commit eec649355b1ab496b58a8e65abc64f9ee7e635ac
from: Oliver Lowe <o@olowe.co>
date: Sat Mar 16 07:45:22 2024 UTC

apub: correctly marshal followers collection from an email recipients

The receiving server can forward the message for us. For us to resolve
the entire collection is a lot of work, especially since paginated
followers collections only contain like 12 entries per page! Lots of
people have over 300 followers.

commit - b526632b614889f059e5aa5d29e84a9f416572da
commit + eec649355b1ab496b58a8e65abc64f9ee7e635ac
blob - 4948c36d47177385965204af8e12e103b013082e
blob + 1e5c0bd4dd580bc4c32e1c2d03f777ca0e989d5e
--- mail.go
+++ mail.go
@@ -112,10 +112,13 @@ func UnmarshalMail(msg *mail.Message) (*Activity, erro
 			return nil, fmt.Errorf("webfinger To addresses: %w", err)
 		}
 		wto = make([]string, len(actors))
-		tags = make([]Activity, len(actors))
 		for i, a := range actors {
 			addr := strings.Trim(to[i].Address, "<>")
-			tags[i] = Activity{Type: "Mention", Href: a.ID, Name: "@" + addr}
+			if strings.Contains(addr, "+followers") {
+				wto[i] = a.Followers
+				continue
+			}
+			tags = append(tags, Activity{Type: "Mention", Href: a.ID, Name: "@" + addr})
 			wto[i] = a.ID
 		}
 	}
@@ -130,6 +133,10 @@ func UnmarshalMail(msg *mail.Message) (*Activity, erro
 		}
 		wcc = make([]string, len(actors))
 		for i, a := range actors {
+			if strings.Contains(cc[i].Address, "+followers") {
+				wcc[i] = a.Followers
+				continue
+			}
 			wcc[i] = a.ID
 		}
 	}
blob - 16154099f40f206a7ceb3e7f4bc6645e68288f8b
blob + 0d990da5a71ad9c617d9fe01e40e1e36be087099
--- testdata/outbound.eml
+++ testdata/outbound.eml
@@ -1,7 +1,7 @@
 From: Oliver Lowe <otl@apubtest2.srcbeat.com>
 Date: Wed, 6 Mar 2024 14:03:33 +1100
 To:  <henfredemars@infosec.pub>
-CC: "Programming" <programming@programming.dev>, <starman@programming.dev>
+CC: "Programming" <programming@programming.dev>, <starman@programming.dev>, <otl+followers@hachyderm.io>
 In-Reply-To: <https://infosec.pub/comment/7135766>
 Subject:
 
blob - 1010ca293ad511037e6e90babb868bf19bad25e4
blob + f872625d946401146d5e4c6104e37b8065d32476
--- webfinger.go
+++ webfinger.go
@@ -8,17 +8,22 @@ import (
 	"webfinger.net/go/webfinger"
 )
 
-// Finger is convenience function returning the corresponding Actor,
+// Finger wraps defaultClient.Finger.
+func Finger(address string) (*Actor, error) {
+	return defaultClient.Finger(address)
+}
+
+// Finger is convenience method returning the corresponding Actor,
 // if any, of an address resolvable by WebFinger.
 // It is equivalent to doing webfinger.Lookup then LookupActor.
-func Finger(address string) (*Actor, error) {
+func (c *Client) Finger(address string) (*Actor, error) {
 	jrd, err := webfinger.Lookup(address, nil)
 	if err != nil {
 		return nil, err
 	}
 	for i := range jrd.Links {
 		if jrd.Links[i].Type == ContentType {
-			return LookupActor(jrd.Links[i].Href)
+			return c.LookupActor(jrd.Links[i].Href)
 		}
 	}
 	return nil, ErrNotExist
@@ -27,18 +32,14 @@ func Finger(address string) (*Actor, error) {
 func fingerAll(alist []*mail.Address) ([]Actor, error) {
 	actors := make([]Actor, len(alist))
 	for i, addr := range alist {
+		q := addr.Address
 		if strings.Contains(addr.Address, "+followers") {
-			addr.Address = strings.Replace(addr.Address, "+followers", "", 1)
-			a, err := Finger(addr.Address)
-			if err != nil {
-				return actors, fmt.Errorf("finger %s: %w", addr.Address, err)
-			}
-			actors[i] = *a
-			continue
+			// strip "+followers" to get the regular address that can be fingered.
+			q = strings.Replace(addr.Address, "+followers", "", 1)
 		}
-		actor, err := Finger(addr.Address)
+		actor, err := Finger(q)
 		if err != nil {
-			return actors, fmt.Errorf("finger %s: %w", addr.Address, err)
+			return actors, fmt.Errorf("finger %s: %w", q, err)
 		}
 		actors[i] = *actor
 	}