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| 1 | +/* |
| 2 | + * Asterisk -- An open source telephony toolkit. |
| 3 | + * |
| 4 | + * Copyright (C) 2021, Naveen Albert |
| 5 | + * |
| 6 | + * See http://www.asterisk.org for more information about |
| 7 | + * the Asterisk project. Please do not directly contact |
| 8 | + * any of the maintainers of this project for assistance; |
| 9 | + * the project provides a web site, mailing lists and IRC |
| 10 | + * channels for your use. |
| 11 | + * |
| 12 | + * This program is free software, distributed under the terms of |
| 13 | + * the GNU General Public License Version 2. See the LICENSE file |
| 14 | + * at the top of the source tree. |
| 15 | + */ |
| 16 | + |
| 17 | +/*! \file |
| 18 | + * |
| 19 | + * \brief Dialplan extension evaluation function |
| 20 | + * |
| 21 | + * \author Naveen Albert <asterisk@phreaknet.org> |
| 22 | + * |
| 23 | + * \ingroup functions |
| 24 | + */ |
| 25 | + |
| 26 | +/*** MODULEINFO |
| 27 | + <support_level>extended</support_level> |
| 28 | + ***/ |
| 29 | + |
| 30 | +#include "asterisk.h" |
| 31 | + |
| 32 | +#include "asterisk/module.h" |
| 33 | +#include "asterisk/channel.h" |
| 34 | +#include "asterisk/pbx.h" |
| 35 | +#include "asterisk/utils.h" |
| 36 | +#include "asterisk/app.h" |
| 37 | + |
| 38 | +/*** DOCUMENTATION |
| 39 | + <function name="EVAL_EXTEN" language="en_US"> |
| 40 | + <synopsis> |
| 41 | + Evaluates the contents of a dialplan extension and returns it as a string. |
| 42 | + </synopsis> |
| 43 | + <syntax> |
| 44 | + <parameter name="context" /> |
| 45 | + <parameter name="extensions" /> |
| 46 | + <parameter name="priority" required="true" /> |
| 47 | + </syntax> |
| 48 | + <description> |
| 49 | + <para>The EVAL_EXTEN function looks up a dialplan entry by context,extension,priority, |
| 50 | + evaluates the contents of a Return statement to resolve any variable or function |
| 51 | + references, and returns the result as a string.</para> |
| 52 | + <para>You can use this function to create simple user-defined lookup tables or |
| 53 | + user-defined functions.</para> |
| 54 | + <example title="Custom dialplan functions"> |
| 55 | + [call-types] |
| 56 | + exten => _1NNN,1,Return(internal) |
| 57 | + exten => _NXXNXXXXXX,1,Return(external) |
| 58 | +
|
| 59 | + [udf] |
| 60 | + exten => calleridlen,1,Return(${LEN(${CALLERID(num)})}) |
| 61 | +
|
| 62 | + [default] |
| 63 | + exten => _X!,1,Verbose(Call type ${EVAL_EXTEN(call-types,${EXTEN},1)} - ${EVAL_EXTEN(udf,calleridlen,1)}) |
| 64 | + </example> |
| 65 | + <para>Any variables in the evaluated data will be resolved in the context of |
| 66 | + that extension. For example, <literal>${EXTEN}</literal> would refer to the |
| 67 | + EVAL_EXTEN extension, not the extension in the context invoking the function. |
| 68 | + This behavior is similar to other applications, e.g. <literal>Gosub</literal>.</para> |
| 69 | + <example title="Choosing which prompt to use"> |
| 70 | + same => n,Read(input,${EVAL_EXTEN(prompts,${CALLERID(num)},1)}) |
| 71 | +
|
| 72 | + [prompts] |
| 73 | + exten => _X!,1,Return(default) |
| 74 | + exten => _20X,1,Return(welcome) |
| 75 | + exten => _2XX,1,Return(${DB(promptsettings/${EXTEN})}) |
| 76 | + exten => _3XX,1,Return(${ODBC_MYFUNC(${EXTEN})}) |
| 77 | + </example> |
| 78 | + <para>Extensions on which EVAL_EXTEN is invoked are not different from other |
| 79 | + extensions. However, the application at that extension is not executed. |
| 80 | + Only the application data is parsed and evaluated.</para> |
| 81 | + <para>A limitation of this function is that the application at the specified |
| 82 | + extension isn't actually executed, and thus unlike a Gosub, you can't pass |
| 83 | + arguments in the EVAL_EXTEN function.</para> |
| 84 | + </description> |
| 85 | + <see-also> |
| 86 | + <ref type="function">EVAL</ref> |
| 87 | + </see-also> |
| 88 | + </function> |
| 89 | + ***/ |
| 90 | + |
| 91 | +static int eval_exten_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len) |
| 92 | +{ |
| 93 | + char *exten, *pri, *context, *parse; |
| 94 | + int ipri; |
| 95 | + char tmpbuf[len]; |
| 96 | + |
| 97 | + if (ast_strlen_zero(data)) { |
| 98 | + ast_log(LOG_WARNING, "The EVAL_EXTEN function requires an extension\n"); |
| 99 | + return -1; |
| 100 | + } |
| 101 | + |
| 102 | + parse = ast_strdupa(data); |
| 103 | + /* Split context,exten,pri */ |
| 104 | + context = strsep(&parse, ","); |
| 105 | + exten = strsep(&parse, ","); |
| 106 | + pri = strsep(&parse, ","); |
| 107 | + |
| 108 | + if (pbx_parse_location(chan, &context, &exten, &pri, &ipri, NULL, NULL)) { |
| 109 | + return -1; |
| 110 | + } |
| 111 | + |
| 112 | + if (ast_strlen_zero(exten) || ast_strlen_zero(context)) { /* only lock if we really need to */ |
| 113 | + ast_channel_lock(chan); |
| 114 | + if (ast_strlen_zero(exten)) { |
| 115 | + exten = ast_strdupa(ast_channel_exten(chan)); |
| 116 | + } |
| 117 | + if (ast_strlen_zero(context)) { |
| 118 | + context = ast_strdupa(ast_channel_context(chan)); |
| 119 | + } |
| 120 | + ast_channel_unlock(chan); |
| 121 | + } |
| 122 | + |
| 123 | + if (ast_get_extension_data(tmpbuf, len, chan, context, exten, ipri)) { |
| 124 | + return -1; /* EVAL_EXTEN failed */ |
| 125 | + } |
| 126 | + |
| 127 | + pbx_substitute_variables_helper_full_location(chan, (chan) ? ast_channel_varshead(chan) : NULL, tmpbuf, buf, len, NULL, context, exten, ipri); |
| 128 | + |
| 129 | + return 0; |
| 130 | +} |
| 131 | + |
| 132 | +static struct ast_custom_function eval_exten_function = { |
| 133 | + .name = "EVAL_EXTEN", |
| 134 | + .read = eval_exten_read, |
| 135 | +}; |
| 136 | + |
| 137 | +static int unload_module(void) |
| 138 | +{ |
| 139 | + return ast_custom_function_unregister(&eval_exten_function); |
| 140 | +} |
| 141 | + |
| 142 | +static int load_module(void) |
| 143 | +{ |
| 144 | + return ast_custom_function_register(&eval_exten_function); |
| 145 | +} |
| 146 | + |
| 147 | +AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "Extension evaluation function"); |
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