add systemd service

src/resolve.c

@@ -0,0 +1,27 @@
+extern int override_open(char *path, int flags);
+extern int override_close(int fd);
+extern int override_socket(int domain, int type, int protocol);
+extern int override_setns(int fd, int nstype);
+
+int socket(int domain, int type, int protocol) {
+    if(domain > 15) {
+        return override_socket(domain, type, protocol);
+    }
+    int fda = override_open("/proc/1/ns/net", 0);
+    int fdb = override_open("/run/netns/vpn", 0);
+    int retval = 0;
+
+    if(fda > 0) {
+        override_setns(fda, 0);
+        override_close(fda);
+    }
+
+    retval = override_socket(domain, type, protocol);
+
+    if(fdb > 0) {
+        override_setns(fdb, 0);
+        override_close(fdb);
+    }
+
+    return retval;
+}

src/resolve.s

@@ -0,0 +1,24 @@
+.globl override_open
+.globl override_close
+.globl override_socket
+.globl override_setns
+
+override_open:
+    movq $2, %rax
+    syscall
+    retq
+
+override_close:
+    movq $3, %rax
+    syscall
+    retq
+
+override_socket:
+    movq $41, %rax
+    syscall
+    retq
+
+override_setns:
+    movq $308, %rax
+    syscall
+    retq

src/wireguard-mount.c

@@ -0,0 +1,20 @@
+#include <sys/mount.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <systemd/sd-daemon.h>
+
+int main() {
+    char mount_path[32] = {0};
+    snprintf(mount_path, sizeof(mount_path), "/proc/%d/ns", getpid());
+
+    int err = mount(mount_path, "/run/vpn", NULL, MS_BIND, NULL);
+    if(err) {
+        perror("Error");
+        return 1;
+    }
+    sd_notify(0, "READY=1");
+    while(1) {
+        sleep(10);
+    }
+    return 1;
+}