autochan.h File Reference

"smart" channels that update automatically if a channel is masqueraded More...

#include "asterisk.h"
#include "asterisk/linkedlists.h"

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Data Structures

struct  ast_autochan


void ast_autochan_destroy (struct ast_autochan *autochan)
 destroy an ast_autochan structure
void ast_autochan_new_channel (struct ast_channel *old_chan, struct ast_channel *new_chan)
 Switch what channel autochans point to.
struct ast_autochanast_autochan_setup (struct ast_channel *chan)
 set up a new ast_autochan structure

Detailed Description

"smart" channels that update automatically if a channel is masqueraded

Mark Michelson <>

Definition in file autochan.h.

Function Documentation

void ast_autochan_destroy ( struct ast_autochan autochan  ) 

destroy an ast_autochan structure

Removes the passed-in autochan from the list of autochans and unrefs the channel that is pointed to. Also frees the autochan struct itself. This function will unref the channel reference which was made in ast_autochan_setup

autochan The autochan that you wish to destroy
Return values:

Definition at line 63 of file autochan.c.

References ast_channel_autochans(), ast_channel_lock, ast_channel_unlock, ast_channel_unref, ast_debug, ast_free, AST_LIST_REMOVE_CURRENT, AST_LIST_TRAVERSE_SAFE_BEGIN, AST_LIST_TRAVERSE_SAFE_END, ast_autochan::chan, and ast_autochan::list.

Referenced by channel_spy(), common_exec(), launch_monitor_thread(), and mixmonitor_thread().

00064 {
00065    struct ast_autochan *autochan_iter;
00067    ast_channel_lock(autochan->chan);
00068    AST_LIST_TRAVERSE_SAFE_BEGIN(ast_channel_autochans(autochan->chan), autochan_iter, list) {
00069       if (autochan_iter == autochan) {
00070          AST_LIST_REMOVE_CURRENT(list);
00071          ast_debug(1, "Removed autochan %p from the list, about to free it\n", autochan);
00072          break;
00073       }
00074    }
00076    ast_channel_unlock(autochan->chan);
00078    autochan->chan = ast_channel_unref(autochan->chan);
00080    ast_free(autochan);
00081 }

void ast_autochan_new_channel ( struct ast_channel old_chan,
struct ast_channel new_chan 

Switch what channel autochans point to.

Traverses the list of autochans. All autochans which point to old_chan will be updated to point to new_chan instead. Currently this is only called during an ast_channel_move() operation in channel.c.

Both channels must be locked before calling this function.
old_chan The channel that autochans may currently point to
new_chan The channel that we want to point those autochans to now
Return values:

Definition at line 83 of file autochan.c.

References ast_channel_autochans(), ast_channel_name(), ast_channel_ref, ast_channel_unref, ast_debug, AST_LIST_APPEND_LIST, AST_LIST_TRAVERSE, ast_autochan::chan, and ast_autochan::list.

Referenced by channel_do_masquerade().

00084 {
00085    struct ast_autochan *autochan;
00087    AST_LIST_APPEND_LIST(ast_channel_autochans(new_chan), ast_channel_autochans(old_chan), list);
00089    AST_LIST_TRAVERSE(ast_channel_autochans(new_chan), autochan, list) {
00090       if (autochan->chan == old_chan) {
00091          autochan->chan = ast_channel_unref(old_chan);
00092          autochan->chan = ast_channel_ref(new_chan);
00094          ast_debug(1, "Autochan %p used to hold channel %s (%p) but now holds channel %s (%p)\n",
00095                autochan, ast_channel_name(old_chan), old_chan, ast_channel_name(new_chan), new_chan);
00096       }
00097    }
00098 }

struct ast_autochan* ast_autochan_setup ( struct ast_channel chan  )  [read]

set up a new ast_autochan structure

Just what the $!# is an autochan?
An ast_autochan is a structure which contains an ast_channel. The pointer inside an autochan has the ability to update itself if the channel it points to is masqueraded into a different channel.

This has a great benefit for any application or service which creates a thread outside of the channel's main operating thread which keeps a pointer to said channel. when a masquerade occurs on the channel, the autochan's chan pointer will automatically update to point to the new channel.

Some rules for autochans

1. If you are going to use an autochan, then be sure to always refer to the channel using the chan pointer inside the autochan if possible, since this is the pointer that will be updated during a masquerade.

2. If you are going to save off a pointer to the autochan's chan, then be sure to save off the pointer using ast_channel_ref and to unref the channel when you are finished with the pointer. If you do not do this and a masquerade occurs on the channel, then it is possible that your saved pointer will become invalid.

Allocates and initializes an ast_autochan, sets the autochan's chan pointer to point to the chan parameter, and adds the autochan to the global list of autochans. The newly- created autochan is returned to the caller. This function will cause the refcount of chan to increase by 1.

chan The channel our new autochan will point to
autochans must be freed using ast_autochan_destroy
Return values:
NULL Failure
non-NULL success

Definition at line 40 of file autochan.c.

References ast_calloc, ast_channel_autochans(), ast_channel_lock, ast_channel_name(), ast_channel_ref, ast_channel_unlock, ast_debug, AST_LIST_INSERT_TAIL, ast_autochan::chan, ast_autochan::list, and NULL.

Referenced by attach_barge(), common_exec(), launch_monitor_thread(), and next_channel().

00041 {
00042    struct ast_autochan *autochan;
00044    if (!chan) {
00045       return NULL;
00046    }
00048    if (!(autochan = ast_calloc(1, sizeof(*autochan)))) {
00049       return NULL;
00050    }
00052    autochan->chan = ast_channel_ref(chan);
00054    ast_channel_lock(autochan->chan);
00055    AST_LIST_INSERT_TAIL(ast_channel_autochans(autochan->chan), autochan, list);
00056    ast_channel_unlock(autochan->chan);
00058    ast_debug(1, "Created autochan %p to hold channel %s (%p)\n", autochan, ast_channel_name(chan), chan);
00060    return autochan;
00061 }

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