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// Copyright 2018-present the CoreDHCP Authors. All rights reserved
// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.
// Package nbp implements handling of an NBP (Network Boot Program) using an
// URL, e.g. http://[fe80::abcd:efff:fe12:3456]/my-nbp or tftp://10.0.0.1/my-nbp .
// The NBP information is only added if it is requested by the client.
//
// Note that for DHCPv4, unless the URL is prefixed with a "http", "https" or
// "ftp" scheme, the URL will be split into TFTP server name (option 66)
// and Bootfile name (option 67), so the scheme will be stripped out, and it
// will be treated as a TFTP URL. Anything other than host name and file path
// will be ignored (no port, no query string, etc).
//
// For DHCPv6 OPT_BOOTFILE_URL (option 59) is used, and the value is passed
// unmodified. If the query string is specified and contains a "param" key,
// its value is also passed as OPT_BOOTFILE_PARAM (option 60), so it will be
// duplicated between option 59 and 60.
//
// Example usage:
//
// server6:
// - plugins:
// - nbp: http://[2001:db8:a::1]/nbp
//
// server4:
// - plugins:
// - nbp: tftp://10.0.0.254/nbp
//
package nbp
import (
"fmt"
"net/url"
"github.com/coredhcp/coredhcp/handler"
"github.com/coredhcp/coredhcp/logger"
"github.com/coredhcp/coredhcp/plugins"
"github.com/insomniacslk/dhcp/dhcpv4"
"github.com/insomniacslk/dhcp/dhcpv6"
)
var log = logger.GetLogger("plugins/nbp")
// Plugin wraps plugin registration information
var Plugin = plugins.Plugin{
Name: "nbp",
Setup6: setup6,
Setup4: setup4,
}
var (
opt59, opt60 dhcpv6.Option
opt66, opt67 *dhcpv4.Option
)
func parseArgs(args ...string) (*url.URL, error) {
if len(args) != 1 {
return nil, fmt.Errorf("Exactly one argument must be passed to NBP plugin, got %d", len(args))
}
return url.Parse(args[0])
}
func setup6(args ...string) (handler.Handler6, error) {
u, err := parseArgs(args...)
if err != nil {
return nil, err
}
opt59 = dhcpv6.OptBootFileURL(u.String())
params := u.Query().Get("params")
if params != "" {
opt60 = &dhcpv6.OptionGeneric{
OptionCode: dhcpv6.OptionBootfileParam,
OptionData: []byte(params),
}
}
log.Printf("loaded NBP plugin for DHCPv6.")
return nbpHandler6, nil
}
func setup4(args ...string) (handler.Handler4, error) {
u, err := parseArgs(args...)
if err != nil {
return nil, err
}
var otsn, obfn dhcpv4.Option
switch u.Scheme {
case "http", "https", "ftp":
obfn = dhcpv4.OptBootFileName(u.String())
default:
otsn = dhcpv4.OptTFTPServerName(u.Host)
obfn = dhcpv4.OptBootFileName(u.Path)
opt66 = &otsn
}
opt67 = &obfn
log.Printf("loaded NBP plugin for DHCPv4.")
return nbpHandler4, nil
}
func nbpHandler6(req, resp dhcpv6.DHCPv6) (dhcpv6.DHCPv6, bool) {
if opt59 == nil {
// nothing to do
return resp, true
}
decap, err := req.GetInnerMessage()
if err != nil {
log.Errorf("Could not decapsulate request: %v", err)
// drop the request, this is probably a critical error in the packet.
return nil, true
}
for _, code := range decap.Options.RequestedOptions() {
if code == dhcpv6.OptionBootfileURL {
// bootfile URL is requested
resp.AddOption(opt59)
} else if code == dhcpv6.OptionBootfileParam {
// optionally add opt60, bootfile params, if requested
if opt60 != nil {
resp.AddOption(opt60)
}
}
}
log.Debugf("Added NBP %s to request", opt59)
return resp, true
}
func nbpHandler4(req, resp *dhcpv4.DHCPv4) (*dhcpv4.DHCPv4, bool) {
if opt67 == nil {
// nothing to do
return resp, true
}
if req.IsOptionRequested(dhcpv4.OptionTFTPServerName) && opt66 != nil {
resp.Options.Update(*opt66)
log.Debugf("Added NBP %s / %s to request", opt66, opt67)
}
if req.IsOptionRequested(dhcpv4.OptionBootfileName) {
resp.Options.Update(*opt67)
log.Debugf("Added NBP %s to request", opt67)
}
return resp, true
}
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