dso.h

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/* dso.h -*- mode:C; c-file-style: "eay" -*- */
/* Written by Geoff Thorpe ([email protected]) for the OpenSSL
 * project 2000.
 */
/* ====================================================================
 * Copyright (c) 2000 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
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 */

#ifndef HEADER_DSO_H
#define HEADER_DSO_H

#include <openssl/crypto.h>

#ifdef __cplusplus
extern "C" {
#endif

/* These values are used as commands to DSO_ctrl() */
#define DSO_CTRL_GET_FLAGS  1
#define DSO_CTRL_SET_FLAGS  2
#define DSO_CTRL_OR_FLAGS   3

/* By default, DSO_load() will translate the provided filename into a form
 * typical for the platform (more specifically the DSO_METHOD) using the
 * dso_name_converter function of the method. Eg. win32 will transform "blah"
 * into "blah.dll", and dlfcn will transform it into "libblah.so". The
 * behaviour can be overriden by setting the name_converter callback in the DSO
 * object (using DSO_set_name_converter()). This callback could even utilise
 * the DSO_METHOD's converter too if it only wants to override behaviour for
 * one or two possible DSO methods. However, the following flag can be set in a
 * DSO to prevent *any* native name-translation at all - eg. if the caller has
 * prompted the user for a path to a driver library so the filename should be
 * interpreted as-is. */
#define DSO_FLAG_NO_NAME_TRANSLATION        0x01
/* An extra flag to give if only the extension should be added as
 * translation.  This is obviously only of importance on Unix and
 * other operating systems where the translation also may prefix
 * the name with something, like 'lib', and ignored everywhere else.
 * This flag is also ignored if DSO_FLAG_NO_NAME_TRANSLATION is used
 * at the same time. */
#define DSO_FLAG_NAME_TRANSLATION_EXT_ONLY  0x02

/* The following flag controls the translation of symbol names to upper
 * case.  This is currently only being implemented for OpenVMS.
 */
#define DSO_FLAG_UPCASE_SYMBOL          0x10

/* This flag loads the library with public symbols.
 * Meaning: The exported symbols of this library are public
 * to all libraries loaded after this library.
 * At the moment only implemented in unix.
 */
#define DSO_FLAG_GLOBAL_SYMBOLS         0x20


typedef void (*DSO_FUNC_TYPE)(void);

typedef struct dso_st DSO;

/* The function prototype used for method functions (or caller-provided
 * callbacks) that transform filenames. They are passed a DSO structure pointer
 * (or NULL if they are to be used independantly of a DSO object) and a
 * filename to transform. They should either return NULL (if there is an error
 * condition) or a newly allocated string containing the transformed form that
 * the caller will need to free with OPENSSL_free() when done. */
typedef char* (*DSO_NAME_CONVERTER_FUNC)(DSO *, const char *);
/* The function prototype used for method functions (or caller-provided
 * callbacks) that merge two file specifications. They are passed a
 * DSO structure pointer (or NULL if they are to be used independantly of
 * a DSO object) and two file specifications to merge. They should
 * either return NULL (if there is an error condition) or a newly allocated
 * string containing the result of merging that the caller will need
 * to free with OPENSSL_free() when done.
 * Here, merging means that bits and pieces are taken from each of the
 * file specifications and added together in whatever fashion that is
 * sensible for the DSO method in question.  The only rule that really
 * applies is that if the two specification contain pieces of the same
 * type, the copy from the first string takes priority.  One could see
 * it as the first specification is the one given by the user and the
 * second being a bunch of defaults to add on if they're missing in the
 * first. */
typedef char* (*DSO_MERGER_FUNC)(DSO *, const char *, const char *);

typedef struct dso_meth_st
    {
    const char *name;
    /* Loads a shared library, NB: new DSO_METHODs must ensure that a
     * successful load populates the loaded_filename field, and likewise a
     * successful unload OPENSSL_frees and NULLs it out. */
    int (*dso_load)(DSO *dso);
    /* Unloads a shared library */
    int (*dso_unload)(DSO *dso);
    /* Binds a variable */
    void *(*dso_bind_var)(DSO *dso, const char *symname);
    /* Binds a function - assumes a return type of DSO_FUNC_TYPE.
     * This should be cast to the real function prototype by the
     * caller. Platforms that don't have compatible representations
     * for different prototypes (this is possible within ANSI C)
     * are highly unlikely to have shared libraries at all, let
     * alone a DSO_METHOD implemented for them. */
    DSO_FUNC_TYPE (*dso_bind_func)(DSO *dso, const char *symname);

/* I don't think this would actually be used in any circumstances. */
#if 0
    /* Unbinds a variable */
    int (*dso_unbind_var)(DSO *dso, char *symname, void *symptr);
    /* Unbinds a function */
    int (*dso_unbind_func)(DSO *dso, char *symname, DSO_FUNC_TYPE symptr);
#endif
    /* The generic (yuck) "ctrl()" function. NB: Negative return
     * values (rather than zero) indicate errors. */
    long (*dso_ctrl)(DSO *dso, int cmd, long larg, void *parg);
    /* The default DSO_METHOD-specific function for converting filenames to
     * a canonical native form. */
    DSO_NAME_CONVERTER_FUNC dso_name_converter;
    /* The default DSO_METHOD-specific function for converting filenames to
     * a canonical native form. */
    DSO_MERGER_FUNC dso_merger;

    /* [De]Initialisation handlers. */
    int (*init)(DSO *dso);
    int (*finish)(DSO *dso);

    /* Return pathname of the module containing location */
    int (*pathbyaddr)(void *addr,char *path,int sz);
    /* Perform global symbol lookup, i.e. among *all* modules */
    void *(*globallookup)(const char *symname);
    } DSO_METHOD;

/**********************************************************************/
/* The low-level handle type used to refer to a loaded shared library */

struct dso_st
    {
    DSO_METHOD *meth;
    /* Standard dlopen uses a (void *). Win32 uses a HANDLE. VMS
     * doesn't use anything but will need to cache the filename
     * for use in the dso_bind handler. All in all, let each
     * method control its own destiny. "Handles" and such go in
     * a STACK. */
    STACK_OF(void) *meth_data;
    int references;
    int flags;
    /* For use by applications etc ... use this for your bits'n'pieces,
     * don't touch meth_data! */
    CRYPTO_EX_DATA ex_data;
    /* If this callback function pointer is set to non-NULL, then it will
     * be used in DSO_load() in place of meth->dso_name_converter. NB: This
     * should normally set using DSO_set_name_converter(). */
    DSO_NAME_CONVERTER_FUNC name_converter;
    /* If this callback function pointer is set to non-NULL, then it will
     * be used in DSO_load() in place of meth->dso_merger. NB: This
     * should normally set using DSO_set_merger(). */
    DSO_MERGER_FUNC merger;
    /* This is populated with (a copy of) the platform-independant
     * filename used for this DSO. */
    char *filename;
    /* This is populated with (a copy of) the translated filename by which
     * the DSO was actually loaded. It is NULL iff the DSO is not currently
     * loaded. NB: This is here because the filename translation process
     * may involve a callback being invoked more than once not only to
     * convert to a platform-specific form, but also to try different
     * filenames in the process of trying to perform a load. As such, this
     * variable can be used to indicate (a) whether this DSO structure
     * corresponds to a loaded library or not, and (b) the filename with
     * which it was actually loaded. */
    char *loaded_filename;
    };


DSO *   DSO_new(void);
DSO *   DSO_new_method(DSO_METHOD *method);
int DSO_free(DSO *dso);
int DSO_flags(DSO *dso);
int DSO_up_ref(DSO *dso);
long    DSO_ctrl(DSO *dso, int cmd, long larg, void *parg);

/* This function sets the DSO's name_converter callback. If it is non-NULL,
 * then it will be used instead of the associated DSO_METHOD's function. If
 * oldcb is non-NULL then it is set to the function pointer value being
 * replaced. Return value is non-zero for success. */
int DSO_set_name_converter(DSO *dso, DSO_NAME_CONVERTER_FUNC cb,
                DSO_NAME_CONVERTER_FUNC *oldcb);
/* These functions can be used to get/set the platform-independant filename
 * used for a DSO. NB: set will fail if the DSO is already loaded. */
const char *DSO_get_filename(DSO *dso);
int DSO_set_filename(DSO *dso, const char *filename);
/* This function will invoke the DSO's name_converter callback to translate a
 * filename, or if the callback isn't set it will instead use the DSO_METHOD's
 * converter. If "filename" is NULL, the "filename" in the DSO itself will be
 * used. If the DSO_FLAG_NO_NAME_TRANSLATION flag is set, then the filename is
 * simply duplicated. NB: This function is usually called from within a
 * DSO_METHOD during the processing of a DSO_load() call, and is exposed so that
 * caller-created DSO_METHODs can do the same thing. A non-NULL return value
 * will need to be OPENSSL_free()'d. */
char    *DSO_convert_filename(DSO *dso, const char *filename);
/* This function will invoke the DSO's merger callback to merge two file
 * specifications, or if the callback isn't set it will instead use the
 * DSO_METHOD's merger.  A non-NULL return value will need to be
 * OPENSSL_free()'d. */
char    *DSO_merge(DSO *dso, const char *filespec1, const char *filespec2);
/* If the DSO is currently loaded, this returns the filename that it was loaded
 * under, otherwise it returns NULL. So it is also useful as a test as to
 * whether the DSO is currently loaded. NB: This will not necessarily return
 * the same value as DSO_convert_filename(dso, dso->filename), because the
 * DSO_METHOD's load function may have tried a variety of filenames (with
 * and/or without the aid of the converters) before settling on the one it
 * actually loaded. */
const char *DSO_get_loaded_filename(DSO *dso);

void    DSO_set_default_method(DSO_METHOD *meth);
DSO_METHOD *DSO_get_default_method(void);
DSO_METHOD *DSO_get_method(DSO *dso);
DSO_METHOD *DSO_set_method(DSO *dso, DSO_METHOD *meth);

/* The all-singing all-dancing load function, you normally pass NULL
 * for the first and third parameters. Use DSO_up and DSO_free for
 * subsequent reference count handling. Any flags passed in will be set
 * in the constructed DSO after its init() function but before the
 * load operation. If 'dso' is non-NULL, 'flags' is ignored. */
DSO *DSO_load(DSO *dso, const char *filename, DSO_METHOD *meth, int flags);

/* This function binds to a variable inside a shared library. */
void *DSO_bind_var(DSO *dso, const char *symname);

/* This function binds to a function inside a shared library. */
DSO_FUNC_TYPE DSO_bind_func(DSO *dso, const char *symname);

/* This method is the default, but will beg, borrow, or steal whatever
 * method should be the default on any particular platform (including
 * DSO_METH_null() if necessary). */
DSO_METHOD *DSO_METHOD_openssl(void);

/* This method is defined for all platforms - if a platform has no
 * DSO support then this will be the only method! */
DSO_METHOD *DSO_METHOD_null(void);

/* If DSO_DLFCN is defined, the standard dlfcn.h-style functions
 * (dlopen, dlclose, dlsym, etc) will be used and incorporated into
 * this method. If not, this method will return NULL. */
DSO_METHOD *DSO_METHOD_dlfcn(void);

/* If DSO_DL is defined, the standard dl.h-style functions (shl_load, 
 * shl_unload, shl_findsym, etc) will be used and incorporated into
 * this method. If not, this method will return NULL. */
DSO_METHOD *DSO_METHOD_dl(void);

/* If WIN32 is defined, use DLLs. If not, return NULL. */
DSO_METHOD *DSO_METHOD_win32(void);

/* If VMS is defined, use shared images. If not, return NULL. */
DSO_METHOD *DSO_METHOD_vms(void);

/* This function writes null-terminated pathname of DSO module
 * containing 'addr' into 'sz' large caller-provided 'path' and
 * returns the number of characters [including trailing zero]
 * written to it. If 'sz' is 0 or negative, 'path' is ignored and
 * required amount of charachers [including trailing zero] to
 * accomodate pathname is returned. If 'addr' is NULL, then
 * pathname of cryptolib itself is returned. Negative or zero
 * return value denotes error.
 */
int DSO_pathbyaddr(void *addr,char *path,int sz);

/* This function should be used with caution! It looks up symbols in
 * *all* loaded modules and if module gets unloaded by somebody else
 * attempt to dereference the pointer is doomed to have fatal
 * consequences. Primary usage for this function is to probe *core*
 * system functionality, e.g. check if getnameinfo(3) is available
 * at run-time without bothering about OS-specific details such as
 * libc.so.versioning or where does it actually reside: in libc
 * itself or libsocket. */
void *DSO_global_lookup(const char *name);

/* If BeOS is defined, use shared images. If not, return NULL. */
DSO_METHOD *DSO_METHOD_beos(void);

/* BEGIN ERROR CODES */
/* The following lines are auto generated by the script mkerr.pl. Any changes
 * made after this point may be overwritten when the script is next run.
 */
void ERR_load_DSO_strings(void);

/* Error codes for the DSO functions. */

/* Function codes. */
#define DSO_F_BEOS_BIND_FUNC                 144
#define DSO_F_BEOS_BIND_VAR              145
#define DSO_F_BEOS_LOAD                  146
#define DSO_F_BEOS_NAME_CONVERTER            147
#define DSO_F_BEOS_UNLOAD                148
#define DSO_F_DLFCN_BIND_FUNC                100
#define DSO_F_DLFCN_BIND_VAR                 101
#define DSO_F_DLFCN_LOAD                 102
#define DSO_F_DLFCN_MERGER               130
#define DSO_F_DLFCN_NAME_CONVERTER           123
#define DSO_F_DLFCN_UNLOAD               103
#define DSO_F_DL_BIND_FUNC               104
#define DSO_F_DL_BIND_VAR                105
#define DSO_F_DL_LOAD                    106
#define DSO_F_DL_MERGER                  131
#define DSO_F_DL_NAME_CONVERTER              124
#define DSO_F_DL_UNLOAD                  107
#define DSO_F_DSO_BIND_FUNC              108
#define DSO_F_DSO_BIND_VAR               109
#define DSO_F_DSO_CONVERT_FILENAME           126
#define DSO_F_DSO_CTRL                   110
#define DSO_F_DSO_FREE                   111
#define DSO_F_DSO_GET_FILENAME               127
#define DSO_F_DSO_GET_LOADED_FILENAME            128
#define DSO_F_DSO_GLOBAL_LOOKUP              139
#define DSO_F_DSO_LOAD                   112
#define DSO_F_DSO_MERGE                  132
#define DSO_F_DSO_NEW_METHOD                 113
#define DSO_F_DSO_PATHBYADDR                 140
#define DSO_F_DSO_SET_FILENAME               129
#define DSO_F_DSO_SET_NAME_CONVERTER             122
#define DSO_F_DSO_UP_REF                 114
#define DSO_F_GLOBAL_LOOKUP_FUNC             138
#define DSO_F_PATHBYADDR                 137
#define DSO_F_VMS_BIND_SYM               115
#define DSO_F_VMS_LOAD                   116
#define DSO_F_VMS_MERGER                 133
#define DSO_F_VMS_UNLOAD                 117
#define DSO_F_WIN32_BIND_FUNC                118
#define DSO_F_WIN32_BIND_VAR                 119
#define DSO_F_WIN32_GLOBALLOOKUP             142
#define DSO_F_WIN32_GLOBALLOOKUP_FUNC            143
#define DSO_F_WIN32_JOINER               135
#define DSO_F_WIN32_LOAD                 120
#define DSO_F_WIN32_MERGER               134
#define DSO_F_WIN32_NAME_CONVERTER           125
#define DSO_F_WIN32_PATHBYADDR               141
#define DSO_F_WIN32_SPLITTER                 136
#define DSO_F_WIN32_UNLOAD               121

/* Reason codes. */
#define DSO_R_CTRL_FAILED                100
#define DSO_R_DSO_ALREADY_LOADED             110
#define DSO_R_EMPTY_FILE_STRUCTURE           113
#define DSO_R_FAILURE                    114
#define DSO_R_FILENAME_TOO_BIG               101
#define DSO_R_FINISH_FAILED              102
#define DSO_R_INCORRECT_FILE_SYNTAX          115
#define DSO_R_LOAD_FAILED                103
#define DSO_R_NAME_TRANSLATION_FAILED            109
#define DSO_R_NO_FILENAME                111
#define DSO_R_NO_FILE_SPECIFICATION          116
#define DSO_R_NULL_HANDLE                104
#define DSO_R_SET_FILENAME_FAILED            112
#define DSO_R_STACK_ERROR                105
#define DSO_R_SYM_FAILURE                106
#define DSO_R_UNLOAD_FAILED              107
#define DSO_R_UNSUPPORTED                108

#ifdef  __cplusplus
}
#endif
#endif