Sat Nov 1 06:28:33 2008

Asterisk developer's documentation

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func_odbc.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (c) 2005, 2006 Tilghman Lesher
 *
 * Tilghman Lesher <func_odbc__200508@the-tilghman.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.
 */

/*!
 * \file
 *
 * \brief ODBC lookups
 *
 * \author Tilghman Lesher <func_odbc__200508@the-tilghman.com>
 */

/*** MODULEINFO
   <depend>unixodbc</depend>
   <depend>ltdl</depend>
   <depend>res_odbc</depend>
 ***/

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 146799 $")

#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#include "asterisk/module.h"
#include "asterisk/file.h"
#include "asterisk/logger.h"
#include "asterisk/options.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/module.h"
#include "asterisk/config.h"
#include "asterisk/res_odbc.h"
#include "asterisk/app.h"

static char *config = "func_odbc.conf";

enum {
   OPT_ESCAPECOMMAS =   (1 << 0),
} odbc_option_flags;

struct acf_odbc_query {
   AST_LIST_ENTRY(acf_odbc_query) list;
   char dsn[30];
   char sql_read[2048];
   char sql_write[2048];
   unsigned int flags;
   struct ast_custom_function *acf;
};

AST_LIST_HEAD_STATIC(queries, acf_odbc_query);

static SQLHSTMT generic_prepare(struct odbc_obj *obj, void *data)
{
   int res;
   char *sql = data;
   SQLHSTMT stmt;

   res = SQLAllocHandle (SQL_HANDLE_STMT, obj->con, &stmt);
   if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
      ast_log(LOG_WARNING, "SQL Alloc Handle failed!\n");
      return NULL;
   }

   res = SQLPrepare(stmt, (unsigned char *)sql, SQL_NTS);
   if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
      ast_log(LOG_WARNING, "SQL Prepare failed![%s]\n", sql);
      SQLCloseCursor(stmt);
      SQLFreeHandle (SQL_HANDLE_STMT, stmt);
      return NULL;
   }

   return stmt;
}

/*
 * Master control routine
 */
static int acf_odbc_write(struct ast_channel *chan, char *cmd, char *s, const char *value)
{
   struct odbc_obj *obj;
   struct acf_odbc_query *query;
   char *t, buf[2048]="", varname[15];
   int i, bogus_chan = 0;
   AST_DECLARE_APP_ARGS(values,
      AST_APP_ARG(field)[100];
   );
   AST_DECLARE_APP_ARGS(args,
      AST_APP_ARG(field)[100];
   );
   SQLHSTMT stmt;
   SQLLEN rows=0;

   AST_LIST_LOCK(&queries);
   AST_LIST_TRAVERSE(&queries, query, list) {
      if (!strcmp(query->acf->name, cmd)) {
         break;
      }
   }

   if (!query) {
      ast_log(LOG_ERROR, "No such function '%s'\n", cmd);
      AST_LIST_UNLOCK(&queries);
      return -1;
   }

   obj = ast_odbc_request_obj(query->dsn, 0);

   if (!obj) {
      ast_log(LOG_ERROR, "No database handle available with the name of '%s' (check res_odbc.conf)\n", query->dsn);
      AST_LIST_UNLOCK(&queries);
      return -1;
   }

   if (!chan) {
      if ((chan = ast_channel_alloc(0, 0, "", "", "", "", "", 0, "Bogus/func_odbc")))
         bogus_chan = 1;
   }

   if (chan)
      ast_autoservice_start(chan);

   /* Parse our arguments */
   t = value ? ast_strdupa(value) : "";

   if (!s || !t) {
      ast_log(LOG_ERROR, "Out of memory\n");
      AST_LIST_UNLOCK(&queries);
      if (chan)
         ast_autoservice_stop(chan);
      if (bogus_chan)
         ast_channel_free(chan);
      return -1;
   }

   AST_STANDARD_APP_ARGS(args, s);
   for (i = 0; i < args.argc; i++) {
      snprintf(varname, sizeof(varname), "ARG%d", i + 1);
      pbx_builtin_pushvar_helper(chan, varname, args.field[i]);
   }

   /* Parse values, just like arguments */
   /* Can't use the pipe, because app Set removes them */
   AST_NONSTANDARD_APP_ARGS(values, t, ',');
   for (i = 0; i < values.argc; i++) {
      snprintf(varname, sizeof(varname), "VAL%d", i + 1);
      pbx_builtin_pushvar_helper(chan, varname, values.field[i]);
   }

   /* Additionally set the value as a whole (but push an empty string if value is NULL) */
   pbx_builtin_pushvar_helper(chan, "VALUE", value ? value : "");

   pbx_substitute_variables_helper(chan, query->sql_write, buf, sizeof(buf) - 1);

   /* Restore prior values */
   for (i = 0; i < args.argc; i++) {
      snprintf(varname, sizeof(varname), "ARG%d", i + 1);
      pbx_builtin_setvar_helper(chan, varname, NULL);
   }

   for (i = 0; i < values.argc; i++) {
      snprintf(varname, sizeof(varname), "VAL%d", i + 1);
      pbx_builtin_setvar_helper(chan, varname, NULL);
   }
   pbx_builtin_setvar_helper(chan, "VALUE", NULL);

   AST_LIST_UNLOCK(&queries);

   stmt = ast_odbc_prepare_and_execute(obj, generic_prepare, buf);

   if (stmt) {
      /* Rows affected */
      SQLRowCount(stmt, &rows);
   }

   /* Output the affected rows, for all cases.  In the event of failure, we
    * flag this as -1 rows.  Note that this is different from 0 affected rows
    * which would be the case if we succeeded in our query, but the values did
    * not change. */
   snprintf(varname, sizeof(varname), "%d", (int)rows);
   pbx_builtin_setvar_helper(chan, "ODBCROWS", varname);

   if (stmt) {
      SQLCloseCursor(stmt);
      SQLFreeHandle(SQL_HANDLE_STMT, stmt);
   }
   if (obj)
      ast_odbc_release_obj(obj);

   if (chan)
      ast_autoservice_stop(chan);
   if (bogus_chan)
      ast_channel_free(chan);

   return 0;
}

static int acf_odbc_read(struct ast_channel *chan, char *cmd, char *s, char *buf, size_t len)
{
   struct odbc_obj *obj;
   struct acf_odbc_query *query;
   char sql[2048] = "", varname[15];
   int res, x, buflen = 1, escapecommas, bogus_chan = 0;
   AST_DECLARE_APP_ARGS(args,
      AST_APP_ARG(field)[100];
   );
   SQLHSTMT stmt;
   SQLSMALLINT colcount=0;
   SQLLEN indicator;

   AST_LIST_LOCK(&queries);
   AST_LIST_TRAVERSE(&queries, query, list) {
      if (!strcmp(query->acf->name, cmd)) {
         break;
      }
   }

   if (!query) {
      ast_log(LOG_ERROR, "No such function '%s'\n", cmd);
      AST_LIST_UNLOCK(&queries);
      return -1;
   }

   obj = ast_odbc_request_obj(query->dsn, 0);

   if (!obj) {
      ast_log(LOG_ERROR, "No such DSN registered (or out of connections): %s (check res_odbc.conf)\n", query->dsn);
      AST_LIST_UNLOCK(&queries);
      return -1;
   }

   if (!chan) {
      if ((chan = ast_channel_alloc(0, 0, "", "", "", "", "", 0, "Bogus/func_odbc")))
         bogus_chan = 1;
   }

   if (chan)
      ast_autoservice_start(chan);

   AST_STANDARD_APP_ARGS(args, s);
   for (x = 0; x < args.argc; x++) {
      snprintf(varname, sizeof(varname), "ARG%d", x + 1);
      pbx_builtin_pushvar_helper(chan, varname, args.field[x]);
   }

   pbx_substitute_variables_helper(chan, query->sql_read, sql, sizeof(sql) - 1);

   /* Restore prior values */
   for (x = 0; x < args.argc; x++) {
      snprintf(varname, sizeof(varname), "ARG%d", x + 1);
      pbx_builtin_setvar_helper(chan, varname, NULL);
   }

   /* Save this flag, so we can release the lock */
   escapecommas = ast_test_flag(query, OPT_ESCAPECOMMAS);

   AST_LIST_UNLOCK(&queries);

   stmt = ast_odbc_prepare_and_execute(obj, generic_prepare, sql);

   if (!stmt) {
      ast_odbc_release_obj(obj);
      if (chan)
         ast_autoservice_stop(chan);
      if (bogus_chan)
         ast_channel_free(chan);
      return -1;
   }

   res = SQLNumResultCols(stmt, &colcount);
   if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
      ast_log(LOG_WARNING, "SQL Column Count error!\n[%s]\n\n", sql);
      SQLCloseCursor(stmt);
      SQLFreeHandle (SQL_HANDLE_STMT, stmt);
      ast_odbc_release_obj(obj);
      if (chan)
         ast_autoservice_stop(chan);
      if (bogus_chan)
         ast_channel_free(chan);
      return -1;
   }

   *buf = '\0';

   res = SQLFetch(stmt);
   if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
      int res1 = -1;
      if (res == SQL_NO_DATA) {
         if (option_verbose > 3) {
            ast_verbose(VERBOSE_PREFIX_4 "Found no rows [%s]\n", sql);
         }
         res1 = 0;
      } else if (option_verbose > 3) {
         ast_log(LOG_WARNING, "Error %d in FETCH [%s]\n", res, sql);
      }
      SQLCloseCursor(stmt);
      SQLFreeHandle(SQL_HANDLE_STMT, stmt);
      ast_odbc_release_obj(obj);
      if (chan)
         ast_autoservice_stop(chan);
      if (bogus_chan)
         ast_channel_free(chan);
      return res1;
   }

   for (x = 0; x < colcount; x++) {
      int i;
      char coldata[256];

      buflen = strlen(buf);
      res = SQLGetData(stmt, x + 1, SQL_CHAR, coldata, sizeof(coldata), &indicator);
      if (indicator == SQL_NULL_DATA) {
         coldata[0] = '\0';
         res = SQL_SUCCESS;
      }

      if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
         ast_log(LOG_WARNING, "SQL Get Data error!\n[%s]\n\n", sql);
         SQLCloseCursor(stmt);
         SQLFreeHandle(SQL_HANDLE_STMT, stmt);
         ast_odbc_release_obj(obj);
         if (chan)
            ast_autoservice_stop(chan);
         if (bogus_chan)
            ast_channel_free(chan);
         return -1;
      }

      /* Copy data, encoding '\' and ',' for the argument parser */
      for (i = 0; i < sizeof(coldata); i++) {
         if (escapecommas && (coldata[i] == '\\' || coldata[i] == ',')) {
            buf[buflen++] = '\\';
         }
         buf[buflen++] = coldata[i];

         if (buflen >= len - 2)
            break;

         if (coldata[i] == '\0')
            break;
      }

      buf[buflen - 1] = ',';
      buf[buflen] = '\0';
   }
   /* Trim trailing comma */
   buf[buflen - 1] = '\0';

   SQLCloseCursor(stmt);
   SQLFreeHandle(SQL_HANDLE_STMT, stmt);
   ast_odbc_release_obj(obj);
   if (chan)
      ast_autoservice_stop(chan);
   if (bogus_chan)
      ast_channel_free(chan);
   return 0;
}

static int acf_escape(struct ast_channel *chan, char *cmd, char *data, char *buf, size_t len)
{
   char *out = buf;

   for (; *data && out - buf < len; data++) {
      if (*data == '\'') {
         *out = '\'';
         out++;
      }
      *out++ = *data;
   }
   *out = '\0';

   return 0;
}

static struct ast_custom_function escape_function = {
   .name = "SQL_ESC",
   .synopsis = "Escapes single ticks for use in SQL statements",
   .syntax = "SQL_ESC(<string>)",
   .desc =
"Used in SQL templates to escape data which may contain single ticks (') which\n"
"are otherwise used to delimit data.  For example:\n"
"SELECT foo FROM bar WHERE baz='${SQL_ESC(${ARG1})}'\n",
   .read = acf_escape,
   .write = NULL,
};

static int init_acf_query(struct ast_config *cfg, char *catg, struct acf_odbc_query **query)
{
   const char *tmp;

   if (!cfg || !catg) {
      return -1;
   }

   *query = ast_calloc(1, sizeof(struct acf_odbc_query));
   if (! (*query))
      return -1;

   if ((tmp = ast_variable_retrieve(cfg, catg, "dsn"))) {
      ast_copy_string((*query)->dsn, tmp, sizeof((*query)->dsn));
   } else if ((tmp = ast_variable_retrieve(cfg, catg, "writehandle")) || (tmp = ast_variable_retrieve(cfg, catg, "readhandle"))) {
      ast_log(LOG_WARNING, "Separate read and write handles are not supported in this version of func_odbc.so\n");
      ast_copy_string((*query)->dsn, tmp, sizeof((*query)->dsn));
   } else {
      free(*query);
      *query = NULL;
      ast_log(LOG_ERROR, "No database handle was specified for func_odbc class '%s'\n", catg);
      return -1;
   }

   if ((tmp = ast_variable_retrieve(cfg, catg, "read")) || (tmp = ast_variable_retrieve(cfg, catg, "readsql"))) {
      ast_copy_string((*query)->sql_read, tmp, sizeof((*query)->sql_read));
   }

   if ((tmp = ast_variable_retrieve(cfg, catg, "write")) || (tmp = ast_variable_retrieve(cfg, catg, "writesql"))) {
      ast_copy_string((*query)->sql_write, tmp, sizeof((*query)->sql_write));
   }

   /* Allow escaping of embedded commas in fields to be turned off */
   ast_set_flag((*query), OPT_ESCAPECOMMAS);
   if ((tmp = ast_variable_retrieve(cfg, catg, "escapecommas"))) {
      if (ast_false(tmp))
         ast_clear_flag((*query), OPT_ESCAPECOMMAS);
   }

   (*query)->acf = ast_calloc(1, sizeof(struct ast_custom_function));
   if (! (*query)->acf) {
      free(*query);
      *query = NULL;
      return -1;
   }

   if ((tmp = ast_variable_retrieve(cfg, catg, "prefix")) && !ast_strlen_zero(tmp)) {
      asprintf((char **)&((*query)->acf->name), "%s_%s", tmp, catg);
   } else {
      asprintf((char **)&((*query)->acf->name), "ODBC_%s", catg);
   }

   if (!((*query)->acf->name)) {
      free((*query)->acf);
      free(*query);
      *query = NULL;
      return -1;
   }

   asprintf((char **)&((*query)->acf->syntax), "%s(<arg1>[...[,<argN>]])", (*query)->acf->name);

   if (!((*query)->acf->syntax)) {
      free((char *)(*query)->acf->name);
      free((*query)->acf);
      free(*query);
      *query = NULL;
      return -1;
   }

   (*query)->acf->synopsis = "Runs the referenced query with the specified arguments";
   if (!ast_strlen_zero((*query)->sql_read) && !ast_strlen_zero((*query)->sql_write)) {
      asprintf((char **)&((*query)->acf->desc),
               "Runs the following query, as defined in func_odbc.conf, performing\n"
                  "substitution of the arguments into the query as specified by ${ARG1},\n"
               "${ARG2}, ... ${ARGn}.  When setting the function, the values are provided\n"
               "either in whole as ${VALUE} or parsed as ${VAL1}, ${VAL2}, ... ${VALn}.\n"
               "\nRead:\n%s\n\nWrite:\n%s\n",
               (*query)->sql_read,
               (*query)->sql_write);
   } else if (!ast_strlen_zero((*query)->sql_read)) {
      asprintf((char **)&((*query)->acf->desc),
               "Runs the following query, as defined in func_odbc.conf, performing\n"
                  "substitution of the arguments into the query as specified by ${ARG1},\n"
               "${ARG2}, ... ${ARGn}.  This function may only be read, not set.\n\nSQL:\n%s\n",
               (*query)->sql_read);
   } else if (!ast_strlen_zero((*query)->sql_write)) {
      asprintf((char **)&((*query)->acf->desc),
               "Runs the following query, as defined in func_odbc.conf, performing\n"
                  "substitution of the arguments into the query as specified by ${ARG1},\n"
               "${ARG2}, ... ${ARGn}.  The values are provided either in whole as\n"
               "${VALUE} or parsed as ${VAL1}, ${VAL2}, ... ${VALn}.\n"
               "This function may only be set.\nSQL:\n%s\n",
               (*query)->sql_write);
   } else {
      ast_log(LOG_ERROR, "No SQL was found for func_odbc class '%s'\n", catg);
   }

   /* Could be out of memory, or could be we have neither sql_read nor sql_write */
   if (! ((*query)->acf->desc)) {
      free((char *)(*query)->acf->syntax);
      free((char *)(*query)->acf->name);
      free((*query)->acf);
      free(*query);
      *query = NULL;
      return -1;
   }

   if (ast_strlen_zero((*query)->sql_read)) {
      (*query)->acf->read = NULL;
   } else {
      (*query)->acf->read = acf_odbc_read;
   }

   if (ast_strlen_zero((*query)->sql_write)) {
      (*query)->acf->write = NULL;
   } else {
      (*query)->acf->write = acf_odbc_write;
   }

   return 0;
}

static int free_acf_query(struct acf_odbc_query *query)
{
   if (query) {
      if (query->acf) {
         if (query->acf->name)
            free((char *)query->acf->name);
         if (query->acf->syntax)
            free((char *)query->acf->syntax);
         if (query->acf->desc)
            free((char *)query->acf->desc);
         free(query->acf);
      }
      free(query);
   }
   return 0;
}

static int odbc_load_module(void)
{
   int res = 0;
   struct ast_config *cfg;
   char *catg;

   AST_LIST_LOCK(&queries);

   cfg = ast_config_load(config);
   if (!cfg) {
      ast_log(LOG_NOTICE, "Unable to load config for func_odbc: %s\n", config);
      AST_LIST_UNLOCK(&queries);
      return AST_MODULE_LOAD_DECLINE;
   }

   for (catg = ast_category_browse(cfg, NULL);
        catg;
        catg = ast_category_browse(cfg, catg)) {
      struct acf_odbc_query *query = NULL;

      if (init_acf_query(cfg, catg, &query)) {
         free_acf_query(query);
      } else {
         AST_LIST_INSERT_HEAD(&queries, query, list);
         ast_custom_function_register(query->acf);
      }
   }

   ast_config_destroy(cfg);
   ast_custom_function_register(&escape_function);

   AST_LIST_UNLOCK(&queries);
   return res;
}

static int odbc_unload_module(void)
{
   struct acf_odbc_query *query;

   AST_LIST_LOCK(&queries);
   while (!AST_LIST_EMPTY(&queries)) {
      query = AST_LIST_REMOVE_HEAD(&queries, list);
      ast_custom_function_unregister(query->acf);
      free_acf_query(query);
   }

   ast_custom_function_unregister(&escape_function);

   /* Allow any threads waiting for this lock to pass (avoids a race) */
   AST_LIST_UNLOCK(&queries);
   AST_LIST_LOCK(&queries);

   AST_LIST_UNLOCK(&queries);
   return 0;
}

static int reload(void)
{
   int res = 0;
   struct ast_config *cfg;
   struct acf_odbc_query *oldquery;
   char *catg;

   AST_LIST_LOCK(&queries);

   while (!AST_LIST_EMPTY(&queries)) {
      oldquery = AST_LIST_REMOVE_HEAD(&queries, list);
      ast_custom_function_unregister(oldquery->acf);
      free_acf_query(oldquery);
   }

   cfg = ast_config_load(config);
   if (!cfg) {
      ast_log(LOG_WARNING, "Unable to load config for func_odbc: %s\n", config);
      goto reload_out;
   }

   for (catg = ast_category_browse(cfg, NULL);
        catg;
        catg = ast_category_browse(cfg, catg)) {
      struct acf_odbc_query *query = NULL;

      if (init_acf_query(cfg, catg, &query)) {
         ast_log(LOG_ERROR, "Cannot initialize query %s\n", catg);
      } else {
         AST_LIST_INSERT_HEAD(&queries, query, list);
         ast_custom_function_register(query->acf);
      }
   }

   ast_config_destroy(cfg);
reload_out:
   AST_LIST_UNLOCK(&queries);
   return res;
}

static int unload_module(void)
{
   return odbc_unload_module();
}

static int load_module(void)
{
   return odbc_load_module();
}

/* XXX need to revise usecount - set if query_lock is set */

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "ODBC lookups",
      .load = load_module,
      .unload = unload_module,
      .reload = reload,
          );

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