evm: Enable CORS on server (#2540)

* Enable CORS on server

* Propagate error

* Add tests

---------

Co-authored-by: Prasanna Loganathar <pvl@prasannavl.com>

Author: shohamc1

lib/Cargo.lock

@@ -67,6 +67,9 @@ hex-literal = "0.4"
 bincode = "1.3"
 serde_with = "3.0"
 heck = "0.4"
+tower-http = { version = "0.4.0", features = ["full"] }
+tower = "0.4.13"
+hyper = "0.14.20"
 
 jsonrpsee = { version = "0.16", features = ["server", "macros", "http-client"] }
 jsonrpsee-core = "0.16"

lib/Cargo.toml

@@ -48,5 +48,6 @@ pub mod ffi {
         fn getDST20Tokens(mnview_ptr: usize) -> Vec<DST20Token>;
         fn getClientVersion() -> String;
         fn getNumCores() -> i32;
+        fn getCORSAllowedOrigin() -> String;
     }
 }

lib/ain-cpp-imports/src/bridge.rs

@@ -94,6 +94,9 @@ mod ffi {
     pub fn getNumCores() -> i32 {
         unimplemented!("{}", UNIMPL_MSG)
     }
+    pub fn getCORSAllowedOrigin() -> String {
+        unimplemented!("{}", UNIMPL_MSG)
+    }
 }
 
 pub use ffi::Attributes;
@@ -196,5 +199,9 @@ pub fn get_num_cores() -> i32 {
     ffi::getNumCores()
 }
 
+pub fn get_cors_allowed_origin() -> String {
+    ffi::getCORSAllowedOrigin()
+}
+
 #[cfg(test)]
 mod tests {}

lib/ain-cpp-imports/src/lib.rs

@@ -29,7 +29,9 @@ rlp.workspace = true
 sha3.workspace = true
 serde_with.workspace = true
 anyhow.workspace = true
-
+tower-http.workspace = true
+tower.workspace = true
+hyper.workspace = true
 [build-dependencies]
 cxx-gen.workspace = true
 heck.workspace = true

lib/ain-grpc/Cargo.toml

@@ -27,10 +27,13 @@ use std::{
 
 use ain_evm::services::{Services, IS_SERVICES_INIT_CALL, SERVICES};
 use anyhow::{format_err, Result};
+use hyper::header::HeaderValue;
+use hyper::Method;
 use jsonrpsee::core::server::rpc_module::Methods;
 use jsonrpsee_server::ServerBuilder as HttpServerBuilder;
 use log::info;
 use logging::CppLogTarget;
+use tower_http::cors::CorsLayer;
 
 use crate::rpc::{
     debug::{MetachainDebugRPCModule, MetachainDebugRPCServer},
@@ -72,9 +75,26 @@ pub fn init_network_json_rpc_service(runtime: &Services, addr: &str) -> Result<(
     let addr = addr.parse::<SocketAddr>()?;
     let max_connections = ain_cpp_imports::get_max_connections();
 
+    let middleware = if !ain_cpp_imports::get_cors_allowed_origin().is_empty() {
+        info!(
+            "Allowed origins: {}",
+            ain_cpp_imports::get_cors_allowed_origin()
+        );
+        let cors = CorsLayer::new()
+            .allow_methods([Method::POST, Method::GET, Method::OPTIONS])
+            .allow_origin(ain_cpp_imports::get_cors_allowed_origin().parse::<HeaderValue>()?)
+            .allow_headers([hyper::header::CONTENT_TYPE, hyper::header::AUTHORIZATION])
+            .allow_credentials(true);
+
+        tower::ServiceBuilder::new().layer(cors)
+    } else {
+        tower::ServiceBuilder::new().layer(CorsLayer::new())
+    };
+
     let handle = runtime.tokio_runtime.clone();
     let server = runtime.tokio_runtime.block_on(
         HttpServerBuilder::default()
+            .set_middleware(middleware)
             .max_connections(max_connections)
             .custom_tokio_runtime(handle)
             .build(addr),

lib/ain-grpc/src/lib.rs

@@ -4,6 +4,7 @@
 #include <key_io.h>
 #include <logging.h>
 #include <clientversion.h>
+#include <httprpc.h>
 
 // TODO: Later switch this to u8 so we skip the
 // conversion and is more efficient.
@@ -290,3 +291,7 @@ int32_t getNumCores() {
     const auto n = GetNumCores() - 1;
     return std::max(1, n);
 }
+
+rust::string getCORSAllowedOrigin() {
+    return gArgs.GetArg("-rpcallowcors", "");
+}

src/ffi/ffiexports.cpp

@@ -3,6 +3,7 @@
 
 #include <chainparams.h>
 #include <ffi/cxx.h>
+#include <httprpc.h>
 
 // Defaults for attributes relating to EVM functionality
 static constexpr uint64_t DEFAULT_EVM_BLOCK_GAS_TARGET = 15000000;
@@ -68,5 +69,6 @@ void CppLogPrintf(rust::string message);
 rust::vec<DST20Token> getDST20Tokens(std::size_t mnview_ptr);
 rust::string getClientVersion();
 int32_t getNumCores();
+rust::string getCORSAllowedOrigin();
 
 #endif  // DEFI_FFI_FFIEXPORTS_H