hatecomputers
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hatecomputers.club
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reimplement-recursive-resolver #6

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simponic merged 2 commits from reimplement-recursive-resolver into main 2024-04-07 21:08:44 -04:00
Conversation 0 Commits 2 Files Changed 4 +232 -92
4 changed files with 232 additions and 92 deletions
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2
Dockerfile
View File

@ -11,4 +11,4 @@ RUN go build -o /app/hatecomputers
EXPOSE 8080
CMD ["/app/hatecomputers", "--server", "--migrate", "--port", "8080", "--template-path", "/app/templates", "--database-path", "/app/db/hatecomputers.db", "--static-path", "/app/static", "--scheduler", "--dns", "--dns-port", "8053"]
CMD ["/app/hatecomputers", "--server", "--migrate", "--port", "8080", "--template-path", "/app/templates", "--database-path", "/app/db/hatecomputers.db", "--static-path", "/app/static", "--scheduler", "--dns", "--dns-port", "8053", "--dns-resolvers", "1.1.1.1,1.0.0.1"]

4
args/args.go
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@ -22,6 +22,7 @@ type Arguments struct {
OauthConfig *oauth2.Config
OauthUserInfoURI string
DnsResolvers []string
Dns bool
DnsPort int
@ -36,6 +37,7 @@ func GetArgs() (*Arguments, error) {
databasePath := flag.String("database-path", "./hatecomputers.db", "Path to the SQLite database")
templatePath := flag.String("template-path", "./templates", "Path to the template directory")
staticPath := flag.String("static-path", "./static", "Path to the static directory")
dnsResolvers := flag.String("dns-resolvers", "1.1.1.1,1.0.0.1", "Comma-separated list of DNS resolvers")
scheduler := flag.Bool("scheduler", false, "Run scheduled jobs via cron")
migrate := flag.Bool("migrate", false, "Run the migrations")
@ -101,8 +103,10 @@ func GetArgs() (*Arguments, error) {
Server: *server,
Migrate: *migrate,
Scheduler: *scheduler,
Dns: *dns,
DnsPort: *dnsPort,
DnsResolvers: strings.Split(*dnsResolvers, ","),
OauthConfig: oauthConfig,
OauthUserInfoURI: oauthUserInfoURI,

184
hcdns/server.go
View File

@ -11,74 +11,139 @@ import (
const MAX_RECURSION = 15
func resolveInternalCNAMEs(dbConn *sql.DB, domain string, qtype uint16, maxDepth int) ([]dns.RR, error) {
internalCnames, err := database.FindDNSRecords(dbConn, domain, "CNAME")
if err != nil {
return nil, err
}
var answers []dns.RR
for _, record := range internalCnames {
cname, err := dns.NewRR(fmt.Sprintf("%s %d IN CNAME %s", record.Name, record.TTL, record.Content))
if err != nil {
log.Println(err)
return nil, err
}
answers = append(answers, cname)
cnameRecursive, err := resolveDNS(dbConn, record.Content, qtype, maxDepth-1)
if err != nil {
log.Println(err)
return nil, err
}
answers = append(answers, cnameRecursive...)
}
qtypeName := dns.TypeToString[qtype]
if qtypeName == "" {
return nil, fmt.Errorf("invalid query type %d", qtype)
}
typeDnsRecords, err := database.FindDNSRecords(dbConn, domain, qtypeName)
if err != nil {
return nil, err
}
for _, record := range typeDnsRecords {
answer, err := dns.NewRR(fmt.Sprintf("%s %d IN %s %s", record.Name, record.TTL, qtypeName, record.Content))
if err != nil {
return nil, err
}
answers = append(answers, answer)
}
return answers, nil
}
func resolveDNS(dbConn *sql.DB, domain string, qtype uint16, maxDepth int) ([]dns.RR, error) {
if maxDepth == 0 {
return nil, fmt.Errorf("too much recursion")
}
answers, err := resolveInternalCNAMEs(dbConn, domain, qtype, maxDepth)
if err != nil {
return nil, err
}
return answers, nil
}
type DnsHandler struct {
DnsResolvers []string
DbConn *sql.DB
}
func (h *DnsHandler) resolveExternal(domain string, qtype uint16) ([]dns.RR, error) {
client := &dns.Client{}
message := &dns.Msg{}
message.SetQuestion(dns.Fqdn(domain), qtype)
message.RecursionDesired = true
if len(h.DnsResolvers) == 0 {
return []dns.RR{}, nil
}
i := 0
in, _, err := client.Exchange(message, h.DnsResolvers[i])
for err != nil && i < len(h.DnsResolvers) {
i++
in, _, err = client.Exchange(message, h.DnsResolvers[i])
}
if err != nil {
return nil, err
}
if len(in.Answer) == 0 {
return nil, nil
}
return in.Answer, nil
}
func resultSetFound(answers []dns.RR, domain string, qtype uint16) bool {
for _, answer := range answers {
if answer.Header().Name == domain && answer.Header().Rrtype == qtype {
return true
}
}
return false
}
func (h *DnsHandler) recursiveResolve(domain string, qtype uint16, maxDepth int) ([]dns.RR, bool, error) {
internalCnames, err := database.FindDNSRecords(h.DbConn, domain, "CNAME")
if err != nil {
return nil, true, err
}
authoritative := true
var answers []dns.RR
for _, record := range internalCnames {
cname, err := dns.NewRR(fmt.Sprintf("%s %d IN CNAME %s", record.Name, record.TTL, record.Content))
if err != nil {
log.Println(err)
return nil, authoritative, err
}
answers = append(answers, cname)
cnameRecursive, cnameAuth, err := h.resolveDNS(record.Content, qtype, maxDepth-1)
if err != nil {
log.Println(err)
return nil, authoritative, err
}
authoritative = authoritative && cnameAuth
answers = append(answers, cnameRecursive...)
}
qtypeName := dns.TypeToString[qtype]
records, err := database.FindDNSRecords(h.DbConn, domain, qtypeName)
if err != nil {
return nil, authoritative, err
}
for _, record := range records {
answer, err := dns.NewRR(fmt.Sprintf("%s %d IN %s %s", record.Name, record.TTL, qtypeName, record.Content))
if err != nil {
return nil, authoritative, err
}
answers = append(answers, answer)
}
return answers, authoritative, nil
}
func (h *DnsHandler) resolveDNS(domain string, qtype uint16, maxDepth int) ([]dns.RR, bool, error) {
log.Println("resolving", domain, dns.TypeToString[qtype], maxDepth)
if maxDepth == 0 {
return nil, false, fmt.Errorf("too much recursion")
}
answers, authoritative, err := h.recursiveResolve(domain, qtype, maxDepth)
if err != nil {
return nil, false, err
}
if len(answers) > 0 { // base case - we got the answer
return answers, authoritative, nil
}
externalAnswers, err := h.resolveExternal(domain, qtype)
if err != nil {
return nil, false, err
}
answers = append(answers, externalAnswers...)
if resultSetFound(externalAnswers, domain, qtype) {
return answers, false, nil
}
for _, answer := range externalAnswers {
cname, ok := answer.(*dns.CNAME)
if !ok {
continue
}
cnameAnswers, _, err := h.resolveDNS(cname.Target, qtype, maxDepth-1)
if err != nil {
return nil, false, err
}
answers = append(answers, cnameAnswers...)
}
return answers, false, nil
}
func (h *DnsHandler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
msg := new(dns.Msg)
msg := &dns.Msg{}
msg.SetReply(r)
msg.Authoritative = true
msg.Authoritative = false
for _, question := range r.Question {
answers, err := resolveDNS(h.DbConn, question.Name, question.Qtype, MAX_RECURSION)
answers, authoritative, err := h.resolveDNS(question.Name, question.Qtype, MAX_RECURSION)
msg.Authoritative = authoritative
if err != nil {
fmt.Println(err)
msg.SetRcode(r, dns.RcodeServerFailure)
@ -99,6 +164,7 @@ func (h *DnsHandler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
func MakeServer(argv *args.Arguments, dbConn *sql.DB) *dns.Server {
handler := &DnsHandler{
DbConn: dbConn,
DnsResolvers: argv.DnsResolvers,
}
addr := fmt.Sprintf(":%d", argv.DnsPort)

124
hcdns/server_test.go
View File

@ -19,9 +19,8 @@ func randomPort() int {
return rand.Intn(3000) + 5192
}
func setup() (*sql.DB, *dns.Server, *string, *sync.Mutex, func()) {
func setup(arguments *args.Arguments) (*sql.DB, *dns.Server, string, func()) {
randomDb := utils.RandomId()
dnsPort := randomPort()
testDb := database.MakeConn(&randomDb)
database.Migrate(testDb)
@ -30,10 +29,15 @@ func setup() (*sql.DB, *dns.Server, *string, *sync.Mutex, func()) {
}
database.FindOrSaveUser(testDb, testUser)
dnsArguments := arguments
if dnsArguments == nil {
dnsArguments = &args.Arguments{
DnsPort: randomPort(),
}
}
waitLock := &sync.Mutex{}
server := hcdns.MakeServer(&args.Arguments{
DnsPort: dnsPort,
}, testDb)
server := hcdns.MakeServer(dnsArguments, testDb)
server.NotifyStartedFunc = func() {
waitLock.Unlock()
}
@ -44,8 +48,9 @@ func setup() (*sql.DB, *dns.Server, *string, *sync.Mutex, func()) {
}()
waitLock.Lock()
address := fmt.Sprintf("127.0.0.1:%d", dnsPort)
return testDb, server, &address, waitLock, func() {
address := fmt.Sprintf("127.0.0.1:%d", dnsArguments.DnsPort)
return testDb, server, address, func() {
waitLock.Unlock()
server.Shutdown()
testDb.Close()
@ -53,12 +58,86 @@ func setup() (*sql.DB, *dns.Server, *string, *sync.Mutex, func()) {
}
}
func TestWhenCNAMEIsResolved(t *testing.T) {
t.Log("TestWhenCNAMEIsResolved")
func TestWhenExternalDomain(t *testing.T) {
externalDb, _, externalAddr, externalCleanup := setup(nil)
internalDb, _, internalAddr, internalCleanup := setup(&args.Arguments{
DnsPort: randomPort(),
DnsResolvers: []string{externalAddr},
})
defer internalCleanup()
defer externalCleanup()
testDb, _, addr, lock, cleanup := setup()
authoritativeRecords := []database.DNSRecord{
{
ID: "1",
UserID: "test",
Name: "external.example.com.",
Type: "CNAME",
Content: "external.internal.example.com.",
},
}
internalRecords := []database.DNSRecord{
{
ID: "1",
UserID: "test",
Name: "external.internal.example.com.",
Type: "A",
Content: "127.0.0.1",
},
{
ID: "2",
UserID: "test",
Name: "test.internal.example.com.",
Type: "CNAME",
Content: "external.example.com.",
},
}
for _, record := range authoritativeRecords {
database.SaveDNSRecord(externalDb, &record)
}
for _, record := range internalRecords {
database.SaveDNSRecord(internalDb, &record)
}
// ensure that if the record doesn't exist in the internal database, it will
// go and query the external dns resolvers, then loop back to the internal
qtype := dns.TypeA
domain := dns.Fqdn("test.internal.example.com.")
client := &dns.Client{}
message := &dns.Msg{}
message.SetQuestion(domain, qtype)
in, _, err := client.Exchange(message, internalAddr)
if err != nil {
t.Fatal(err)
}
if len(in.Answer) != 3 {
t.Fatalf("expected 3 answers, got %d", len(in.Answer))
}
aRecord := in.Answer[2]
if aRecord.Header().Name != internalRecords[0].Name {
t.Fatalf("expected %s, got %s", domain, aRecord.Header().Name)
}
if aRecord.Header().Rrtype != dns.TypeA {
t.Fatalf("expected %s, got %s", dns.TypeToString[aRecord.Header().Rrtype], internalRecords[1].Type)
}
if aRecord.(*dns.A).A.String() != internalRecords[0].Content {
t.Fatalf("expected %s, got %s", internalRecords[0].Content, aRecord.(*dns.A).A.String())
}
if in.Authoritative {
t.Fatalf("expected non-authoritative response")
}
}
func TestWhenCNAMEIsResolved(t *testing.T) {
testDb, _, addr, cleanup := setup(nil)
defer cleanup()
defer lock.Unlock()
records := []*database.DNSRecord{
{
@ -99,7 +178,7 @@ func TestWhenCNAMEIsResolved(t *testing.T) {
message := &dns.Msg{}
message.SetQuestion(domain, qtype)
in, _, err := client.Exchange(message, *addr)
in, _, err := client.Exchange(message, addr)
if err != nil {
t.Fatal(err)
}
@ -132,11 +211,8 @@ func TestWhenCNAMEIsResolved(t *testing.T) {
}
func TestWhenNoRecordNxDomain(t *testing.T) {
t.Log("TestWhenNoRecordNxDomain")
_, _, addr, lock, cleanup := setup()
_, _, addr, cleanup := setup(nil)
defer cleanup()
defer lock.Unlock()
qtype := dns.TypeA
domain := dns.Fqdn("nonexistant.example.com.")
@ -144,7 +220,7 @@ func TestWhenNoRecordNxDomain(t *testing.T) {
message := &dns.Msg{}
message.SetQuestion(domain, qtype)
in, _, err := client.Exchange(message, *addr)
in, _, err := client.Exchange(message, addr)
if err != nil {
t.Fatal(err)
@ -160,11 +236,8 @@ func TestWhenNoRecordNxDomain(t *testing.T) {
}
func TestWhenUnresolvingCNAME(t *testing.T) {
t.Log("TestWhenUnresolvingCNAME")
testDb, _, addr, lock, cleanup := setup()
testDb, _, addr, cleanup := setup(nil)
defer cleanup()
defer lock.Unlock()
cname := &database.DNSRecord{
ID: "1",
@ -183,7 +256,7 @@ func TestWhenUnresolvingCNAME(t *testing.T) {
message := &dns.Msg{}
message.SetQuestion(domain, qtype)
in, _, err := client.Exchange(message, *addr)
in, _, err := client.Exchange(message, addr)
if err != nil {
t.Fatal(err)
@ -215,11 +288,8 @@ func TestWhenUnresolvingCNAME(t *testing.T) {
}
func TestWhenUnresolvingCNAMEWithMaxDepth(t *testing.T) {
t.Log("TestWhenUnresolvingCNAMEWithMaxDepth")
testDb, _, addr, lock, cleanup := setup()
testDb, _, addr, cleanup := setup(nil)
defer cleanup()
defer lock.Unlock()
cname := &database.DNSRecord{
ID: "1",
@ -238,7 +308,7 @@ func TestWhenUnresolvingCNAMEWithMaxDepth(t *testing.T) {
message := &dns.Msg{}
message.SetQuestion(domain, qtype)
in, _, err := client.Exchange(message, *addr)
in, _, err := client.Exchange(message, addr)
if err != nil {
t.Fatal(err)