From 21b3f96d7807d09f503ef409626ab5b21a663c7a Mon Sep 17 00:00:00 2001
From: Ruben De Smet <ruben.de.smet@rubdos.be>
Date: Mon, 4 Sep 2023 15:57:52 +0200
Subject: [PATCH 1/2] Add server_guid to Metadata

This is unlike Signal Android, where the Envelope is also continously
passed while processing the already decrypted content.  In Rust, we
logically would *consume* the envelope to yield the Metadata and
Content, so I prefer the Metadata to contain this information.
---
 libsignal-service/src/cipher.rs  | 13 +++++++++++++
 libsignal-service/src/content.rs |  3 +++
 2 files changed, 16 insertions(+)

diff --git a/libsignal-service/src/cipher.rs b/libsignal-service/src/cipher.rs
index 8154cad54..1448b69b1 100644
--- a/libsignal-service/src/cipher.rs
+++ b/libsignal-service/src/cipher.rs
@@ -103,6 +103,15 @@ where
             });
         };
 
+        let server_guid =
+            envelope.server_guid.as_ref().and_then(|g| match g.parse() {
+                Ok(uuid) => Some(uuid),
+                Err(e) => {
+                    log::error!("Unparseable server_guid ({})", e);
+                    None
+                },
+            });
+
         use crate::proto::envelope::Type;
         let plaintext = match envelope.r#type() {
             Type::PrekeyBundle => {
@@ -118,6 +127,7 @@ where
                     timestamp: envelope.server_timestamp(),
                     needs_receipt: false,
                     unidentified_sender: false,
+                    server_guid,
                 };
 
                 let mut data = message_decrypt_prekey(
@@ -154,6 +164,7 @@ where
                     timestamp: envelope.server_timestamp(),
                     needs_receipt: false,
                     unidentified_sender: false,
+                    server_guid,
                 };
                 Plaintext {
                     metadata,
@@ -173,6 +184,7 @@ where
                     timestamp: envelope.timestamp(),
                     needs_receipt: false,
                     unidentified_sender: false,
+                    server_guid,
                 };
 
                 let mut data = message_decrypt_signal(
@@ -241,6 +253,7 @@ where
                     timestamp: envelope.timestamp(),
                     unidentified_sender: true,
                     needs_receipt,
+                    server_guid,
                 };
 
                 strip_padding(&mut message)?;
diff --git a/libsignal-service/src/content.rs b/libsignal-service/src/content.rs
index 6804b9dff..d4a377eba 100644
--- a/libsignal-service/src/content.rs
+++ b/libsignal-service/src/content.rs
@@ -1,4 +1,5 @@
 use libsignal_protocol::ProtocolAddress;
+use uuid::Uuid;
 
 pub use crate::{
     proto::{
@@ -22,6 +23,8 @@ pub struct Metadata {
     pub timestamp: u64,
     pub needs_receipt: bool,
     pub unidentified_sender: bool,
+
+    pub server_guid: Option<Uuid>,
 }
 
 impl Metadata {

From 6a8b73af9775e68f47f169d158f40a802ec7e349 Mon Sep 17 00:00:00 2001
From: Ruben De Smet <ruben.de.smet@rubdos.be>
Date: Thu, 26 Oct 2023 11:21:28 +0200
Subject: [PATCH 2/2] document server guid

---
 libsignal-service/src/content.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libsignal-service/src/content.rs b/libsignal-service/src/content.rs
index d4a377eba..16c83dcf2 100644
--- a/libsignal-service/src/content.rs
+++ b/libsignal-service/src/content.rs
@@ -24,6 +24,9 @@ pub struct Metadata {
     pub needs_receipt: bool,
     pub unidentified_sender: bool,
 
+    /// A unique UUID for this specific message, produced by the Signal servers.
+    ///
+    /// The server GUID is used to report spam messages.
     pub server_guid: Option<Uuid>,
 }