283 lines
10 KiB
C
283 lines
10 KiB
C
#include "kms_client.h"
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <unistd.h>
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#include <signal.h>
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#include <stdbool.h>
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#include <fcntl.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <sys/wait.h>
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#include <sys/capability.h>
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static bool generate_random_characters(char *buffer, int buffer_size, const char *alphabet, size_t alphabet_size) {
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int fd = open("/dev/urandom", O_RDONLY);
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if(fd == -1) {
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perror("/dev/urandom");
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return false;
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}
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if(read(fd, buffer, buffer_size) < buffer_size) {
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fprintf(stderr, "Failed to read %d bytes from /dev/urandom\n", buffer_size);
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close(fd);
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return false;
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}
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for(int i = 0; i < buffer_size; ++i) {
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unsigned char c = *(unsigned char*)&buffer[i];
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buffer[i] = alphabet[c % alphabet_size];
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}
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close(fd);
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return true;
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}
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static int send_msg_to_server(int server_fd, gsr_kms_request *request) {
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struct iovec iov;
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iov.iov_base = request;
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iov.iov_len = sizeof(*request);
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struct msghdr request_message = {0};
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request_message.msg_iov = &iov;
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request_message.msg_iovlen = 1;
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return sendmsg(server_fd, &request_message, 0);
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}
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static int recv_msg_from_server(int server_fd, gsr_kms_response *response) {
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struct iovec iov;
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iov.iov_base = response;
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iov.iov_len = sizeof(*response);
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struct msghdr response_message = {0};
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response_message.msg_iov = &iov;
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response_message.msg_iovlen = 1;
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char cmsgbuf[CMSG_SPACE(sizeof(int))];
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memset(cmsgbuf, 0, sizeof(cmsgbuf));
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response_message.msg_control = cmsgbuf;
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response_message.msg_controllen = sizeof(cmsgbuf);
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int res = recvmsg(server_fd, &response_message, MSG_WAITALL);
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if(res <= 0)
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return res;
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if(response->result == KMS_RESULT_OK)
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response->data.fd.fd = 0;
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struct cmsghdr *cmsg = CMSG_FIRSTHDR(&response_message);
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if(cmsg) {
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if(cmsg->cmsg_type == SCM_RIGHTS) {
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int kms_fd = 0;
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memcpy(&kms_fd, CMSG_DATA(cmsg), sizeof(int));
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response->data.fd.fd = kms_fd;
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}
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}
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return res;
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}
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static bool create_socket_path(char *output_path, size_t output_path_size) {
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// Can't use /tmp because of flatpak, but fallback to it if we fail to get a valid runtime dir
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char runtime_dir_path[PATH_MAX];
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const char *runtime_dir = getenv("XDG_RUNTIME_DIR");
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const char *flatpak_id = getenv("FLATPAK_ID");
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if(runtime_dir) {
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if(flatpak_id)
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snprintf(runtime_dir_path, sizeof(runtime_dir_path), "%s/app/%s", runtime_dir, flatpak_id);
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else
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strcpy(runtime_dir_path, runtime_dir);
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} else {
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const uint32_t uid = getuid();
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if(flatpak_id)
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snprintf(runtime_dir_path, sizeof(runtime_dir_path), "/run/user/%u/app/%s", uid, flatpak_id);
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else
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snprintf(runtime_dir_path, sizeof(runtime_dir_path), "/run/user/%u", uid);
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}
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if(access(runtime_dir_path, F_OK) != 0)
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strcpy(runtime_dir_path, "/tmp");
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char random_characters[11];
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random_characters[10] = '\0';
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if(!generate_random_characters(random_characters, 10, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789", 62))
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return false;
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snprintf(output_path, output_path_size, "%s/gsr-kms-socket-%s", runtime_dir_path, random_characters);
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return true;
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}
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int gsr_kms_client_init(gsr_kms_client *self, const char *card_path) {
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self->kms_server_pid = -1;
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self->socket_fd = -1;
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self->client_fd = -1;
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self->socket_path[0] = '\0';
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struct sockaddr_un local_addr = {0};
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struct sockaddr_un remote_addr = {0};
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if(!create_socket_path(self->socket_path, sizeof(self->socket_path))) {
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fprintf(stderr, "gsr error: gsr_kms_client_init: failed to create path to kms socket\n");
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return -1;
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}
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// This doesn't work on nixos, but we dont want to use $PATH because we want to make this as safe as possible by running pkexec
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// on a path that only root can modify. If we use "gsr-kms-server" instead then $PATH can be modified in ~/.bashrc for example
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// which will overwrite the path to gsr-kms-server and the user can end up running a malicious program that pretends to be gsr-kms-server.
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// If there is a safe way to do this on nixos, then please tell me; or use gpu-screen-recorder flatpak instead.
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const char *server_filepath = "/usr/bin/gsr-kms-server";
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bool has_perm = 0;
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const bool inside_flatpak = getenv("FLATPAK_ID") != NULL;
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if(!inside_flatpak) {
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if(access("/usr/bin/gsr-kms-server", F_OK) != 0) {
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fprintf(stderr, "gsr error: gsr_kms_client_init: /usr/bin/gsr-kms-server not found, please install gpu-screen-recorder first\n");
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return -1;
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}
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if(geteuid() == 0) {
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has_perm = true;
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} else {
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cap_t kms_server_cap = cap_get_file(server_filepath);
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if(kms_server_cap) {
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cap_flag_value_t res = 0;
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cap_get_flag(kms_server_cap, CAP_SYS_ADMIN, CAP_PERMITTED, &res);
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if(res == CAP_SET) {
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//fprintf(stderr, "has permission!\n");
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has_perm = true;
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} else {
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//fprintf(stderr, "No permission:(\n");
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}
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cap_free(kms_server_cap);
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} else {
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if(errno == ENODATA)
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fprintf(stderr, "gsr info: gsr_kms_client_init: gsr-kms-server is missing sys_admin cap and will require root authentication. To bypass this automatically, run: sudo setcap cap_sys_admin+ep '%s'\n", server_filepath);
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else
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fprintf(stderr, "gsr info: gsr_kms_client_init: failed to get cap\n");
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}
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}
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}
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self->socket_fd = socket(AF_UNIX, SOCK_STREAM, 0);
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if(self->socket_fd == -1) {
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fprintf(stderr, "gsr error: gsr_kms_client_init: socket failed, error: %s\n", strerror(errno));
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goto err;
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}
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local_addr.sun_family = AF_UNIX;
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strncpy(local_addr.sun_path, self->socket_path, sizeof(local_addr.sun_path));
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if(bind(self->socket_fd, (struct sockaddr*)&local_addr, sizeof(local_addr.sun_family) + strlen(local_addr.sun_path)) == -1) {
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fprintf(stderr, "gsr error: gsr_kms_client_init: failed to bind socket, error: %s\n", strerror(errno));
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goto err;
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}
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if(listen(self->socket_fd, 1) == -1) {
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fprintf(stderr, "gsr error: gsr_kms_client_init: failed to listen on socket, error: %s\n", strerror(errno));
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goto err;
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}
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pid_t pid = fork();
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if(pid == -1) {
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fprintf(stderr, "gsr error: gsr_kms_client_init: fork failed, error: %s\n", strerror(errno));
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goto err;
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} else if(pid == 0) { /* child */
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if(inside_flatpak) {
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const char *args[] = { "flatpak-spawn", "--host", "pkexec", "flatpak", "run", "--command=gsr-kms-server", "com.dec05eba.gpu_screen_recorder", self->socket_path, card_path, NULL };
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execvp(args[0], (char *const*)args);
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} else if(has_perm) {
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const char *args[] = { server_filepath, self->socket_path, card_path, NULL };
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execvp(args[0], (char *const*)args);
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} else {
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const char *args[] = { "pkexec", server_filepath, self->socket_path, card_path, NULL };
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execvp(args[0], (char *const*)args);
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}
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fprintf(stderr, "gsr error: gsr_kms_client_init: execvp failed, error: %s\n", strerror(errno));
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_exit(127);
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} else { /* parent */
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self->kms_server_pid = pid;
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}
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fprintf(stderr, "gsr info: gsr_kms_client_init: waiting for server to connect\n");
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for(;;) {
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struct timeval tv;
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fd_set rfds;
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FD_ZERO(&rfds);
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FD_SET(self->socket_fd, &rfds);
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tv.tv_sec = 0;
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tv.tv_usec = 100 * 1000; // 100 ms
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int select_res = select(1 + self->socket_fd, &rfds, NULL, NULL, &tv);
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if(select_res > 0) {
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socklen_t sock_len = 0;
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self->client_fd = accept(self->socket_fd, (struct sockaddr*)&remote_addr, &sock_len);
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if(self->client_fd == -1) {
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fprintf(stderr, "gsr error: gsr_kms_client_init: accept failed on socket, error: %s\n", strerror(errno));
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goto err;
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}
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break;
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} else {
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int status;
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int wait_result = waitpid(self->kms_server_pid, &status, WNOHANG);
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if(wait_result != 0) {
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fprintf(stderr, "gsr error: gsr_kms_client_init: kms server died or never started, error: %s\n", strerror(errno));
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goto err;
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}
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}
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}
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fprintf(stderr, "gsr info: gsr_kms_client_init: server connected\n");
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return 0;
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err:
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gsr_kms_client_deinit(self);
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return -1;
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}
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void gsr_kms_client_deinit(gsr_kms_client *self) {
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if(self->client_fd != -1) {
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close(self->client_fd);
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self->client_fd = -1;
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}
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if(self->socket_fd != -1) {
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close(self->socket_fd);
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self->socket_fd = -1;
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}
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if(self->kms_server_pid != -1) {
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kill(self->kms_server_pid, SIGINT);
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int status;
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waitpid(self->kms_server_pid, &status, 0);
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self->kms_server_pid = -1;
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}
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if(self->socket_path[0] != '\0') {
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remove(self->socket_path);
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self->socket_path[0] = '\0';
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}
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}
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int gsr_kms_client_get_kms(gsr_kms_client *self, gsr_kms_response *response) {
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response->result = KMS_RESULT_FAILED_TO_SEND;
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strcpy(response->data.err_msg, "failed to send");
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gsr_kms_request request;
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request.type = KMS_REQUEST_TYPE_GET_KMS;
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if(send_msg_to_server(self->client_fd, &request) == -1) {
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fprintf(stderr, "gsr error: gsr_kms_client_get_kms: failed to send request message to server\n");
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return -1;
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}
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const int recv_res = recv_msg_from_server(self->client_fd, response);
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if(recv_res == 0) {
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fprintf(stderr, "gsr warning: gsr_kms_client_get_kms: kms server shut down\n");
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return -1;
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} else if(recv_res == -1) {
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fprintf(stderr, "gsr error: gsr_kms_client_get_kms: failed to receive response\n");
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return -1;
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}
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return 0;
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}
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