JSON-RPC: add get_http_blob API

deltachat-jsonrpc/src/api/mod.rs

@@ -1610,6 +1610,17 @@ impl CommandApi {
         Ok(general_purpose::STANDARD_NO_PAD.encode(blob))
     }
 
+    /// Makes an HTTP GET request and returns base64-encoded contents.
+    ///
+    /// `url` is the HTTP or HTTPS URL.
+    async fn get_http_blob(&self, account_id: u32, url: String) -> Result<String> {
+        let ctx = self.get_context(account_id).await?;
+        let blob = deltachat::net::read_url_blob(&ctx, &url).await?;
+
+        use base64::{engine::general_purpose, Engine as _};
+        Ok(general_purpose::STANDARD_NO_PAD.encode(blob))
+    }
+
     /// Forward messages to another chat.
     ///
     /// All types of messages can be forwarded,