mod_asterisk_ami: Add ability to associate Softmodem sessions.

Using a new AMI command added to the Softmodem application, we can
query the Asterisk server to determine the identity of the caller
associated with the modem session - in particular, the Caller ID
Number and Name. This is possible because we can use the TCP port
to associate the session with a channel on the Asterisk server.
We can determine if an incoming TCP connection did, in fact, originate
from the Asterisk server, and if so, what the Caller ID is.

This allows us to extract caller information from the BBS, similar to
how an application running on a PC with a modem connected to it would
be able to get Caller ID from the incoming call prior to answering.
This association has to be done manually in this sort of way since
the TCP connection itself doesn't contain any of this information.

The end result is a new API that allows BBS applications to simply
query a node for the associated Caller ID.

Author: InterLinked1

include/mod_asterisk_ami.h

@@ -23,7 +23,7 @@
  *
  * This can be NULL for the default connection.
  *
- * Currently, only connection is supported so this argument
+ * Currently, only one connection is supported so this argument
  * is ignored, but if in the future multiple sessions
  * were supported (see [LBBS-111]), then it would be used. */
 
@@ -36,6 +36,21 @@ int bbs_ami_action_redirect(const char *session, const char *channel, const char
 #define bbs_ami_action_axfer(sess, chan, exten, context) bbs_ami_action(sess, "Atxfer", "Channel:%s\r\nExten:%s\r\nContext:%s", chan, exten, context)
 #define bbs_ami_action_cancel_axfer(sess, chan) bbs_ami_action(sess, "CancelAtxfer", "Channel:%s", chan)
 
+/* Forward declaration for modules that don't need to include <cami/cami.h> */
+struct ami_event;
+
+/*!
+ * \brief Get Caller ID information for the caller associated with an incoming softmodem call via TCP
+ * \param node
+ * \param[out] numberbuf Buffer for Caller ID number. May be empty.
+ * \param num_len Length of numberbuf. Should be at least 16.
+ * \param[out] namebuf Buffer for Caller ID name. May be empty.
+ * \param num_len Length of namebuf. Should be at least 16.
+ * \retval 0 on success (successfully retrieved a session with associated Caller ID information)
+ * \retval -1 No Softmodem session corresponds with this TCP connection
+ */
+int bbs_ami_softmodem_get_callerid(struct bbs_node *node, char *numberbuf, size_t num_len, char *namebuf, size_t name_len);
+
 int __bbs_ami_callback_register(int (*callback)(struct ami_event *event, const char *eventname), void *mod);
 
 /*!

modules/mod_asterisk_ami.c

@@ -40,6 +40,8 @@
 #include "include/alertpipe.h"
 #include "include/linkedlists.h"
 #include "include/cli.h"
+#include "include/node.h"
+#include "include/utils.h"
 
 #include "include/mod_asterisk_ami.h"
 
@@ -162,6 +164,58 @@ int bbs_ami_action_redirect(const char *session, const char *channel, const char
 	return res;
 }
 
+int bbs_ami_softmodem_get_callerid(struct bbs_node *node, char *numberbuf, size_t num_len, char *namebuf, size_t name_len)
+{
+	int i;
+	const char *number = NULL, *name = NULL;
+	struct ami_response *resp;
+
+	*numberbuf = '\0';
+	*namebuf = '\0';
+
+	/*
+	 * The sender is not sent as part of the payload itself via TCP.
+	 * We need to query the phone system for the caller's number/name.
+	 * If the Asterisk softmodem is being used, we need to figure this out from Asterisk.
+	 *
+	 * We can correlate the sessions because on our end, we know the TCP port number on the client side,
+	 * as opened by the Softmodem application. The Softmodem application can therefore save this
+	 * information on the channel, and we can look for a channel that has the correct port number saved.
+	 *
+	 * If we cannot determine the caller information, the application can reject the connection.
+	 * In that sense, it also functions as a partial security check, since it requires the connecting port
+	 * to be used by the softmodem (though the IP address itself is not checked here).
+	 */
+	resp = bbs_ami_action(NULL, "SoftmodemSessions", "Port:%u", node->rport);
+	if (!resp || !resp->success) {
+		bbs_warning("Failed to get caller info\n");
+		if (resp) {
+			ami_resp_free(resp);
+		}
+		return -1;
+	}
+
+	/* Since we applied a filter for only port node->rport, we'll only get back one session, at most */
+	for (i = 1; i < resp->size - 1; i++) {
+		struct ami_event *e = resp->events[i];
+		const char *event = ami_keyvalue(e, "Event");
+		if (!strcmp(event, "SoftmodemSession")) {
+			number = ami_keyvalue(e, "CallerIDNumber");
+			name = ami_keyvalue(e, "CallerIDName");
+			break;
+		}
+	}
+	bbs_debug(5, "Softmodem caller: %s (%s)\n", S_IF(number), S_IF(name));
+	if (strlen_zero(number)) {
+		safe_strncpy(numberbuf, number, num_len);
+	}
+	if (!strlen_zero(name)) {
+		safe_strncpy(namebuf, name, name_len);
+	}
+	ami_resp_free(resp);
+	return 0;
+}
+
 static void set_ami_status(int up)
 {
 	asterisk_up = up;