96 lines
1.8 KiB
Bash
Executable file
96 lines
1.8 KiB
Bash
Executable file
#!/usr/local/bin/bash
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set -euo pipefail
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readonly DHCPD_CONF_FILE="${DHCPD_CONF_FILE:-/etc/dhcpd.conf}"
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readonly DHCPD_LEASES_FILE="${DHCPD_LEASES_FILE:-/var/db/dhcpd.leases}"
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DHCPD_CONF_FILE_AWK_SCRIPT=$(cat << 'EOF'
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/^[ \t]*host[ \t]+[^ \t]+[ \t]+\{[ \t]*$/ {
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ip = ""
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hostname = $2
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next
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}
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/^[ \t]*fixed-address[ \t]+([0-9]{1,3}\.){3}[0-9]{1,3}[ \t]*;[ \t]*$/ {
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ip = substr($2, 1, length($2)-1)
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next
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}
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/\}/ {
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if (hostname && ip) {
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print hostname "\t" ip
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}
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hostname = ""
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ip = ""
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next
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}
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EOF
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)
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readonly DHCPD_CONF_FILE_AWK_SCRIPT
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DHCPD_LEASES_FILE_AWK_SCRIPT=$(cat << 'EOF'
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function parse_datetime(datetime) {
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command = "TZ=UTC date -j -f \"%w %Y/%m/%d %H:%M:%S %Z;\" +%s \"" datetime "\""
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if (command | getline unix_time < 0) {
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exit 1
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}
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close(command)
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return unix_time
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}
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/^[ \t]*lease[ \t]+([0-9]{1,3}\.){3}[0-9]{1,3}[ \t]+\{[ \t]*$/ {
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ip = $2
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next
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}
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/^[ \t]*(starts|ends)[ \t]+[0-6][ \t]+[0-9]+\/[0-9]+\/[0-9]+[ \t]+[0-9]+:[0-9]+:[0-9]+([ \t]+[a-zA-Z0-9]+)?[ \t]*;[ \t]*$/ {
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if ($1 == "starts") {
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$1 = ""
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# remove the leading space caused by setting $1 to ""
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starts = parse_datetime(substr($0, 2))
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} else {
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$1 = ""
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# remove the leading space caused by setting $1 to ""
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ends = parse_datetime(substr($0, 2))
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}
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next
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}
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/^[ \t]*(client-)?hostname[ \t]+\"[^\"]+\"[ \t]*;[ \t]*$/ {
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hostname = gensub("\"|;", "", "g", $2)
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next
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}
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/^[ \t]*abandoned[ \t]*;[ \t]*$/ {
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abandoned = 1
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next
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}
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/\}/ {
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now = systime()
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if (!abandoned && hostname && ip && starts && ends && now >= starts && now < ends) {
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print hostname "\t" ip
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}
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hostname = ""
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ip = ""
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starts = 0
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ends = 0
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abandoned = 0
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}
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EOF
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)
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readonly DHCPD_LEASES_FILE_AWK_SCRIPT
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(
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awk "${DHCPD_CONF_FILE_AWK_SCRIPT}" "${DHCPD_CONF_FILE}"
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awk "${DHCPD_LEASES_FILE_AWK_SCRIPT}" "${DHCPD_LEASES_FILE}"
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) | sort -u | column -c 2 -t
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