From b1733bc0070cba5a82efb65f4857119ada934671 Mon Sep 17 00:00:00 2001
From: BodgeMaster <>
Date: Wed, 20 Jul 2022 08:06:04 +0200
Subject: [PATCH] tools/hexnet: initial implementation of TCP receive only
 server

---
 src/tools/hexnet.cpp | 65 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 55 insertions(+), 10 deletions(-)

diff --git a/src/tools/hexnet.cpp b/src/tools/hexnet.cpp
index 06125db..80e4230 100644
--- a/src/tools/hexnet.cpp
+++ b/src/tools/hexnet.cpp
@@ -14,9 +14,11 @@
 //If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
 
 #include <iostream>
+#include <iomanip>
 #include <string>
 #include <cstdint>
 #include <cctype>
+#include <sockpp/tcp_acceptor.h>
 
 #include "../lib/error.h++"
 #include "../lib/cli.h++"
@@ -34,8 +36,9 @@ int main(int argc, char* argv[]){
     bool tcp = true;
     bool udp = true;
     bool listen = false;
+    int64_t mtu = 1500;
     std::string host;
-    uint16_t port;
+    in_port_t port;
 
     std::vector<CLI::Flag> flags;
     flags.push_back(CLI::Flag('4', "ipv4", "use IPv4, defaults to both when -4 and -6 are omitted, otherwise uses what is specified"));
@@ -45,6 +48,7 @@ int main(int argc, char* argv[]){
 
     std::vector<CLI::UnpositionalArgument> unpositionalArguments;
     unpositionalArguments.push_back(CLI::UnpositionalArgument('c', "connect", "HOST", "connect to HOST, listen for incoming connections if omitted"));
+    unpositionalArguments.push_back(CLI::UnpositionalArgument('m', "mtu-optimize", "MTU", "Optimize for a specific maximum transfer unit by reading MTU bytes at a time."));
 
     std::vector<CLI::PositionalArgument> positionalArguments;
     positionalArguments.push_back(CLI::PositionalArgument("PORT", "the port to use"));
@@ -66,15 +70,56 @@ int main(int argc, char* argv[]){
     if (cliParser.getUnpositionalArgument('c').errorCode == ErrorCodes::NOT_PRESENT) {
         listen = true;
     }
+    if (cliParser.getUnpositionalArgument('m').errorCode == ErrorCodes::SUCCESS) {
+        mtu = std::stol(cliParser.getUnpositionalArgument('m').value);
+    }
     host = cliParser.getUnpositionalArgument('c').value;
-    //FIXME: use a function that returns a fixed-width data type instead
-    port = (uint16_t) std::stoi(cliParser.getPositionalArgument(0).value);
+    //FIXME: use a function that returns a fixed-width data type instead,
+    //       ensure that the given value is a valid port
+    port = (in_port_t) std::stoi(cliParser.getPositionalArgument(0).value);
 
-    std::cerr << "Port: " << (int) port << std::endl;
-    std::cerr << (listen? "Listening" : "Host: ") << host << std::endl;
-    std::cerr << "IPv4: " << (ipv4? "yes" : "no") << std::endl;
-    std::cerr << "IPv6: " << (ipv6? "yes" : "no") << std::endl;
-    std::cerr << "TCP:  " << ( tcp? "yes" : "no") << std::endl;
-    std::cerr << "UDP:  " << ( udp? "yes" : "no") << std::endl;
-    return EXIT_UNIMPLEMENTED;
+    if (listen) {
+        if (ipv6) {
+            std::cerr << "IPv6 support is not implented yet." << std::endl;
+            return EXIT_UNIMPLEMENTED;
+        }
+        if (udp) {
+            std::cerr << "UDP support is not implemented yet." << std::endl;
+            return EXIT_UNIMPLEMENTED;
+        }
+        std::cerr << "Listening on port " << port << "." << std::endl;
+
+        sockpp::socket_initializer socketInitializer;
+        sockpp::tcp_acceptor tcpAcceptor(port);
+
+        if (!tcpAcceptor) {
+            std::cerr << "Error while creating TCP acceptor: " << tcpAcceptor.last_error_str() << std::endl;
+            return EXIT_RUNTIME;
+        }
+
+        sockpp::inet_address peer;
+        sockpp::tcp_socket tcpSocket = tcpAcceptor.accept(&peer);
+        std::cerr << "Incoming connection from " << peer << std::endl;
+
+        if (!tcpSocket) {
+            std::cerr << "Error on incoming connection: " << tcpAcceptor.last_error_str() << std::endl;
+            return EXIT_RUNTIME;
+        }
+
+        ssize_t numBytes;
+        uint8_t buffer[mtu];
+        while ((numBytes = tcpSocket.read(buffer, sizeof(buffer))) > 0) {
+            for (ssize_t i=0; i<numBytes; i++) {
+                std::cout << std::hex << std::setfill('0') << std::setw(2) << (short) buffer[i];
+            }
+            std::cout.flush();
+        }
+
+        std::cerr << std::endl << "Connection closed." << std::endl;
+        return EXIT_SUCCESS;
+
+    } else {
+        std::cerr << "Client mode is not implemented yet." << std::endl;
+        return EXIT_UNIMPLEMENTED;
+    }
 }