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-rw-r--r--src/fastd.c157
1 files changed, 133 insertions, 24 deletions
diff --git a/src/fastd.c b/src/fastd.c
index 3cc7d37..a9cb0c4 100644
--- a/src/fastd.c
+++ b/src/fastd.c
@@ -39,6 +39,7 @@
#include <string.h>
#include <syslog.h>
#include <sys/resource.h>
+#include <sys/wait.h>
#ifdef HAVE_LIBSODIUM
#include <sodium/core.h>
@@ -68,34 +69,49 @@ static void on_sigusr1(int signo UNUSED) {
dump = true;
}
+static void on_sigchld(int signo UNUSED) {
+}
+
static void init_signals(fastd_context_t *ctx) {
struct sigaction action;
action.sa_flags = 0;
sigemptyset(&action.sa_mask);
+ /* unblock all signals */
+ sigprocmask(SIG_SETMASK, &action.sa_mask, NULL);
+
action.sa_handler = on_sighup;
- if(sigaction(SIGHUP, &action, NULL))
+ if (sigaction(SIGHUP, &action, NULL))
exit_errno(ctx, "sigaction");
action.sa_handler = on_terminate;
- if(sigaction(SIGTERM, &action, NULL))
+ if (sigaction(SIGTERM, &action, NULL))
exit_errno(ctx, "sigaction");
- if(sigaction(SIGQUIT, &action, NULL))
+ if (sigaction(SIGQUIT, &action, NULL))
exit_errno(ctx, "sigaction");
- if(sigaction(SIGINT, &action, NULL))
+ if (sigaction(SIGINT, &action, NULL))
exit_errno(ctx, "sigaction");
action.sa_handler = on_sigusr1;
- if(sigaction(SIGUSR1, &action, NULL))
+ if (sigaction(SIGUSR1, &action, NULL))
+ exit_errno(ctx, "sigaction");
+
+ action.sa_handler = on_sigchld;
+ if (sigaction(SIGCHLD, &action, NULL))
exit_errno(ctx, "sigaction");
action.sa_handler = SIG_IGN;
- if(sigaction(SIGPIPE, &action, NULL))
+ if (sigaction(SIGPIPE, &action, NULL))
+ exit_errno(ctx, "sigaction");
+ if (sigaction(SIGTTIN, &action, NULL))
+ exit_errno(ctx, "sigaction");
+ if (sigaction(SIGTTOU, &action, NULL))
exit_errno(ctx, "sigaction");
+
}
-static void init_pipes(fastd_context_t *ctx) {
+static void open_pipe(fastd_context_t *ctx, int *readfd, int *writefd) {
int pipefd[2];
if (pipe(pipefd))
@@ -104,8 +120,12 @@ static void init_pipes(fastd_context_t *ctx) {
fastd_setfd(ctx, pipefd[0], FD_CLOEXEC, 0);
fastd_setfd(ctx, pipefd[1], FD_CLOEXEC, 0);
- ctx->resolverfd = pipefd[0];
- ctx->resolvewfd = pipefd[1];
+ *readfd = pipefd[0];
+ *writefd = pipefd[1];
+}
+
+static inline void init_pipes(fastd_context_t *ctx) {
+ open_pipe(ctx, &ctx->resolverfd, &ctx->resolvewfd);
}
static void init_log(fastd_context_t *ctx) {
@@ -737,6 +757,96 @@ static void drop_caps(fastd_context_t *ctx) {
fastd_cap_drop(ctx);
}
+/* will double fork and forward potential exit codes from the child to the parent */
+static int daemonize(fastd_context_t *ctx) {
+ static const uint8_t ERROR_STATUS = 1;
+
+ uint8_t status = 1;
+ int parent_rpipe, parent_wpipe;
+ open_pipe(ctx, &parent_rpipe, &parent_wpipe);
+
+ pid_t fork1 = fork();
+
+ if (fork1 < 0) {
+ exit_errno(ctx, "fork");
+ }
+ else if (fork1 == 0) {
+ /* child 1 */
+ if (close(parent_rpipe) < 0)
+ pr_error_errno(ctx, "close");
+
+ if (setsid() < 0)
+ pr_error_errno(ctx, "setsid");
+
+ int child_rpipe, child_wpipe;
+ open_pipe(ctx, &child_rpipe, &child_wpipe);
+
+ pid_t fork2 = fork();
+
+ if (fork2 < 0) {
+ write(parent_wpipe, &ERROR_STATUS, 1);
+ exit_errno(ctx, "fork");
+ }
+ else if (fork2 == 0) {
+ /* child 2 */
+
+ if (close(child_rpipe) < 0 || close(parent_wpipe) < 0) {
+ write(child_wpipe, &ERROR_STATUS, 1);
+ pr_error_errno(ctx, "close");
+ }
+
+ return child_wpipe;
+ }
+ else {
+ /* still child 1 */
+ int child_status;
+ pid_t ret;
+ do {
+ if (read(child_rpipe, &status, 1) > 0) {
+ write(parent_wpipe, &status, 1);
+ exit(0);
+ }
+
+ ret = waitpid(fork2, &child_status, WNOHANG);
+ } while (!ret);
+
+ if (ret < 0) {
+ write(child_wpipe, &ERROR_STATUS, 1);
+ pr_error_errno(ctx, "waitpid");
+ }
+
+ if (WIFEXITED(child_status)) {
+ status = WEXITSTATUS(child_status);
+ write(parent_wpipe, &status, 1);
+ exit(status);
+ }
+ else {
+ write(parent_wpipe, &ERROR_STATUS, 1);
+ if (WIFSIGNALED(child_status))
+ exit_error(ctx, "child exited with signal %i", WTERMSIG(child_status));
+ exit(1);
+ }
+ }
+ }
+ else {
+ /* parent */
+ struct sigaction action;
+ action.sa_flags = 0;
+ sigemptyset(&action.sa_mask);
+ action.sa_handler = SIG_IGN;
+
+ if (sigaction(SIGCHLD, &action, NULL))
+ exit_errno(ctx, "sigaction");
+
+ if (read(parent_rpipe, &status, 1) < 0)
+ exit_errno(ctx, "read");
+
+ exit(status);
+ }
+
+ return -1;
+}
+
int main(int argc, char *argv[]) {
#ifdef HAVE_LIBSODIUM
sodium_init();
@@ -749,6 +859,7 @@ int main(int argc, char *argv[]) {
#endif
fastd_context_t ctx = {};
+ int status_fd = -1;
close_fds(&ctx);
@@ -771,9 +882,13 @@ int main(int argc, char *argv[]) {
exit(0);
}
- init_log(&ctx);
init_signals(&ctx);
+ if (conf.daemon)
+ status_fd = daemonize(&ctx);
+
+ init_log(&ctx);
+
update_time(&ctx);
conf.long_ago = ctx.now;
@@ -799,21 +914,15 @@ int main(int argc, char *argv[]) {
fastd_tuntap_open(&ctx);
init_peer_groups(&ctx);
- if (conf.daemon) {
- pid_t pid = fork();
- if (pid < 0) {
- exit_errno(&ctx, "fork");
- }
- else if (pid > 0) {
- write_pid(&ctx, pid);
- exit(0);
- }
- if (setsid() < 0)
- pr_error_errno(&ctx, "setsid");
- }
- else {
- write_pid(&ctx, getpid());
+ write_pid(&ctx, getpid());
+
+ if (status_fd >= 0) {
+ static const uint8_t STATUS = 0;
+ if (write(status_fd, &STATUS, 1) < 0)
+ exit_errno(&ctx, "status: write");
+ if (close(status_fd))
+ exit_errno(&ctx, "status: close");
}
if (conf.drop_caps == DROP_CAPS_EARLY)