mess about with some structure to help w/ deref

internal/transport/derefinstance.go

@@ -0,0 +1,185 @@
+package transport
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strings"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/id"
+)
+
+func (t *transport) DereferenceInstance(c context.Context, iri *url.URL) (*gtsmodel.Instance, error) {
+	l := t.log.WithField("func", "DereferenceInstance")
+
+	var i *gtsmodel.Instance
+	var err error
+
+	// First try to dereference using /api/v1/instance.
+	// This will provide the most complete picture of an instance, and avoid unnecessary api calls.
+	//
+	// This will only work with Mastodon-api compatible instances: Mastodon, some Pleroma instances, GoToSocial.
+	l.Debugf("trying to dereference instance %s by /api/v1/instance", iri.Host)
+	i, err = dereferenceByAPIV1Instance(t, c, iri)
+	if err == nil {
+		l.Debugf("successfully dereferenced instance using /api/v1/instance")
+		return i, nil
+	}
+	l.Debugf("couldn't dereference instance using /api/v1/instance: %s", err)
+
+	// If that doesn't work, try to dereference using /.well-known/nodeinfo.
+	// This will involve two API calls and return less info overall, but should be more widely compatible.
+	l.Debugf("trying to dereference instance %s by /.well-known/nodeinfo", iri.Host)
+	i, err = dereferenceByNodeInfo(t, c, iri)
+	if err == nil {
+		l.Debugf("successfully dereferenced instance using /.well-known/nodeinfo")
+		return i, nil
+	}
+	l.Debugf("couldn't dereference instance using /.well-known/nodeinfo: %s", err)
+
+	return nil, fmt.Errorf("couldn't dereference instance %s using either /api/v1/instance or /.well-known/nodeinfo", iri.Host)
+}
+
+func dereferenceByAPIV1Instance(t *transport, c context.Context, iri *url.URL) (*gtsmodel.Instance, error) {
+	l := t.log.WithField("func", "dereferenceByAPIV1Instance")
+
+	cleanIRI := &url.URL{
+		Scheme: iri.Scheme,
+		Host:   iri.Host,
+		Path:   "api/v1/instance",
+	}
+
+	l.Debugf("performing GET to %s", cleanIRI.String())
+	req, err := http.NewRequest("GET", cleanIRI.String(), nil)
+	if err != nil {
+		return nil, err
+	}
+	req = req.WithContext(c)
+	req.Header.Add("Accept", "application/json")
+	req.Header.Add("Date", t.clock.Now().UTC().Format("Mon, 02 Jan 2006 15:04:05")+" GMT")
+	req.Header.Add("User-Agent", fmt.Sprintf("%s %s", t.appAgent, t.gofedAgent))
+	req.Header.Set("Host", cleanIRI.Host)
+	t.getSignerMu.Lock()
+	err = t.getSigner.SignRequest(t.privkey, t.pubKeyID, req, nil)
+	t.getSignerMu.Unlock()
+	if err != nil {
+		return nil, err
+	}
+	resp, err := t.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("GET request to %s failed (%d): %s", cleanIRI.String(), resp.StatusCode, resp.Status)
+	}
+	b, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(b) == 0 {
+		return nil, errors.New("response bytes was len 0")
+	}
+
+	// try to parse the returned bytes directly into an Instance model
+	apiResp := &apimodel.Instance{}
+	if err := json.Unmarshal(b, apiResp); err != nil {
+		return nil, err
+	}
+
+	var contactUsername string
+	if apiResp.ContactAccount != nil {
+		contactUsername = apiResp.ContactAccount.Username
+	}
+
+	ulid, err := id.NewRandomULID()
+	if err != nil {
+		return nil, err
+	}
+
+	i := &gtsmodel.Instance{
+		ID:                     ulid,
+		Domain:                 iri.Host,
+		Title:                  apiResp.Title,
+		URI:                    fmt.Sprintf("%s://%s", iri.Scheme, iri.Host),
+		ShortDescription:       apiResp.ShortDescription,
+		Description:            apiResp.Description,
+		ContactEmail:           apiResp.Email,
+		ContactAccountUsername: contactUsername,
+		Version:                apiResp.Version,
+	}
+
+	return i, nil
+}
+
+func dereferenceByNodeInfo(t *transport, c context.Context, iri *url.URL) (*gtsmodel.Instance, error) {
+	l := t.log.WithField("func", "dereferenceByNodeInfo")
+
+	cleanIRI := &url.URL{
+		Scheme: iri.Scheme,
+		Host:   iri.Host,
+		Path:   ".well-known/nodeinfo",
+	}
+
+	l.Debugf("performing GET to %s", cleanIRI.String())
+	req, err := http.NewRequest("GET", cleanIRI.String(), nil)
+	if err != nil {
+		return nil, err
+	}
+	req = req.WithContext(c)
+	req.Header.Add("Accept", "application/json")
+	req.Header.Add("Date", t.clock.Now().UTC().Format("Mon, 02 Jan 2006 15:04:05")+" GMT")
+	req.Header.Add("User-Agent", fmt.Sprintf("%s %s", t.appAgent, t.gofedAgent))
+	req.Header.Set("Host", cleanIRI.Host)
+	t.getSignerMu.Lock()
+	err = t.getSigner.SignRequest(t.privkey, t.pubKeyID, req, nil)
+	t.getSignerMu.Unlock()
+	if err != nil {
+		return nil, err
+	}
+	resp, err := t.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("GET request to %s failed (%d): %s", cleanIRI.String(), resp.StatusCode, resp.Status)
+	}
+	b, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(b) == 0 {
+		return nil, errors.New("dereferenceByNodeInfo: response bytes was len 0")
+	}
+
+	wellKnownResp := &apimodel.WellKnownResponse{}
+	if err := json.Unmarshal(b, wellKnownResp); err != nil {
+		return nil, fmt.Errorf("dereferenceByNodeInfo: could not unmarshal server response as WellKnownResponse: %s", err)
+	}
+
+	// look through the links for the first one that matches the nodeinfo schema, this is what we need
+	var nodeinfoHref *url.URL
+	for _, l := range wellKnownResp.Links {
+		if l.Href == "" || !strings.HasPrefix(l.Rel, "http://nodeinfo.diaspora.software/ns/schema") {
+			continue
+		}
+		nodeinfoHref, err = url.Parse(l.Href)
+		if err != nil {
+			return nil, fmt.Errorf("dereferenceByNodeInfo: couldn't parse url %s: %s", l.Href, err)
+		}
+	}
+	if nodeinfoHref == nil {
+		return nil, errors.New("could not find nodeinfo rel in well known response")
+	}
+aaaaaaaaaaaaaaaaa // do the second query
+	return nil, errors.New("not yet implemented")
+}