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Mozilla Public License Version 2.0
==================================
1. Definitions
--------------
1.1. "Contributor"
means each individual or legal entity that creates, contributes to
the creation of, or owns Covered Software.
1.2. "Contributor Version"
means the combination of the Contributions of others (if any) used
by a Contributor and that particular Contributor's Contribution.
1.3. "Contribution"
means Covered Software of a particular Contributor.
1.4. "Covered Software"
means Source Code Form to which the initial Contributor has attached
the notice in Exhibit A, the Executable Form of such Source Code
Form, and Modifications of such Source Code Form, in each case
including portions thereof.
1.5. "Incompatible With Secondary Licenses"
means
(a) that the initial Contributor has attached the notice described
in Exhibit B to the Covered Software; or
(b) that the Covered Software was made available under the terms of
version 1.1 or earlier of the License, but not also under the
terms of a Secondary License.
1.6. "Executable Form"
means any form of the work other than Source Code Form.
1.7. "Larger Work"
means a work that combines Covered Software with other material, in
a separate file or files, that is not Covered Software.
1.8. "License"
means this document.
1.9. "Licensable"
means having the right to grant, to the maximum extent possible,
whether at the time of the initial grant or subsequently, any and
all of the rights conveyed by this License.
1.10. "Modifications"
means any of the following:
(a) any file in Source Code Form that results from an addition to,
deletion from, or modification of the contents of Covered
Software; or
(b) any new file in Source Code Form that contains any Covered
Software.
1.11. "Patent Claims" of a Contributor
means any patent claim(s), including without limitation, method,
process, and apparatus claims, in any patent Licensable by such
Contributor that would be infringed, but for the grant of the
License, by the making, using, selling, offering for sale, having
made, import, or transfer of either its Contributions or its
Contributor Version.
1.12. "Secondary License"
means either the GNU General Public License, Version 2.0, the GNU
Lesser General Public License, Version 2.1, the GNU Affero General
Public License, Version 3.0, or any later versions of those
licenses.
1.13. "Source Code Form"
means the form of the work preferred for making modifications.
1.14. "You" (or "Your")
means an individual or a legal entity exercising rights under this
License. For legal entities, "You" includes any entity that
controls, is controlled by, or is under common control with You. For
purposes of this definition, "control" means (a) the power, direct
or indirect, to cause the direction or management of such entity,
whether by contract or otherwise, or (b) ownership of more than
fifty percent (50%) of the outstanding shares or beneficial
ownership of such entity.
2. License Grants and Conditions
--------------------------------
2.1. Grants
Each Contributor hereby grants You a world-wide, royalty-free,
non-exclusive license:
(a) under intellectual property rights (other than patent or trademark)
Licensable by such Contributor to use, reproduce, make available,
modify, display, perform, distribute, and otherwise exploit its
Contributions, either on an unmodified basis, with Modifications, or
as part of a Larger Work; and
(b) under Patent Claims of such Contributor to make, use, sell, offer
for sale, have made, import, and otherwise transfer either its
Contributions or its Contributor Version.
2.2. Effective Date
The licenses granted in Section 2.1 with respect to any Contribution
become effective for each Contribution on the date the Contributor first
distributes such Contribution.
2.3. Limitations on Grant Scope
The licenses granted in this Section 2 are the only rights granted under
this License. No additional rights or licenses will be implied from the
distribution or licensing of Covered Software under this License.
Notwithstanding Section 2.1(b) above, no patent license is granted by a
Contributor:
(a) for any code that a Contributor has removed from Covered Software;
or
(b) for infringements caused by: (i) Your and any other third party's
modifications of Covered Software, or (ii) the combination of its
Contributions with other software (except as part of its Contributor
Version); or
(c) under Patent Claims infringed by Covered Software in the absence of
its Contributions.
This License does not grant any rights in the trademarks, service marks,
or logos of any Contributor (except as may be necessary to comply with
the notice requirements in Section 3.4).
2.4. Subsequent Licenses
No Contributor makes additional grants as a result of Your choice to
distribute the Covered Software under a subsequent version of this
License (see Section 10.2) or under the terms of a Secondary License (if
permitted under the terms of Section 3.3).
2.5. Representation
Each Contributor represents that the Contributor believes its
Contributions are its original creation(s) or it has sufficient rights
to grant the rights to its Contributions conveyed by this License.
2.6. Fair Use
This License is not intended to limit any rights You have under
applicable copyright doctrines of fair use, fair dealing, or other
equivalents.
2.7. Conditions
Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted
in Section 2.1.
3. Responsibilities
-------------------
3.1. Distribution of Source Form
All distribution of Covered Software in Source Code Form, including any
Modifications that You create or to which You contribute, must be under
the terms of this License. You must inform recipients that the Source
Code Form of the Covered Software is governed by the terms of this
License, and how they can obtain a copy of this License. You may not
attempt to alter or restrict the recipients' rights in the Source Code
Form.
3.2. Distribution of Executable Form
If You distribute Covered Software in Executable Form then:
(a) such Covered Software must also be made available in Source Code
Form, as described in Section 3.1, and You must inform recipients of
the Executable Form how they can obtain a copy of such Source Code
Form by reasonable means in a timely manner, at a charge no more
than the cost of distribution to the recipient; and
(b) You may distribute such Executable Form under the terms of this
License, or sublicense it under different terms, provided that the
license for the Executable Form does not attempt to limit or alter
the recipients' rights in the Source Code Form under this License.
3.3. Distribution of a Larger Work
You may create and distribute a Larger Work under terms of Your choice,
provided that You also comply with the requirements of this License for
the Covered Software. If the Larger Work is a combination of Covered
Software with a work governed by one or more Secondary Licenses, and the
Covered Software is not Incompatible With Secondary Licenses, this
License permits You to additionally distribute such Covered Software
under the terms of such Secondary License(s), so that the recipient of
the Larger Work may, at their option, further distribute the Covered
Software under the terms of either this License or such Secondary
License(s).
3.4. Notices
You may not remove or alter the substance of any license notices
(including copyright notices, patent notices, disclaimers of warranty,
or limitations of liability) contained within the Source Code Form of
the Covered Software, except that You may alter any license notices to
the extent required to remedy known factual inaccuracies.
3.5. Application of Additional Terms
You may choose to offer, and to charge a fee for, warranty, support,
indemnity or liability obligations to one or more recipients of Covered
Software. However, You may do so only on Your own behalf, and not on
behalf of any Contributor. You must make it absolutely clear that any
such warranty, support, indemnity, or liability obligation is offered by
You alone, and You hereby agree to indemnify every Contributor for any
liability incurred by such Contributor as a result of warranty, support,
indemnity or liability terms You offer. You may include additional
disclaimers of warranty and limitations of liability specific to any
jurisdiction.
4. Inability to Comply Due to Statute or Regulation
---------------------------------------------------
If it is impossible for You to comply with any of the terms of this
License with respect to some or all of the Covered Software due to
statute, judicial order, or regulation then You must: (a) comply with
the terms of this License to the maximum extent possible; and (b)
describe the limitations and the code they affect. Such description must
be placed in a text file included with all distributions of the Covered
Software under this License. Except to the extent prohibited by statute
or regulation, such description must be sufficiently detailed for a
recipient of ordinary skill to be able to understand it.
5. Termination
--------------
5.1. The rights granted under this License will terminate automatically
if You fail to comply with any of its terms. However, if You become
compliant, then the rights granted under this License from a particular
Contributor are reinstated (a) provisionally, unless and until such
Contributor explicitly and finally terminates Your grants, and (b) on an
ongoing basis, if such Contributor fails to notify You of the
non-compliance by some reasonable means prior to 60 days after You have
come back into compliance. Moreover, Your grants from a particular
Contributor are reinstated on an ongoing basis if such Contributor
notifies You of the non-compliance by some reasonable means, this is the
first time You have received notice of non-compliance with this License
from such Contributor, and You become compliant prior to 30 days after
Your receipt of the notice.
5.2. If You initiate litigation against any entity by asserting a patent
infringement claim (excluding declaratory judgment actions,
counter-claims, and cross-claims) alleging that a Contributor Version
directly or indirectly infringes any patent, then the rights granted to
You by any and all Contributors for the Covered Software under Section
2.1 of this License shall terminate.
5.3. In the event of termination under Sections 5.1 or 5.2 above, all
end user license agreements (excluding distributors and resellers) which
have been validly granted by You or Your distributors under this License
prior to termination shall survive termination.
************************************************************************
* *
* 6. Disclaimer of Warranty *
* ------------------------- *
* *
* Covered Software is provided under this License on an "as is" *
* basis, without warranty of any kind, either expressed, implied, or *
* statutory, including, without limitation, warranties that the *
* Covered Software is free of defects, merchantable, fit for a *
* particular purpose or non-infringing. The entire risk as to the *
* quality and performance of the Covered Software is with You. *
* Should any Covered Software prove defective in any respect, You *
* (not any Contributor) assume the cost of any necessary servicing, *
* repair, or correction. This disclaimer of warranty constitutes an *
* essential part of this License. No use of any Covered Software is *
* authorized under this License except under this disclaimer. *
* *
************************************************************************
************************************************************************
* *
* 7. Limitation of Liability *
* -------------------------- *
* *
* Under no circumstances and under no legal theory, whether tort *
* (including negligence), contract, or otherwise, shall any *
* Contributor, or anyone who distributes Covered Software as *
* permitted above, be liable to You for any direct, indirect, *
* special, incidental, or consequential damages of any character *
* including, without limitation, damages for lost profits, loss of *
* goodwill, work stoppage, computer failure or malfunction, or any *
* and all other commercial damages or losses, even if such party *
* shall have been informed of the possibility of such damages. This *
* limitation of liability shall not apply to liability for death or *
* personal injury resulting from such party's negligence to the *
* extent applicable law prohibits such limitation. Some *
* jurisdictions do not allow the exclusion or limitation of *
* incidental or consequential damages, so this exclusion and *
* limitation may not apply to You. *
* *
************************************************************************
8. Litigation
-------------
Any litigation relating to this License may be brought only in the
courts of a jurisdiction where the defendant maintains its principal
place of business and such litigation shall be governed by laws of that
jurisdiction, without reference to its conflict-of-law provisions.
Nothing in this Section shall prevent a party's ability to bring
cross-claims or counter-claims.
9. Miscellaneous
----------------
This License represents the complete agreement concerning the subject
matter hereof. If any provision of this License is held to be
unenforceable, such provision shall be reformed only to the extent
necessary to make it enforceable. Any law or regulation which provides
that the language of a contract shall be construed against the drafter
shall not be used to construe this License against a Contributor.
10. Versions of the License
---------------------------
10.1. New Versions
Mozilla Foundation is the license steward. Except as provided in Section
10.3, no one other than the license steward has the right to modify or
publish new versions of this License. Each version will be given a
distinguishing version number.
10.2. Effect of New Versions
You may distribute the Covered Software under the terms of the version
of the License under which You originally received the Covered Software,
or under the terms of any subsequent version published by the license
steward.
10.3. Modified Versions
If you create software not governed by this License, and you want to
create a new license for such software, you may create and use a
modified version of this License if you rename the license and remove
any references to the name of the license steward (except to note that
such modified license differs from this License).
10.4. Distributing Source Code Form that is Incompatible With Secondary
Licenses
If You choose to distribute Source Code Form that is Incompatible With
Secondary Licenses under the terms of this version of the License, the
notice described in Exhibit B of this License must be attached.
Exhibit A - Source Code Form License Notice
-------------------------------------------
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at https://mozilla.org/MPL/2.0/.
If it is not possible or desirable to put the notice in a particular
file, then You may include the notice in a location (such as a LICENSE
file in a relevant directory) where a recipient would be likely to look
for such a notice.
You may add additional accurate notices of copyright ownership.
Exhibit B - "Incompatible With Secondary Licenses" Notice
---------------------------------------------------------
This Source Code Form is "Incompatible With Secondary Licenses", as
defined by the Mozilla Public License, v. 2.0.

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# ProfileFed
ProfileFed is a simple, lightweight federation protocol for platforms that host user profiles. This repository contains a reference implementation of the protocol, written in Go.
## Specification
### WebFinger
ProfileFed endpoints are discovered via [WebFinger](https://datatracker.ietf.org/doc/html/rfc7033). ProfileFed WebFinger responses must contain a link with a `rel` of `self` and a `type` of `application/x-pfd+json`. Requests to the URL contained within the `href` of that link must return a Profile Descriptor as defined below.
### Profile Descriptor (PFD)
This object represents a user profile returned by a ProfileFed server in response to a request to the ProfileFed URL discovered via WebFinger, as defined above.
This response must include a message signature. It should be transferred via the `X-ProfileFed-Sig` header, which must contain an Ed25519 signature of the response encoded in base64. The message must be verified against this signature before any further processing takes place. If the signature does not match, the response must be ignored and an error must be returned.
If the `all` query parameter is set to `1` in the request, the server must return all the profiles it has for the user, encoded as a JSON object with arbitrary ID strings mapped to profile descriptors. If the optional `id` query parameter is set to a specific descriptor ID, the server should respond with the corresponding profile. If no `id` is provided, the server may decide which profile to respond with.
The response should use the MIME type `application/x-pfd+json`.
**Profile Descriptor Object:**
| Property | Type | Description |
|----------------|----------|--------------------------------------------|
| `id` | string | Arbitrary ID string for the profile |
| `namespaces` | []string | List of namespaces used in the profile |
| `display_name` | string | User's preferred display name |
| `username` | string | User's username |
| `bio` | string | User's bio text |
| `role` | string | User's role on the server |
| `extra` | []extra | Additional user data defined by namespaces |
If `role` is empty or not provided, `user` should be assumed
The `namespace` URLs should point to human-readable documentation of the types and data that can be used in the objects that they define.
Possible values for `role` are `server_host`, `admin`, `moderator`, `developer`, or `user`. The server can arbitrarily decide which roles apply to the user. If the user has multiple roles, they should be delimited by commas. If any other custom roles are required, they should be specified in `extra` and defined in a custom namespace.
**`extra` Object:**
| Property | Type | Description |
|-------------|--------|-------------------------------------------|
| `namespace` | string | The namespace URL used in this object |
| `type` | string | The type of data described by this object |
| `data` | any | Arbitrary custom data |
The `namespace` can be any URL that's defined in the `namespaces` array. The URL fragment is ignored when checking if the namespace is defined.
The `type` can be any arbitrary string describing the data, for example: `category`, `donation_url`, etc.
### Server Info
This object represents information about a server in response to a server info request. It must be returned in respoonse to a request to `/_profilefed/server`. The host and port of the URL discovered via WebFinger will be used to make this request.
The `pubkey` should be stored to check against further responses.
This response must include a message signature. It should be transferred via the `X-ProfileFed-Sig` header, which must contain an Ed25519 signature of the response encoded in base64. Except for the first time a server is contacted, the message must be verified against this signature before any further processing takes place. If the signature does not match, the response must be ignored and an error must be returned.
If the server switches to a new key, this message must be signed with every previously-used key. These signatures must be provided in `X-ProfileFed-Previous` headers, encoded as base64. If the public key doesn't match and there are no matching signatures, any responses signed with the new key must return an error and must not be processed.
**Properties:**
| Property | Type | Description |
|------------------|--------|--------------------------------------------------|
| `server_name` | string | Name of the server |
| `previous_names` | array | List of previous names used by the server |
| `pubkey` | string | Base64-encoded Ed25519 public key of the server |

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package profilefed
import (
"bytes"
"crypto/ed25519"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
"io"
"net/http"
"net/url"
"sync"
"queerdevs.org/profilefed/webfinger"
)
const responseSizeLimit = 32_000_000
var (
// ErrPubkeyNotFound signifies that the server public key is not found.
ErrPubkeyNotFound = errors.New("server pubkey not found")
// ErrNoSignature signifies that the response contains no signature.
ErrNoSignature = errors.New("response contains no signature")
// ErrSignatureMismatch signifies that the message does not match the server signature.
ErrSignatureMismatch = errors.New("message does not match server signature")
)
// DefaultClient returns a default client for ProfileFed.
//
// It uses an in-memory synchronized map to store public keys.
// For production, it's highly recommended to implement a custom
// client that persists the keys to a database or similar, so that
// restarting your app doesn't provide opportunities for malicious servers.
func DefaultClient() Client {
defaultMap := sync.Map{}
return Client{
SavePubkey: func(serverName string, previousNames []string, pubkey ed25519.PublicKey) error {
defaultMap.Store(serverName, pubkey)
for _, name := range previousNames {
defaultMap.Delete(name)
}
return nil
},
GetPubkey: func(serverName string) (ed25519.PublicKey, error) {
pubkey, ok := defaultMap.Load(serverName)
if !ok {
return nil, ErrPubkeyNotFound
}
return pubkey.(ed25519.PublicKey), nil
},
}
}
// Client represents a ProfileFed client
type Client struct {
// SavePubkey saves the public key for a given server.
SavePubkey func(serverName string, previousNames []string, pubkey ed25519.PublicKey) error
// GetPubkey retrieves the public key for a given server.
// If the key isn't found, GetPubkey should return [ErrPubkeyNotFound]
GetPubkey func(serverName string) (ed25519.PublicKey, error)
}
// Lookup looks up the profile descriptor for the given ID.
func (c Client) Lookup(id string) (*Descriptor, error) {
wfdesc, err := webfinger.LookupAcct(id)
if err != nil {
return nil, err
}
pfdLink, ok := wfdesc.LinkByType("application/x-pfd+json")
if !ok {
return nil, errors.New("server does not support the profilefed protocol")
}
pfdURL, err := url.Parse(pfdLink.Href)
if err != nil {
return nil, err
}
pubkeySaved := false
pubkey, err := c.GetPubkey(pfdURL.Host)
if errors.Is(err, ErrPubkeyNotFound) {
info, _, err := getServerInfo(pfdURL.Scheme, pfdURL.Host)
if err != nil {
return nil, err
}
pubkey, err = base64.StdEncoding.DecodeString(info.Pubkey)
if err != nil {
return nil, err
}
err = c.SavePubkey(pfdURL.Host, info.PreviousNames, pubkey)
if err != nil {
return nil, err
}
pubkeySaved = true
} else if err != nil {
return nil, err
}
res, err := http.Get(pfdLink.Href)
if err != nil {
return nil, err
}
defer res.Body.Close()
if err := checkResp(res, "getProfileDescriptor"); err != nil {
return nil, err
}
data, err := io.ReadAll(io.LimitReader(res.Body, responseSizeLimit))
if err != nil {
return nil, err
}
if err := res.Body.Close(); err != nil {
return nil, err
}
sig, err := getSignature(res)
if err != nil {
return nil, err
}
if !ed25519.Verify(pubkey, data, sig) {
// If the pubkey was just saved in the current request, we probably
// already have the newest one, so just return a mismatch error.
if pubkeySaved {
return nil, ErrSignatureMismatch
}
res, err := serverInfoReq(pfdURL.Scheme, pfdURL.Host)
if err != nil {
return nil, err
}
serverData, err := io.ReadAll(io.LimitReader(res.Body, responseSizeLimit))
if err != nil {
return nil, err
}
var info serverInfoData
err = json.Unmarshal(serverData, &info)
if err != nil {
return nil, err
}
newPubkey, err := base64.StdEncoding.DecodeString(info.Pubkey)
if err != nil {
return nil, err
}
if bytes.Equal(pubkey, newPubkey) {
return nil, ErrSignatureMismatch
}
verified := false
sigs := getPrevSignatures(res)
for _, sig := range sigs {
if ed25519.Verify(pubkey, serverData, sig) {
verified = true
break
}
}
if !verified {
return nil, ErrSignatureMismatch
}
infoSig, err := getSignature(res)
if err != nil {
return nil, err
}
if !ed25519.Verify(newPubkey, infoSig, serverData) {
return nil, ErrSignatureMismatch
}
err = c.SavePubkey(pfdURL.Host, info.PreviousNames, newPubkey)
if err != nil {
return nil, err
}
if !ed25519.Verify(newPubkey, data, sig) {
return nil, ErrSignatureMismatch
}
}
desc := &Descriptor{}
err = json.Unmarshal(data, desc)
if err != nil {
return nil, err
}
if desc.Role == "" {
desc.Role = RoleUser
}
return desc, nil
}
// serverInfoReq performs an HTTP request to retrieve server information.
func serverInfoReq(scheme, host string) (*http.Response, error) {
serverInfoURL := url.URL{
Scheme: scheme,
Host: host,
Path: "/_profilefed/server",
}
return http.Get(serverInfoURL.String())
}
// getServerInfo retrieves server information.
func getServerInfo(scheme, host string) (serverInfoData, [][]byte, error) {
res, err := serverInfoReq(scheme, host)
if err != nil {
return serverInfoData{}, nil, err
}
defer res.Body.Close()
if err := checkResp(res, "getServerInfo"); err != nil {
return serverInfoData{}, nil, err
}
var out serverInfoData
err = json.NewDecoder(io.LimitReader(res.Body, responseSizeLimit)).Decode(&out)
return out, getPrevSignatures(res), err
}
// getPrevSignatures extracts previous signatures from a response.
func getPrevSignatures(res *http.Response) [][]byte {
var sigs [][]byte
sigStrs := res.Header[http.CanonicalHeaderKey("X-ProfileFed-Previous")]
for _, sigStr := range sigStrs {
sig, err := base64.StdEncoding.DecodeString(sigStr)
if err != nil {
continue // Skip invalid signatures
}
sigs = append(sigs, sig)
}
return sigs
}
// getSignature extracts the signature from a response.
func getSignature(res *http.Response) ([]byte, error) {
sigStr := res.Header.Get("X-ProfileFed-Sig")
if sigStr == "" {
return nil, ErrNoSignature
}
return base64.StdEncoding.DecodeString(sigStr)
}
// checkResp returns an error if the response is not 200 OK.
func checkResp(res *http.Response, opName string) error {
if res.StatusCode != 200 {
return fmt.Errorf("%s: %s", opName, res.Status)
}
return nil
}

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module queerdevs.org/profilefed
go 1.22.0

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package profilefed
import (
"crypto/ed25519"
"encoding/base64"
"encoding/json"
"errors"
"net/http"
"slices"
"strings"
)
// ErrDescriptorNotFound should be returned
var ErrDescriptorNotFound = errors.New("descriptor not found")
// AddExtra is a convenience function that adds an extra data object to the descriptor.
// It defines any undefined namespaces and marshals the data parameter into JSON.
func (d *Descriptor) AddExtra(namespace, etype string, data any) error {
// Remove the fragment from the namespace URL if it exists
urlStr, _, _ := strings.Cut(namespace, "#")
if !slices.Contains(d.Namespaces, urlStr) {
d.Namespaces = append(d.Namespaces, urlStr)
}
msg, err := json.Marshal(data)
if err != nil {
return err
}
d.Extra = append(d.Extra, Extra{
Namespace: namespace,
Type: etype,
Data: msg,
})
return nil
}
type Handler struct {
// PrivateKey contains the server's Ed25519 private key for signing responses
PrivateKey ed25519.PrivateKey
// AllDescriptorsFunc should return all the profile descriptors known to the server.
// If no matching descriptors can be found, AllDescriptorsFunc should reutnr
// [ErrDescriptorNotFound].
AllDescriptorsFunc func(req *http.Request) (map[string]*Descriptor, error)
// DescriptorFunc should return a single descriptor. Make sure to check the `id`
// query parameter if your user has several descriptors available. If a matching
// descriptor cannot be found, DescriptorFunc should return [ErrDescriptorNotFound].
DescriptorFunc func(req *http.Request) (*Descriptor, error)
// ErrorHandler is called whenever an error is encountered.
ErrorHandler func(err error, res http.ResponseWriter)
}
// ServeHTTP implements the [http.Handler] interface
func (h Handler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
var data []byte
if req.URL.Query().Get("all") == "1" {
descriptors, err := h.AllDescriptorsFunc(req)
if err != nil {
h.ErrorHandler(err, res)
return
}
data, err = json.Marshal(descriptors)
if err != nil {
h.ErrorHandler(err, res)
return
}
} else {
descriptor, err := h.DescriptorFunc(req)
if err != nil {
h.ErrorHandler(err, res)
return
}
data, err = json.Marshal(descriptor)
if err != nil {
h.ErrorHandler(err, res)
return
}
}
sig := ed25519.Sign(h.PrivateKey, data)
res.Header().Set("X-ProfileFed-Sig", base64.StdEncoding.EncodeToString(sig))
res.Header().Set("Content-Type", "application/x-pfd+json")
_, err := res.Write(data)
if err != nil {
h.ErrorHandler(err, res)
return
}
}

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package profilefed
import (
"crypto/ed25519"
"crypto/rand"
"crypto/x509"
"encoding/pem"
"errors"
"os"
)
// LoadOrGenerateKeys checks whether the file at path exists. If it does,
// the private and public keys at that path are loaded and returned.
// If not, new keys are generated and saved to the given path.
func LoadOrGenerateKeys(path string) (ed25519.PublicKey, ed25519.PrivateKey, error) {
if _, err := os.Stat(path); err != nil {
return generateKeys(path)
}
return loadKeys(path)
}
func loadKeys(path string) (ed25519.PublicKey, ed25519.PrivateKey, error) {
privData, err := os.ReadFile(path)
if err != nil {
return nil, nil, err
}
pubData, err := os.ReadFile(path + ".pub")
if err != nil {
return nil, nil, err
}
privBlock, _ := pem.Decode(privData)
pubBlock, _ := pem.Decode(pubData)
if privBlock == nil {
return nil, nil, errors.New("invalid private key data")
}
if pubBlock == nil {
return nil, nil, errors.New("invalid public key data")
}
privkey, err := x509.ParsePKCS8PrivateKey(privBlock.Bytes)
if err != nil {
return nil, nil, err
}
pubkey, err := x509.ParsePKIXPublicKey(pubBlock.Bytes)
if err != nil {
return nil, nil, err
}
priv, ok := privkey.(ed25519.PrivateKey)
if !ok {
return nil, nil, errors.New("invalid private key type")
}
pub, ok := pubkey.(ed25519.PublicKey)
if !ok {
return nil, nil, errors.New("invalid public key type")
}
return pub, priv, nil
}
func generateKeys(path string) (ed25519.PublicKey, ed25519.PrivateKey, error) {
pub, priv, err := ed25519.GenerateKey(rand.Reader)
if err != nil {
return nil, nil, err
}
privData, err := x509.MarshalPKCS8PrivateKey(priv)
if err != nil {
return nil, nil, err
}
privBlock := &pem.Block{
Type: "ED25519 PRIVATE KEY",
Bytes: privData,
}
err = os.WriteFile(path, pem.EncodeToMemory(privBlock), 0o600)
if err != nil {
return nil, nil, err
}
pubData, err := x509.MarshalPKIXPublicKey(pub)
if err != nil {
return nil, nil, err
}
pubBlock := &pem.Block{
Type: "ED25519 PUBLIC KEY",
Bytes: pubData,
}
err = os.WriteFile(path+".pub", pem.EncodeToMemory(pubBlock), 0o644)
if err != nil {
return nil, nil, err
}
return pub, priv, nil
}

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package profilefed
import (
"crypto/ed25519"
"encoding/base64"
"encoding/json"
"net/http"
)
// ServerInfoHandler handles the server info endpoint
// defined by ProfileFed.
type ServerInfoHandler struct {
// ServerName is the current name of the server. This
// should be the same as the domain used to access it.
ServerName string
// PreviousNames should contain any previous names this server used.
PreviousNames []string
// Pubkey should contain the server's public Ed25519 key.
Pubkey ed25519.PublicKey
// Privkey should contain the server's private Ed25519 key.
Privkey ed25519.PrivateKey
// PreviousKeys should contain any previously-used private keys.
// If this is not provided when the key changes, servers will not
// trust the new key and all responses will be rejected.
PreviousKeys []ed25519.PrivateKey
// ErrorHandler is called whenever an error is encountered.
ErrorHandler func(err error, res http.ResponseWriter)
}
type serverInfoData struct {
ServerName string `json:"server_name"`
PreviousNames []string `json:"previous_names"`
Pubkey string `json:"pubkey"`
}
// ServeHTTP implements the http.Handler interface
func (sih ServerInfoHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
data, err := json.Marshal(serverInfoData{
ServerName: sih.ServerName,
PreviousNames: sih.PreviousNames,
Pubkey: base64.StdEncoding.EncodeToString(sih.Pubkey),
})
if err != nil {
sih.ErrorHandler(err, res)
return
}
for _, key := range sih.PreviousKeys {
sig := ed25519.Sign(key, data)
res.Header().Add("X-ProfileFed-Previous", base64.StdEncoding.EncodeToString(sig))
}
sig := ed25519.Sign(sih.Privkey, data)
res.Header().Set("X-ProfileFed-Sig", base64.StdEncoding.EncodeToString(sig))
_, err = res.Write(data)
if err != nil {
sih.ErrorHandler(err, res)
return
}
}

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types.go Normal file
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package profilefed
import "encoding/json"
// Role represents a user's role on a server
type Role string
// Server roles
const (
RoleServerHost Role = "server_host"
RoleAdmin Role = "admin"
RoleModerator Role = "moderator"
RoleDeveloper Role = "developer"
RoleUser Role = "user"
)
// Descriptor represents a ProfileFed descriptor
type Descriptor struct {
// ID is an arbitrary ID string for the profile.
ID string `json:"id"`
// Namespaces is a list of namespaces used in the profile.
Namespaces []string `json:"namespaces"`
// DisplayName is the user's preferred display name.
DisplayName string `json:"display_name"`
// Username is the user's username.
Username string `json:"username"`
// Bio is the user's bio text.
Bio string `json:"bio"`
// Role is the user's role on the server. If not set,
// [RoleUser] is assumed.
Role Role `json:"role"`
// Extra is additional user data defined by namespaces
Extra []Extra `json:"extra"`
}
// Extra represents additional user data defined by namespaces
type Extra struct {
// Namespace is the namespace URL used in this object
Namespace string `json:"namespace"`
// Type is an arbitrary string that represents the type of
// data in the Data field.
Type string `json:"type"`
// Data is the arbitrary additional user data
Data json.RawMessage `json:"data"`
}

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# WebFinger
This is a simple implementation of a Go server handler and client for the WebFinger discovery protocol ([RFC7033](https://datatracker.ietf.org/doc/html/rfc7033)).
## `wflookup`
This package includes a command that looks up WebFinger descriptors. You can install it with the following command:
```bash
go install queerdevs.org/profilefed/webfinger/cmd/wflookup@latest
```
Here are some examples for how to use it:
```bash
wflookup acct:user@example.com
wflookup http://example.com/resource/1
wflookup user@example.com # wflookup will infer the acct scheme
```
If you'd like to specify the server that's going to be used instead of it being inferred, you can do so using the `--server` flag.
## Example library usage
### Server
```go
package main
import (
"net/http"
"queerdevs.org/profilefed/webfinger"
)
func main() {
mux := http.NewServeMux()
mux.Handle("GET /.well-known/webfinger", Handler{
DescriptorFunc: func(resource string) (*Descriptor, error) {
// You can query a database here, or do whatever you need
// to in order to get the descriptor data.
return desc, nil
},
})
err := http.ListenAndServe(":8080", mux)
if err != nil {
panic(err)
}
}
```
### Client
```go
package main
import (
"fmt"
"queerdevs.org/profilefed/webfinger"
)
func main() {
desc, err := webfinger.Lookup("acct:user@example.com", "example.com:8080")
if err != nil {
panic(err)
}
fmt.Println(desc)
desc, err = webfinger.LookupAcct("user@example.com")
if err != nil {
panic(err)
}
fmt.Println(desc)
desc, err = webfinger.LookupURL("http://example.com/resource/1")
if err != nil {
panic(err)
}
fmt.Println(desc)
}

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package main
import (
"encoding/json"
"flag"
"log"
"os"
"strings"
"queerdevs.org/go-webfinger"
)
func main() {
server := flag.String("server", "", "The server to query for the WebFinger descriptor (e.g. example.com)")
flag.Parse()
if len(os.Args) < 2 {
log.Fatalln("wflookup requires at least one argument")
}
res := os.Args[1]
var desc *webfinger.Descriptor
var err error
if *server != "" {
desc, err = webfinger.Lookup(res, *server)
} else if strings.HasPrefix(res, "http") {
desc, err = webfinger.LookupURL(res)
} else if strings.HasPrefix(res, "acct:") || strings.Contains(res, "@") {
desc, err = webfinger.LookupAcct(res)
}
if err != nil {
log.Fatalln("Lookup error:", err)
}
enc := json.NewEncoder(os.Stdout)
enc.SetIndent("", " ")
err = enc.Encode(desc)
if err != nil {
log.Fatalln("JSON encode error:", err)
}
}

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package webfinger
import (
"encoding/json"
"net/http"
)
// Handler handles WebFinger requests to an HTTP server
type Handler struct {
// DescriptorFunc is the function used to resolve resource strings
// to WebFinger descriptors. It's called on every request to the
// WebFinger endpoint. The errors it returns are handled by ErrorHandler.
DescriptorFunc func(resource string) (*Descriptor, error)
// ErrorHandler handles any errors that occur in the process of performing
// a WebFinger lookup. If not provided, a simple default handler is used.
ErrorHandler func(err error, res http.ResponseWriter)
}
// ServeHTTP implements the http.Handler interface
func (h Handler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
if h.ErrorHandler == nil {
h.ErrorHandler = func(err error, res http.ResponseWriter) {
http.Error(res, err.Error(), http.StatusInternalServerError)
}
}
descriptor, err := h.DescriptorFunc(req.URL.Query().Get("resource"))
if err != nil {
h.ErrorHandler(err, res)
return
}
data, err := json.Marshal(descriptor)
if err != nil {
h.ErrorHandler(err, res)
return
}
res.Header().Set("Content-Type", "application/jrd+json")
_, err = res.Write(data)
if err != nil {
h.ErrorHandler(err, res)
return
}
}

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package webfinger
import (
"errors"
"net/http"
"net/http/httptest"
"reflect"
"testing"
)
func TestHandler(t *testing.T) {
testdata := map[string]*Descriptor{
"acct:user@example.com": {
Subject: "acct:user@example.com",
Aliases: []string{
"mailto:user@example.com",
"https://www.example.com/user",
},
Links: []Link{
{
Rel: "http://webfinger.net/rel/profile-page",
Type: "text/html",
Href: "https://www.example.com/user",
},
},
},
"http://example.com/resource/1": {
Subject: "http://example.com/resource/1",
Properties: map[string]string{
"http://example.com/ns/example#publish-date": "2023-04-26",
},
},
}
srv := httptest.NewServer(Handler{
DescriptorFunc: func(resource string) (*Descriptor, error) {
// Look for the descriptor in the testdata map
desc, ok := testdata[resource]
if !ok {
return nil, errors.New("descriptor not found")
}
return desc, nil
},
ErrorHandler: func(err error, res http.ResponseWriter) {
http.Error(res, err.Error(), http.StatusInternalServerError)
},
})
defer srv.Close()
// Look up acct resource
desc, err := Lookup("acct:user@example.com", srv.Listener.Addr().String())
if err != nil {
t.Fatalf("Lookup error: %s", err)
}
if !reflect.DeepEqual(desc, testdata["acct:user@example.com"]) {
t.Errorf("Descriptors are not equal:\n%#v\n\n%#v", desc, testdata["acct:user@example.com"])
}
// Look up URL resource
desc, err = Lookup("http://example.com/resource/1", srv.Listener.Addr().String())
if err != nil {
t.Fatalf("Lookup error: %s", err)
}
if !reflect.DeepEqual(desc, testdata["http://example.com/resource/1"]) {
t.Errorf("Descriptors are not equal:\n%#v\n\n%#v", desc, testdata["http://example.com/resource/1"])
}
// Look up a non-existent resource to test error handling
desc, err = Lookup("http://example.com/resource/2", srv.Listener.Addr().String())
if err == nil {
t.Fatalf("Expected error, got nil")
}
}

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package webfinger
import (
"encoding/json"
"errors"
"net/http"
"net/url"
"strings"
)
// Lookup looks up the given resource string at the given server.
// The server parameter shouldn't contain a URL scheme.
func Lookup(resource, server string) (desc *Descriptor, err error) {
u := url.URL{
Scheme: "http",
Host: server,
Path: "/.well-known/webfinger",
RawQuery: "resource=" + url.QueryEscape(resource),
}
res, err := http.Get(u.String())
if err != nil {
return nil, err
}
defer res.Body.Close()
if res.StatusCode != http.StatusOK {
return nil, errors.New(res.Status)
}
desc = &Descriptor{}
err = json.NewDecoder(res.Body).Decode(desc)
if err != nil {
return nil, err
}
return desc, nil
}
// LookupAcct looks up the given account ID. It uses the
// server in the ID to do the lookup. For example, user@example.com
// would use example.com as the server.
func LookupAcct(id string) (*Descriptor, error) {
_, server, ok := strings.Cut(id, "@")
if !ok {
return nil, errors.New("invalid acct id")
}
if !strings.HasPrefix(id, "acct:") {
id = "acct:" + id
}
return Lookup(id, server)
}
// LookupURL looks up the given resource URL. It uses the
// URL host to do the lookup. For example, http://example.com/1
// would use example.com as the server.
func LookupURL(resource string) (*Descriptor, error) {
u, err := url.ParseRequestURI(resource)
if err != nil {
return nil, err
}
return Lookup(resource, u.Host)
}

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package webfinger
// Descriptor represents a WebFinger JSON Resource Descriptor (JRD)
type Descriptor struct {
Subject string `json:"subject"`
Aliases []string `json:"aliases"`
Properties map[string]string `json:"properties,omitempty"`
Links []Link `json:"links"`
}
// Link represents a JRD link item
type Link struct {
Rel string `json:"rel"`
Type string `json:"type,omitempty"`
Href string `json:"href"`
}
// LinkByType searches for a link with the given type. If found, it returns
// the link and true. Otherwise, it returns the zero value and false.
func (d *Descriptor) LinkByType(linkType string) (Link, bool) {
for _, link := range d.Links {
if link.Type == linkType {
return link, true
}
}
return Link{}, false
}
// LinkByRel searches for a link with the given rel value. If found, it returns
// the link and true. Otherwise, it returns the zero value and false.
func (d *Descriptor) LinkByRel(rel string) (Link, bool) {
for _, link := range d.Links {
if link.Rel == rel {
return link, true
}
}
return Link{}, false
}