crash: discard envelopes that do not contain a crash

pkg/sentry/envelope.zig

@@ -17,6 +17,12 @@ pub const Envelope = opaque {
         ) != 0) return error.WriteFailed;
     }
 
+    pub fn serialize(self: *Envelope) []u8 {
+        var len: usize = 0;
+        const ptr = c.sentry_envelope_serialize(@ptrCast(self), &len).?;
+        return ptr[0..len];
+    }
+
     pub fn event(self: *Envelope) ?Value {
         const val: Value = .{ .value = c.sentry_envelope_get_event(@ptrCast(self)) };
         if (val.isNull()) return null;

pkg/sentry/main.zig

@@ -18,6 +18,10 @@ pub fn setTag(key: []const u8, value: []const u8) void {
     c.sentry_set_tag_n(key.ptr, key.len, value.ptr, value.len);
 }
 
+pub fn free(ptr: *anyopaque) void {
+    c.sentry_free(ptr);
+}
+
 test {
     @import("std").testing.refAllDecls(@This());
 }

src/crash/sentry.zig

@@ -5,6 +5,7 @@ const builtin = @import("builtin");
 const build_config = @import("../build_config.zig");
 const sentry = @import("sentry");
 const internal_os = @import("../os/main.zig");
+const crash = @import("main.zig");
 const state = &@import("../global.zig").state;
 
 const log = std.log.scoped(.sentry);
@@ -89,13 +90,16 @@ pub const Transport = struct {
 
     /// Implementation of send but we can use Zig errors.
     fn sendInternal(envelope: *sentry.Envelope) !void {
-        // If our envelope doesn't have an event then we don't do anything.
-        // TODO: figure out how to not encode empty envelopes.
-
         var arena = std.heap.ArenaAllocator.init(state.alloc);
         defer arena.deinit();
         const alloc = arena.allocator();
 
+        // Some envelopes don't contain a crash report. Discord them.
+        if (try shouldDiscard(alloc, envelope)) {
+            log.info("sentry envelope does not contain crash, discarding", .{});
+            return;
+        }
+
         // Generate a UUID for this envelope. The envelope DOES have an event_id
         // header but I don't think there is any public API way to get it
         // afaict so we generate a new UUID for the filename just so we don't
@@ -117,4 +121,26 @@ pub const Transport = struct {
 
         log.warn("crash report written to disk path={s}", .{path});
     }
+
+    fn shouldDiscard(alloc: Allocator, envelope: *sentry.Envelope) !bool {
+        // If our envelope doesn't have an event then we don't do anything.
+        // To figure this out we first encode it into a string, parse it,
+        // and check if it has an event. Kind of wasteful but the best
+        // option we have at the time of writing this since the C API doesn't
+        // expose this information.
+        const json = envelope.serialize();
+        defer sentry.free(@ptrCast(json.ptr));
+
+        // Parse into an envelope structure
+        var fbs = std.io.fixedBufferStream(json);
+        var parsed = try crash.Envelope.parse(alloc, fbs.reader());
+        defer parsed.deinit();
+
+        // If we have an event item then we're good.
+        for (parsed.items) |item| {
+            if (item.type == .event) return false;
+        }
+
+        return true;
+    }
 };

src/crash/sentry_envelope.zig

@@ -138,10 +138,13 @@ pub const Envelope = struct {
 
         // Parse the header JSON
         const headers: std.json.ObjectMap = headers: {
+            const line = std.mem.trim(u8, buf.items, " \t");
+            if (line.len == 0) return null;
+
             const value = try std.json.parseFromSliceLeaky(
                 std.json.Value,
                 alloc,
-                buf.items,
+                line,
                 .{ .allocate = .alloc_if_needed },
             );
 
@@ -262,3 +265,20 @@ test "Envelope parse session" {
     try testing.expectEqual(@as(usize, 1), v.items.len);
     try testing.expectEqual(ItemType.session, v.items[0].type);
 }
+
+test "Envelope parse end in new line" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var fbs = std.io.fixedBufferStream(
+        \\{}
+        \\{"type":"session","length":218}
+        \\{"init":true,"sid":"c148cc2f-5f9f-4231-575c-2e85504d6434","status":"abnormal","errors":0,"started":"2024-08-29T02:38:57.607016Z","duration":0.000343,"attrs":{"release":"0.1.0-HEAD+d37b7d09","environment":"production"}}
+        \\
+    );
+    var v = try Envelope.parse(alloc, fbs.reader());
+    defer v.deinit();
+
+    try testing.expectEqual(@as(usize, 1), v.items.len);
+    try testing.expectEqual(ItemType.session, v.items[0].type);
+}