DataScript: Functions


DataScripts are comprised of any number of function or method calls which can be used to inspect and act on traffic flowing through a virtual service. DataScript’s functions are exposed via Lua libraries and grouped into modules: string, vs, http, pool, ssl and crypto. Other Lua libraries may also be used, following the documentation from The following functions are available.


String Description
string.beginswith( source, target ) Search for string in beginning of a string
string.contains( source, target ) Search contains a string in another string
string.endswith( source, target ) Search for string at the end of a string
string.len( source ) Returns number of characters in string
string.lower( source ) Change a string to lower case
string.split( source_string, delimiter ) Parses a string into substrings
string.sub( source, begin, [end] ) Extract a sub-string from a string
string.upper( source ) Change a string to upper case
L4 Read the payload from the socket buffer. This function is available starting with 18.2.5.
avi.l4.collect(num_bytes) Gather the num_bytes before subjecting the payload to the DataScript. This function is available starting with 18.2.5.
VS, [operation], [value]) Creates and manipulates a counter-type metric. Refer to User-defined Metrics., [operation], [value]) Creates and manipulates a gauge-type metric. Refer to User-defined Metrics., metric_type) Return the user-defined metric value if one with the given name and given type exists. Refer to User-defined Metrics.
avi.vs.client_ip( ) Returns the client IP address
avi.vs.client_port( ) Returns the client source port
avi.vs.close_conn([reset]) Close the current TCP/UDP connection
avi.vs.ip( ) Returns IP address of the VS
avi.vs.log( ) Write a custom log to VS > client logs ) Returns the name of the VS
avi.vs.port( ) Returns the VS port of the connection
avi.vs.persist(key, [lifetime], [pool]) Creates peristence entry using the key used after load balancing traffic
avi.vs.rate_limit( type, string_to_limit, [defer_action=False] ) Rate limits entities of various kinds.
avi.vs.reqvar.* Set a global variable usable across events
avi.vs.table_insert( [table_name,] key, value [, lifetime] ) Store custom data in a time based table
avi.vs.table_lookup( [table_name,] key [, lifetime_exten] ) Lookup data in a table
avi.vs.table_refresh( [table_name,] key [, lifetime_exten] ) Update the expire time for a table entry
avi.vs.table_remove( [table_name,] key ) Remove data from a table Returns the UUID of the service engine handling the request
avi.http.add_cookie( table ) Insert a new cookie
avi.http.add_header( name, value ) Insert a new header and value
avi.http.close_conn( [reset] ) Close or reset a TCP connection
avi.http.cookie_exists( name, [context] ) Validate if a cookie already exists
avi.http.disable() Upgrade (disable) HTTP processing for the current connection, which will subsequently be treated as layer 4 TCP
avi.http.get_cookie( name [, context] ) Return the values of a cookie
avi.http.get_cookie_names ( [context] ) Return the names of cookies
avi.http.get_header( [[name] [context]] ) Return header names or their values
avi.http.get_host_tokens( [start [, end]] ) Return a subsection of the host
avi.http.get_path( [false] ) Returns the URI's path /path.index.htm
avi.http.get_path_tokens( [start [, end]] ) Return a subsection of the path
avi.http.get_query( [arg_name | avi.QUERY_TABLE] [, decode] ) Returns the URI's query ?a=1&b=2
avi.http.get_req_body([size_in_kb]) Returns part or all of the client request body.
avi.http.get_request_id() Returns the request ID.
avi.http.get_reqvar() Gets (reads) data stored in a variable via the avi.http.set() function.
avi.http.get_response_body(size [, offset]) Gets (reads) a specified number of kilobytes from the buffered response body starting at the specified kilobyte offset.
avi.http.get_uri( [false] ) Returns the URI (path plus query)
avi.http.get_userid( ) Returns the user ID for the session
avi.http.hostname( ) Return the hostname requested by client
avi.http.internal_status() Returns HTTP status as a string
avi.http.method( ) Return the client's request method
avi.http.protocol( ) Returns the session protocol, http or https
avi.http.redirect( uri [,status] ) Redirect a request
avi.http.remove_cookie( name1, [name2, ...] ) Remove an existing cookie
avi.http.remove_header( name ) Remove all instances of a header
avi.http.replace_cookie( table ) Replace an existing cookies values
avi.http.replace_header( name, value ) Replace an existing header's value
avi.http.response( status, [headers, [body]] ) Send a defined HTTP response page
avi.http.saml_session_decrypt( ) Returns a string of the decrypted SAML session cookie if it exists; else nil
avi.http.scheme( ) Returns http:// or https:// ) Returns on for https, nil for http
avi.http.set_path( new_uri ) Modify the path of a request
avi.http.set_query( integer | string | table ) Modify the query of a request
avi.http.set_reqvar() Sets (write) arbitrary data from an HTTP request event into a variable. These variables have scope across the HTTP_REQ and HTTP_RESP events.
avi.http.set_response_body_buffer_size(size) Sets the maximum response body to be buffered.
avi.http.set_server_timeout( time ) Set a custom timeout value for a particular request.
avi.http.set_uri( new_uri ) Change the URI
avi.http.set_userid( ) Sets the user ID for the session
avi.http.status( ) Returns status code to be sent to client
avi.http.disable_auth Disables the client authentication
avi.pool.get_server_status( pool, server, port ) Returns the up/down status of the server
avi.pool.get_servers( pool ) Returns up and total server count
avi.pool.get_active_server_list( pool ) Returns the IP addresses of all active servers in a pool pool [, server [, port]] ) Pick a specific pool
avi.pool.server_ip( ) Returns the IP of the selected server
avi.pool.get_server_info() Returns the IP address and port of the server pool ) Pick a specific pool group
avi.pool.chash( string ) Sets the string value that the consistent hash load-balancing algorithm hashes on to choose a server within the selected pool
avi.ipgroup.contains( ipgroup, ip-address ) Compare an IP address against IPs within an IP Group
avi.stringgroup.beginswith( stringgroup, string ) Compare a string against a list of strings within a string group
avi.stringgroup.contains( stringgroup, string ) Compare a string against a list of strings within a string group
avi.stringgroup.equals( stringgroup, string ) Compare a string against a list of strings within a string group
avi.stringgroup.endswith( stringgroup, string ) Compare a string against a list of strings within a string group
avi.ssl.cipher( [true] ) Return the SSL ciphers and settings
avi.ssl.client_cert( [ [avi.CLIENT_CERT] [, avi.CLIENT_CERT_FINGERPRINT] [, avi.CLIENT_CERT_SUBJECT] [, avi.CLIENT_CERT_ISSUER] [, avi.CLIENT_CERT_SERIAL]] ) Returns the client's certificate, or part of it
avi.ssl.protocol( ) Return the SSL version
avi.ssl.server_name( ) Return SNI name field
avi.crypto.decrypt( ciphertext, key [, iv [, algo]] ) Decrypt content
avi.crypto.encrypt( plaintext, key [, iv [, algo]] ) Encrypt content
avi.utils.base64_decode( string ) Decode content
avi.utils.base64_encode( string ) Encode content
avi.utils.get_geo_from_ip (ip_string, [flag]) Used to extract geolocation database information
avi.utils.ip.addr (ipaddr, netmask) Accepts an IP address and netmask and returns the network address
avi.utils.murmur_hash ( string )
avi.utils.sha1_hash ( string )
avi.utils.md5_hash ( string )
Hash content
avi.utils.rand_bytes( num_bytes ) Generate cryptographically secure random bytes
avi.utils.get_ip_reputation(ip_addr) Used to check IP reputation of a given IP address

Note: Starting with Avi Vantage 17.1.10 and 17.2.3, DataScripts can hash arbitrary data using one of three functions supporting their corresponding named hashing methods: MurmurHash, SHA-1, and MD5.
For more information, refer to DataScript: avi.utils.murmur_hash (), avi.utils.sha1_hash (), avi.utils.md5_hash ().

Document Revision History

Date Change Summary
December 07, 2020 Updated the content for avi.http.disable_auth(Version 20.1.3)