1 /* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */ 2 /* include/k5-tls.h - internal pluggable interface for TLS */ 3 /* 4 * Copyright (C) 2014 by the Massachusetts Institute of Technology. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * * Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 14 * * Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in 16 * the documentation and/or other materials provided with the 17 * distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 22 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 23 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 24 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 25 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 26 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 28 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 30 * OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 * This internal pluggable interface allows libkrb5 to load an in-tree module 35 * providing TLS support at runtime. It is currently tailored for the needs of 36 * the OpenSSL module as used for HTTP proxy support. As an internal 37 * interface, it can be changed to fit different implementations and consumers 38 * without regard for backward compatibility. 39 */ 40 41 #ifndef K5_TLS_H 42 #define K5_TLS_H 43 44 #include "k5-int.h" 45 46 /* An abstract type for localauth module data. */ 47 typedef struct k5_tls_handle_st *k5_tls_handle; 48 49 typedef enum { 50 DATA_READ, DONE, WANT_READ, WANT_WRITE, ERROR_TLS 51 } k5_tls_status; 52 53 /* 54 * Create a handle for fd, where the server certificate must match servername 55 * and be trusted according to anchors. anchors is a null-terminated list 56 * using the DIR:/FILE:/ENV: syntax borrowed from PKINIT. If anchors is null, 57 * use the system default trust anchors. 58 */ 59 typedef krb5_error_code 60 (*k5_tls_setup_fn)(krb5_context context, SOCKET fd, const char *servername, 61 char **anchors, k5_tls_handle *handle_out); 62 63 /* 64 * Write len bytes of data using TLS. Return DONE if writing is complete, 65 * WANT_READ or WANT_WRITE if the underlying socket must be readable or 66 * writable to continue, and ERROR_TLS if the TLS channel or underlying socket 67 * experienced an error. After WANT_READ or WANT_WRITE, the operation will be 68 * retried with the same arguments even if some data has already been written. 69 * (OpenSSL makes this contract easy to fulfill. For other implementations we 70 * might want to change it.) 71 */ 72 typedef k5_tls_status 73 (*k5_tls_write_fn)(krb5_context context, k5_tls_handle handle, 74 const void *data, size_t len); 75 76 /* 77 * Read up to data_size bytes of data using TLS. Return DATA_READ and set 78 * *len_out if any data is read. Return DONE if there is no more data to be 79 * read on the connection, WANT_READ or WANT_WRITE if the underlying socket 80 * must be readable or writable to continue, and ERROR_TLS if the TLS channel 81 * or underlying socket experienced an error. 82 * 83 * After DATA_READ, there may still be pending buffered data to read. The 84 * caller must call this method again with additional buffer space before 85 * selecting for reading on the underlying socket. 86 */ 87 typedef k5_tls_status 88 (*k5_tls_read_fn)(krb5_context context, k5_tls_handle handle, void *data, 89 size_t data_size, size_t *len_out); 90 91 /* Release a handle. Do not pass a null pointer. */ 92 typedef void 93 (*k5_tls_free_handle_fn)(krb5_context context, k5_tls_handle handle); 94 95 /* All functions are mandatory unless they are all null, in which case the 96 * caller should assume that TLS is unsupported. */ 97 typedef struct k5_tls_vtable_st { 98 k5_tls_setup_fn setup; 99 k5_tls_write_fn write; 100 k5_tls_read_fn read; 101 k5_tls_free_handle_fn free_handle; 102 } *k5_tls_vtable; 103 104 #endif /* K5_TLS_H */ 105