Merge pull request #9 from OpenCHAMI/synackd/custom-script

bootloop: Add built-in reboot script, ability to specify alternate script

README.md

@@ -209,19 +209,16 @@ configured in the CoreDHCP config file.
 
 ### Preparation: TFTP
 
-Neither CoreDHCP nor this plugin provide TFTP capability, so a separate TFTP
-server is required to be running[^tftp]. The IP address that this server listens
-on should match the `server_id` directive in the CoreDHCP config file. This
-server should serve the following files:
-
-- `reboot.ipxe` --- This file is located `resources/` in this repository.
-- `ipxe.efi` --- The iPXE x86\_64 EFI bootloader. This can be found
-  [here](https://boot.ipxe.org/ipxe.efi).
-- `undionly.kpxe` --- The iPXE x86 legacy bootloader. This can be found
-  [here](https://boot.ipxe.org/undionly.kpxe).
-
-[^tftp]: [Here](https://github.com/aguslr/docker-atftpd) is one that is easy to
-    get running.
+With default configuration, no preparation is needed.
+
+Coresmd comes with a built-in TFTP server that includes iPXE bootloader binaries
+for 32-/64-bit x86/ARM (EFI) and legacy x86 CPU architectures.
+
+When using the bootloop plugin, if the boot script path is set to "default" (see
+example config file), then the built-in reboot iPXE script is used for unknown
+nodes. This can be changed to a path in TFTP to an alternate custom iPXE boot
+script if different functionality is desired. Of course, whatever path is
+specified must exist on the TFTP server.
 
 ### Running CoreDHCP
 

bootloop/main.go

@@ -41,10 +41,11 @@ type PluginState struct {
 var log = logger.GetLogger("plugins/bootloop")
 
 var (
-	ipv4Start net.IP
-	ipv4End   net.IP
-	ipv4Range int
-	p         PluginState
+	ipv4Start  net.IP
+	ipv4End    net.IP
+	ipv4Range  int
+	p          PluginState
+	scriptPath string
 )
 
 var Plugin = plugins.Plugin{
@@ -61,8 +62,8 @@ func setup4(args ...string) (handler.Handler4, error) {
 	log.Infof("initializing coresmd/bootloop %s (%s), built %s", version.Version, version.GitCommit, version.BuildTime)
 
 	// Ensure all required args were passed
-	if len(args) != 4 {
-		return nil, fmt.Errorf("wanted 4 arguments (file name, lease duration, IPv4 range start, IPv4 range end), got %d", len(args))
+	if len(args) != 5 {
+		return nil, fmt.Errorf("wanted 5 arguments (file name, iPXE script path, lease duration, IPv4 range start, IPv4 range end), got %d", len(args))
 	}
 	var err error
 
@@ -73,20 +74,26 @@ func setup4(args ...string) (handler.Handler4, error) {
 		return nil, fmt.Errorf("file path cannot be empty")
 	}
 
+	// Parse boot script path
+	scriptPath = args[1]
+	if filename == "" {
+		return nil, fmt.Errorf("script path cannot be empty; use 'default' if unsure")
+	}
+
 	// Parse short lease duration
-	p.LeaseTime, err = time.ParseDuration(args[1])
+	p.LeaseTime, err = time.ParseDuration(args[2])
 	if err != nil {
 		return nil, fmt.Errorf("failed to parse short lease duration %q: %w", args[0], err)
 	}
 
 	// Parse start IP
-	ipv4Start := net.ParseIP(args[2])
+	ipv4Start := net.ParseIP(args[3])
 	if ipv4Start.To4() == nil {
 		return nil, fmt.Errorf("invalid IPv4 address for range start: %s", args[1])
 	}
 
 	// Parse end IP
-	ipv4End := net.ParseIP(args[3])
+	ipv4End := net.ParseIP(args[4])
 	if ipv4End.To4() == nil {
 		return nil, fmt.Errorf("invalid IPv4 address for range end: %s", args[2])
 	}
@@ -173,7 +180,7 @@ func (p *PluginState) Handler4(req, resp *dhcpv4.DHCPv4) (*dhcpv4.DHCPv4, bool)
 	} else {
 		if string(cinfo) == "iPXE" {
 			// BOOT STAGE 2: Send URL to BSS boot script
-			resp.Options.Update(dhcpv4.OptBootFileName("reboot.ipxe"))
+			resp.Options.Update(dhcpv4.OptBootFileName(scriptPath))
 			resp.YourIPAddr = record.IP
 			resp.Options.Update(dhcpv4.OptIPAddressLeaseTime(p.LeaseTime.Round(time.Second)))
 		} else {
@@ -186,6 +193,7 @@ func (p *PluginState) Handler4(req, resp *dhcpv4.DHCPv4) (*dhcpv4.DHCPv4, bool)
 				dhcpv4.WithMessageType(dhcpv4.MessageTypeNak),
 				dhcpv4.WithTransactionID(req.TransactionID),
 				dhcpv4.WithHwAddr(req.ClientHWAddr),
+				dhcpv4.WithServerIP(resp.ServerIPAddr),
 			)
 			if err != nil {
 				log.Errorf("failed to create new %s message: %w", dhcpv4.MessageTypeNak, err)

coresmd/tftp.go

@@ -8,6 +8,19 @@ import (
 	"github.com/pin/tftp"
 )
 
+const defaultScriptName = "default"
+
+var defaultScript = `#!ipxe
+reboot
+`
+
+type ScriptReader struct{}
+
+func (sr ScriptReader) Read(b []byte) (int, error) {
+	nBytes := copy(b, []byte(defaultScript))
+	return nBytes, io.EOF
+}
+
 func startTFTPServer(directory string) {
 	s := tftp.NewServer(readHandler(directory), nil)
 	err := s.ListenAndServe(":69") // default TFTP port
@@ -18,6 +31,11 @@ func startTFTPServer(directory string) {
 
 func readHandler(directory string) func(string, io.ReaderFrom) error {
 	return func(filename string, rf io.ReaderFrom) error {
+		if filename == defaultScriptName {
+			var sr ScriptReader
+			_, err := rf.ReadFrom(sr)
+			return err
+		}
 		filePath := filepath.Join(directory, filename)
 		file, err := os.Open(filePath)
 		if err != nil {

resources/config.example.yaml

@@ -84,8 +84,12 @@ server4:
     # ARGUMENTS:
     #   1. Path to database file that keeps track of leased IPs. This will be
     #      created if it does not already exist.
-    #   2. Lease duration.
-    #   3. IP address beginning range.
-    #   4. IP address ending range.
+    #   2. Path of iPXE to use. If using the built-in coresmd TFTP server, if
+    #      this argument is 'default', the default reboot.ipxe script is used.
+    #      This should really only be used if it is desired to do something
+    #      custom instead of rebooting.
+    #   3. Lease duration.
+    #   4. IP address beginning range.
+    #   5. IP address ending range.
     #
-    - bootloop: /tmp/coredhcp.db 5m 172.16.0.156 172.16.0.200
+    - bootloop: /tmp/coredhcp.db default 5m 172.16.0.156 172.16.0.200