be7a5399e3
This adds a new util package with some useful functionality which could be implemented as pure mcl, but instead we add it here as a good place to help with code reuse.
111 lines
3.3 KiB
Go
111 lines
3.3 KiB
Go
// Mgmt
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// Copyright (C) 2013-2024+ James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//
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// Additional permission under GNU GPL version 3 section 7
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//
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// If you modify this program, or any covered work, by linking or combining it
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// with embedded mcl code and modules (and that the embedded mcl code and
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// modules which link with this program, contain a copy of their source code in
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// the authoritative form) containing parts covered by the terms of any other
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// license, the licensors of this program grant you additional permission to
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// convey the resulting work. Furthermore, the licensors of this program grant
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// the original author, James Shubin, additional permission to update this
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// additional permission if he deems it necessary to achieve the goals of this
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// additional permission.
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package coreutil
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import (
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"context"
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"fmt"
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"net"
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"strings"
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"github.com/purpleidea/mgmt/lang/funcs/simple"
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"github.com/purpleidea/mgmt/lang/types"
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)
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func init() {
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simple.ModuleRegister(ModuleName, "hostname_mapper", &simple.Scaffold{
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T: types.NewType("func(map{str:str}) str"),
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F: HostnameMapper,
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})
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}
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// HostnameMapper takes a map from mac address to hostname, and finds a hostname
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// that corresponds to one of the mac addresses on this machine. If it cannot
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// find a match, it returns the empty string. If it's ambiguous, it errors. This
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// is useful for bootstrapping the hostname setup on hosts.
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//
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// XXX: This should produce new values if the list of interfaces change.
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func HostnameMapper(ctx context.Context, input []types.Value) (types.Value, error) {
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ifs, err := net.Interfaces()
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if err != nil {
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return nil, err
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}
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v := input[0].Value() // interface{}
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m, ok := v.(map[string]string)
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if !ok {
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// programming error
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return nil, err
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}
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hostnamesMap := make(map[string]struct{})
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for _, iface := range ifs {
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// Check if the interface has the loopback flag set
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if iface.Flags&net.FlagLoopback != 0 {
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continue
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}
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mac := iface.HardwareAddr.String()
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// Check if the MAC address is valid.
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if len(mac) != len("00:00:00:00:00:00") {
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continue // maybe something weird we want to ignore...
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}
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hostname, exists := m[mac]
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if !exists {
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continue
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}
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if hostname == "" {
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// TODO: should we error here?
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continue
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}
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hostnamesMap[hostname] = struct{}{} // found
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}
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hostnames := []string{}
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for k := range hostnamesMap {
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hostnames = append(hostnames, k)
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}
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if len(hostnames) > 1 {
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return nil, fmt.Errorf("multiple hostnames found: %s", strings.Join(hostnames, ", "))
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}
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result := ""
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if len(hostnames) == 1 {
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result = hostnames[0]
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}
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return &types.StrValue{
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V: result,
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}, nil
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}
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