app_chanisavail.c: Simplify dialplan using ChanIsAvail.

Dialplan has to be careful about passing an empty device list or empty
positions in the list.  As a result, dialplan has to check for these
conditions before using ChanIsAvail.  Simplify dialplan by making
ChanIsAvail handle these conditions gracefully.

* Made tolerate empty positions in the device list.

* Simplified the code and eliminated some unnecessary indention.

ASTERISK-28638

Change-Id: I9e4b67e2cbf26b2417c2d03485b8568e898931d3

diff --git a/apps/app_chanisavail.c b/apps/app_chanisavail.c
index 1c7c1ec3bf79993f07c2bd2ac807b7439154ef47..c75bb792089fc1453793bd40581719e52e5d24a4 100644 (file)
--- a/apps/app_chanisavail.c
+++ b/apps/app_chanisavail.c
@@ -51,16 +51,18 @@ static const char app[] = "ChanIsAvail";
                        Check channel availability
                </synopsis>
                <syntax>
-                       <parameter name="Technology/Resource" required="true" argsep="&amp;">
+                       <parameter name="Technology/Resource" required="false" argsep="&amp;">
+                               <argument name="Technology/Resource" required="true">
+                                       <para>Specification of the device(s) to check.  These must be in the format of
+                                       <literal>Technology/Resource</literal>, where <replaceable>Technology</replaceable>
+                                       represents a particular channel driver, and <replaceable>Resource</replaceable>
+                                       represents a resource available to that particular channel driver.</para>
+                               </argument>
                                <argument name="Technology2/Resource2" multiple="true">
                                        <para>Optional extra devices to check</para>
                                        <para>If you need more than one enter them as
                                        Technology2/Resource2&amp;Technology3/Resource3&amp;.....</para>
                                </argument>
-                               <para>Specification of the device(s) to check.  These must be in the format of
-                               <literal>Technology/Resource</literal>, where <replaceable>Technology</replaceable>
-                               represents a particular channel driver, and <replaceable>Resource</replaceable>
-                               represents a resource available to that particular channel driver.</para>
                        </parameter>
                        <parameter name="options" required="false">
                                <optionlist>
@@ -99,25 +101,28 @@ static const char app[] = "ChanIsAvail";
 
 static int chanavail_exec(struct ast_channel *chan, const char *data)
 {
-       int inuse=-1, option_state=0, string_compare=0, option_all_avail=0;
+       int inuse = -1;
+       int option_state = 0;
+       int string_compare = 0;
+       int option_all_avail = 0;
        int status;
-       char *info, tmp[512], trychan[512], *peers, *tech, *number, *rest, *cur;
+       char *info;
+       char trychan[512];
+       char *rest;
+       char *tech;
+       char *number;
        struct ast_str *tmp_availchan = ast_str_alloca(2048);
        struct ast_str *tmp_availorig = ast_str_alloca(2048);
        struct ast_str *tmp_availstat = ast_str_alloca(2048);
        struct ast_str *tmp_availcause = ast_str_alloca(2048);
        struct ast_channel *tempchan;
+       struct ast_custom_function *cdr_prop_func = ast_custom_function_find("CDR_PROP");
        AST_DECLARE_APP_ARGS(args,
                AST_APP_ARG(reqchans);
                AST_APP_ARG(options);
        );
 
-       if (ast_strlen_zero(data)) {
-               ast_log(LOG_WARNING, "ChanIsAvail requires an argument (DAHDI/1&DAHDI/2)\n");
-               return -1;
-       }
-
-       info = ast_strdupa(data);
+       info = ast_strdupa(data ?: "");
 
        AST_STANDARD_APP_ARGS(args, info);
 
@@ -132,68 +137,68 @@ static int chanavail_exec(struct ast_channel *chan, const char *data)
                        string_compare = 1;
                }
        }
-       peers = args.reqchans;
-       if (peers) {
-               struct ast_custom_function *cdr_prop_func = ast_custom_function_find("CDR_PROP");
-
-               cur = peers;
-               do {
-                       /* remember where to start next time */
-                       rest = strchr(cur, '&');
-                       if (rest) {
-                               *rest = 0;
-                               rest++;
-                       }
-                       tech = cur;
-                       number = strchr(tech, '/');
-                       if (!number) {
-                               ast_log(LOG_WARNING, "ChanIsAvail argument takes format ([technology]/[device])\n");
-                               return -1;
-                       }
-                       *number = '\0';
-                       number++;
-
-                       status = AST_DEVICE_UNKNOWN;
 
-                       if (string_compare) {
-                               /* ast_parse_device_state checks for "SIP/1234" as a channel name.
-                                  ast_device_state will ask the SIP driver for the channel state. */
+       rest = args.reqchans;
+       if (!rest) {
+               rest = "";
+       }
+       while ((tech = strsep(&rest, "&"))) {
+               tech = ast_strip(tech);
+
+               number = strchr(tech, '/');
+               if (!number) {
+                       if (!ast_strlen_zero(tech)) {
+                               ast_log(LOG_WARNING, "Invalid ChanIsAvail technology/resource argument: '%s'\n",
+                                       tech);
+                       }
 
-                               snprintf(trychan, sizeof(trychan), "%s/%s",cur,number);
-                               status = inuse = ast_parse_device_state(trychan);
-                       } else if (option_state) {
-                               /* If the pbx says in use then don't bother trying further.
-                                  This is to permit testing if someone's on a call, even if the
-                                  channel can permit more calls (ie callwaiting, sip calls, etc).  */
+                       ast_str_append(&tmp_availstat, 0, "%s%d",
+                               ast_str_strlen(tmp_availstat) ? "&" : "", AST_DEVICE_INVALID);
+                       continue;
+               }
+               *number++ = '\0';
 
-                               snprintf(trychan, sizeof(trychan), "%s/%s",cur,number);
-                               status = inuse = ast_device_state(trychan);
-                       }
-                       snprintf(tmp, sizeof(tmp), "%d", status);
-                       ast_str_append(&tmp_availstat, 0, "%s%s", ast_str_strlen(tmp_availstat) ? "&" : "", tmp);
-                       if ((inuse <= 1) && (tempchan = ast_request(tech, ast_channel_nativeformats(chan), NULL, chan, number, &status))) {
-                                       ast_str_append(&tmp_availchan, 0, "%s%s", ast_str_strlen(tmp_availchan) ? "&" : "", ast_channel_name(tempchan));
+               status = AST_DEVICE_UNKNOWN;
 
-                                       snprintf(tmp, sizeof(tmp), "%s/%s", tech, number);
-                                       ast_str_append(&tmp_availorig, 0, "%s%s", ast_str_strlen(tmp_availorig) ? "&" : "", tmp);
+               if (string_compare) {
+                       /* ast_parse_device_state checks for "SIP/1234" as a channel name.
+                          ast_device_state will ask the SIP driver for the channel state. */
 
-                                       snprintf(tmp, sizeof(tmp), "%d", status);
-                                       ast_str_append(&tmp_availcause, 0, "%s%s", ast_str_strlen(tmp_availcause) ? "&" : "", tmp);
+                       snprintf(trychan, sizeof(trychan), "%s/%s", tech, number);
+                       status = inuse = ast_parse_device_state(trychan);
+               } else if (option_state) {
+                       /* If the pbx says in use then don't bother trying further.
+                          This is to permit testing if someone's on a call, even if the
+                          channel can permit more calls (ie callwaiting, sip calls, etc).  */
 
-                                       /* Disable CDR for this temporary channel. */
-                                       if (cdr_prop_func) {
-                                               ast_func_write(tempchan, "CDR_PROP(disable)", "1");
-                                       }
+                       snprintf(trychan, sizeof(trychan), "%s/%s", tech, number);
+                       status = inuse = ast_device_state(trychan);
+               }
+               ast_str_append(&tmp_availstat, 0, "%s%d",
+                       ast_str_strlen(tmp_availstat) ? "&" : "", status);
+               if ((inuse <= (int) AST_DEVICE_NOT_INUSE)
+                       && (tempchan = ast_request(tech, ast_channel_nativeformats(chan), NULL, chan, number, &status))) {
+                       ast_str_append(&tmp_availchan, 0, "%s%s",
+                               ast_str_strlen(tmp_availchan) ? "&" : "", ast_channel_name(tempchan));
+
+                       ast_str_append(&tmp_availorig, 0, "%s%s/%s",
+                               ast_str_strlen(tmp_availorig) ? "&" : "", tech, number);
+
+                       ast_str_append(&tmp_availcause, 0, "%s%d",
+                               ast_str_strlen(tmp_availcause) ? "&" : "", status);
+
+                       /* Disable CDR for this temporary channel. */
+                       if (cdr_prop_func) {
+                               ast_func_write(tempchan, "CDR_PROP(disable)", "1");
+                       }
 
-                                       ast_hangup(tempchan);
-                                       tempchan = NULL;
+                       ast_hangup(tempchan);
+                       tempchan = NULL;
 
-                                       if (!option_all_avail) {
-                                               break;
-                                       }
+                       if (!option_all_avail) {
+                               break;
                        }
-                       cur = rest;
-               } while (cur);
+               }
        }
 
        pbx_builtin_setvar_helper(chan, "AVAILCHAN", ast_str_buffer(tmp_availchan));

diff --git a/doc/CHANGES-staging/app_chanisavail_empty_device_list.txt b/doc/CHANGES-staging/app_chanisavail_empty_device_list.txt
new file mode 100644 (file)
index 0000000..bf06c31
--- /dev/null
+++ b/doc/CHANGES-staging/app_chanisavail_empty_device_list.txt
@@ -0,0 +1,5 @@
+Subject: app_chanisavail
+
+The ChanIsAvail application now tolerates empty positions in the supplied
+device list.  Dialplan can now be simplified by not having to check for
+empty positions in the device list.