tools/hexnet: Implement function for reading bytes from stdin

src/tools/hexnet.cpp

@@ -16,6 +16,7 @@
 //version 3 along with this program.
 //If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
 
+#include <chrono>
 #include <csignal>
 #include <iomanip>
 #include <iostream>
@@ -70,6 +71,38 @@ in_port_t port;
 const uint32_t bufferSize = 2048;
 uint8_t networkBuffer[bufferSize];
 
+std::string readByteFromStdin() {
+    std::string input = "";
+    // read 2 characters from stdin
+    char characterInput;
+    bool readByte = false;
+    uint16_t iterationsSinceLastInput = 0;
+    while (input.length() < 2 && !exitProgram) {
+        if (std::cin.good()) {
+            std::cin.get(characterInput);
+            readByte = true;
+        } else {
+            readByte = false;
+        }
+        // ignore space, tabs, and newlines
+        if (readByte && characterInput!=' ' && characterInput!='\n' && characterInput!='\r' && characterInput!='\t') {
+            input.push_back(characterInput);
+        }
+
+        iterationsSinceLastInput++;
+        if (readByte) {
+            iterationsSinceLastInput = 0;
+        }
+        if (iterationsSinceLastInput>1024) {
+            // prevent integer overflow
+            iterationsSinceLastInput = 1024;
+
+            std::this_thread::sleep_for(std::chrono::milliseconds(1000));
+        }
+    }
+    return exitProgram? "" : std::string(1, (char) std::stoi(input, nullptr, 16));
+}
+
 void signalHandler(int signal) {
     // shut down gracefully
     exitProgram = true;
@@ -148,7 +181,7 @@ int main(int argc, char* argv[]) {
     std::vector<CLI::Argument> arguments;
     arguments.push_back(CLI::Argument("PORT", "the port to lsiten on (or connect to)"));
 
-    CLI::ArgumentsParser cliParser = CLI::ArgumentsParser(argc, argv, flags, options, arguments, "Arbitrary TCP/UDP connections in hex format", "Note: Make sure your terminal is set up so it doesn't buffer input and, if desired, disable input echoing.\n\tSomething like `stty -echo cbreak` should do but it will also disable some key combinations.");
+    CLI::ArgumentsParser cliParser = CLI::ArgumentsParser(argc, argv, flags, options, arguments, "Arbitrary TCP/UDP connections in hex format", "Spaces, tabs, newlines, and carriage returns in the input are ignored.\n\tYou may want to disable input echoing using `stty -echo` (reenable using `stty echo`).\n\tNote that many terminals do line buffering on the input by default.");
 
     if (cliParser.getFlag("help").value) {
         std::cout << cliParser.getUsage() << std::endl;