| 1 | // SPDX-License-Identifier: GPL-3.0-or-later |
| 2 | |
| 3 | //go:build linux || freebsd || openbsd || netbsd || dragonfly |
| 4 | |
| 5 | package isc_dhcpd |
| 6 | |
| 7 | import ( |
| 8 | "os" |
| 9 | ) |
| 10 | |
| 11 | /* |
| 12 | dhcpd.leases db (file), see details: https://kb.isc.org/docs/en/isc-dhcp-44-manual-pages-dhcpdleases#dhcpdleases |
| 13 | |
| 14 | Every time a lease is acquired, renewed or released, its new value is recorded at the end of the lease file. |
| 15 | So if more than one declaration appears for a given lease, the last one in the file is the current one. |
| 16 | |
| 17 | In order to prevent the lease database from growing without bound, the file is rewritten from time to time. |
| 18 | First, a temporary lease database is created and all known leases are dumped to it. |
| 19 | Then, the old lease database is renamed DBDIR/dhcpd.leases~. |
| 20 | Finally, the newly written lease database is moved into place. |
| 21 | |
| 22 | In order to process both DHCPv4 and DHCPv6 messages you will need to run two separate instances of the dhcpd process. |
| 23 | Each of these instances will need its own lease file. |
| 24 | */ |
| 25 | |
| 26 | func (c *Collector) collect() (map[string]int64, error) { |
| 27 | fi, err := os.Stat(c.LeasesPath) |
| 28 | if err != nil { |
| 29 | return nil, err |
| 30 | } |
| 31 | |
| 32 | if c.leasesModTime.Equal(fi.ModTime()) { |
| 33 | c.Debugf("leases file is not modified, returning cached metrics ('%s')", c.LeasesPath) |
| 34 | return c.collected, nil |
| 35 | } |
| 36 | |
| 37 | c.leasesModTime = fi.ModTime() |
| 38 | |
| 39 | leases, err := parseDHCPdLeasesFile(c.LeasesPath) |
| 40 | if err != nil { |
| 41 | return nil, err |
| 42 | } |
| 43 | |
| 44 | activeLeases := removeInactiveLeases(leases) |
| 45 | c.Debugf("found total/active %d/%d leases ('%s')", len(leases), len(activeLeases), c.LeasesPath) |
| 46 | |
| 47 | for _, pool := range c.pools { |
| 48 | collectPool(c.collected, pool, activeLeases) |
| 49 | } |
| 50 | c.collected["active_leases_total"] = int64(len(activeLeases)) |
| 51 | |
| 52 | return c.collected, nil |
| 53 | } |
| 54 | |
| 55 | const precision = 100 |
| 56 | |
| 57 | func collectPool(collected map[string]int64, pool ipPool, leases []leaseEntry) { |
| 58 | n := calcPoolActiveLeases(pool, leases) |
| 59 | collected["dhcp_pool_"+pool.name+"_active_leases"] = n |
| 60 | collected["dhcp_pool_"+pool.name+"_utilization"] = int64(calcPoolUtilizationPercentage(pool, n) * precision) |
| 61 | } |
| 62 | |
| 63 | func calcPoolActiveLeases(pool ipPool, leases []leaseEntry) (num int64) { |
| 64 | for _, l := range leases { |
| 65 | if pool.addresses.Contains(l.addr) { |
| 66 | num++ |
| 67 | } |
| 68 | } |
| 69 | return num |
| 70 | } |
| 71 | |
| 72 | func calcPoolUtilizationPercentage(pool ipPool, leases int64) float64 { |
| 73 | size := pool.addresses.Size() |
| 74 | if leases == 0 || !size.IsInt64() { |
| 75 | return 0 |
| 76 | } |
| 77 | if size.Int64() == 0 { |
| 78 | return 100 |
| 79 | } |
| 80 | return float64(leases) / float64(size.Int64()) * 100 |
| 81 | } |
| 82 | |
| 83 | func removeInactiveLeases(leases []leaseEntry) (active []leaseEntry) { |
| 84 | active = leases[:0] |
| 85 | for _, l := range leases { |
| 86 | if l.bindingState == "active" { |
| 87 | active = append(active, l) |
| 88 | } |
| 89 | } |
| 90 | return active |
| 91 | } |