mirror of https://github.com/hashicorp/consul
347 lines
11 KiB
Go
347 lines
11 KiB
Go
// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: BUSL-1.1
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package dns
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import (
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"encoding/hex"
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"net"
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"strings"
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"github.com/miekg/dns"
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"github.com/hashicorp/go-hclog"
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"github.com/hashicorp/consul/acl"
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"github.com/hashicorp/consul/agent/discovery"
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"github.com/hashicorp/consul/agent/structs"
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"github.com/hashicorp/consul/internal/dnsutil"
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)
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// discoveryResultsFetcher is a facade for the DNS router to formulate
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// and execute discovery queries.
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type discoveryResultsFetcher struct{}
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// getQueryOptions is a struct to hold the options for getQueryResults method.
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type getQueryOptions struct {
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req *dns.Msg
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reqCtx Context
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qName string
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remoteAddress net.Addr
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processor DiscoveryQueryProcessor
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logger hclog.Logger
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domain string
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altDomain string
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}
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// getQueryResults returns a discovery.Result from a DNS message.
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func (d discoveryResultsFetcher) getQueryResults(opts *getQueryOptions) ([]*discovery.Result, *discovery.Query, error) {
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reqType := parseRequestType(opts.req)
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switch reqType {
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case requestTypeConsul:
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// This is a special case of discovery.QueryByName where we know that we need to query the consul service
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// regardless of the question name.
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query := &discovery.Query{
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QueryType: discovery.QueryTypeService,
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QueryPayload: discovery.QueryPayload{
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Name: structs.ConsulServiceName,
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Tenancy: discovery.QueryTenancy{
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// We specify the partition here so that in the case we are a client agent in a non-default partition.
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// We don't want the query processors default partition to be used.
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// This is a small hack because for V1 CE, this is not the correct default partition name, but we
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// need to add something to disambiguate the empty field.
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Partition: acl.DefaultPartitionName, //NOTE: note this won't work if we ever have V2 client agents
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},
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Limit: 3,
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},
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}
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results, err := opts.processor.QueryByName(query, discovery.Context{Token: opts.reqCtx.Token})
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return results, query, err
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case requestTypeName:
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query, err := buildQueryFromDNSMessage(opts.req, opts.reqCtx, opts.domain, opts.altDomain, opts.remoteAddress)
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if err != nil {
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opts.logger.Error("error building discovery query from DNS request", "error", err)
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return nil, query, err
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}
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results, err := opts.processor.QueryByName(query, discovery.Context{Token: opts.reqCtx.Token})
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if getErrorFromECSNotGlobalError(err) != nil {
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opts.logger.Error("error processing discovery query", "error", err)
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return nil, query, err
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}
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return results, query, err
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case requestTypeIP:
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ip := dnsutil.IPFromARPA(opts.qName)
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if ip == nil {
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opts.logger.Error("error building IP from DNS request", "name", opts.qName)
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return nil, nil, errNameNotFound
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}
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results, err := opts.processor.QueryByIP(ip, discovery.Context{Token: opts.reqCtx.Token})
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return results, nil, err
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case requestTypeAddress:
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results, err := buildAddressResults(opts.req)
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if err != nil {
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opts.logger.Error("error processing discovery query", "error", err)
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return nil, nil, err
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}
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return results, nil, nil
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}
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opts.logger.Error("error parsing discovery query type", "requestType", reqType)
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return nil, nil, errInvalidQuestion
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}
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// buildQueryFromDNSMessage returns a discovery.Query from a DNS message.
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func buildQueryFromDNSMessage(req *dns.Msg, reqCtx Context, domain, altDomain string,
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remoteAddress net.Addr) (*discovery.Query, error) {
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queryType, queryParts, querySuffixes := getQueryTypePartsAndSuffixesFromDNSMessage(req, domain, altDomain)
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queryTenancy, err := getQueryTenancy(reqCtx, queryType, querySuffixes)
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if err != nil {
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return nil, err
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}
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name, tag := getQueryNameAndTagFromParts(queryType, queryParts)
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portName := parsePort(queryParts)
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switch {
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case queryType == discovery.QueryTypeWorkload && req.Question[0].Qtype == dns.TypeSRV:
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// Currently we do not support SRV records for workloads
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return nil, errNotImplemented
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case queryType == discovery.QueryTypeInvalid, name == "":
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return nil, errInvalidQuestion
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}
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return &discovery.Query{
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QueryType: queryType,
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QueryPayload: discovery.QueryPayload{
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Name: name,
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Tenancy: queryTenancy,
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Tag: tag,
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PortName: portName,
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SourceIP: getSourceIP(req, queryType, remoteAddress),
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},
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}, nil
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}
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// buildAddressResults returns a discovery.Result from a DNS request for addr. records.
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func buildAddressResults(req *dns.Msg) ([]*discovery.Result, error) {
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domain := dns.CanonicalName(req.Question[0].Name)
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labels := dns.SplitDomainName(domain)
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hexadecimal := labels[0]
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if len(hexadecimal)/2 != 4 && len(hexadecimal)/2 != 16 {
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return nil, errNameNotFound
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}
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var ip net.IP
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ip, err := hex.DecodeString(hexadecimal)
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if err != nil {
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return nil, errNameNotFound
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}
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return []*discovery.Result{
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{
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Node: &discovery.Location{
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Address: ip.String(),
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},
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Type: discovery.ResultTypeNode, // We choose node by convention since we do not know the origin of the IP
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},
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}, nil
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}
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// getQueryNameAndTagFromParts returns the query name and tag from the query parts that are taken from the original dns question.
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func getQueryNameAndTagFromParts(queryType discovery.QueryType, queryParts []string) (string, string) {
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n := len(queryParts)
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if n == 0 {
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return "", ""
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}
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switch queryType {
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case discovery.QueryTypeService:
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// Support RFC 2782 style syntax
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if n == 2 && strings.HasPrefix(queryParts[1], "_") && strings.HasPrefix(queryParts[0], "_") {
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// Grab the tag since we make nuke it if it's tcp
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tag := queryParts[1][1:]
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// Treat _name._tcp.service.consul as a default, no need to filter on that tag
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if tag == "tcp" {
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tag = ""
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}
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name := queryParts[0][1:]
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// _name._tag.service.consul
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return name, tag
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}
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return queryParts[n-1], ""
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case discovery.QueryTypePreparedQuery:
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name := ""
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// If the first and last DNS query parts begin with _, this is an RFC 2782 style SRV lookup.
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// This allows for prepared query names to include "." (for backwards compatibility).
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// Otherwise, this is a standard prepared query lookup.
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if n >= 2 && strings.HasPrefix(queryParts[0], "_") && strings.HasPrefix(queryParts[n-1], "_") {
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// The last DNS query part is the protocol field (ignored).
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// All prior parts are the prepared query name or ID.
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name = strings.Join(queryParts[:n-1], ".")
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// Strip leading underscore
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name = name[1:]
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} else {
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// Allow a "." in the query name, just join all the parts.
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name = strings.Join(queryParts, ".")
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}
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return name, ""
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}
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return queryParts[n-1], ""
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}
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// getQueryTenancy returns a discovery.QueryTenancy from a DNS message.
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func getQueryTenancy(reqCtx Context, queryType discovery.QueryType, querySuffixes []string) (discovery.QueryTenancy, error) {
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labels, ok := parseLabels(querySuffixes)
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if !ok {
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return discovery.QueryTenancy{}, errNameNotFound
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}
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// If we don't have an explicit partition in the request, try the first fallback
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// which was supplied in the request context. The agent's partition will be used as the last fallback
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// later in the query processor.
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if labels.Partition == "" {
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labels.Partition = reqCtx.DefaultPartition
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}
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// If we have a sameness group, we can return early without further data massage.
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if labels.SamenessGroup != "" {
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return discovery.QueryTenancy{
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Namespace: labels.Namespace,
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Partition: labels.Partition,
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SamenessGroup: labels.SamenessGroup,
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Datacenter: reqCtx.DefaultDatacenter,
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}, nil
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}
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if queryType == discovery.QueryTypeVirtual {
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if labels.Peer == "" {
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// If the peer name was not explicitly defined, fall back to the ambiguously-parsed version.
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labels.Peer = labels.PeerOrDatacenter
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}
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}
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return discovery.QueryTenancy{
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Namespace: labels.Namespace,
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Partition: labels.Partition,
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Peer: labels.Peer,
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Datacenter: getEffectiveDatacenter(labels, reqCtx.DefaultDatacenter),
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}, nil
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}
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// getEffectiveDatacenter returns the effective datacenter from the parsed labels.
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func getEffectiveDatacenter(labels *parsedLabels, defaultDC string) string {
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switch {
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case labels.Datacenter != "":
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return labels.Datacenter
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case labels.PeerOrDatacenter != "" && labels.Peer != labels.PeerOrDatacenter:
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return labels.PeerOrDatacenter
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}
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return defaultDC
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}
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// getQueryTypePartsAndSuffixesFromDNSMessage returns the query type, the parts, and suffixes of the query name.
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func getQueryTypePartsAndSuffixesFromDNSMessage(req *dns.Msg, domain, altDomain string) (queryType discovery.QueryType, parts []string, suffixes []string) {
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// Get the QName without the domain suffix
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// TODO (v2-dns): we will also need to handle the "failover" and "no-failover" suffixes here.
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// They come AFTER the domain. See `stripAnyFailoverSuffix` in router.go
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qName := trimDomainFromQuestionName(req.Question[0].Name, domain, altDomain)
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// Split into the label parts
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labels := dns.SplitDomainName(qName)
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done := false
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for i := len(labels) - 1; i >= 0 && !done; i-- {
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queryType = getQueryTypeFromLabels(labels[i])
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switch queryType {
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case discovery.QueryTypeService, discovery.QueryTypeWorkload,
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discovery.QueryTypeConnect, discovery.QueryTypeVirtual, discovery.QueryTypeIngress,
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discovery.QueryTypeNode, discovery.QueryTypePreparedQuery:
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parts = labels[:i]
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suffixes = labels[i+1:]
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done = true
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case discovery.QueryTypeInvalid:
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fallthrough
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default:
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// If this is a SRV query the "service" label is optional, we add it back to use the
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// existing code-path.
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if req.Question[0].Qtype == dns.TypeSRV && strings.HasPrefix(labels[i], "_") {
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queryType = discovery.QueryTypeService
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parts = labels[:i+1]
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suffixes = labels[i+1:]
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done = true
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}
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}
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}
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return queryType, parts, suffixes
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}
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// trimDomainFromQuestionName returns the question name without the domain suffix.
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func trimDomainFromQuestionName(questionName, domain, altDomain string) string {
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qName := dns.CanonicalName(questionName)
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longer := domain
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shorter := altDomain
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if len(shorter) > len(longer) {
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longer, shorter = shorter, longer
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}
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if strings.HasSuffix(qName, "."+strings.TrimLeft(longer, ".")) {
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return strings.TrimSuffix(qName, longer)
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}
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return strings.TrimSuffix(qName, shorter)
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}
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// getQueryTypeFromLabels returns the query type from the labels.
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func getQueryTypeFromLabels(label string) discovery.QueryType {
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switch label {
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case "service":
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return discovery.QueryTypeService
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case "connect":
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return discovery.QueryTypeConnect
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case "virtual":
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return discovery.QueryTypeVirtual
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case "ingress":
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return discovery.QueryTypeIngress
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case "node":
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return discovery.QueryTypeNode
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case "query":
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return discovery.QueryTypePreparedQuery
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case "workload":
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return discovery.QueryTypeWorkload
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default:
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return discovery.QueryTypeInvalid
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}
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}
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// getSourceIP returns the source IP from the dns request.
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func getSourceIP(req *dns.Msg, queryType discovery.QueryType, remoteAddr net.Addr) (sourceIP net.IP) {
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if queryType == discovery.QueryTypePreparedQuery {
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subnet := ednsSubnetForRequest(req)
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if subnet != nil {
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sourceIP = subnet.Address
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} else {
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switch v := remoteAddr.(type) {
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case *net.UDPAddr:
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sourceIP = v.IP
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case *net.TCPAddr:
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sourceIP = v.IP
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case *net.IPAddr:
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sourceIP = v.IP
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}
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}
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}
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return sourceIP
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}
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