feat: webxdc sending contexts

Author: r10s

deltachat-ffi/deltachat.h

@@ -4234,6 +4234,10 @@ char*             dc_msg_get_webxdc_blob      (const dc_msg_t* msg, const char*
  *   true if the Webxdc should get internet access;
  *   this is the case i.e. for experimental maps integration.
  * - self_addr: address to be used for `window.webxdc.selfAddr` in JS land.
+ * - app_sender_addr: address of the peer who initially shared the webxdc in the chat.
+ *   Can be compared to self_addr to determine whether the app runs for the sender or a receiver.
+ * - can_only_send_updates_to_app_sender: true if updates sent by the local user
+ *   will only be seen by the app sender.
  * - send_update_interval: Milliseconds to wait before calling `sendUpdate()` again since the last call.
  *   Should be exposed to `webxdc.sendUpdateInterval` in JS land.
  * - send_update_max_size: Maximum number of bytes accepted for a serialized update object.

deltachat-jsonrpc/src/api/types/webxdc.rs

@@ -37,6 +37,11 @@ pub struct WebxdcMessageInfo {
     internet_access: bool,
     /// Address to be used for `window.webxdc.selfAddr` in JS land.
     self_addr: String,
+    /// Address of the peer who initially shared the webxdc in the chat.
+    app_sender_addr: String,
+    /// True if updates sent by the local user
+    /// will only be seen by the app sender.
+    can_only_send_updates_to_app_sender: bool,
     /// Milliseconds to wait before calling `sendUpdate()` again since the last call.
     /// Should be exposed to `window.sendUpdateInterval` in JS land.
     send_update_interval: usize,
@@ -60,6 +65,8 @@ impl WebxdcMessageInfo {
             request_integration: _,
             internet_access,
             self_addr,
+            app_sender_addr,
+            can_only_send_updates_to_app_sender,
             send_update_interval,
             send_update_max_size,
         } = message.get_webxdc_info(context).await?;
@@ -72,6 +79,8 @@ impl WebxdcMessageInfo {
             source_code_url: maybe_empty_string_to_option(source_code_url),
             internet_access,
             self_addr,
+            app_sender_addr,
+            can_only_send_updates_to_app_sender,
             send_update_interval,
             send_update_max_size,
         })

src/webxdc.rs

@@ -36,7 +36,7 @@ use tokio::{fs::File, io::BufReader};
 
 use crate::chat::{self, Chat};
 use crate::constants::Chattype;
-use crate::contact::ContactId;
+use crate::contact::{Contact, ContactId};
 use crate::context::Context;
 use crate::events::EventType;
 use crate::key::self_fingerprint;
@@ -111,6 +111,15 @@ pub struct WebxdcInfo {
     /// Address to be used for `window.webxdc.selfAddr` in JS land.
     pub self_addr: String,
 
+    /// Address of the peer who initially shared the webxdc in the chat.
+    /// Can be compared to `self_addr` to determine
+    /// whether the app runs for the sender or a receiver.
+    pub app_sender_addr: String,
+
+    /// `true` if updates sent by the local user
+    /// will only be seen by the app sender.
+    pub can_only_send_updates_to_app_sender: bool,
+
     /// Milliseconds to wait before calling `sendUpdate()` again since the last call.
     /// Should be exposed to `window.sendUpdateInterval` in JS land.
     pub send_update_interval: usize,
@@ -923,6 +932,12 @@ impl Message {
         let internet_access = is_integrated;
 
         let self_addr = self.get_webxdc_self_addr(context).await?;
+        let app_sender_addr = self.get_webxdc_app_sender_addr(context).await?;
+
+        let chat = Chat::load_from_db(context, self.chat_id)
+            .await
+            .with_context(|| "Failed to load chat from the database")?;
+        let can_only_send_updates_to_app_sender = chat.typ == Chattype::InBroadcast;
 
         Ok(WebxdcInfo {
             name: if let Some(name) = manifest.name {
@@ -961,6 +976,8 @@ impl Message {
             request_integration,
             internet_access,
             self_addr,
+            app_sender_addr,
+            can_only_send_updates_to_app_sender,
             send_update_interval: context.ratelimit.read().await.update_interval(),
             send_update_max_size: RECOMMENDED_FILE_SIZE as usize,
         })
@@ -973,6 +990,29 @@ impl Message {
         Ok(format!("{hash:x}"))
     }
 
+    /// Computes the webxdc address of the message sender.
+    async fn get_webxdc_app_sender_addr(&self, context: &Context) -> Result<String> {
+        // UNDEFINED may be preset during drafts or tests, will be SELF on sending
+        let fingerprint = if self.from_id == ContactId::SELF || self.from_id == ContactId::UNDEFINED
+        {
+            self_fingerprint(context).await?.to_string()
+        } else {
+            let contact = Contact::get_by_id(context, self.from_id).await?;
+            contact
+                .fingerprint()
+                .with_context(|| {
+                    format!(
+                        "No fingerprint for contact {} (webxdc sender)",
+                        self.from_id
+                    )
+                })?
+                .hex()
+        };
+        let data = format!("{}-{}", fingerprint, self.rfc724_mid);
+        let hash = Sha256::digest(data.as_bytes());
+        Ok(format!("{hash:x}"))
+    }
+
     /// Get link attached to an info message.
     ///
     /// The info message needs to be of type SystemMessage::WebxdcInfoMessage.

src/webxdc/webxdc_tests.rs

@@ -12,6 +12,7 @@ use crate::chatlist::Chatlist;
 use crate::config::Config;
 use crate::ephemeral;
 use crate::receive_imf::receive_imf;
+use crate::securejoin::get_securejoin_qr;
 use crate::test_utils::{E2EE_INFO_MSGS, TestContext, TestContextManager};
 use crate::tools::{self, SystemTime};
 use crate::{message, sql};
@@ -2195,3 +2196,44 @@ async fn test_self_addr_consistency() -> Result<()> {
     assert_eq!(db_msg.get_webxdc_self_addr(alice).await?, self_addr);
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_webxdc_info_fields() -> Result<()> {
+    let mut tcm = TestContextManager::new();
+    let alice = &tcm.alice().await;
+    let bob = &tcm.bob().await;
+
+    // Alice sends webxdc in a group chat
+    let alice_chat_id = alice.create_group_with_members("Group", &[bob]).await;
+    let alice_instance = send_webxdc_instance(alice, alice_chat_id).await?;
+    let sent1 = alice.pop_sent_msg().await;
+    let alice_info = alice_instance.get_webxdc_info(alice).await?;
+    assert_eq!(alice_info.self_addr, alice_info.app_sender_addr);
+    assert!(!alice_info.can_only_send_updates_to_app_sender);
+
+    // Bob receives group webxdc
+    let bob_instance = bob.recv_msg(&sent1).await;
+    let bob_info = bob_instance.get_webxdc_info(bob).await?;
+    assert_ne!(bob_info.self_addr, bob_info.app_sender_addr);
+    assert_eq!(bob_info.app_sender_addr, alice_info.self_addr);
+    assert!(!bob_info.can_only_send_updates_to_app_sender);
+
+    // Alice sends webxdc to broadcast channel
+    let alice_chat_id = create_broadcast(alice, "Broadcast".to_string()).await?;
+    let qr = get_securejoin_qr(alice, Some(alice_chat_id)).await.unwrap();
+    tcm.exec_securejoin_qr(bob, alice, &qr).await;
+    let alice_instance = send_webxdc_instance(alice, alice_chat_id).await?;
+    let sent2 = alice.pop_sent_msg().await;
+    let alice_info = alice_instance.get_webxdc_info(alice).await?;
+    assert_eq!(alice_info.self_addr, alice_info.app_sender_addr);
+    assert!(!alice_info.can_only_send_updates_to_app_sender);
+
+    // Bob receives broadcast webxdc
+    let bob_instance = bob.recv_msg(&sent2).await;
+    let bob_info = bob_instance.get_webxdc_info(bob).await?;
+    assert_ne!(bob_info.self_addr, bob_info.app_sender_addr);
+    assert_eq!(bob_info.app_sender_addr, alice_info.self_addr);
+    assert!(bob_info.can_only_send_updates_to_app_sender);
+
+    Ok(())
+}