DNSMasq is basically everywhere, but has no easy to use API - let's (try to) fix that!
DNSMasq logs all DNS queries when log-queries flag is used. It also has an ability to write it's logs to syslog, file
and stderr. For a real time log streaming, named pipes can be used as a very basic method of IPC. Named pipe is a
blocking FIFO queue and therefore must be used with extra care (dnsmasq process will not start if there is no reader on
the other end of a pipe).
To gather all DNS queries resolved by DNSMasq, use following configuration options:
log-queries=extra
log-async=100
log-facility=/tmp/dnsmasq/log.fifo
Before starting dnsmasq, start dnsmasq.WatchLogs(...) function which will create Unix named pipe, parse all incoming
logs and publish resolved DNS queries over a Golang channel.
Reading DHCP leases doesn't require specific configuration changes. Leases file can be simply parsed using
dnsmasq.ReadLeases(...) function.
Additionally, function dnsmasq.WatchLeases(...) extends parsing with a Goroutine that reloads leases file when it was
modified (by listening on IN_MODIFY syscall signal) and sends all parsed leases over a channel.
go get github.com/b0ch3nski/go-dnsmasq-utils
ctx := context.Background()
queries := make(chan *dnsmasq.Query)
go dnsmasq.WatchLogs(ctx, "/tmp/dnsmasq/log.fifo", queries, nil)
leases := make(chan []*dnsmasq.Lease)
go dnsmasq.WatchLeases(ctx, "/tmp/dnsmasq/dhcp.leases", leases)Also see docker-compose.yaml file.