/pub/util.go: wrapInCreate: nil pointer dereference

kissen commented 4 years ago

I'm currently playing around with with go-fed, in particular with the social API. Having set up an actor with pub.NewActor and a handler with pub.NewActivityStreamsHandler, I try to post the following JSON taken from the ActivityPub documentation to a users outbox.

{"@context": "https://www.w3.org/ns/activitystreams",
 "type": "Note",
 "to": ["https://chatty.example/ben/"],
 "attributedTo": "https://social.example/alyssa/",
 "content": "Say, did you finish reading that book I lent you?"}

Seems like go-fed correctly tries to wrap the Note into a Create, but doing so I get a nil dereference error in activity/pub/util.go in line 284. Full stack trace further down.

How your code uses this library: Currently I have a bare-bones implementation of the social protocol. You can look at the code here if you want.

What troubleshooting has already been tried: As a workaround/fix(?) I find that checking all properties for nil in wrapInCreate gets rid of the panic.


diff --git a/pub/util.go b/pub/util.go
index 34d2a24..ddf0f01 100644
--- a/pub/util.go
+++ b/pub/util.go
@@ -266,69 +266,74 @@ func wrapInCreate(ctx context.Context, o vocab.Type, actor *url.URL) (c vocab.Ac
}
// Copying over properties.
if v, ok := o.(toer); ok {

activityTo := streams.NewActivityStreamsToProperty()
to := v.GetActivityStreamsTo()
for iter := to.Begin(); iter != to.End(); iter = iter.Next() {
var id *url.URL
id, err = ToId(iter)
if err != nil {
return
if to := v.GetActivityStreamsTo(); to != nil {
activityTo := streams.NewActivityStreamsToProperty()
for iter := to.Begin(); iter != to.End(); iter = iter.Next() {
var id *url.URL
id, err = ToId(iter)
if err != nil {
return
}
activityTo.AppendIRI(id) }
activityTo.AppendIRI(id)
c.SetActivityStreamsTo(activityTo) }
c.SetActivityStreamsTo(activityTo) } if v, ok := o.(btoer); ok {
activityBto := streams.NewActivityStreamsBtoProperty()
bto := v.GetActivityStreamsBto()
for iter := bto.Begin(); iter != bto.End(); iter = iter.Next() {
var id *url.URL
id, err = ToId(iter)
if err != nil {
return
if bto := v.GetActivityStreamsBto(); bto != nil {
activityBto := streams.NewActivityStreamsBtoProperty()
for iter := bto.Begin(); iter != bto.End(); iter = iter.Next() {
var id *url.URL
id, err = ToId(iter)
if err != nil {
return
}
activityBto.AppendIRI(id) }
activityBto.AppendIRI(id)
c.SetActivityStreamsBto(activityBto) }
c.SetActivityStreamsBto(activityBto) } if v, ok := o.(ccer); ok {
activityCc := streams.NewActivityStreamsCcProperty()
cc := v.GetActivityStreamsCc()
for iter := cc.Begin(); iter != cc.End(); iter = iter.Next() {
var id *url.URL
id, err = ToId(iter)
if err != nil {
return
if cc := v.GetActivityStreamsCc(); cc != nil {
activityCc := streams.NewActivityStreamsCcProperty()
for iter := cc.Begin(); iter != cc.End(); iter = iter.Next() {
var id *url.URL
id, err = ToId(iter)
if err != nil {
return
}
activityCc.AppendIRI(id) }
activityCc.AppendIRI(id)
c.SetActivityStreamsCc(activityCc) }
c.SetActivityStreamsCc(activityCc) } if v, ok := o.(bccer); ok {
activityBcc := streams.NewActivityStreamsBccProperty()
bcc := v.GetActivityStreamsBcc()
for iter := bcc.Begin(); iter != bcc.End(); iter = iter.Next() {
var id *url.URL
id, err = ToId(iter)
if err != nil {
return
if bcc := v.GetActivityStreamsBcc(); bcc != nil {
activityBcc := streams.NewActivityStreamsBccProperty()
for iter := bcc.Begin(); iter != bcc.End(); iter = iter.Next() {
var id *url.URL
id, err = ToId(iter)
if err != nil {
return
}
activityBcc.AppendIRI(id) }
activityBcc.AppendIRI(id)
c.SetActivityStreamsBcc(activityBcc) }
c.SetActivityStreamsBcc(activityBcc) } if v, ok := o.(audiencer); ok {
activityAudience := streams.NewActivityStreamsAudienceProperty()
aud := v.GetActivityStreamsAudience()
for iter := aud.Begin(); iter != aud.End(); iter = iter.Next() {
var id *url.URL
id, err = ToId(iter)
if err != nil {
return
if aud := v.GetActivityStreamsAudience(); aud != nil {
activityAudience := streams.NewActivityStreamsAudienceProperty()
for iter := aud.Begin(); iter != aud.End(); iter = iter.Next() {
var id *url.URL
id, err = ToId(iter)
if err != nil {
return
}
activityAudience.AppendIRI(id) }
activityAudience.AppendIRI(id)
c.SetActivityStreamsAudience(activityAudience) }
c.SetActivityStreamsAudience(activityAudience) } return }

Any shareable logs of observations: Here is the full stacktrace.

goroutine 19 [running]:
net/http.(*conn).serve.func1(0xc00013cbe0)
/proj/ciptmp/ru64tiji/go/src/net/http/server.go:1767 +0x139
panic(0x11e2500, 0x2587900)
/proj/ciptmp/ru64tiji/go/src/runtime/panic.go:679 +0x1b2
github.com/go-fed/activity/pub.wrapInCreate(0x1d13d60, 0xc000136e40, 0x7f74feee01c0, 0xc0000c9200, 0xc0000f8a80, 0x0, 0x0, 0xc0001038a8, 0xe38b15)
/home/cip/2014/ru64tiji/Go/src/github.com/go-fed/activity/pub/util.go:284 +0xa3e
github.com/go-fed/activity/pub.(*sideEffectActor).WrapInCreate(0xc0000c0370, 0x1d13d60, 0xc000136e40, 0x7f74feee01c0, 0xc0000c9200, 0xc0000f8800, 0xc000136e40, 0xc0000fa300, 0x7f74feee01c0, 0xc0000c9200)
/home/cip/2014/ru64tiji/Go/src/github.com/go-fed/activity/pub/side_effect_actor.go:423 +0x1b7
github.com/go-fed/activity/pub.(*baseActor).deliver(0xc0000a1e90, 0x1d13d60, 0xc000136e40, 0xc0000f8800, 0x7f74feee01c0, 0xc0000c9200, 0xc000136e70, 0xc000136e40, 0x0, 0x0, ...)
/home/cip/2014/ru64tiji/Go/src/github.com/go-fed/activity/pub/base_actor.go:419 +0x415
github.com/go-fed/activity/pub.(*baseActor).PostOutbox(0xc0000a1e90, 0x1d13d60, 0xc000136e40, 0x1d12520, 0xc00011c700, 0xc0000fa300, 0xc0000f8800, 0x0, 0x0)
/home/cip/2014/ru64tiji/Go/src/github.com/go-fed/activity/pub/base_actor.go:347 +0x3a9
main.newOutboxHandler.func1(0x1d12520, 0xc00011c700, 0xc0000fa300)
/home/cip/2014/ru64tiji/Go/src/gitlab.cs.fau.de/kissen/fed/ap_handlers.go:50 +0x121
net/http.HandlerFunc.ServeHTTP(0xc000136240, 0x1d12520, 0xc00011c700, 0xc0000fa300)
/proj/ciptmp/ru64tiji/go/src/net/http/server.go:2007 +0x44
github.com/gorilla/mux.(*Router).ServeHTTP(0xc000132000, 0x1d12520, 0xc00011c700, 0xc0000fa100)
/home/cip/2014/ru64tiji/Go/src/github.com/gorilla/mux/mux.go:210 +0xe2
net/http.serverHandler.ServeHTTP(0xc00011c620, 0x1d12520, 0xc00011c700, 0xc0000fa100)
/proj/ciptmp/ru64tiji/go/src/net/http/server.go:2802 +0xa4
net/http.(*conn).serve(0xc00013cbe0, 0x1d13ca0, 0xc0000cec80)
/proj/ciptmp/ru64tiji/go/src/net/http/server.go:1890 +0x875
created by net/http.(*Server).Serve

Resulting impact of the defective behavior: Posting a plain Note into a users outbox results in that request panicking.

Please Describe The Expected Behavior I expect the Note to be properly wrapped in a Create without a nil reference.

cjslep commented 4 years ago

Awesome bug report! Thanks a ton for documenting all of this.

Also, if you have a fediverse account, please do reach out to me at @cj@mastodon.technology. I would love to learn more about your experience using this library. Especially as I am actively updating https://go-fed.org.

cjslep commented 4 years ago

Hi @kissen

With the latest merge, can you confirm if this issue is fixed for you?

kissen commented 4 years ago

Yes, this fixes the bug from what I can tell. Thank you!

(Unfortunately I don't really have time to work on any ActiviyPub projects this summer, but maybe I'll look into it again later. I certainly continue to be interested in it.)

go-fed / activity

/pub/util.go: wrapInCreate: nil pointer dereference #131