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