go-ap / client / #75

Committed 23 Jul 2026 11:50AM UTC coverage: 76.66% (-0.2%) from 76.873%

Build # #75

Build Type

push

sourcehut

Committed by

mariusor

Commit Message

Add a logger function to the s2s authorization logic

Coverage Stats

6 of 11 new or added lines in 1 file covered. (54.55%)

716 of 934 relevant lines covered (76.66%)

6.94 hits per line

Source File
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62.55

/s2s/httpsignatures.go

package s2s

import (
        "bytes"
        "context"
        "crypto"
        "crypto/ecdsa"
        "crypto/ed25519"
        "crypto/rsa"
        "crypto/x509"
        "encoding/pem"
        "io"
        "net/http"
        "slices"

        rfc "github.com/dadrus/httpsig"
        vocab "github.com/go-ap/activitypub"
        "github.com/go-ap/errors"
        draft "github.com/go-fed/httpsig"
)

type Signer struct {
        // RFC9421 relevant data
        nonceFn           noncer
        coveredComponents []string
        // tag is an application-specific tag for the signature as a String value.
        // This value is used by applications to help identify signatures relevant for specific applications or protocols.
        // See: https://www.rfc-editor.org/rfc/rfc9421.html#section-2.3-4.12
        tag string

        Alg   KeyEncoding
        Key   crypto.PrivateKey
        Actor *vocab.Actor

        lFn func(string, ...any)
}

func (s *Signer) logFn(f string, p ...any) {
        if s.lFn == nil {
                return
        }
        s.lFn(f, p...)
}

type OptionFn func(transport *Signer)

func WithNonce(nonceFn func() (string, error)) OptionFn {
        return func(h *Signer) {
                h.nonceFn = nonceFn
        }
}

func WithCoveredComponents(comp ...string) OptionFn {
        return func(h *Signer) {
                h.coveredComponents = comp
        }
}

func WithLogFn(fn func(string, ...any)) OptionFn {
        return func(h *Signer) {
                h.lFn = fn
        }
}

func WithAlg(alg KeyEncoding) OptionFn {
        return func(h *Signer) {
                h.Alg = alg
        }
}

func WithActor(act *vocab.Actor, prv crypto.PrivateKey) OptionFn {
        return func(h *Signer) {
                h.Actor = act
                h.Key = prv
        }
}

func WithApplicationTag(t string) OptionFn {
        return func(h *Signer) {
                h.tag = t
        }
}

// New initializes the Signer
// that might come from the initialization functions.
func New(initFns ...OptionFn) *Signer {
        h := new(Signer)
        for _, fn := range initFns {
                fn(h)
        }
        return h
}

type noncer func() (string, error)

func (n noncer) GetNonce(_ context.Context) (string, error) {
        return n()
}

func validateActorPublicKey(key crypto.PrivateKey, actorPubKey crypto.PublicKey) error {
        switch pk := key.(type) {
        case *rsa.PrivateKey:
                pub := &pk.PublicKey
                if !pub.Equal(actorPubKey) {
                        return keyMismatchErr(pk, actorPubKey)
                }
        case *ecdsa.PrivateKey:
                pub, ok := pk.Public().(*ecdsa.PublicKey)
                if !ok || !pub.Equal(actorPubKey) {
                        return keyMismatchErr(pk, actorPubKey)
                }
        case ed25519.PrivateKey:
                pub, _ := pk.Public().(ed25519.PublicKey)
                if !pub.Equal(actorPubKey) {
                        return keyMismatchErr(pk, actorPubKey)
                }
        }
        return nil
}

func rfcAlgorithmFromPrivateKey(key crypto.PrivateKey, typ KeyEncoding) rfc.SignatureAlgorithm {
        // NOTE(marius): I'm not sure what purpose it serves to validate the public key of the actor
        // against the private key
        var alg rfc.SignatureAlgorithm = ""

        switch pk := key.(type) {
        case *rsa.PrivateKey:
                switch pk.Size() {
                case 128, 256:
                        switch typ {
                        case KeyTypePSS:
                                alg = rfc.RsaPssSha256
                        case KeyTypePKCS:
                                fallthrough
                        default:
                                alg = rfc.RsaPkcs1v15Sha256
                        }
                case 384:
                        switch typ {
                        case KeyTypePSS:
                                alg = rfc.RsaPssSha384
                        case KeyTypePKCS:
                                fallthrough
                        default:
                                alg = rfc.RsaPkcs1v15Sha384
                        }
                case 512:
                        switch typ {
                        case KeyTypePSS:
                                alg = rfc.RsaPssSha512
                        case KeyTypePKCS:
                                fallthrough
                        default:
                                alg = rfc.RsaPkcs1v15Sha512
                        }
                }
        case *ecdsa.PrivateKey:
                if p := pk.Params(); p != nil {
                        switch p.BitSize {
                        case 128, 256:
                                alg = rfc.EcdsaP256Sha256
                        case 384:
                                alg = rfc.EcdsaP384Sha384
                        case 512:
                                alg = rfc.EcdsaP521Sha512
                        }
                }
        case ed25519.PrivateKey:
                alg = rfc.Ed25519
        }
        return alg
}

func (s *Signer) signRequestRFC(coveredComponents []string) func(req *http.Request) error {
        return func(req *http.Request) error {
                if s.Actor == nil {
                        return errors.Newf("unable to sign request, Actor is invalid")
                }
                if s.Key == nil {
                        return errors.Newf("unable to sign request, private key is invalid")
                }
                s.logFn("Signing request: %s", s.Actor.ID)

                pubKey, err := toCryptoPublicKey(s.Actor.PublicKey)
                if err != nil {
                        return errors.Annotatef(err, "unable to sign request, unable to validate the Actor's public key")
                }
                if err = validateActorPublicKey(s.Key, pubKey); err != nil {
                        return errors.Annotatef(err, "unable to sign request, Actor public key does not match it's private key")
                }

                key := rfc.Key{
                        KeyID:     string(s.Actor.PublicKey.ID),
                        Algorithm: rfcAlgorithmFromPrivateKey(s.Key, s.Alg),
                        Key:       s.Key,
                }

                initFns := []rfc.SignerOption{
                        rfc.WithTTL(sigValidDuration),
                }

                if s.tag != "" {
                        initFns = append(initFns, rfc.WithTag(s.tag))
                }

                if coveredComponents != nil {
                        initFns = append(initFns, rfc.WithComponents(coveredComponents...))
                }
                if req.Method == http.MethodPost {
                        initFns = append(initFns, rfc.WithContentDigestAlgorithm(rfc.Sha256))
                }
                if s.nonceFn != nil {
                        initFns = append(initFns, rfc.WithNonce(s.nonceFn))
                }
                signer, err := rfc.NewSigner(key, initFns...)
                if err != nil {
                        return err
                }
                msg := rfc.MessageFromRequest(req)
                // NOTE(marius): for some fetch requests, we have a non empty fragment
                // I'm not clear if this case is handled correctly on the verifier side.
                //if msg.URL.Fragment != "" {
                //        req.URL.Fragment = ""
                //}
                postSignHeaders, err := signer.Sign(msg)
                if err != nil {
                        return err
                }
                req.Header = postSignHeaders
                return nil
        }
}

type KeyEncoding int

const (
        KeyTypeUnknown KeyEncoding = 0
        KeyTypePKCS    KeyEncoding = 1
        KeyTypePSS     KeyEncoding = 2
)

func toCryptoPublicKey(key vocab.PublicKey) (crypto.PublicKey, error) {
        pubBytes, _ := pem.Decode([]byte(key.PublicKeyPem))
        if pubBytes == nil {
                return nil, errors.Newf("unable to decode PEM payload for public key")
        }
        pk, _ := x509.ParsePKIXPublicKey(pubBytes.Bytes)
        if pk != nil {
                return pk, nil
        }
        pk, err := x509.ParsePKCS1PublicKey(pubBytes.Bytes)
        return pk, err
}

func keyMismatchErr(pk crypto.PrivateKey, pub crypto.PublicKey) error {
        return errors.Newf("unable to sign request, mismatch between the Actor's public and private key: %T : %T", pub, pk)
}

func draftAlgorithmFromPrivateKey(prv crypto.PrivateKey) draft.Algorithm {
        switch pk := prv.(type) {
        case *rsa.PrivateKey:
                switch pk.Size() {
                case 128, 256:
                        return draft.RSA_SHA256
                case 384:
                        return draft.RSA_SHA384
                case 512:
                        return draft.RSA_SHA512
                }
        case *ecdsa.PrivateKey:
                if p := pk.Params(); p != nil {
                        switch p.BitSize {
                        case 128, 256:
                                return draft.ECDSA_SHA256
                        case 384:
                                return draft.ECDSA_SHA384
                        case 512:
                                return draft.ECDSA_SHA512
                        }
                }
        case ed25519.PrivateKey:
                return draft.ED25519
        }
        return ""
}

func (s *Signer) signRequestDraft(req *http.Request) error {
        if s.Actor == nil {
                return errors.Newf("unable to sign request, Actor is invalid")
        }
        if s.Key == nil {
                return errors.Newf("unable to sign request, private key is invalid")
        }
        if !s.Actor.PublicKey.ID.IsValid() {
                return errors.Newf("unable to sign request, invalid Actor public key ID")
        }
        s.logFn("Signing request: %s", s.Actor.ID)

        keyID := s.Actor.PublicKey.ID

        headers := HeadersToSign
        bodyBuf := bytes.Buffer{}
        if req.Body != nil {
                if _, err := io.Copy(&bodyBuf, req.Body); err == nil {
                        req.Body = io.NopCloser(&bodyBuf)
                        if bodyBuf.Len() > 0 {
                                headers = append(HeadersToSign, "digest")
                        }
                }
        }

        algo := draftAlgorithmFromPrivateKey(s.Key)
        secToExpiration := int64(sigValidDuration.Seconds())
        // NOTE(marius): The only http-signatures accepted by Mastodon instances is "Signature", not "Authorization"
        sig, _, err := draft.NewSigner([]draft.Algorithm{algo}, draft.DigestSha256, headers, draft.Signature, secToExpiration)
        if err != nil {
                return err
        }
        return sig.SignRequest(s.Key, string(keyID), req, bodyBuf.Bytes())
}

func (s *Signer) SignRFC9421(req *http.Request) error {
        coveredComponents := s.coveredComponents
        if coveredComponents == nil {
                // NOTE(marius): ideally the caller knows if we're about to sign a Fetch or not,
                // and provide all necessary covered components at initialization time.
                coveredComponents = FetchCoveredComponents
                if !slices.Contains([]string{http.MethodGet, http.MethodHead}, req.Method) {
                        coveredComponents = append(coveredComponents, AdditionalPostCoveredComponents...)
                }
        }
        return s.signRequestRFC(coveredComponents)(req)
}

func (s *Signer) SignDraft(req *http.Request) error {
        return s.signRequestDraft(req)
}

1	package s2s
2
3	import (
4	"bytes"
5	"context"
6	"crypto"
7	"crypto/ecdsa"
8	"crypto/ed25519"
9	"crypto/rsa"
10	"crypto/x509"
11	"encoding/pem"
12	"io"
13	"net/http"
14	"slices"
15
16	rfc "github.com/dadrus/httpsig"
17	vocab "github.com/go-ap/activitypub"
18	"github.com/go-ap/errors"
19	draft "github.com/go-fed/httpsig"
20	)
21
22	type Signer struct {
23	// RFC9421 relevant data
24	nonceFn noncer
25	coveredComponents []string
26	// tag is an application-specific tag for the signature as a String value.
27	// This value is used by applications to help identify signatures relevant for specific applications or protocols.
28	// See: https://www.rfc-editor.org/rfc/rfc9421.html#section-2.3-4.12
29	tag string
30
31	Alg KeyEncoding
32	Key crypto.PrivateKey
33	Actor *vocab.Actor
34
35	lFn func(string, ...any)
36	}
37
38	func (s *Signer) logFn(f string, p ...any) {	2✔
39	if s.lFn == nil {	4✔
40	return	2✔
41	}	2✔
NEW 42	s.lFn(f, p...)	×
43	}
44
45	type OptionFn func(transport *Signer)
46
47	func WithNonce(nonceFn func() (string, error)) OptionFn {	1✔
48	return func(h *Signer) {	2✔
49	h.nonceFn = nonceFn	1✔
50	}	1✔
51	}
52
53	func WithCoveredComponents(comp ...string) OptionFn {	1✔
54	return func(h *Signer) {	2✔
55	h.coveredComponents = comp	1✔
56	}	1✔
57	}
58
NEW 59	func WithLogFn(fn func(string, ...any)) OptionFn {	×
NEW 60	return func(h *Signer) {	×
NEW 61	h.lFn = fn	×
NEW 62	}	×
63	}
64
65	func WithAlg(alg KeyEncoding) OptionFn {	1✔
66	return func(h *Signer) {	2✔
67	h.Alg = alg	1✔
68	}	1✔
69	}
70
71	func WithActor(act *vocab.Actor, prv crypto.PrivateKey) OptionFn {	10✔
72	return func(h *Signer) {	20✔
73	h.Actor = act	10✔
74	h.Key = prv	10✔
75	}	10✔
76	}
77
78	func WithApplicationTag(t string) OptionFn {	2✔
79	return func(h *Signer) {	4✔
80	h.tag = t	2✔
81	}	2✔
82	}
83
84	// New initializes the Signer
85	// that might come from the initialization functions.
86	func New(initFns ...OptionFn) *Signer {	4✔
87	h := new(Signer)	4✔
88	for _, fn := range initFns {	9✔
89	fn(h)	5✔
90	}	5✔
91	return h	4✔
92	}
93
94	type noncer func() (string, error)
95
96	func (n noncer) GetNonce(_ context.Context) (string, error) {	1✔
97	return n()	1✔
98	}	1✔
99
100	func validateActorPublicKey(key crypto.PrivateKey, actorPubKey crypto.PublicKey) error {	1✔
101	switch pk := key.(type) {	1✔
102	case *rsa.PrivateKey:	1✔
103	pub := &pk.PublicKey	1✔
104	if !pub.Equal(actorPubKey) {	1✔
105	return keyMismatchErr(pk, actorPubKey)	×
106	}	×
107	case *ecdsa.PrivateKey:	×
108	pub, ok := pk.Public().(*ecdsa.PublicKey)	×
109	if !ok \|\| !pub.Equal(actorPubKey) {	×
110	return keyMismatchErr(pk, actorPubKey)	×
111	}	×
112	case ed25519.PrivateKey:	×
113	pub, _ := pk.Public().(ed25519.PublicKey)	×
114	if !pub.Equal(actorPubKey) {	×
115	return keyMismatchErr(pk, actorPubKey)	×
116	}	×
117	}
118	return nil	1✔
119	}
120
121	func rfcAlgorithmFromPrivateKey(key crypto.PrivateKey, typ KeyEncoding) rfc.SignatureAlgorithm {	2✔
122	// NOTE(marius): I'm not sure what purpose it serves to validate the public key of the actor	2✔
123	// against the private key	2✔
124	var alg rfc.SignatureAlgorithm = ""	2✔
125		2✔
126	switch pk := key.(type) {	2✔
127	case *rsa.PrivateKey:	1✔
128	switch pk.Size() {	1✔
129	case 128, 256:	1✔
130	switch typ {	1✔
131	case KeyTypePSS:	×
132	alg = rfc.RsaPssSha256	×
133	case KeyTypePKCS:	1✔
134	fallthrough	1✔
135	default:	1✔
136	alg = rfc.RsaPkcs1v15Sha256	1✔
137	}
138	case 384:	×
139	switch typ {	×
140	case KeyTypePSS:	×
141	alg = rfc.RsaPssSha384	×
142	case KeyTypePKCS:	×
143	fallthrough	×
144	default:	×
145	alg = rfc.RsaPkcs1v15Sha384	×
146	}
147	case 512:	×
148	switch typ {	×
149	case KeyTypePSS:	×
150	alg = rfc.RsaPssSha512	×
151	case KeyTypePKCS:	×
152	fallthrough	×
153	default:	×
154	alg = rfc.RsaPkcs1v15Sha512	×
155	}
156	}
157	case *ecdsa.PrivateKey:	×
158	if p := pk.Params(); p != nil {	×
159	switch p.BitSize {	×
160	case 128, 256:	×
161	alg = rfc.EcdsaP256Sha256	×
162	case 384:	×
163	alg = rfc.EcdsaP384Sha384	×
164	case 512:	×
165	alg = rfc.EcdsaP521Sha512	×
166	}
167	}
168	case ed25519.PrivateKey:	×
169	alg = rfc.Ed25519	×
170	}
171	return alg	2✔
172	}
173
174	func (s Signer) signRequestRFC(coveredComponents []string) func(req http.Request) error {	2✔
175	return func(req *http.Request) error {	4✔
176	if s.Actor == nil {	3✔
177	return errors.Newf("unable to sign request, Actor is invalid")	1✔
178	}	1✔
179	if s.Key == nil {	1✔
180	return errors.Newf("unable to sign request, private key is invalid")	×
181	}	×
182	s.logFn("Signing request: %s", s.Actor.ID)	1✔
183		1✔
184	pubKey, err := toCryptoPublicKey(s.Actor.PublicKey)	1✔
185	if err != nil {	1✔
186	return errors.Annotatef(err, "unable to sign request, unable to validate the Actor's public key")	×
187	}	×
188	if err = validateActorPublicKey(s.Key, pubKey); err != nil {	1✔
189	return errors.Annotatef(err, "unable to sign request, Actor public key does not match it's private key")	×
190	}	×
191
192	key := rfc.Key{	1✔
193	KeyID: string(s.Actor.PublicKey.ID),	1✔
194	Algorithm: rfcAlgorithmFromPrivateKey(s.Key, s.Alg),	1✔
195	Key: s.Key,	1✔
196	}	1✔
197		1✔
198	initFns := []rfc.SignerOption{	1✔
199	rfc.WithTTL(sigValidDuration),	1✔
200	}	1✔
201		1✔
202	if s.tag != "" {	1✔
203	initFns = append(initFns, rfc.WithTag(s.tag))	×
204	}	×
205
206	if coveredComponents != nil {	2✔
207	initFns = append(initFns, rfc.WithComponents(coveredComponents...))	1✔
208	}	1✔
209	if req.Method == http.MethodPost {	2✔
210	initFns = append(initFns, rfc.WithContentDigestAlgorithm(rfc.Sha256))	1✔
211	}	1✔
212	if s.nonceFn != nil {	2✔
213	initFns = append(initFns, rfc.WithNonce(s.nonceFn))	1✔
214	}	1✔
215	signer, err := rfc.NewSigner(key, initFns...)	1✔
216	if err != nil {	1✔
217	return err	×
218	}	×
219	msg := rfc.MessageFromRequest(req)	1✔
220	// NOTE(marius): for some fetch requests, we have a non empty fragment	1✔
221	// I'm not clear if this case is handled correctly on the verifier side.	1✔
222	//if msg.URL.Fragment != "" {	1✔
223	// req.URL.Fragment = ""	1✔
224	//}	1✔
225	postSignHeaders, err := signer.Sign(msg)	1✔
226	if err != nil {	1✔
227	return err	×
228	}	×
229	req.Header = postSignHeaders	1✔
230	return nil	1✔
231	}
232	}
233
234	type KeyEncoding int
235
236	const (
237	KeyTypeUnknown KeyEncoding = 0
238	KeyTypePKCS KeyEncoding = 1
239	KeyTypePSS KeyEncoding = 2
240	)
241
242	func toCryptoPublicKey(key vocab.PublicKey) (crypto.PublicKey, error) {	1✔
243	pubBytes, _ := pem.Decode([]byte(key.PublicKeyPem))	1✔
244	if pubBytes == nil {	1✔
245	return nil, errors.Newf("unable to decode PEM payload for public key")	×
246	}	×
247	pk, _ := x509.ParsePKIXPublicKey(pubBytes.Bytes)	1✔
248	if pk != nil {	1✔
249	return pk, nil	×
250	}	×
251	pk, err := x509.ParsePKCS1PublicKey(pubBytes.Bytes)	1✔
252	return pk, err	1✔
253	}
254
255	func keyMismatchErr(pk crypto.PrivateKey, pub crypto.PublicKey) error {	×
256	return errors.Newf("unable to sign request, mismatch between the Actor's public and private key: %T : %T", pub, pk)	×
257	}	×
258
259	func draftAlgorithmFromPrivateKey(prv crypto.PrivateKey) draft.Algorithm {	2✔
260	switch pk := prv.(type) {	2✔
261	case *rsa.PrivateKey:	1✔
262	switch pk.Size() {	1✔
263	case 128, 256:	1✔
264	return draft.RSA_SHA256	1✔
265	case 384:	×
266	return draft.RSA_SHA384	×
267	case 512:	×
268	return draft.RSA_SHA512	×
269	}
270	case *ecdsa.PrivateKey:	×
271	if p := pk.Params(); p != nil {	×
272	switch p.BitSize {	×
273	case 128, 256:	×
274	return draft.ECDSA_SHA256	×
275	case 384:	×
276	return draft.ECDSA_SHA384	×
277	case 512:	×
278	return draft.ECDSA_SHA512	×
279	}
280	}
281	case ed25519.PrivateKey:	×
282	return draft.ED25519	×
283	}
284	return ""	1✔
285	}
286
287	func (s Signer) signRequestDraft(req http.Request) error {	2✔
288	if s.Actor == nil {	3✔
289	return errors.Newf("unable to sign request, Actor is invalid")	1✔
290	}	1✔
291	if s.Key == nil {	1✔
292	return errors.Newf("unable to sign request, private key is invalid")	×
293	}	×
294	if !s.Actor.PublicKey.ID.IsValid() {	1✔
295	return errors.Newf("unable to sign request, invalid Actor public key ID")	×
296	}	×
297	s.logFn("Signing request: %s", s.Actor.ID)	1✔
298		1✔
299	keyID := s.Actor.PublicKey.ID	1✔
300		1✔
301	headers := HeadersToSign	1✔
302	bodyBuf := bytes.Buffer{}	1✔
303	if req.Body != nil {	2✔
304	if _, err := io.Copy(&bodyBuf, req.Body); err == nil {	2✔
305	req.Body = io.NopCloser(&bodyBuf)	1✔
306	if bodyBuf.Len() > 0 {	1✔
307	headers = append(HeadersToSign, "digest")	×
308	}	×
309	}
310	}
311
312	algo := draftAlgorithmFromPrivateKey(s.Key)	1✔
313	secToExpiration := int64(sigValidDuration.Seconds())	1✔
314	// NOTE(marius): The only http-signatures accepted by Mastodon instances is "Signature", not "Authorization"	1✔
315	sig, _, err := draft.NewSigner([]draft.Algorithm{algo}, draft.DigestSha256, headers, draft.Signature, secToExpiration)	1✔
316	if err != nil {	1✔
317	return err	×
318	}	×
319	return sig.SignRequest(s.Key, string(keyID), req, bodyBuf.Bytes())	1✔
320	}
321
322	func (s Signer) SignRFC9421(req http.Request) error {	2✔
323	coveredComponents := s.coveredComponents	2✔
324	if coveredComponents == nil {	4✔
325	// NOTE(marius): ideally the caller knows if we're about to sign a Fetch or not,	2✔
326	// and provide all necessary covered components at initialization time.	2✔
327	coveredComponents = FetchCoveredComponents	2✔
328	if !slices.Contains([]string{http.MethodGet, http.MethodHead}, req.Method) {	4✔
329	coveredComponents = append(coveredComponents, AdditionalPostCoveredComponents...)	2✔
330	}	2✔
331	}
332	return s.signRequestRFC(coveredComponents)(req)	2✔
333	}
334
335	func (s Signer) SignDraft(req http.Request) error {	2✔
336	return s.signRequestDraft(req)	2✔
337	}	2✔

go-ap / client / #75

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