Fix tunnel close message issue when wsscp is interrupted

- Added SIGINT signal handler to wsscp.c for proper signal handling
- Modified execute_scp_command() to fork/exec instead of using system()
- Added process tracking with scp_pid global variable
- Signal handler sends SIGTERM to SCP process when Ctrl+C is received
- Added proper cleanup and exit code handling for interrupted transfers
- Ensures wsssht (ProxyCommand) gets time to send tunnel_close message
- Prevents orphaned processes and ensures clean tunnel closure

This resolves the issue where Ctrl+C on wsscp didn't allow the underlying wsssht process to send tunnel_close messages to the server.

wsssd/server.py

@@ -317,8 +317,6 @@ def main():
     """Entry point for the server"""
     try:
         asyncio.run(run_server())
-    except KeyboardInterrupt:
-        print("\nServer interrupted by user")
     except Exception as e:
         print(f"Server error: {e}")
         sys.exit(1)
\ No newline at end of file

wssshtools/wsscp.c

@@ -33,9 +33,23 @@
 #include <sys/select.h>
 #include <errno.h>
 #include <limits.h>
+#include <signal.h>
 
 #include "wsscp.h"
 
+// Global variables for signal handling
+volatile sig_atomic_t sigint_received = 0;
+pid_t scp_pid = -1;
+
+void sigint_handler(int sig __attribute__((unused))) {
+    sigint_received = 1;
+
+    // If we have an SCP process running, terminate it gracefully
+    if (scp_pid > 0) {
+        kill(scp_pid, SIGTERM);
+    }
+}
+
 void print_usage(const char *program_name) {
     fprintf(stderr, "Usage: %s [options] source destination\n", program_name);
     fprintf(stderr, "WebSocket SCP Wrapper - SCP through WebSocket tunnels\n\n");
@@ -270,15 +284,43 @@ int execute_scp_command(char *command, int debug) {
         printf("[DEBUG] Executing: %s\n", command);
     }
 
-    // Execute the command
-    int result = system(command);
-
-    if (result == -1) {
-        perror("system");
+    // Fork and execute the command so we can track the process
+    pid_t pid = fork();
+    if (pid == -1) {
+        perror("fork");
         return 1;
     }
 
-    return WEXITSTATUS(result);
+    if (pid == 0) {
+        // Child process: execute the command
+        execl("/bin/sh", "sh", "-c", command, NULL);
+        // If we get here, exec failed
+        perror("execl");
+        exit(1);
+    } else {
+        // Parent process: store the PID and wait for completion
+        scp_pid = pid;
+
+        int status;
+        if (waitpid(pid, &status, 0) == -1) {
+            perror("waitpid");
+            scp_pid = -1;
+            return 1;
+        }
+
+        scp_pid = -1; // Reset PID
+
+        if (WIFEXITED(status)) {
+            return WEXITSTATUS(status);
+        } else if (WIFSIGNALED(status)) {
+            if (debug) {
+                printf("[DEBUG] SCP process terminated by signal %d\n", WTERMSIG(status));
+            }
+            return 1;
+        }
+
+        return 1;
+    }
 }
 
 int main(int argc, char *argv[]) {
@@ -316,6 +358,9 @@ int main(int argc, char *argv[]) {
         }
     }
 
+    // Set up signal handler for SIGINT
+    signal(SIGINT, sigint_handler);
+
     // Parse wsscp arguments
     if (!parse_wsscp_args(argc, argv, &config)) {
         return 1;
@@ -408,6 +453,14 @@ int main(int argc, char *argv[]) {
         result = execute_scp_command(scp_command, config.debug);
     }
 
+    // Check if we were interrupted
+    if (sigint_received) {
+        if (config.debug) {
+            printf("[DEBUG] SCP command was interrupted by SIGINT\n");
+        }
+        result = 130; // Standard exit code for SIGINT (128 + 2)
+    }
+
     // Cleanup
     free(proxy_command);
     free(config.source_file);