Add /dhcp/interfaces API call to list available network interfaces.

control.go

@@ -720,6 +720,7 @@ func registerControlHandlers() {
 	http.HandleFunc("/control/safesearch/disable", optionalAuth(ensurePOST(handleSafeSearchDisable)))
 	http.HandleFunc("/control/safesearch/status", optionalAuth(ensureGET(handleSafeSearchStatus)))
 	http.HandleFunc("/control/dhcp/status", optionalAuth(ensureGET(handleDHCPStatus)))
+	http.HandleFunc("/control/dhcp/interfaces", optionalAuth(ensureGET(handleDHCPInterfaces)))
 	http.HandleFunc("/control/dhcp/set_config", optionalAuth(ensurePOST(handleDHCPSetConfig)))
 	http.HandleFunc("/control/dhcp/find_active_dhcp", optionalAuth(ensurePOST(handleDHCPFindActiveServer)))
 }

dhcp.go

@@ -3,6 +3,7 @@ package main
 import (
 	"encoding/json"
 	"math/rand"
+	"net"
 	"net/http"
 )
 
@@ -31,6 +32,76 @@ func handleDHCPSetConfig(w http.ResponseWriter, r *http.Request) {
 	config.DHCP.Config = newconfig
 }
 
+func handleDHCPInterfaces(w http.ResponseWriter, r *http.Request) {
+	response := map[string]interface{}{}
+
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		httpError(w, http.StatusInternalServerError, "Couldn't get list of interfaces: %s", err)
+		return
+	}
+
+	type address struct {
+		IP      string
+		Netmask string
+	}
+
+	type responseInterface struct {
+		Name         string
+		MTU          int
+		HardwareAddr string
+		Addresses    []string
+	}
+
+	for i := range ifaces {
+		if ifaces[i].Flags&net.FlagLoopback != 0 {
+			// it's a loopback, skip it
+			continue
+		}
+		if ifaces[i].Flags&net.FlagBroadcast == 0 {
+			// this interface doesn't support broadcast, skip it
+			continue
+		}
+		if ifaces[i].Flags&net.FlagPointToPoint != 0 {
+			// this interface is ppp, don't do dhcp over it
+			continue
+		}
+		iface := responseInterface{
+			Name:         ifaces[i].Name,
+			MTU:          ifaces[i].MTU,
+			HardwareAddr: ifaces[i].HardwareAddr.String(),
+		}
+		addrs, err := ifaces[i].Addrs()
+		if err != nil {
+			httpError(w, http.StatusInternalServerError, "Failed to get addresses for interface %v: %s", ifaces[i].Name, err)
+			return
+		}
+		for _, addr := range addrs {
+			// ip, ok := addr.(*net.IPNet)
+			// if !ok {
+			// 	// not an IP address
+			// 	continue
+			// }
+			// responseAddr := address{
+			// 	IP:      ip.IP.String(),
+			// 	Netmask: ip.Mask.String(),
+			// }
+			iface.Addresses = append(iface.Addresses, addr.String())
+		}
+		if len(iface.Addresses) == 0 {
+			// this interface has no addresses, skip it
+			continue
+		}
+		response[ifaces[i].Name] = iface
+	}
+
+	err = json.NewEncoder(w).Encode(response)
+	if err != nil {
+		httpError(w, http.StatusInternalServerError, "Failed to marshal json with available interfaces: %s", err)
+		return
+	}
+}
+
 // TODO: implement
 func handleDHCPFindActiveServer(w http.ResponseWriter, r *http.Request) {
 	found := map[string]bool{
@@ -39,7 +110,7 @@ func handleDHCPFindActiveServer(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json")
 	err := json.NewEncoder(w).Encode(found)
 	if err != nil {
-		httpError(w, http.StatusBadRequest, "Failed to marshal DHCP found json: %s", err)
+		httpError(w, http.StatusInternalServerError, "Failed to marshal DHCP found json: %s", err)
 		return
 	}
 }