base/frameworks/logging/main.bro

Log

The Bro logging interface.

See Logging Framework for an introduction to Bro’s logging framework.

Namespace:Log Imports:base/bif/logging.bif.bro Source File:/scripts/base/frameworks/logging/main.bro

Summary

Options

Log::default_ext_prefix: string &redef	A prefix for extension fields which can be optionally prefixed on all log lines by setting the ext_func field in the log filter.
Log::default_field_name_map: table &redef	Default field name mapping for renaming fields in a logging framework filter.
Log::default_mail_alarms_interval: interval &redef	Default alarm summary mail interval.
Log::default_rotation_date_format: string &redef	Default naming format for timestamps embedded into filenames.
Log::default_rotation_interval: interval &redef	Default rotation interval to use for filters that do not specify an interval.
Log::default_rotation_postprocessor_cmd: string &redef	Default shell command to run on rotated files.
Log::default_rotation_postprocessors: table &redef	Specifies the default postprocessor function per writer type.
Log::default_scope_sep: string &redef	Default separator for log field scopes when logs are unrolled and flattened.
Log::default_writer: Log::Writer &redef	Default writer to use if a filter does not specify anything else.
Log::empty_field: string &redef	Default string to use for empty fields.
Log::enable_local_logging: bool &redef	Dummy place-holder.
Log::enable_remote_logging: bool &redef	If true, remote logging is by default enabled for all filters.
Log::separator: string &redef	Default separator to use between fields.
Log::set_separator: string &redef	Default separator to use between elements of a set.
Log::unset_field: string &redef	Default string to use for an unset &optional field.

Constants

Log::no_filter: Log::Filter

Sentinel value for indicating that a filter was not found when looked up.

State Variables

Log::active_streams: table

The streams which are currently active and not disabled.

Types

Log::Filter: record	A filter type describes how to customize logging streams.
Log::RotationInfo: record	Information passed into rotation callback functions.
Log::Stream: record	Type defining the content of a logging stream.

Functions

Log::add_default_filter: function	Adds a default Log::Filter record with name field set as “default” to a given logging stream.
Log::add_filter: function	Adds a custom filter to an existing logging stream.
Log::create_stream: function	Creates a new logging stream with the default filter.
Log::default_ext_func: function &redef	Default log extension function in the case that you would like to apply the same extensions to all logs.
Log::default_path_func: function &redef	Builds the default path values for log filters if not otherwise specified by a filter.
Log::disable_stream: function	Disables a currently enabled logging stream.
Log::enable_stream: function	Enables a previously disabled logging stream.
Log::flush: function	Flushes any currently buffered output for all the writers of a given logging stream.
Log::get_filter: function	Gets a filter associated with an existing logging stream.
Log::remove_default_filter: function	Removes the Log::Filter with name field equal to “default”.
Log::remove_filter: function	Removes a filter from an existing logging stream.
Log::remove_stream: function	Removes a logging stream completely, stopping all the threads.
Log::run_rotation_postprocessor_cmd: function	Runs a command given by Log::default_rotation_postprocessor_cmd on a rotated file.
Log::set_buf: function	Sets the buffering status for all the writers of a given logging stream.
Log::write: function	Writes a new log line/entry to a logging stream.

Detailed Interface

Options

Log::default_ext_prefix

Type:string Attributes:&redef Default:"_"

A prefix for extension fields which can be optionally prefixed on all log lines by setting the ext_func field in the log filter.

Log::default_field_name_map

Type:table [string] of string Attributes:&redef Default:{}

Default field name mapping for renaming fields in a logging framework filter. This is typically used to ease integration with external data storage and analysis systems.

Log::default_mail_alarms_interval

Type:interval Attributes:&redef Default:0 secs

Default alarm summary mail interval. Zero disables alarm summary mails.

Note that this is overridden by the BroControl MailAlarmsInterval option.

Log::default_rotation_date_format

Type:string Attributes:&redef Default:"%Y-%m-%d-%H-%M-%S"

Default naming format for timestamps embedded into filenames. Uses a strftime() style.

Log::default_rotation_interval

Type:interval Attributes:&redef Default:0 secs

Default rotation interval to use for filters that do not specify an interval. Zero disables rotation.

Note that this is overridden by the BroControl LogRotationInterval option.

Log::default_rotation_postprocessor_cmd

Type:string Attributes:&redef Default:""

Default shell command to run on rotated files. Empty for none.

Log::default_rotation_postprocessors

Type:table [Log::Writer] of function (info: Log::RotationInfo) : bool Attributes:&redef Default:

{
   [Log::WRITER_NONE] = LogNone::default_rotation_postprocessor_func
   {
   return (T);
   },
   [Log::WRITER_ASCII] = LogAscii::default_rotation_postprocessor_func
   {
   LogAscii::dst = fmt("%s.%s.log", LogAscii::info$path, strftime(Log::default_rotation_date_format, LogAscii::info$open));
   system(fmt("/bin/mv %s %s", LogAscii::info$fname, LogAscii::dst));
   return (Log::run_rotation_postprocessor_cmd(LogAscii::info, LogAscii::dst));
   }
}

Specifies the default postprocessor function per writer type. Entries in this table are initialized by each writer type.

Log::default_scope_sep

Type:string Attributes:&redef Default:"."

Default separator for log field scopes when logs are unrolled and flattened. This will be the string between field name components. For example, setting this to “_” will cause the typical field “id.orig_h” to turn into “id_orig_h”.

Log::default_writer

Type:Log::Writer Attributes:&redef Default:Log::WRITER_ASCII

Default writer to use if a filter does not specify anything else.

Log::empty_field

Type:string Attributes:&redef Default:"(empty)"

Default string to use for empty fields. This should be different from unset_field to make the output unambiguous. Individual writers can use a different value.

Log::enable_local_logging

Type:bool Attributes:&redef Default:T

Dummy place-holder. If true, local logging is by default enabled for all filters.

Log::enable_remote_logging

Type:bool Attributes:&redef Default:T

If true, remote logging is by default enabled for all filters.

Log::separator

Type:string Attributes:&redef Default:"\x09"

Default separator to use between fields. Individual writers can use a different value.

Log::set_separator

Type:string Attributes:&redef Default:","

Default separator to use between elements of a set. Individual writers can use a different value.

Log::unset_field

Type:string Attributes:&redef Default:"-"

Default string to use for an unset &optional field. Individual writers can use a different value.

Constants

Log::no_filter

Type:Log::Filter Default:

{
   name="<not found>"
   writer=Log::WRITER_ASCII
   pred=<uninitialized>
   path=<uninitialized>
   path_func=<uninitialized>
   include=<uninitialized>
   exclude=<uninitialized>
   log_local=T
   log_remote=T
   field_name_map={

   }
   scope_sep="."
   ext_prefix="_"
   ext_func=anonymous-function
   ;
   interv=0 secs
   postprocessor=<uninitialized>
   config={

   }
}

Sentinel value for indicating that a filter was not found when looked up.

State Variables

Log::active_streams

Type:table [Log::ID] of Log::Stream Default:{}

The streams which are currently active and not disabled. This table is not meant to be modified by users! Only use it for examining which streams are active.

Types

Log::Filter

Type:

record

name: string

Descriptive name to reference this filter.

writer: Log::Writer &default = Log::default_writer &optional

The logging writer implementation to use.

pred: function (rec: any) : bool &optional

Indicates whether a log entry should be recorded. If not given, all entries are recorded.

rec:An instance of the stream’s columns type with its fields set to the values to be logged. returns:True if the entry is to be recorded.

path: string &optional

Output path for recording entries matching this filter.

The specific interpretation of the string is up to the logging writer, and may for example be the destination file name. Generally, filenames are expected to be given without any extensions; writers will add appropriate extensions automatically.

If this path is found to conflict with another filter’s for the same writer type, it is automatically corrected by appending “-N”, where N is the smallest integer greater or equal to 2 that allows the corrected path name to not conflict with another filter’s.

path_func: function (id: Log::ID, path: string, rec: any) : string &optional

A function returning the output path for recording entries matching this filter. This is similar to path yet allows to compute the string dynamically. It is ok to return different strings for separate calls, but be careful: it’s easy to flood the disk by returning a new string for each connection. Upon adding a filter to a stream, if neither path nor path_func is explicitly set by them, then Log::default_path_func is used.

id:The ID associated with the log stream. path:A suggested path value, which may be either the filter’s path if defined, else a previous result from the function. If no path is defined for the filter, then the first call to the function will contain an empty string. rec:An instance of the stream’s columns type with its fields set to the values to be logged. returns:The path to be used for the filter, which will be subject to the same automatic correction rules as the path field of Log::Filter in the case of conflicts with other filters trying to use the same writer/path pair.

include: set [string] &optional

Subset of column names to record. If not given, all columns are recorded.

exclude: set [string] &optional

Subset of column names to exclude from recording. If not given, all columns are recorded.

log_local: bool &default = Log::enable_local_logging &optional

If true, entries are recorded locally.

log_remote: bool &default = Log::enable_remote_logging &optional

If true, entries are passed on to remote peers.

field_name_map: table [string] of string &default = Log::default_field_name_map &optional

Field name map to rename fields before the fields are written to the output.

scope_sep: string &default = Log::default_scope_sep &optional

A string that is used for unrolling and flattening field names for nested record types.

ext_prefix: string &default = Log::default_ext_prefix &optional

Default prefix for all extension fields. It’s typically prudent to set this to something that Bro’s logging framework can’t normally write out in a field name.

ext_func: function (path: string) : any &default = Log::default_ext_func &optional

Function to collect a log extension value. If not specified, no log extension will be provided for the log. The return value from the function must be a record.

interv: interval &default = Log::default_rotation_interval &optional

Rotation interval. Zero disables rotation.

postprocessor: function (info: Log::RotationInfo) : bool &optional

Callback function to trigger for rotated files. If not set, the default comes out of Log::default_rotation_postprocessors.

config: table [string] of string &default = {  } &optional

A key/value table that will be passed on to the writer. Interpretation of the values is left to the writer, but usually they will be used for configuration purposes.

A filter type describes how to customize logging streams.

Log::RotationInfo

Type:

record

writer: Log::Writer

The log writer being used.

fname: string

Full name of the rotated file.

path: string

Original path value.

open: time

Time when opened.

close: time

Time when closed.

terminating: bool

True if rotation occured due to Bro shutting down.

Information passed into rotation callback functions.

Log::Stream

Type:

record

columns: any

A record type defining the log’s columns.

ev: any &optional

Event that will be raised once for each log entry. The event receives a single same parameter, an instance of type columns.

path: string &optional

A path that will be inherited by any filters added to the stream which do not already specify their own path.

Type defining the content of a logging stream.

Functions

Log::add_default_filter

Type:function (id: Log::ID) : bool

Adds a default Log::Filter record with name field set as “default” to a given logging stream.

Id:The ID associated with a logging stream for which to add a default filter. Returns:The status of a call to Log::add_filter using a default Log::Filter argument with name field set to “default”.

See also: Log::add_filter, Log::remove_filter, Log::remove_default_filter

Log::add_filter

Type:function (id: Log::ID, filter: Log::Filter) : bool

Adds a custom filter to an existing logging stream. If a filter with a matching name field already exists for the stream, it is removed when the new filter is successfully added.

Id:The ID associated with the logging stream to filter. Filter:A record describing the desired logging parameters. Returns:True if the filter was successfully added, false if the filter was not added or the filter argument was not the correct type.

See also: Log::remove_filter, Log::add_default_filter, Log::remove_default_filter

Log::create_stream

Type:function (id: Log::ID, stream: Log::Stream) : bool

Creates a new logging stream with the default filter.

Id:The ID enum to be associated with the new logging stream. Stream:A record defining the content that the new stream will log. Returns:True if a new logging stream was successfully created and a default filter added to it.

See also: Log::add_default_filter, Log::remove_default_filter

Log::default_ext_func

Type:function (path: string) : any Attributes:&redef

Default log extension function in the case that you would like to apply the same extensions to all logs. The function must return a record with all of the fields to be included in the log. The default function included here does not return a value, which indicates that no extensions are added.

Log::default_path_func

Type:function (id: Log::ID, path: string, rec: any) : string Attributes:&redef

Builds the default path values for log filters if not otherwise specified by a filter. The default implementation uses id to derive a name. Upon adding a filter to a stream, if neither path nor path_func is explicitly set by them, then this function is used as the path_func.

Id:The ID associated with the log stream. Path:A suggested path value, which may be either the filter’s path if defined, else a previous result from the function. If no path is defined for the filter, then the first call to the function will contain an empty string. Rec:An instance of the stream’s columns type with its fields set to the values to be logged. Returns:The path to be used for the filter.

Log::disable_stream

Type:function (id: Log::ID) : bool

Disables a currently enabled logging stream. Disabled streams will not be written to until they are enabled again. New streams are enabled by default.

Id:The ID associated with the logging stream to disable. Returns:True if the stream is now disabled or was already disabled.

See also: Log::enable_stream

Log::enable_stream

Type:function (id: Log::ID) : bool

Enables a previously disabled logging stream. Disabled streams will not be written to until they are enabled again. New streams are enabled by default.

Id:The ID associated with the logging stream to enable. Returns:True if the stream is re-enabled or was not previously disabled.

See also: Log::disable_stream

Log::flush

Type:function (id: Log::ID) : bool

Flushes any currently buffered output for all the writers of a given logging stream.

Id:The ID associated with a logging stream for which to flush buffered data. Returns:True if all writers of a log stream were signalled to flush buffered data or if the logging stream is disabled, false if the logging stream does not exist.

See also: Log::set_buf, Log::enable_stream, Log::disable_stream

Log::get_filter

Type:function (id: Log::ID, name: string) : Log::Filter

Gets a filter associated with an existing logging stream.

Id:The ID associated with a logging stream from which to obtain one of its filters. Name:A string to match against the name field of a Log::Filter for identification purposes. Returns:A filter attached to the logging stream id matching name or, if no matches are found returns the Log::no_filter sentinel value.

See also: Log::add_filter, Log::remove_filter, Log::add_default_filter, Log::remove_default_filter

Log::remove_default_filter

Type:function (id: Log::ID) : bool

Removes the Log::Filter with name field equal to “default”.

Id:The ID associated with a logging stream from which to remove the default filter. Returns:The status of a call to Log::remove_filter using “default” as the argument.

See also: Log::add_filter, Log::remove_filter, Log::add_default_filter

Log::remove_filter

Type:function (id: Log::ID, name: string) : bool

Removes a filter from an existing logging stream.

Id:The ID associated with the logging stream from which to remove a filter. Name:A string to match against the name field of a Log::Filter for identification purposes. Returns:True if the logging stream’s filter was removed or if no filter associated with name was found.

See also: Log::remove_filter, Log::add_default_filter, Log::remove_default_filter

Log::remove_stream

Type:function (id: Log::ID) : bool

Removes a logging stream completely, stopping all the threads.

Id:The ID associated with the logging stream. Returns:True if the stream was successfully removed.

See also: Log::create_stream

Log::run_rotation_postprocessor_cmd

Type:function (info: Log::RotationInfo, npath: string) : bool

Runs a command given by Log::default_rotation_postprocessor_cmd on a rotated file. Meant to be called from postprocessor functions that are added to Log::default_rotation_postprocessors.

Info:A record holding meta-information about the log being rotated. Npath:The new path of the file (after already being rotated/processed by writer-specific postprocessor as defined in Log::default_rotation_postprocessors). Returns:True when Log::default_rotation_postprocessor_cmd is empty or the system command given by it has been invoked to postprocess a rotated log file.

See also: Log::default_rotation_date_format, Log::default_rotation_postprocessor_cmd, Log::default_rotation_postprocessors

Log::set_buf

Type:function (id: Log::ID, buffered: bool) : bool

Sets the buffering status for all the writers of a given logging stream. A given writer implementation may or may not support buffering and if it doesn’t then toggling buffering with this function has no effect.

Id:The ID associated with a logging stream for which to enable/disable buffering. Buffered:Whether to enable or disable log buffering. Returns:True if buffering status was set, false if the logging stream does not exist.

See also: Log::flush

Log::write

Type:function (id: Log::ID, columns: any) : bool

Writes a new log line/entry to a logging stream.

Id:The ID associated with a logging stream to be written to. Columns:A record value describing the values of each field/column to write to the log stream. Returns:True if the stream was found and no error occurred in writing to it or if the stream was disabled and nothing was written. False if the stream was not found, or the columns argument did not match what the stream was initially defined to handle, or one of the stream’s filters has an invalid path_func.

See also: Log::enable_stream, Log::disable_stream