Implemented a new LimiterService within the utils library to control the maximum number of TCP connections for a service. This feature was created to prevent services, such as gRPC, JSON RPC, REST, etc., from exceeding their maximum allowed active TCP connections. This enhancement will avoid server overload and ensure more stable and reliable service performance. Other additions include appropriate dependencies in the Cargo.toml file and necessary modifications to the Cargo.lock file to support this implementation.

Added optional TCP connection limit functionality to the gRPC server Adaptor, ConnectionHandler, and GrpcService classes. This change allows limiting the number of active TCP connections to the gRPC server. If set, the server will refuse new connections once the limit is reached. This is intended to prevent server overload from too many concurrent connections. Implemented by using a TCP limiter method from the kaspa_utils library and integrating it with the gRPC server setup. This feature is optional and can be enabled by passing the limiter object during server creation. If not passed, the server will accept an unlimited number of connections.

Introduced an optional TCP connection limit to the gRPC server in Adaptor, ConnectionHandler, and GrpcService. This change allows the server to manage the number of active TCP connections, enhancing its ability to prevent server overload due to excess concurrent connections. Implemented via the TCP limiter method from the kaspa_utils library and integrated into the gRPC server setup. This functionality can be enabled during server creation via passing a limiter object. If not provided, the server will operate with an unlimited number of connections.

The import statements in service.rs and layer.rs files in the tcp_limiter module were refactored for better code readability. Additional '\http' dependency was added in the Cargo.toml file which was reflected in the Cargo.lock file. Removing 'http' from 'tonic' in service.rs was necessary as it is now directly added as a dependency.

Replaced the serve method with serve_with_shutdown in both p2p and gRPC connection handlers. This change resolves the previous issue of lacking server shutdown functionality. The termination_receiver.map(drop) is now properly incorporated, enabling a more controlled server termination.

This commit updates our crate dependencies by changing the tonic and tonic-build packages to reference the workspace instead of specific external versions. This will allow us to keep our internal versions in sync and avoid potential incompatibility issues. We have also added required updates in utils, rpc, protocol and grabbed the latest versions of pin-project and pin-project-internal. This optimizes the dependencies of the project and reduces the build size and time. Changes present in rpc/grpc/server, rpc/grpc/core, protocol/p2p, utils, rpc/grpc/client Cargo.toml, Cargo.lock and in Cargo.toml files.

The commit removes the gRPC-specific connection limiter and introduces a shared TCP connection limiter. The previous implementation was specific to gRPC only, but we want a solution that works across different services like gRPC, JSON RPC, REST, etc. As a result, the 'grpc' module has been deleted, and a new 'tcp_wrapper' module has been created. The new TCP limiter is shared and tracks the number of active TCP connections against a maximum limit.

The TCP connection limiter has been made protocol agnostic, allowing it to work with multiple services like gRPC, JSON RPC, REST, etc. Previously, the limiter was limited to gRPC only. This change involved removing the gRPC-specific 'LimitLayer' and replacing it with a shared 'Wrapper' from the 'tcp_limiter' module. This refactoring makes it more reusable and simplifies the management of active TCP connections."

Updated the TCP connection limiter to use a loop for sync and made it protocol agnostic. Previously, the limiter was tightly coupled with gRPC, this change allows it to work with any protocol and makes it more reusable.

Also, Removed redundant connection tests in client_server, as they were excessive and not related to the primary server functionality. These changes simplify management of active connections and improve test efficiency."

Integrate TCP limit option in daemon and rpc/wrpc modules to control the number of incoming connections. The limit option can be set during the launch of these services. By default, the value is None, meaning the number of connections are unlimited. This is essential for system resources optimization and prevention of any potential DoS attacks."

Added a new argument 'max_tcp_connections' to allow user to set a limit on number of TCP connections for kaspad. This helps in optimization of system resources and also acts as a preventive measure against potential DoS attacks. In absence of argument, defaults to 'None', indicating unlimited number of connections."

Applied conditional compilation to the tcp_limiter module to exclude it when targeting wasm32. TCP connection limiting is not applicable in the context of WebAssembly, thereby removing unnecessary dependencies and reducing compilation time. Also reordered dependencies in utils/Cargo.toml under a specific target architecture to maintain clean code organization."

Moved the TCP limit calculation from main.rs to daemon.rs to improve code coherence. Now, error management related to TCP limit exceeding is also done within daemon.rs. This change enhances code organization and readability by keeping all TCP-related logic in one place."

Inserted comments in adaptor.rs and connection_handler.rs as reminders to implement TCP limit in connect_peer and connect_with_retry functions. These additions highlight the need to consider TCP limits when connecting to a peer and retrying connections respectively."

In tests, implemented new parameters for max_tcp_connections in both daemon.rs and daemon_integration_tests.rs. This changes the total file descriptor limit calculation by dividing it by two. This is critical in improving the robustness of our tests by ensuring they work under hardened network conditions."

# Conflicts:
#	Cargo.toml
#	protocol/p2p/Cargo.toml
#	rpc/grpc/client/Cargo.toml
#	rpc/grpc/core/Cargo.toml
#	rpc/grpc/server/Cargo.toml
#	rpc/grpc/server/src/adaptor.rs
#	rpc/grpc/server/src/connection_handler.rs
#	rpc/grpc/server/src/service.rs
#	rpc/grpc/server/src/tests/client_server.rs
#	testing/integration/src/daemon_integration_tests.rs

Changed the hardcoded file descriptors limit to a dynamic computation based on system's limitations in integration tests. This change makes the test environment more reliable because the file descriptor limit is adjusted according to the system's configuration and prevents potential issues with resource exhaustion. Also, set the maximum TCP connections for devnet in daemon cleaning test.