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   HTTP Request Handling
   Copyright (C) 1999-2002, Joe Orton <joe@manyfish.co.uk>

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.
   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
   MA 02111-1307, USA


#ifndef NE_REQUEST_H
#define NE_REQUEST_H

#include "ne_utils.h" /* For ne_status */
#include "ne_string.h" /* For ne_buffer */
#include "ne_session.h"


#define NE_OK (0) /* Success */
#define NE_ERROR (1) /* Generic error; use ne_get_error(session) for message */
#define NE_LOOKUP (2) /* Server or proxy hostname lookup failed */
#define NE_AUTH (3) /* User authentication failed on server */
#define NE_PROXYAUTH (4) /* User authentication failed on proxy */
#define NE_CONNECT (5) /* Could not connect to server */
#define NE_TIMEOUT (6) /* Connection timed out */
#define NE_FAILED (7) /* The precondition failed */
#define NE_RETRY (8) /* Retry request (ne_end_request ONLY) */
#define NE_REDIRECT (9) /* See ne_redirect.h */

/* FIXME: remove this */
#define EOL "\r\n"

/* Opaque object representing a single HTTP request. */
typedef struct ne_request_s ne_request;

/***** Request Handling *****/

/* Create a request in session 'sess', with given method and path.
 * 'path' must conform to the 'abs_path' grammar in RFC2396, with an
 * optional "? query" part, and MUST be URI-escaped by the caller. */
ne_request *ne_request_create(ne_session *sess,
                        const char *method, const char *path);

/* 'buffer' will be sent as the request body with given request. */
void ne_set_request_body_buffer(ne_request *req, const char *buffer,
                        size_t size);

/* Send the contents of a file as the request body; 'fd' must be a
 * file descriptor of an open, seekable file.  Current file offset of
 * fd is not retained (and ignored: the file is read from the the
 * first byte). Returns:
 *  0 on okay.
 *  non-zero if could not determine length of file.  */
int ne_set_request_body_fd(ne_request *req, int fd);

/* "Pull"-based request body provider: a callback which is invoked to
 * provide blocks of request body on demand.
 * Before each time the body is provided, the callback will be called
 * once with buflen == 0.  The body may have to be provided >1 time
 * per request (for authentication retries etc.).
 * The callback must return:
 *        <0           : error, abort request.
 *         0           : ignore 'buffer' contents, end of body.
 *     0 < x <= buflen : buffer contains x bytes of body data.  */
typedef ssize_t (*ne_provide_body)(void *userdata, 
                           char *buffer, size_t buflen);

/* Install a callback which is invoked as needed to provide request
 * body blocks.  Total request body is 'size' bytes: the callback MUST
 * ensure it returns in total exactly 'size' bytes each time the
 * request body is provided. */
void ne_set_request_body_provider(ne_request *req, size_t size,
                          ne_provide_body provider, void *userdata);

/* Handling response bodies... you provide TWO callbacks:
 * 1) 'acceptance' callback: determines whether you want to handle the
 * response body given the response-status information, e.g., if you
 * only want 2xx responses, say so here.
 * 2) 'reader' callback: passed blocks of the response-body as they
 * arrive, if the acceptance callback returned non-zero.  */

/* 'acceptance' callback type. Return non-zero to accept the response,
 * else zero to ignore it. */
typedef int (*ne_accept_response)(
    void *userdata, ne_request *req, const ne_status *st);

/* An 'acceptance' callback which only accepts 2xx-class responses.
 * Ignores userdata. */
int ne_accept_2xx(void *userdata, ne_request *req, const ne_status *st);

/* An acceptance callback which accepts all responses.  Ignores
 * userdata. */
int ne_accept_always(void *userdata, ne_request *req, const ne_status *st);

/* Callback for reading a block of data. */
typedef void (*ne_block_reader)(void *userdata, const char *buf, size_t len);

/* Add a response reader for the given request, with the given
 * acceptance function. userdata is passed as the first argument to
 * the acceptance + reader callbacks. 
 * The acceptance callback is called once each time the request is
 * sent: it may be sent >1 time because of authentication retries etc.
 * For each time the acceptance callback is called, if it returns
 * non-zero, blocks of the response body will be passed to the reader
 * callback as the response is read.  After all the response body has
 * been read, the callback will be called with a 'len' argument of
 * zero.  */
void ne_add_response_body_reader(ne_request *req, ne_accept_response accpt,
                         ne_block_reader reader, void *userdata);

/* Handle response headers. Each handler is associated with a specific
 * header field (indicated by name). The handler is then passed the
 * value of this header field. */

/* The header handler callback type */
typedef void (*ne_header_handler)(void *userdata, const char *value);

/* Adds a response header handler for the given request. userdata is passed
 * as the first argument to the header handler, and the 'value' is the
 * header field value (i.e. doesn't include the "Header-Name: " part").
void ne_add_response_header_handler(ne_request *req, const char *name, 
                            ne_header_handler hdl, void *userdata);

/* Add handler which is passed ALL header values regardless of name */
void ne_add_response_header_catcher(ne_request *req, 
                            ne_header_handler hdl, void *userdata);

/* Stock header handlers:
 *  'duplicate': *(char **)userdata = strdup(value)
 *  'numeric':   *(int *)userdata = atoi(value)
 * e.g.
 *   int mynum;
 *   ne_add_response_header_handler(myreq, "Content-Length",
 *                                    ne_handle_numeric_handler, &mynum);
 * ... arranges mynum to be set to the value of the Content-Length header.
void ne_duplicate_header(void *userdata, const char *value);
void ne_handle_numeric_header(void *userdata, const char *value);

/* Adds a header to the request with given name and value. */
void ne_add_request_header(ne_request *req, const char *name, 
                     const char *value);
/* Adds a header to the request with given name, using printf-like
 * format arguments for the value. */
void ne_print_request_header(ne_request *req, const char *name,
                       const char *format, ...) 
    ne_attribute((format(printf, 3, 4)));

/* ne_request_dispatch: Sends the given request, and reads the
 * response. Response-Status information can be retrieve with
 * ne_get_status(req).
 *  NE_OK         if request sent + response read okay.
 *  NE_AUTH       user not authorised on server
 *  NE_PROXYAUTH  user not authorised on proxy server
 *  NE_CONNECT    could not connect to server/proxy server
 *  NE_TIMEOUT    connection timed out mid-request
 *  NE_ERROR      for other errors, and ne_get_error() should
 *                  return a meaningful error string
int ne_request_dispatch(ne_request *req);

/* Returns a pointer to the response status information for the given
 * request; pointer is valid until request object is destroyed. */
const ne_status *ne_get_status(const ne_request *req) ne_attribute((const));

/* Returns pointer to session associated with request. */
ne_session *ne_get_session(const ne_request *req);

/* Destroy memory associated with request pointer */
void ne_request_destroy(ne_request *req);

/* "Caller-pulls" request interface.  This is an ALTERNATIVE interface
 * to ne_request_dispatch: either use that, or do all this yourself:
 * caller must call:
 *  1. ne_begin_request (fail if returns non-NE_OK)
 *  2. while(ne_read_response_block(...) > 0) ... loop ...;
 *     (fail if ne_read_response_block returns <0)
 *  3. ne_end_request
 * ne_end_request and ne_begin_request both return an NE_* code; if
 * ne_end_request returns NE_RETRY, you must restart the loop from (1)
 * above. */
int ne_begin_request(ne_request *req);
int ne_end_request(ne_request *req);

/* Read a block of the response.  buffer must be at least 128 bytes.
 * 'buflen' must be length of buffer.
 * Returns:
 *  <0 - error, stop reading.
 *   0 - end of response
 *  >0 - number of bytes read into buffer.
ssize_t ne_read_response_block(ne_request *req, char *buffer, size_t buflen);

/**** Request hooks handling *****/

typedef void (*ne_free_hooks)(void *cookie);

/* Hook called when a create is created; passed the request method,
 * and the string used as the Request-URI (which may be an abs_path,
 * or an absoluteURI, depending on whether an HTTP proxy is in
 * use).  */
typedef void (*ne_create_request_fn)(ne_request *req, void *userdata,
                             const char *method, const char *requri);
void ne_hook_create_request(ne_session *sess, 
                      ne_create_request_fn fn, void *userdata);

/* Hook called before the request is sent.  'header' is the raw HTTP
 * header before the trailing CRLF is added: add in more here. */
typedef void (*ne_pre_send_fn)(ne_request *req, void *userdata, 
                         ne_buffer *header);
void ne_hook_pre_send(ne_session *sess, ne_pre_send_fn fn, void *userdata);

/* Hook called after the request is sent. May return:
 *  NE_OK     everything is okay
 *  NE_RETRY  try sending the request again.
 * anything else signifies an error, and the request is failed. The return
 * code is passed back the _dispatch caller, so the session error must
 * also be set appropriately (ne_set_error).
typedef int (*ne_post_send_fn)(ne_request *req, void *userdata,
                         const ne_status *status);
void ne_hook_post_send(ne_session *sess, ne_post_send_fn fn, void *userdata);

/* Hook called when the function is destroyed. */
typedef void (*ne_destroy_req_fn)(ne_request *req, void *userdata);
void ne_hook_destroy_request(ne_session *sess,
                       ne_destroy_req_fn fn, void *userdata);

typedef void (*ne_destroy_sess_fn)(void *userdata);
/* Hook called when the session is destroyed. */
void ne_hook_destroy_session(ne_session *sess,
                       ne_destroy_sess_fn fn, void *userdata);

/* Store an opaque context for the request, 'priv' is returned by a
 * call to ne_request_get_private with the same ID. */
void ne_set_request_private(ne_request *req, const char *id, void *priv);
void *ne_get_request_private(ne_request *req, const char *id);


#endif /* NE_REQUEST_H */

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