HTTP_ASYNC_CLIENT Module

Federico Cabiddu

   <federico.cabiddu@gmail.com>

Giacomo Vacca

   <giacomo.vacca@gmail.com>

Camille Oudot

   Orange
   <camille.oudot@orange.com>

Edited by

Federico Cabiddu

   <federico.cabiddu@gmail.com>

   Copyright © 2016 Federico Cabiddu
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. workers (int)
              3.2. connection_timeout (str)
              3.3. hash_size (str)
              3.4. tls_version (int)
              3.5. tls_verify_host (int)
              3.6. tls_verify_peer (int)
              3.7. curl_verbose (int)
              3.8. memory_manager (string)
              3.9. tls_client_cert (int)
              3.10. tls_client_key (int)
              3.11. tls_ca_path (int)

        4. Functions

              4.1. http_async_query(url, [post_data], route_name)
              4.2. http_async_suspend(suspend)
              4.3. tls_verify_host(verify)
              4.4. tls_verify_peer(verify)
              4.5. http_set_timeout(timeout)
              4.6. http_append_header(header)
              4.7. http_set_method(method)
              4.8. http_set_tls_client_cert(path)
              4.9. http_set_tls_client_key(path)
              4.10. http_set_tls_ca_path(path)

        5. Pseudo Variables
        6. Statistics

              6.1. requests
              6.2. replies
              6.3. errors
              6.4. timeouts

   List of Examples

   1.1. Set workers parameter
   1.2. Set connection_timeout parameter
   1.3. Set hash_size parameter
   1.4. Set tls_version parameter
   1.5. Set tls_verify_host parameter
   1.6. Set tls_verify_peer parameter
   1.7. Set curl_verbose parameter
   1.8. Set memory_manager parameter
   1.9. Set tls_client_cert parameter
   1.10. Set tls_client_key parameter
   1.11. Set tls_ca_path parameter
   1.12. http_async_query() usage
   1.13. http_async_suspend() usage
   1.14. tls_verify_host() usage
   1.15. tls_verify_peer() usage
   1.16. http_set_timeout() usage
   1.17. http_append_header() usage
   1.18. http_set_method() usage
   1.19. http_set_tls_client_cert() usage
   1.20. http_set_tls_client_key() usage
   1.21. http_set_tls_ca_path() usage
   1.22. $http_req(key) variable usage

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications

   3. Parameters

        3.1. workers (int)
        3.2. connection_timeout (str)
        3.3. hash_size (str)
        3.4. tls_version (int)
        3.5. tls_verify_host (int)
        3.6. tls_verify_peer (int)
        3.7. curl_verbose (int)
        3.8. memory_manager (string)
        3.9. tls_client_cert (int)
        3.10. tls_client_key (int)
        3.11. tls_ca_path (int)

   4. Functions

        4.1. http_async_query(url, [post_data], route_name)
        4.2. http_async_suspend(suspend)
        4.3. tls_verify_host(verify)
        4.4. tls_verify_peer(verify)
        4.5. http_set_timeout(timeout)
        4.6. http_append_header(header)
        4.7. http_set_method(method)
        4.8. http_set_tls_client_cert(path)
        4.9. http_set_tls_client_key(path)
        4.10. http_set_tls_ca_path(path)

   5. Pseudo Variables
   6. Statistics

        6.1. requests
        6.2. replies
        6.3. errors
        6.4. timeouts

1. Overview

   This module performs asynchronous HTTP queries.

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications

2.1. Kamailio Modules

   The following modules must be loaded before this module:
     * tm - Transaction module
     * pv - Pseudo-Variables module

2.2. External Libraries or Applications

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * libcurl libev

3. Parameters

   3.1. workers (int)
   3.2. connection_timeout (str)
   3.3. hash_size (str)
   3.4. tls_version (int)
   3.5. tls_verify_host (int)
   3.6. tls_verify_peer (int)
   3.7. curl_verbose (int)
   3.8. memory_manager (string)
   3.9. tls_client_cert (int)
   3.10. tls_client_key (int)
   3.11. tls_ca_path (int)

3.1. workers (int)

   Number of worker processes to be started to send HTTP requests and
   asynchronously handle responses.

   Default value is 1.

   Example 1.1. Set workers parameter
...
modparam("http_async_client", "workers", 2)
...

3.2. connection_timeout (str)

   Defines in milliseconds how long Kamailio waits for response from HTTP
   server.

   Default value is 500ms.

   Example 1.2. Set connection_timeout parameter
...
modparam("http_async_client", "connection_timeout", 1000)
...

3.3. hash_size (str)

   The size of the hash table internally used to keep the requests. A
   larger table is much faster but consumes more memory. The hash size
   must be a power of two, otherwise it will be rounded down to the
   nearest power of two.

   Default value is 2048.

   Example 1.3. Set hash_size parameter
...
modparam("http_async_client", "hash_size", 1024)
...

3.4. tls_version (int)

   For HTTPS connections, what's the preferred SSL version.
   http://curl.haxx.se/libcurl/c/CURLOPT_SSLVERSION.html

   Default value is 0 (default SSL version).

   Example 1.4. Set tls_version parameter
...
modparam("http_async_client", "tls_version", 6)
...

3.5. tls_verify_host (int)

   For HTTPS connections, whether the client should verify the server
   host. http://curl.haxx.se/libcurl/c/CURLOPT_SSL_VERIFYHOST.html

   Default value is 2 (enabled).

   Example 1.5. Set tls_verify_host parameter
...
modparam("http_async_client", "tls_verify_host", 0)
...

3.6. tls_verify_peer (int)

   For HTTPS connections, whether the client should verify the server
   identity. http://curl.haxx.se/libcurl/c/CURLOPT_SSL_VERIFYPEER.html

   Default value is 1 (enabled).

   Example 1.6. Set tls_verify_peer parameter
...
modparam("http_async_client", "tls_verify_peer", 0)
...

3.7. curl_verbose (int)

   If defined to a non-zero value, extra informations from cURL (request
   and response headers) will be included in the kamailio logs, with
   LM_INFO priority.

   Default value is 0 (disabled).

   Example 1.7. Set curl_verbose parameter
...
modparam("http_async_client", "curl_verbose", 1)
...

3.8. memory_manager (string)

   Choose the memory manager used by curl:
     * shm: curl will use kamailio's SHM pool and memory manager
     * sys: curl will use the system memory and memory manager (malloc,
       free, ...)

   Note: if this module is used in conjunction with another module using
   libcurl (http_client, utils, xcap, xcap_client), it must be loaded as
   first one for this parameter to have effect, otherwise curl will likely
   use the system memory allocator by default. On the other hand if the
   module is loaded before any other module using libcurl, all the modules
   will use the memory manager specified by this parameter.

   Default value "shm"

   Example 1.8. Set memory_manager parameter
...
modparam("http_async_client", "memory_manager", "sys")
...

3.9. tls_client_cert (int)

   For HTTPS connections, the file path of the TLS client certificate to
   be used http://curl.haxx.se/libcurl/c/CURLOPT_SSLCERT.html

   Default value is NULL (not used). Default type is PEM.

   Example 1.9. Set tls_client_cert parameter
...
modparam("http_async_client", "tls_client_cert", "/etc/kamailio/ssl/clientcert.p
em")
...

3.10. tls_client_key (int)

   For HTTPS connections, the file path of the TLS client certificate key
   http://curl.haxx.se/libcurl/c/CURLOPT_SSLKEY.html

   Default value is NULL (not used).

   Example 1.10. Set tls_client_key parameter
...
modparam("http_async_client", "tls_client_key", "/etc/kamailio/ssl/clientcert.ke
y")
...

3.11. tls_ca_path (int)

   The path of the directory holding the CA certificates.
   http://curl.haxx.se/libcurl/c/CURLOPT_CAPATH.html

   Default value is NULL..

   Example 1.11. Set tls_ca_path parameter
...
modparam("http_async_client", "tls_ca_path", "/etc/kamailio/ssl/ca/")
...

4. Functions

   4.1. http_async_query(url, [post_data], route_name)
   4.2. http_async_suspend(suspend)
   4.3. tls_verify_host(verify)
   4.4. tls_verify_peer(verify)
   4.5. http_set_timeout(timeout)
   4.6. http_append_header(header)
   4.7. http_set_method(method)
   4.8. http_set_tls_client_cert(path)
   4.9. http_set_tls_client_key(path)
   4.10. http_set_tls_ca_path(path)

4.1.  http_async_query(url, [post_data], route_name)

   Sends HTTP(S) request asyncronously to the URL given in “url”
   parameter, which is a string that may contain pseudo variables.

   Unless a specific HTTP method was specified using
   http_async_set_method(), it defaults to a GET request, or to a POST
   request if “post_data” is issued as second argument.

   Parameter “post_data”, optional, which is sent as the body of the
   request, may also contain pseudo variables.

   Parameter “route_name” defines the route to be executed upon reception
   of HTTP reply, on error or on timeout. If a transaction exists before
   calling http_async_query(), it will be paused and resumed in this
   route, while the routing script execution will be stopped. If executed
   in a transactionless context, or if http_async_suspend_transaction() or
   $http_req(suspend) are used to not suspend the transaction, the routing
   script execution will continue and the query result will be available
   in “route_name”.

   Return value: 0 (stop script execution) on success in transaction
   context, 1 (continue script execution) in transaction-less context (or
   if http_async_suspend_transaction(0) or $http_req(suspend) are used),
   -1 on error.

   This function can be used from ANY_ROUTE.

   This method is executed asynchronously. The HTTP return code, body and
   error are returned in the module-specific $http_* PVs (see below). See
   example on how to retrieve return values.

   Example 1.12. http_async_query() usage
...
# create a transaction to be paused, and resumed in route[HTTP_REPLY]
t_newtran();
# GET
http_async_query("http://example.com/test.php?r_uri=$rU&f_uri=$fU", "HTTP_REPLY"
);
...
# POST
http_async_query("http://example.com/test.php", "{'r_uri':'$rU', 'f_uri':'$fU'}"
, "HTTP_REPLY");
...
route[HTTP_REPLY] {
    if ($http_ok) {
        xlog("L_INFO", "route[HTTP_REPLY]: status $http_rs\n");
        xlog("L_INFO", "route[HTTP_REPLY]: body   $http_rb\n");
    } else {
        xlog("L_INFO", "route[HTTP_REPLY]: error  $http_err)\n");
    }
}
...

4.2.  http_async_suspend(suspend)

   In a transaction context if the transaction must be suspended and
   script execution stopped.

   Parameter “suspend” set to "1" to suspend the transaction, "0" to not
   suspend and continue with script execution. Default: 1 (transaction
   suspended).

   Example 1.13. http_async_suspend() usage
...
t_newtran();
http_async_suspend(0);
# the transaction won't be suspended for the next query
http_async_query("http://example.com/test.php", "HTTP_REPLY");
xlog("L_INFO", "query sent\n");
t_reply("200", "Ok");

...

4.3.  tls_verify_host(verify)

   For the next HTTPS connection, whether the client should verify the
   server host.

   Parameter “verify” set to "1" to enable the host verification, "0" to
   disable. Default: the global value set as verify_host module parameter.

   Example 1.14. tls_verify_host() usage
...
tls_verify_host("0");
# host verification is disabled for the next query
http_async_query("https://example.com/test.php", "HTTP_REPLY");
...

4.4.  tls_verify_peer(verify)

   For the next HTTPS connection, whether the client should verify the
   server identity.

   Parameter “verify” set to "1" to enable the identity verification, "0"
   to disable. Default: the global value set as verify_peer module
   parameter.

   Example 1.15. tls_verify_peer() usage
...
tls_verify_peer("0");
# server identity verification is disabled for the next query
http_async_query("https://example.com/test.php", "HTTP_REPLY");
...

4.5.  http_set_timeout(timeout)

   For the next HTTP query, set the response timeout.

   Parameter “timeout” string representing the timeout in milliseconds.
   Default: the global value set as http_timeout module parameter.

   Example 1.16. http_set_timeout() usage
...
http_set_timeout("200");
# the server must respond in maximum 200ms, otherwise the query will fail
http_async_query("https://example.com/test.php", "HTTP_REPLY");
...

4.6.  http_append_header(header)

   Set/remove/replace a header in the next HTTP query.

   From libcurl's documentation:

   “If you add a header that is otherwise generated and used by libcurl
   internally, your added one will be used instead. If you add a header
   with no content as in 'Accept:' (no data on the right side of the
   colon), the internally used header will get disabled. With this option
   you can add new headers, replace internal headers and remove internal
   headers. To add a header with no content (nothing to the right side of
   the colon), use the form 'MyHeader;' (note the ending semicolon).”

   “The headers included in the linked list must not be CRLF-terminated,
   because libcurl adds CRLF after each header item.”

   Parameter “header” string representing the header to pass to libcurl
   for the next query.

   Example 1.17. http_append_header() usage
...
http_append_header("X-Sip-Call-Id: $ci");
# a new 'X-Sip-Call-Id' header will be added to the next query
http_append_header("Content-Type": application/json");
# the curl default 'application/x-www-form-urlencoded' Content-Type will be repl
aced
http_async_query("https://example.com/test.php", "{'foo': 'bar'}", "HTTP_REPLY")
;
...

4.7.  http_set_method(method)

   For the next HTTP query, set the method.

   Parameter “method” string representing the method (verb): either "GET",
   "POST", "PUT" or "DELETE" (these are the only supported methods).
   (Note: if http_set_method() is not called before a query, curl will use
   GET, or POST if a body is specified)

   Example 1.18. http_set_method() usage
...
http_set_method("PUT");
# the next query will be a HTTP PUT request
http_async_query("https://example.com/test.php", "{'foo': 'bar'}", "HTTP_REPLY")
;
...

4.8.  http_set_tls_client_cert(path)

   For the next HTTPS connection, what client certificate to use.

   Default: the global value set as tls_client_cert module parameter.

   Example 1.19. http_set_tls_client_cert() usage
...
http_set_tls_client_cert("/etc/kamailio/ssl/cert.pem");
# Next query will use the client cert above
http_async_query("https://example.com/test.php", "HTTP_REPLY");
...

4.9.  http_set_tls_client_key(path)

   For the next HTTPS connection, what client certificate key to use.

   Default: the global value set as tls_client_key module parameter.

   Example 1.20. http_set_tls_client_key() usage
...
http_set_tls_client_key("/etc/kamailio/ssl/cert.key");
# Next query will use the client cert key above
http_async_query("https://example.com/test.php", "HTTP_REPLY");
...

4.10.  http_set_tls_ca_path(path)

   For the next HTTP connection, what CA certificate files to use.

   Default: the global value set as tls_ca_path module parameter.

   Example 1.21. http_set_tls_ca_path() usage
...
http_set_tls_client_key("/etc/kamailio/ssl/ca/");
# Next query will use the CA certs above
http_async_query("https://example.com/test.php", "HTTP_REPLY");
...

5. Pseudo Variables

   The $http_req(key) write-only variable can be used to set custom
   parameters before sending a HTTP query

   setting this variable has the same effect than using the
   http_set_*()functions

   key can be one of:
     * all: if set to $null, resets all the parameters to their default
       value (the ones defined in modparam)
     * hdr: sets/modifies/remove a HTTP header (see http_append_header()).
       N.B.: setting this variable multiple times will add several headers
       to the query.
     * method: sets the HTTP method (see http_set_method())
     * timeout: sets the HTTP timeout (see http_set_timeout())
     * tls_client_cert: sets the client certificate to use (see
       http_set_tls_client_cert())
     * tls_client_key: sets the client certificate key to use (see
       http_set_tls_client_key())
     * tls_ca_path: sets the CA certificate files to use (see
       http_set_tls_ca_path())
     * suspend: if set to 0 doesn't suspend the current transaction before
       performing the query (see http_async_suspend())

   Example 1.22. $http_req(key) variable usage
...
$http_req(all) = $null;                    # reset the parameters
$http_req(timeout) = 100;                  # 100 ms
$http_req(method) = "DELETE";
$http_req(hdr) = "X-Sip-Call-Id: " + $ci;
$http_req(hdr) = "X-Foo: bar";             # add a 2nd header
$http_req(suspend) = 0;             # don't suspend the transaction, continue ro
uting script's execution
# the following request will use the above parameters
http_async_query("https://example.com/test.php", "HTTP_REPLY");
...

   The following read-only pseudo variables can only be used in the
   callback routes executed by http_async_query()
     * $http_ok: 1 if cURL executed the request successfully, 0 otherwise
       (check $http_err for details)
     * $http_err: cURL error string if an error occured, $null otherwise
     * $http_rs: http status
     * $http_rr: http reason phrase
     * $http_hdr(Name): value of the Name header (the $(http_hdr(Name)[N])
       syntax can also be used, check the SIP $hdr() PV documentation for
       details)
     * $http_mb and $http_ml: HTTP response buffer (including headers) and
       length
     * $http_rb and $http_bs: HTTP response body and body length

6. Statistics

   6.1. requests
   6.2. replies
   6.3. errors
   6.4. timeouts

6.1. requests

   The number of http requests sent.

6.2. replies

   The number of received http replies.

6.3. errors

   The number of errors.

6.4. timeouts

   The number of timed out requests.
