since) flag is specified, and the .Va ims_time field is set in .Vt "struct url" , then .Fn fetchXGetHTTP and .Fn fetchGetHTTP will send a conditional .Li If-Modified-Since HTTP header to only fetch the content if it is newer than .Va ims_time . .Pp The function .Fn fetchReqHTTP can be used to make requests with an arbitrary HTTP verb, including POST, DELETE, CONNECT, OPTIONS, TRACE or PATCH. This can be done by setting the argument .Fa method to the intended verb, such as .Ql POST , and .Fa body to the content. .Pp Since there seems to be no good way of implementing the HTTP PUT method in a manner consistent with the rest of the .Nm fetch library, .Fn fetchPutHTTP is currently unimplemented. .Sh HTTPS SCHEME Based on HTTP SCHEME. The CA bundle used for peer verification can be changed by setting the environment variables .Ev SSL_CA_CERT_FILE to point to a concatenated bundle of trusted certificates and .Ev SSL_CA_CERT_PATH to point to a directory containing hashes of trusted CAs (see .Xr verify 1 ) . .Pp A certificate revocation list (CRL) can be used by setting the environment variable .Ev SSL_CRL_FILE (see .Xr crl 1 ) . .Pp Peer verification can be disabled by setting the environment variable .Ev SSL_NO_VERIFY_PEER . Note that this also disables CRL checking. .Pp By default the service identity is verified according to the rules detailed in RFC6125 (also known as hostname verification). This feature can be disabled by setting the environment variable .Ev SSL_NO_VERIFY_HOSTNAME . .Pp Client certificate based authentication is supported. The environment variable .Ev SSL_CLIENT_CERT_FILE should be set to point to a file containing key and client certificate to be used in PEM format. When a PEM-format key is in a separate file from the client certificate, the environment variable .Ev SSL_CLIENT_KEY_FILE can be set to point to the key file. In case the key uses a password, the user will be prompted on standard input. .Pp By default .Nm libfetch allows TLSv1 and newer when negotiating the connecting with the remote peer. You can change this behavior by setting the .Ev SSL_NO_TLS1 , .Ev SSL_NO_TLS1_1 and .Ev SSL_NO_TLS1_2 environment variables to disable TLS 1.0, 1.1 and 1.2 respectively. .Sh AUTHENTICATION Apart from setting the appropriate environment variables and specifying the user name and password in the URL or the .Vt struct url , the calling program has the option of defining an authentication function with the following prototype: .Pp .Ft int .Fn myAuthMethod "struct url *u" .Pp The callback function should fill in the .Fa user and .Fa pwd fields in the provided .Vt struct url and return 0 on success, or any other value to indicate failure. .Pp To register the authentication callback, simply set .Va fetchAuthMethod to point at it. The callback will be used whenever a site requires authentication and the appropriate environment variables are not set. .Pp This interface is experimental and may be subject to change. .Sh RETURN VALUES .Fn fetchParseURL returns a pointer to a .Vt struct url containing the individual components of the URL. If it is unable to allocate memory, or the URL is syntactically incorrect, .Fn fetchParseURL returns a NULL pointer. .Pp The .Fn fetchStat functions return 0 on success and -1 on failure. .Pp All other functions return a stream pointer which may be used to access the requested document, or NULL if an error occurred. .Pp The following error codes are defined in .In fetch.h : .Bl -tag -width 18n .It Bq Er FETCH_ABORT Operation aborted .It Bq Er FETCH_AUTH Authentication failed .It Bq Er FETCH_DOWN Service unavailable .It Bq Er FETCH_EXISTS File exists .It Bq Er FETCH_FULL File system full .It Bq Er FETCH_INFO Informational response .It Bq Er FETCH_MEMORY Insufficient memory .It Bq Er FETCH_MOVED File has moved .It Bq Er FETCH_NETWORK Network error .It Bq Er FETCH_OK No error .It Bq Er FETCH_PROTO Protocol error .It Bq Er FETCH_RESOLV Resolver error .It Bq Er FETCH_SERVER Server error .It Bq Er FETCH_TEMP Temporary error .It Bq Er FETCH_TIMEOUT Operation timed out .It Bq Er FETCH_UNAVAIL File is not available .It Bq Er FETCH_UNKNOWN Unknown error .It Bq Er FETCH_URL Invalid URL .El .Pp The accompanying error message includes a protocol-specific error code and message, like "File is not available (404 Not Found)" .Sh ENVIRONMENT .Bl -tag -width ".Ev FETCH_BIND_ADDRESS" .It Ev FETCH_BIND_ADDRESS Specifies a hostname or IP address to which sockets used for outgoing connections will be bound. .It Ev FTP_LOGIN Default FTP login if none was provided in the URL. .It Ev FTP_PASSIVE_MODE If set to .Ql no , forces the FTP code to use active mode. If set to any other value, forces passive mode even if the application requested active mode. .It Ev FTP_PASSWORD Default FTP password if the remote server requests one and none was provided in the URL. .It Ev FTP_PROXY URL of the proxy to use for FTP requests. The document part is ignored. FTP and HTTP proxies are supported; if no scheme is specified, FTP is assumed. If the proxy is an FTP proxy, .Nm libfetch will send .Ql user@host as user name to the proxy, where .Ql user is the real user name, and .Ql host is the name of the FTP server. .Pp If this variable is set to an empty string, no proxy will be used for FTP requests, even if the .Ev HTTP_PROXY variable is set. .It Ev ftp_proxy Same as .Ev FTP_PROXY , for compatibility. .It Ev HTTP_ACCEPT Specifies the value of the .Va Accept header for HTTP requests. If empty, no .Va Accept header is sent. The default is .Dq */* . .It Ev 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, the .Dq basic and .Dq digest authorization methods are supported. .Pp Both methods require two parameters: the user name and password, in that order. .Pp This variable is only used if the server requires authorization and no user name or password was specified in the URL. .It Ev HTTP_PROXY URL of the proxy to use for HTTP requests. The document part is ignored. Only HTTP proxies are supported for HTTP requests. If no port number is specified, the default is 3128. .Pp Note that this proxy will also be used for FTP documents, unless the .Ev FTP_PROXY variable is set. .It Ev http_proxy Same as .Ev HTTP_PROXY , for compatibility. .It Ev HTTP_PROXY_AUTH Specifies authorization parameters for the HTTP proxy in the same format as the .Ev HTTP_AUTH variable. .Pp This variable is used if and only if connected to an HTTP proxy, and is ignored if a user and/or a password were specified in the proxy URL. .It Ev HTTP_REFERER Specifies the referrer URL to use for HTTP requests. If set to .Dq auto , the document URL will be used as referrer URL. .It Ev 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. If defined but empty, no User-Agent header is sent. .It Ev NETRC Specifies a file to use instead of .Pa ~/.netrc to look up login names and passwords for FTP and HTTP sites as well as HTTP proxies. See .Xr ftp 1 for a description of the file format. .It Ev NO_PROXY Either a single asterisk, which disables the use of proxies altogether, or a comma- or whitespace-separated list of hosts for which proxies should not be used. .It Ev no_proxy Same as .Ev NO_PROXY , for compatibility. .It Ev SOCKS5_PROXY Uses SOCKS version 5 to make connection. The format must be the IP or hostname followed by a colon for the port. IPv6 addresses must enclose the address in brackets. If no port is specified, the default is 1080. This setting will supercede a connection to an .Ev HTTP_PROXY . .It Ev SSL_CA_CERT_FILE CA certificate bundle containing trusted CA certificates. Default value: See HTTPS SCHEME above. .It Ev SSL_CA_CERT_PATH Path containing trusted CA hashes. .It Ev SSL_CLIENT_CERT_FILE PEM encoded client certificate/key which will be used in client certificate authentication. .It Ev SSL_CLIENT_KEY_FILE PEM encoded client key in case key and client certificate are stored separately. .It Ev SSL_CRL_FILE File containing certificate revocation list. .It Ev SSL_NO_TLS1 Do not allow TLS version 1.0 when negotiating the connection. .It Ev SSL_NO_TLS1_1 Do not allow TLS version 1.1 when negotiating the connection. .It Ev SSL_NO_TLS1_2 Do not allow TLS version 1.2 when negotiating the connection. .It Ev SSL_NO_VERIFY_HOSTNAME If set, do not verify that the hostname matches the subject of the certificate presented by the server. .It Ev SSL_NO_VERIFY_PEER If set, do not verify the peer certificate against trusted CAs. .El .Sh EXAMPLES To access a proxy server on .Pa proxy.example.com port 8080, set the .Ev HTTP_PROXY environment variable in a manner similar to this: .Pp .Dl HTTP_PROXY=http://proxy.example.com:8080 .Pp If the proxy server requires authentication, there are two options available for passing the authentication data. The first method is by using the proxy URL: .Pp .Dl HTTP_PROXY=http://:@proxy.example.com:8080 .Pp The second method is by using the .Ev HTTP_PROXY_AUTH environment variable: .Bd -literal -offset indent HTTP_PROXY=http://proxy.example.com:8080 HTTP_PROXY_AUTH=basic:*:: .Ed .Pp To disable the use of a proxy for an HTTP server running on the local host, define .Ev NO_PROXY as follows: .Bd -literal -offset indent NO_PROXY=localhost,127.0.0.1 .Ed .Pp To use a SOCKS5 proxy, set the .Ev SOCKS5_PROXY environment variable to a valid host or IP followed by an optional colon and the port. IPv6 addresses must be enclosed in brackets. The following are examples of valid settings: .Bd -literal -offset indent SOCKS5_PROXY=proxy.example.com SOCKS5_PROXY=proxy.example.com:1080 SOCKS5_PROXY=192.0.2.0 SOCKS5_PROXY=198.51.100.0:1080 SOCKS5_PROXY=[2001:db8::1] SOCKS5_PROXY=[2001:db8::2]:1080 .Ed .Pp Access HTTPS website without any certificate verification whatsoever: .Bd -literal -offset indent SSL_NO_VERIFY_PEER=1 SSL_NO_VERIFY_HOSTNAME=1 .Ed .Pp Access HTTPS website using client certificate based authentication and a private CA: .Bd -literal -offset indent SSL_CLIENT_CERT_FILE=/path/to/client.pem SSL_CA_CERT_FILE=/path/to/myca.pem .Ed .Sh SEE ALSO .Xr fetch 1 , .Xr ip 4 .Rs .%A J. Postel .%A J. K. Reynolds .%D October 1985 .%B File Transfer Protocol .%O RFC959 .Re .Rs .%A P. Deutsch .%A A. Emtage .%A A. Marine. .%D May 1994 .%T How to Use Anonymous FTP .%O RFC1635 .Re .Rs .%A T. Berners-Lee .%A L. Masinter .%A M. McCahill .%D December 1994 .%T Uniform Resource Locators (URL) .%O RFC1738 .Re .Rs .%A R. Fielding .%A J. Gettys .%A J. Mogul .%A H. Frystyk .%A L. Masinter .%A P. Leach .%A T. Berners-Lee .%D January 1999 .%B Hypertext Transfer Protocol -- HTTP/1.1 .%O RFC2616 .Re .Rs .%A J. Franks .%A P. Hallam-Baker .%A J. Hostetler .%A S. Lawrence .%A P. Leach .%A A. Luotonen .%A L. Stewart .%D June 1999 .%B HTTP Authentication: Basic and Digest Access Authentication .%O RFC2617 .Re .Sh HISTORY The .Nm fetch library first appeared in .Fx 3.0 . .Sh AUTHORS .An -nosplit The .Nm fetch library was mostly written by .An Dag-Erling Sm\(/orgrav Aq Mt des@FreeBSD.org with numerous suggestions and contributions from .An Jordan K. Hubbard Aq Mt jkh@FreeBSD.org , .An Eugene Skepner Aq Mt eu@qub.com , .An Hajimu Umemoto Aq Mt ume@FreeBSD.org , .An Henry Whincup Aq Mt henry@techiebod.com , .An Jukka A. Ukkonen Aq Mt jau@iki.fi , .An Jean-Fran\(,cois Dockes Aq Mt jf@dockes.org , .An Michael Gmelin Aq Mt freebsd@grem.de and others. It replaces the older .Nm ftpio library written by .An Poul-Henning Kamp Aq Mt phk@FreeBSD.org and .An Jordan K. Hubbard Aq Mt jkh@FreeBSD.org . .Pp This manual page was written by .An Dag-Erling Sm\(/orgrav Aq Mt des@FreeBSD.org and .An Michael Gmelin Aq Mt freebsd@grem.de . .Sh BUGS Some parts of the library are not yet implemented. The most notable examples of this are .Fn fetchPutHTTP , .Fn fetchListHTTP , .Fn fetchListFTP and FTP proxy support. .Pp There is no way to select a proxy at run-time other than setting the .Ev HTTP_PROXY or .Ev FTP_PROXY environment variables as appropriate. .Pp .Nm libfetch does not understand or obey 305 (Use Proxy) replies. .Pp 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. .Pp .Fn fetchStatFTP does not check that the result of an MDTM command is a valid date. .Pp In case password protected keys are used for client certificate based authentication the user is prompted for the password on each and every fetch operation. .Pp The man page is incomplete, poorly written and produces badly formatted text. .Pp The error reporting mechanism is unsatisfactory. .Pp Some parts of the code are not fully reentrant.