A parser for syslog messages.
Blazing fast RFC5424-compliant parsers
To wrap up, this package provides:
- a RFC5424-compliant parser
- a RFC5424-compliant builder
- a parser which works on streams for syslog with octet counting framing technique
- a parser which works on streams for syslog with non-transparent framing technique
This library provides the pieces to parse syslog messages transported following various RFCs.
For example:
- TLS with octet count (RFC5425)
- TCP with non-transparent framing or with octet count (RFC 6587)
- UDP carrying one message per packet (RFC5426)
go get github.com/influxdata/go-syslog
The docs directory contains .dot files representing the FSM parts of a RFC5424 syslog message and also the ones representing the other transport parsers.
Suppose you want to parse a given sequence of bytes as a RFC5424 message.
i := []byte(`<165>4 2018-10-11T22:14:15.003Z mymach.it e - 1 [ex@32473 iut="3"] An application event log entry...`)
p := rfc5424.NewParser()
m, e := p.Parse(i, nil)This results in m being equal to:
// (*rfc5424.SyslogMessage)({
// priority: (*uint8)(165),
// facility: (*uint8)(20),
// severity: (*uint8)(5),
// version: (uint16) 4,
// timestamp: (*time.Time)(2018-10-11 22:14:15.003 +0000 UTC),
// hostname: (*string)((len=9) "mymach.it"),
// appname: (*string)((len=1) "e"),
// procID: (*string)(<nil>),
// msgID: (*string)((len=1) "1"),
// structuredData: (*map[string]map[string]string)((len=1) {
// (string) (len=8) "ex@32473": (map[string]string) (len=1) {
// (string) (len=3) "iut": (string) (len=1) "3"
// }
// }),
// message: (*string)((len=33) "An application event log entry...")
// })And e being equal to nil, since the i is a perfectly valid RFC5424 message.
RFC5424 parser has the ability to perform partial matches (until it can).
With this mode enabled, when the parsing process errors out it returns the message collected until that position, and the error that caused the parser to stop.
Notice that in this modality the output is returned iff it represents a minimally valid message - ie., a message containing almost a priority field in [1,191] within angular brackets, followed by a version in ]0,999].
Let's look at an example.
bestEffortOn := true
i := []byte("<1>1 A - - - - - -")
p := NewParser()
m, e := p.Parse(i, &bestEffortOn)This results in m being equal to the following SyslogMessage instance.
// (*rfc5424.SyslogMessage)({
// priority: (*uint8)(1),
// facility: (*uint8)(0),
// severity: (*uint8)(1),
// version: (uint16) 1,
// timestamp: (*time.Time)(<nil>),
// hostname: (*string)(<nil>),
// appname: (*string)(<nil>),
// procID: (*string)(<nil>),
// msgID: (*string)(<nil>),
// structuredData: (*map[string]map[string]string)(<nil>),
// message: (*string)(<nil>)
// })And, at the same time, in e reporting the error that actually stopped the parser.
expecting a RFC3339MICRO timestamp or a nil value [col 5]Both m and e have a value since at the column the parser stopped it already was able to construct a minimally valid SyslogMessage.
This library also provides a builder to construct valid syslog messages.
Notice that its API ignores input values that does not match the grammar.
Let's have a look to an example.
msg := &SyslogMessage{}
msg.SetTimestamp("not a RFC3339MICRO timestamp")
msg.Valid() // Not yet a valid message (try msg.Valid())
msg.SetPriority(191)
msg.SetVersion(1)
msg.Valid() // Now it is minimally validPrinting msg you will verify it contains a nil timestamp (since an invalid one has been given).
// (*rfc5424.SyslogMessage)({
// priority: (*uint8)(191),
// facility: (*uint8)(23),
// severity: (*uint8)(7),
// version: (uint16) 1,
// timestamp: (*time.Time)(<nil>),
// hostname: (*string)(<nil>),
// appname: (*string)(<nil>),
// procID: (*string)(<nil>),
// msgID: (*string)(<nil>),
// structuredData: (*map[string]map[string]string)(<nil>),
// message: (*string)(<nil>)
// })Finally you can serialize the message into a string.
str, _ := msg.String()
// <191>1 - - - - - -Excluding encapsulating one message for packet in packet protocols there are two ways to transfer syslog messages over streams.
The older - ie., the non-transparent framing - and the newer one - ie., the octet counting framing - which is reliable and has not been seen to cause problems noted with the non-transparent one.
This library provide stream parsers for both.
In short, RFC5425 and RFC6587, aside from the protocol considerations, describe a transparent framing technique for syslog messages that uses the octect counting technique - ie., the message lenght of the incoming message.
Each syslog message is sent with a prefix representing the number of bytes it is made of.
This package parses messages stream following such rule.
To quickly understand how to use it please have a look at the example file.
The RFC6587 also describes the non-transparent framing transport of syslog messages.
In such case the messages are separated by a trailer, usually a line feed.
This package parses message stream following such technique.
To quickly understand how to use it please have a look at the example file.
Things we do not support:
- trailers other than
LForNUL - trailer which length is greater than 1 byte
- trailer change on a frame-by-frame basis
To run the benchmark execute the following command.
make benchOn my machine1 this are the results obtained in best effort mode.
[no]_empty_input__________________________________-4 30000000 253 ns/op 224 B/op 3 allocs/op
[no]_multiple_syslog_messages_on_multiple_lines___-4 20000000 433 ns/op 304 B/op 12 allocs/op
[no]_impossible_timestamp_________________________-4 10000000 1080 ns/op 528 B/op 11 allocs/op
[no]_malformed_structured_data____________________-4 20000000 552 ns/op 400 B/op 12 allocs/op
[no]_with_duplicated_structured_data_id___________-4 5000000 1246 ns/op 688 B/op 17 allocs/op
[ok]_minimal______________________________________-4 30000000 264 ns/op 247 B/op 9 allocs/op
[ok]_average_message______________________________-4 5000000 1984 ns/op 1536 B/op 26 allocs/op
[ok]_complicated_message__________________________-4 5000000 1644 ns/op 1280 B/op 25 allocs/op
[ok]_very_long_message____________________________-4 2000000 3826 ns/op 2464 B/op 28 allocs/op
[ok]_all_max_length_and_complete__________________-4 3000000 2792 ns/op 1888 B/op 28 allocs/op
[ok]_all_max_length_except_structured_data_and_mes-4 5000000 1830 ns/op 883 B/op 13 allocs/op
[ok]_minimal_with_message_containing_newline______-4 20000000 294 ns/op 250 B/op 10 allocs/op
[ok]_w/o_procid,_w/o_structured_data,_with_message-4 10000000 956 ns/op 364 B/op 11 allocs/op
[ok]_minimal_with_UTF-8_message___________________-4 20000000 586 ns/op 359 B/op 10 allocs/op
[ok]_with_structured_data_id,_w/o_structured_data_-4 10000000 998 ns/op 592 B/op 14 allocs/op
[ok]_with_multiple_structured_data________________-4 5000000 1538 ns/op 1232 B/op 22 allocs/op
[ok]_with_escaped_backslash_within_structured_data-4 5000000 1316 ns/op 920 B/op 20 allocs/op
[ok]_with_UTF-8_structured_data_param_value,_with_-4 5000000 1580 ns/op 1050 B/op 21 allocs/op
As you can see it takes:
-
~250ns to parse the smallest legal message
-
~2µs to parse an average legal message
-
~4µs to parse a very long legal message
Other RFC5424 implementations, like this one in Rust, spend 8µs to parse an average legal message.
TBD: comparation against other golang parsers.
- [1]: Intel Core i7-7600U CPU @ 2.80GHz