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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* include/k5-tls.h - internal pluggable interface for TLS */
/*
* Copyright (C) 2014 by the Massachusetts Institute of Technology.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * 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 COPYRIGHT HOLDERS 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
* COPYRIGHT HOLDER 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.
*/
/*
* This internal pluggable interface allows libkrb5 to load an in-tree module
* providing TLS support at runtime. It is currently tailored for the needs of
* the OpenSSL module as used for HTTP proxy support. As an internal
* interface, it can be changed to fit different implementations and consumers
* without regard for backward compatibility.
*/
#ifndef K5_TLS_H
#define K5_TLS_H
#include "k5-int.h"
/* An abstract type for localauth module data. */
typedef struct k5_tls_handle_st *k5_tls_handle;
typedef enum {
DATA_READ, DONE, WANT_READ, WANT_WRITE, ERROR_TLS
} k5_tls_status;
/*
* Create a handle for fd, where the server certificate must match servername
* and be trusted according to anchors. anchors is a null-terminated list
* using the DIR:/FILE:/ENV: syntax borrowed from PKINIT. If anchors is null,
* use the system default trust anchors.
*/
typedef krb5_error_code
(*k5_tls_setup_fn)(krb5_context context, SOCKET fd, const char *servername,
char **anchors, k5_tls_handle *handle_out);
/*
* Write len bytes of data using TLS. Return DONE if writing is complete,
* WANT_READ or WANT_WRITE if the underlying socket must be readable or
* writable to continue, and ERROR_TLS if the TLS channel or underlying socket
* experienced an error. After WANT_READ or WANT_WRITE, the operation will be
* retried with the same arguments even if some data has already been written.
* (OpenSSL makes this contract easy to fulfill. For other implementations we
* might want to change it.)
*/
typedef k5_tls_status
(*k5_tls_write_fn)(krb5_context context, k5_tls_handle handle,
const void *data, size_t len);
/*
* Read up to data_size bytes of data using TLS. Return DATA_READ and set
* *len_out if any data is read. Return DONE if there is no more data to be
* read on the connection, WANT_READ or WANT_WRITE if the underlying socket
* must be readable or writable to continue, and ERROR_TLS if the TLS channel
* or underlying socket experienced an error.
*
* After DATA_READ, there may still be pending buffered data to read. The
* caller must call this method again with additional buffer space before
* selecting for reading on the underlying socket.
*/
typedef k5_tls_status
(*k5_tls_read_fn)(krb5_context context, k5_tls_handle handle, void *data,
size_t data_size, size_t *len_out);
/* Release a handle. Do not pass a null pointer. */
typedef void
(*k5_tls_free_handle_fn)(krb5_context context, k5_tls_handle handle);
/* All functions are mandatory unless they are all null, in which case the
* caller should assume that TLS is unsupported. */
typedef struct k5_tls_vtable_st {
k5_tls_setup_fn setup;
k5_tls_write_fn write;
k5_tls_read_fn read;
k5_tls_free_handle_fn free_handle;
} *k5_tls_vtable;
#endif /* K5_TLS_H */
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