Add initial gdbremote implementation

1 files changed, 100 insertions, 0 deletions

diff --git a/gdbremote.cpp b/gdbremote.cpp
new file mode 100644
index 0000000..98a0e2a
--- /dev/null
+++ b/gdbremote.cpp
@@ -0,0 +1,100 @@
+/* SPDX-License-Identifier: Unlicense
+ */
+
+#include "gdbremote_parser.hpp"
+
+#include <cstdlib>
+#include <cstdio>
+#include <cstdint>
+#include <cstring>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+
+#define MESSAGE_BUFFER_SIZE 1
+
+char msg_buf[MESSAGE_BUFFER_SIZE];
+
+static int set_socket_reuseaddr(int socket_fd)
+{
+    const int val = 1;
+    const socklen_t len = sizeof(val);
+    return setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, (void*)&val, len);
+}
+
+static inline struct sockaddr_in sockaddr_in_any_ip_with_port(uint16_t port) {
+    struct sockaddr_in server{};
+    server.sin_family = AF_INET;
+    server.sin_addr.s_addr = INADDR_ANY;
+    server.sin_port = htons(port);
+    return server;
+}
+
+static int setup_socket(uint16_t port)
+{
+    // This creates the socket - or quits
+    const int socket_fd = socket(AF_INET, SOCK_STREAM, 0);
+    if (socket_fd == -1) {
+        perror("Could not create socket");
+        return -1;
+    }
+    // Make TCP port reusable in case of kill or crash.
+    // Deliberate explanation: https://stackoverflow.com/a/3233022
+    if (set_socket_reuseaddr(socket_fd) == -1) {
+        perror("setsockopt failed");
+        close(socket_fd);
+        return -1;
+    }
+    puts("Socket created");
+    const struct sockaddr_in server = sockaddr_in_any_ip_with_port(port);
+    if (bind(socket_fd, (struct sockaddr *)&server, sizeof(server)) == -1) {
+        perror("Bind failed");
+        close(socket_fd);
+        return -1;
+    }
+    printf("Binding to 0.0.0.0:%u done\n", port);
+    return socket_fd;
+}
+
+int main(int argc, char *argv[])
+{
+    const int port = argc > 1 ? atoi(argv[1]) : 3333;
+    const int socket_fd = setup_socket(port);
+    if (socket_fd == -1)
+        return EXIT_FAILURE;
+    printf("Listening TCP 0.0.0.0:%u\n", port);
+    listen(socket_fd, 4); // Mark socket as listener
+    struct sockaddr client_address;
+    socklen_t address_len;
+    const int conn_fd = accept(socket_fd, &client_address, &address_len);
+    if (conn_fd == -1) {
+        perror("Accept failed");
+        close(socket_fd);
+        return EXIT_FAILURE;
+    }
+    puts("Connection accepted");
+    GDBRemote::ExchangeContext exchange_ctx{};
+    ssize_t read_size;
+    while ((read_size = recv(conn_fd, msg_buf, MESSAGE_BUFFER_SIZE, 0)) > 0) {
+        for (size_t i = 0; i < static_cast<size_t>(read_size); i++) {
+            const auto res = exchange_ctx.Consume(msg_buf[i]);
+            if (res != nullptr) {
+                if (res->packet.length() > 0) {
+                    printf("<- \"%s\"\n", res->packet.c_str());
+                }
+                if (res->response.length() > 0) {
+                    printf("-> \"%s\"\n", res->response.c_str());
+                    if (send(conn_fd, &res->response[0], res->response.length(), 0) == -1)
+                        perror("Send failed");
+                }
+            }
+        }
+        memset(msg_buf, '\0', MESSAGE_BUFFER_SIZE);
+    }
+    if (read_size == 0) {
+        puts("Client disconnected");
+    } else if (read_size == -1) {
+        perror("Recv failed");
+    }
+    close(socket_fd);
+}