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dhcp4d: make hostname override settable from status page

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This commit is contained in:
Michael Stapelberg 2020-04-12 10:33:11 +02:00
parent 4f0efc7b18
commit 2b6ab5b2bd
2 changed files with 66 additions and 10 deletions
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27
cmd/dhcp4d/dhcp4d.go
View File

@ -137,6 +137,9 @@ span.hostname-override {
tr:nth-child(even) { tr:nth-child(even) {
background: #eee; background: #eee;
} }
form {
display: inline;
}
</style> </style>
</head> </head>
<body> <body>
@ -152,7 +155,10 @@ tr:nth-child(even) {
<tr> <tr>
<td class="ipaddr">{{$l.Addr}}</td> <td class="ipaddr">{{$l.Addr}}</td>
<td> <td>
{{$l.Hostname}} <form action="/sethostname" method="post">
<input type="hidden" name="hardwareaddr" value="{{$l.HardwareAddr}}">
<input type="text" name="hostname" value="{{$l.Hostname}}">
</form>
{{ if (ne $l.HostnameOverride "") }} {{ if (ne $l.HostnameOverride "") }}
<span class="hostname-override">!</span> <span class="hostname-override">!</span>
{{ end }} {{ end }}
@ -258,6 +264,25 @@ func newSrv(permDir string) (*srv, error) {
return nil, err return nil, err
} }
http.HandleFunc("/sethostname", func(w http.ResponseWriter, r *http.Request) {
if r.Method != "POST" {
http.Error(w, "want POST", http.StatusMethodNotAllowed)
return
}
hwaddr := r.FormValue("hardwareaddr")
if hwaddr == "" {
http.Error(w, "missing hardwareaddr parameter", http.StatusBadRequest)
return
}
hostname := r.FormValue("hostname")
if hostname == "" {
http.Error(w, "missing hostname parameter", http.StatusBadRequest)
return
}
handler.SetHostname(hwaddr, hostname)
http.Redirect(w, r, "/", http.StatusFound)
})
http.HandleFunc("/lease/", func(w http.ResponseWriter, r *http.Request) { http.HandleFunc("/lease/", func(w http.ResponseWriter, r *http.Request) {
hostname := strings.TrimPrefix(r.URL.Path, "/lease/") hostname := strings.TrimPrefix(r.URL.Path, "/lease/")
if hostname == "" { if hostname == "" {

49
internal/dhcp4d/dhcp4d.go
View File

@ -19,6 +19,7 @@ import (
"log" "log"
"math/rand" "math/rand"
"net" "net"
"sync"
"syscall" "syscall"
"time" "time"
@ -49,8 +50,6 @@ type Handler struct {
leaseRange int // number of IP addresses to hand out leaseRange int // number of IP addresses to hand out
LeasePeriod time.Duration LeasePeriod time.Duration
options dhcp4.Options options dhcp4.Options
leasesHW map[string]int // points into leasesIP
leasesIP map[int]*Lease
rawConn net.PacketConn rawConn net.PacketConn
iface *net.Interface iface *net.Interface
@ -58,6 +57,10 @@ type Handler struct {
// Leases is called whenever a new lease is handed out // Leases is called whenever a new lease is handed out
Leases func([]*Lease, *Lease) Leases func([]*Lease, *Lease)
leasesMu sync.Mutex
leasesHW map[string]int // points into leasesIP
leasesIP map[int]*Lease
} }
func NewHandler(dir string, iface *net.Interface, ifaceName string, conn net.PacketConn) (*Handler, error) { func NewHandler(dir string, iface *net.Interface, ifaceName string, conn net.PacketConn) (*Handler, error) {
@ -105,6 +108,8 @@ func NewHandler(dir string, iface *net.Interface, ifaceName string, conn net.Pac
// loaded from persistent storage. There is no locking, so SetLeases must be // loaded from persistent storage. There is no locking, so SetLeases must be
// called before Serve. // called before Serve.
func (h *Handler) SetLeases(leases []*Lease) { func (h *Handler) SetLeases(leases []*Lease) {
h.leasesMu.Lock()
defer h.leasesMu.Unlock()
h.leasesHW = make(map[string]int) h.leasesHW = make(map[string]int)
h.leasesIP = make(map[int]*Lease) h.leasesIP = make(map[int]*Lease)
for _, l := range leases { for _, l := range leases {
@ -113,7 +118,30 @@ func (h *Handler) SetLeases(leases []*Lease) {
} }
} }
func (h *Handler) callLeasesLocked(lease *Lease) {
if h.Leases == nil {
return
}
var leases []*Lease
for _, l := range h.leasesIP {
leases = append(leases, l)
}
h.Leases(leases, lease)
}
func (h *Handler) SetHostname(hwaddr, hostname string) {
h.leasesMu.Lock()
defer h.leasesMu.Unlock()
leaseNum := h.leasesHW[hwaddr]
lease := h.leasesIP[leaseNum]
lease.Hostname = hostname
lease.HostnameOverride = hostname
h.callLeasesLocked(lease)
}
func (h *Handler) findLease() int { func (h *Handler) findLease() int {
h.leasesMu.Lock()
defer h.leasesMu.Unlock()
now := h.timeNow() now := h.timeNow()
if len(h.leasesIP) < h.leaseRange { if len(h.leasesIP) < h.leaseRange {
// TODO: hash the hwaddr like dnsmasq // TODO: hash the hwaddr like dnsmasq
@ -140,6 +168,8 @@ func (h *Handler) canLease(reqIP net.IP, hwaddr string) int {
return -1 return -1
} }
h.leasesMu.Lock()
defer h.leasesMu.Unlock()
l, ok := h.leasesIP[leaseNum] l, ok := h.leasesIP[leaseNum]
if !ok { if !ok {
return leaseNum // lease available return leaseNum // lease available
@ -156,6 +186,7 @@ func (h *Handler) canLease(reqIP net.IP, hwaddr string) int {
return -1 // lease unavailable return -1 // lease unavailable
} }
// ServeDHCP is always called from the same goroutine, so no locking is required.
func (h *Handler) ServeDHCP(p dhcp4.Packet, msgType dhcp4.MessageType, options dhcp4.Options) dhcp4.Packet { func (h *Handler) ServeDHCP(p dhcp4.Packet, msgType dhcp4.MessageType, options dhcp4.Options) dhcp4.Packet {
reply := h.serveDHCP(p, msgType, options) reply := h.serveDHCP(p, msgType, options)
if reply == nil { if reply == nil {
@ -205,6 +236,8 @@ func (h *Handler) ServeDHCP(p dhcp4.Packet, msgType dhcp4.MessageType, options d
} }
func (h *Handler) leaseHW(hwAddr string) (*Lease, bool) { func (h *Handler) leaseHW(hwAddr string) (*Lease, bool) {
h.leasesMu.Lock()
defer h.leasesMu.Unlock()
num, ok := h.leasesHW[hwAddr] num, ok := h.leasesHW[hwAddr]
if !ok { if !ok {
return nil, false return nil, false
@ -284,18 +317,16 @@ func (h *Handler) serveDHCP(p dhcp4.Packet, msgType dhcp4.MessageType, options d
} }
// Release any old leases for this client // Release any old leases for this client
h.leasesMu.Lock()
delete(h.leasesIP, l.Num) delete(h.leasesIP, l.Num)
h.leasesMu.Unlock()
} }
h.leasesMu.Lock()
defer h.leasesMu.Unlock()
h.leasesIP[leaseNum] = lease h.leasesIP[leaseNum] = lease
h.leasesHW[lease.HardwareAddr] = leaseNum h.leasesHW[lease.HardwareAddr] = leaseNum
if h.Leases != nil { h.callLeasesLocked(lease)
var leases []*Lease
for _, l := range h.leasesIP {
leases = append(leases, l)
}
h.Leases(leases, lease)
}
return dhcp4.ReplyPacket(p, dhcp4.ACK, h.serverIP, reqIP, h.LeasePeriod, return dhcp4.ReplyPacket(p, dhcp4.ACK, h.serverIP, reqIP, h.LeasePeriod,
h.options.SelectOrderOrAll(options[dhcp4.OptionParameterRequestList])) h.options.SelectOrderOrAll(options[dhcp4.OptionParameterRequestList]))
} }