res_odbc_transaction.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2016, Digium, Inc.
 *
 * Mark Michelson <mmichelson@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */
 
#include "asterisk.h"
 
#include "asterisk/res_odbc.h"
#include "asterisk/res_odbc_transaction.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/app.h"
#include "asterisk/module.h"
 
/*** MODULEINFO
    <depend>generic_odbc</depend>
    <support_level>core</support_level>
 ***/
 
/*** DOCUMENTATION
    <function name="ODBC" language="en_US">
        <synopsis>
            Controls ODBC transaction properties.
        </synopsis>
        <syntax>
            <parameter name="property" required="true">
                <enumlist>
                    <enum name="transaction">
                        <para>Gets or sets the active transaction ID.  If set, and the transaction ID does not
                        exist and a <replaceable>database name</replaceable> is specified as an argument, it will be created.</para>
                    </enum>
                    <enum name="forcecommit">
                        <para>Controls whether a transaction will be automatically committed when the channel
                        hangs up.  Defaults to forcecommit value from the relevant DSN (which defaults to false).
                        If a <replaceable>transaction ID</replaceable> is specified in the optional argument,
                        the property will be applied to that ID, otherwise to the current active ID.</para>
                    </enum>
                    <enum name="isolation">
                        <para>Controls the data isolation on uncommitted transactions.  May be one of the
                        following: <literal>read_committed</literal>, <literal>read_uncommitted</literal>,
                        <literal>repeatable_read</literal>, or <literal>serializable</literal>.  Defaults to the
                        database setting in <filename>res_odbc.conf</filename> or <literal>read_committed</literal>
                        if not specified.  If a <replaceable>transaction ID</replaceable> is specified as an optional argument, it will be
                        applied to that ID, otherwise the current active ID.</para>
                    </enum>
                </enumlist>
            </parameter>
            <parameter name="argument" required="false" />
        </syntax>
        <description>
            <para>The ODBC() function allows setting several properties to influence how a connected
            database processes transactions.</para>
        </description>
    </function>
    <application name="ODBC_Commit" language="en_US">
        <synopsis>
            Commits a currently open database transaction.
        </synopsis>
        <syntax>
            <parameter name="transaction ID" required="no" />
        </syntax>
        <description>
            <para>Commits the database transaction specified by <replaceable>transaction ID</replaceable>
            or the current active transaction, if not specified.</para>
        </description>
    </application>
    <application name="ODBC_Rollback" language="en_US">
        <synopsis>
            Rollback a currently open database transaction.
        </synopsis>
        <syntax>
            <parameter name="transaction ID" required="no" />
        </syntax>
        <description>
            <para>Rolls back the database transaction specified by <replaceable>transaction ID</replaceable>
            or the current active transaction, if not specified.</para>
        </description>
    </application>
 ***/
 
struct odbc_txn_frame {
    AST_LIST_ENTRY(odbc_txn_frame) list;
    struct odbc_obj *obj;        /*!< Database handle within which transacted statements are run */
    /*!\brief Is this record the current active transaction within the channel?
     * Note that the active flag is really only necessary for statements which
     * are triggered from the dialplan, as there isn't a direct correlation
     * between multiple statements.  Applications wishing to use transactions
     * may simply perform each statement on the same odbc_obj, which keeps the
     * transaction persistent.
     */
    unsigned int active:1;
    unsigned int forcecommit:1;     /*!< Should uncommitted transactions be auto-committed on handle release? */
    unsigned int isolation;         /*!< Flags for how the DB should deal with data in other, uncommitted transactions */
    char name[0];                   /*!< Name of this transaction ID */
};
 
static struct odbc_txn_frame *release_transaction(struct odbc_txn_frame *tx);
 
static void odbc_txn_free(void *vdata)
{
    struct odbc_txn_frame *tx;
    AST_LIST_HEAD(, odbc_txn_frame) *oldlist = vdata;
 
    ast_debug(2, "odbc_txn_free(%p) called\n", vdata);
 
    AST_LIST_LOCK(oldlist);
    while ((tx = AST_LIST_REMOVE_HEAD(oldlist, list))) {
        release_transaction(tx);
    }
    AST_LIST_UNLOCK(oldlist);
    AST_LIST_HEAD_DESTROY(oldlist);
    ast_free(oldlist);
}
 
static const struct ast_datastore_info txn_info = {
    .type = "ODBC_Transaction",
    .destroy = odbc_txn_free,
};
 
static struct odbc_txn_frame *create_transaction(struct ast_channel *chan, const char *name, const char *dsn)
{
    struct ast_datastore *txn_store;
    AST_LIST_HEAD(, odbc_txn_frame) *oldlist;
    struct odbc_txn_frame *txn = NULL;
    struct odbc_txn_frame *otxn;
 
    if (ast_strlen_zero(dsn)) {
        return NULL;
    }
 
    ast_channel_lock(chan);
    if ((txn_store = ast_channel_datastore_find(chan, &txn_info, NULL))) {
        oldlist = txn_store->data;
    } else {
        if (!(txn_store = ast_datastore_alloc(&txn_info, NULL))) {
            ast_log(LOG_ERROR, "Unable to allocate a new datastore.  Cannot create a new transaction.\n");
            ast_channel_unlock(chan);
            return NULL;
        }
 
        if (!(oldlist = ast_calloc(1, sizeof(*oldlist)))) {
            ast_log(LOG_ERROR, "Unable to allocate datastore list head.  Cannot create a new transaction.\n");
            ast_datastore_free(txn_store);
            ast_channel_unlock(chan);
            return NULL;
        }
 
        txn_store->data = oldlist;
        AST_LIST_HEAD_INIT(oldlist);
        ast_channel_datastore_add(chan, txn_store);
    }
    ast_channel_unlock(chan);
 
    txn = ast_calloc(1, sizeof(*txn) + strlen(name) + 1);
    if (!txn) {
        return NULL;
    }
 
    strcpy(txn->name, name); /* SAFE */
    txn->obj = ast_odbc_request_obj(dsn, 0);
    if (!txn->obj) {
        ast_free(txn);
        return NULL;
    }
    txn->isolation = ast_odbc_class_get_isolation(txn->obj->parent);
    txn->forcecommit = ast_odbc_class_get_forcecommit(txn->obj->parent);
    txn->active = 1;
 
    if (SQLSetConnectAttr(txn->obj->con, SQL_ATTR_AUTOCOMMIT, (void *)SQL_AUTOCOMMIT_OFF, 0) == SQL_ERROR) {
        ast_odbc_print_errors(SQL_HANDLE_DBC, txn->obj->con, "SetConnectAttr (Autocommit)");
        ast_odbc_release_obj(txn->obj);
        ast_free(txn);
        return NULL;
    }
 
    /* Set the isolation property */
    if (SQLSetConnectAttr(txn->obj->con, SQL_ATTR_TXN_ISOLATION, (void *)(long)txn->isolation, 0) == SQL_ERROR) {
        ast_odbc_print_errors(SQL_HANDLE_DBC, txn->obj->con, "SetConnectAttr");
        ast_odbc_release_obj(txn->obj);
        ast_free(txn);
        return NULL;
    }
 
    /* On creation, the txn becomes active, and all others inactive */
    AST_LIST_LOCK(oldlist);
    AST_LIST_TRAVERSE(oldlist, otxn, list) {
        otxn->active = 0;
    }
    AST_LIST_INSERT_TAIL(oldlist, txn, list);
    AST_LIST_UNLOCK(oldlist);
 
    return txn;
}
 
static struct odbc_txn_frame *find_transaction(struct ast_channel *chan, const char *name, int active)
{
    struct ast_datastore *txn_store;
    AST_LIST_HEAD(, odbc_txn_frame) *oldlist;
    struct odbc_txn_frame *txn = NULL;
 
    if (!chan || (!active && !name)) {
        return NULL;
    }
 
    ast_channel_lock(chan);
    txn_store = ast_channel_datastore_find(chan, &txn_info, NULL);
    ast_channel_unlock(chan);
 
    if (!txn_store) {
        /* No datastore? Definitely no transaction then */
        return NULL;
    }
 
    oldlist = txn_store->data;
    AST_LIST_LOCK(oldlist);
 
    AST_LIST_TRAVERSE(oldlist, txn, list) {
        if (active) {
            if (txn->active) {
                break;
            }
        } else if (!strcasecmp(txn->name, name)) {
            break;
        }
    }
    AST_LIST_UNLOCK(oldlist);
 
    return txn;
}
 
static struct odbc_txn_frame *release_transaction(struct odbc_txn_frame *tx)
{
    if (!tx) {
        return NULL;
    }
 
    ast_debug(2, "release_transaction(%p) called (tx->obj = %p\n", tx, tx->obj);
 
    ast_debug(1, "called on a transactional handle with %s\n", tx->forcecommit ? "COMMIT" : "ROLLBACK");
    if (SQLEndTran(SQL_HANDLE_DBC, tx->obj->con, tx->forcecommit ? SQL_COMMIT : SQL_ROLLBACK) == SQL_ERROR) {
        ast_odbc_print_errors(SQL_HANDLE_DBC, tx->obj->con, "SQLEndTran");
    }
 
    /* Transaction is done, reset autocommit
     *
     * XXX I'm unsure if this is actually necessary, since we're releasing
     * the connection back to unixODBC. However, if unixODBC pooling is enabled,
     * it can't hurt to do just in case.
     */
    if (SQLSetConnectAttr(tx->obj->con, SQL_ATTR_AUTOCOMMIT, (void *)SQL_AUTOCOMMIT_ON, 0) == SQL_ERROR) {
        ast_odbc_print_errors(SQL_HANDLE_DBC, tx->obj->con, "SQLSetAttr");
    }
 
    ast_odbc_release_obj(tx->obj);
    ast_free(tx);
    return NULL;
}
 
static int commit_exec(struct ast_channel *chan, const char *data)
{
    struct odbc_txn_frame *tx;
 
    if (ast_strlen_zero(data)) {
        tx = find_transaction(chan, NULL, 1);
    } else {
        tx = find_transaction(chan, data, 0);
    }
 
    /* XXX COMMIT_RESULT is set to OK even if no transaction was found. Very misleading */
    pbx_builtin_setvar_helper(chan, "COMMIT_RESULT", "OK");
 
    if (tx) {
        if (SQLEndTran(SQL_HANDLE_DBC, tx->obj->con, SQL_COMMIT) == SQL_ERROR) {
            struct ast_str *errors = ast_odbc_print_errors(SQL_HANDLE_DBC, tx->obj->con, "SQLEndTran");
            pbx_builtin_setvar_helper(chan, "COMMIT_RESULT", ast_str_buffer(errors));
        }
    }
    return 0;
}
 
static int rollback_exec(struct ast_channel *chan, const char *data)
{
    struct odbc_txn_frame *tx;
 
    if (ast_strlen_zero(data)) {
        tx = find_transaction(chan, NULL, 1);
    } else {
        tx = find_transaction(chan, data, 0);
    }
 
    /* XXX ROLLBACK_RESULT is set to OK even if no transaction was found. Very misleading */
    pbx_builtin_setvar_helper(chan, "ROLLBACK_RESULT", "OK");
 
    if (tx) {
        if (SQLEndTran(SQL_HANDLE_DBC, tx->obj->con, SQL_ROLLBACK) == SQL_ERROR) {
            struct ast_str *errors = ast_odbc_print_errors(SQL_HANDLE_DBC, tx->obj->con, "SQLEndTran");
            pbx_builtin_setvar_helper(chan, "ROLLBACK_RESULT", ast_str_buffer(errors));
        }
    }
    return 0;
}
 
static int acf_transaction_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
    AST_DECLARE_APP_ARGS(args,
        AST_APP_ARG(property);
        AST_APP_ARG(opt);
    );
    struct odbc_txn_frame *tx;
 
    AST_STANDARD_APP_ARGS(args, data);
    if (strcasecmp(args.property, "transaction") == 0) {
        if ((tx = find_transaction(chan, NULL, 1))) {
            ast_copy_string(buf, tx->name, len);
            return 0;
        }
    } else if (strcasecmp(args.property, "isolation") == 0) {
        if (!ast_strlen_zero(args.opt)) {
            tx = find_transaction(chan, args.opt, 0);
        } else {
            tx = find_transaction(chan, NULL, 1);
        }
        if (tx) {
            ast_copy_string(buf, ast_odbc_isolation2text(tx->isolation), len);
            return 0;
        }
    } else if (strcasecmp(args.property, "forcecommit") == 0) {
        if (!ast_strlen_zero(args.opt)) {
            tx = find_transaction(chan, args.opt, 0);
        } else {
            tx = find_transaction(chan, NULL, 1);
        }
        if (tx) {
            ast_copy_string(buf, tx->forcecommit ? "1" : "0", len);
            return 0;
        }
    }
    return -1;
}
 
/* XXX The idea of "active" transactions is silly and makes things
 * more prone to error. It would be much better if the transaction
 * always had to be specified by name so that no implicit behavior
 * occurred.
 */
static int mark_transaction_active(struct ast_channel *chan, struct odbc_txn_frame *tx)
{
    struct ast_datastore *txn_store;
    AST_LIST_HEAD(, odbc_txn_frame) *oldlist;
    struct odbc_txn_frame *active = NULL, *txn;
 
    if (!chan) {
        return -1;
    }
 
    ast_channel_lock(chan);
    if (!(txn_store = ast_channel_datastore_find(chan, &txn_info, NULL))) {
        ast_channel_unlock(chan);
        return -1;
    }
 
    oldlist = txn_store->data;
    AST_LIST_LOCK(oldlist);
    AST_LIST_TRAVERSE(oldlist, txn, list) {
        if (txn == tx) {
            txn->active = 1;
            active = txn;
        } else {
            txn->active = 0;
        }
    }
    AST_LIST_UNLOCK(oldlist);
    ast_channel_unlock(chan);
    return active ? 0 : -1;
}
 
static int acf_transaction_write(struct ast_channel *chan, const char *cmd, char *s, const char *value)
{
    AST_DECLARE_APP_ARGS(args,
        AST_APP_ARG(property);
        AST_APP_ARG(opt);
    );
    struct odbc_txn_frame *tx;
 
    AST_STANDARD_APP_ARGS(args, s);
    if (strcasecmp(args.property, "transaction") == 0) {
        /* Set active transaction */
        if ((tx = find_transaction(chan, value, 0))) {
            mark_transaction_active(chan, tx);
        } else if (!create_transaction(chan, value, args.opt)) {
            pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "FAILED_TO_CREATE");
            return -1;
        }
        pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "OK");
        return 0;
    } else if (strcasecmp(args.property, "forcecommit") == 0) {
        /* Set what happens when an uncommitted transaction ends without explicit Commit or Rollback */
        if (ast_strlen_zero(args.opt)) {
            tx = find_transaction(chan, NULL, 1);
        } else {
            tx = find_transaction(chan, args.opt, 0);
        }
        if (!tx) {
            pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "FAILED_TO_CREATE");
            return -1;
        }
        if (ast_true(value)) {
            tx->forcecommit = 1;
        } else if (ast_false(value)) {
            tx->forcecommit = 0;
        } else {
            ast_log(LOG_ERROR, "Invalid value for forcecommit: '%s'\n", S_OR(value, ""));
            pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "INVALID_VALUE");
            return -1;
        }
 
        pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "OK");
        return 0;
    } else if (strcasecmp(args.property, "isolation") == 0) {
        /* How do uncommitted transactions affect reads? */
        /* XXX This is completely useless. The problem is that setting the isolation here
         * does not actually alter the connection. The only time the isolation gets set is
         * when the transaction is created. The only way to set isolation is to set it on
         * the ODBC class's configuration in res_odbc.conf.
         */
        int isolation = ast_odbc_text2isolation(value);
        if (ast_strlen_zero(args.opt)) {
            tx = find_transaction(chan, NULL, 1);
        } else {
            tx = find_transaction(chan, args.opt, 0);
        }
        if (!tx) {
            pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "FAILED_TO_CREATE");
            return -1;
        }
        if (isolation == 0) {
            pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "INVALID_VALUE");
            ast_log(LOG_ERROR, "Invalid isolation specification: '%s'\n", S_OR(value, ""));
        } else if (SQLSetConnectAttr(tx->obj->con, SQL_ATTR_TXN_ISOLATION, (void *)(long)isolation, 0) == SQL_ERROR) {
            pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "SQL_ERROR");
            ast_odbc_print_errors(SQL_HANDLE_DBC, tx->obj->con, "SetConnectAttr (Txn isolation)");
        } else {
            pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "OK");
            tx->isolation = isolation;
        }
        return 0;
    } else {
        ast_log(LOG_ERROR, "Unknown property: '%s'\n", args.property);
        return -1;
    }
}
 
struct odbc_obj *ast_odbc_retrieve_transaction_obj(struct ast_channel *chan, const char *objname)
{
    struct ast_datastore *txn_store;
    AST_LIST_HEAD(, odbc_txn_frame) *oldlist;
    struct odbc_txn_frame *txn = NULL;
 
    if (!chan || !objname) {
        /* No channel == no transaction */
        return NULL;
    }
 
    ast_channel_lock(chan);
    if ((txn_store = ast_channel_datastore_find(chan, &txn_info, NULL))) {
        oldlist = txn_store->data;
    } else {
        ast_channel_unlock(chan);
        return NULL;
    }
 
    AST_LIST_LOCK(oldlist);
    ast_channel_unlock(chan);
 
    AST_LIST_TRAVERSE(oldlist, txn, list) {
        if (txn->obj && txn->obj->parent && !strcmp(ast_odbc_class_get_name(txn->obj->parent), objname)) {
            AST_LIST_UNLOCK(oldlist);
            return txn->obj;
        }
    }
    AST_LIST_UNLOCK(oldlist);
    return NULL;
}
 
static struct ast_custom_function odbc_function = {
    .name = "ODBC",
    .read = acf_transaction_read,
    .write = acf_transaction_write,
};
 
static const char * const app_commit = "ODBC_Commit";
static const char * const app_rollback = "ODBC_Rollback";
 
/* XXX res_odbc takes the path of disallowing unloads from happening.
 * It's not a great precedent, but since trying to deal with unloading the module
 * while transactions are active seems like a huge pain to deal with, we'll go
 * the same way here.
 */
static int unload_module(void)
{
    return -1;
}
 
static int load_module(void)
{
    ast_register_application_xml(app_commit, commit_exec);
    ast_register_application_xml(app_rollback, rollback_exec);
    ast_custom_function_register(&odbc_function);
    return 0;
}
 
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "ODBC transaction resource",
    .support_level = AST_MODULE_SUPPORT_CORE,
    .load = load_module,
    .unload = unload_module,
    .load_pri = AST_MODPRI_REALTIME_DEPEND,
);