1 files changed, 460 insertions, 0 deletions

diff --git a/src/protocol.c b/src/protocol.c
new file mode 100644
index 0000000..4b832ab
--- /dev/null
+++ b/src/protocol.c
@@ -0,0 +1,460 @@
+#include <errno.h>
+#include <json.h>
+#include <libwebsockets.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/wait.h>
+
+#include "server.h"
+#include "terminal.h"
+#include "utils.h"
+
+// initial message list
+static char initial_cmds[] = {SET_WINDOW_TITLE, SET_PREFERENCES};
+
+static int send_initial_message(struct lws *wsi, int index) {
+  unsigned char message[LWS_PRE + 1 + 4096];
+  unsigned char *p = &message[LWS_PRE];
+  char buffer[128];
+  int n = 0;
+
+  char cmd = initial_cmds[index];
+  switch (cmd) {
+    case SET_WINDOW_TITLE:
+      gethostname(buffer, sizeof(buffer) - 1);
+      n = sprintf((char *)p, "%c%s (%s)", cmd, server->command, buffer);
+      break;
+    case SET_PREFERENCES:
+      n = sprintf((char *)p, "%c%s", cmd, server->prefs_json);
+      break;
+    default:
+      break;
+  }
+
+  return lws_write(wsi, p, (size_t)n, LWS_WRITE_BINARY);
+}
+
+static bool parse_window_size(struct pss_tty *pss, int *cols, int *rows) {
+  char json[pss->len];
+  strncpy(json, pss->buffer + 1, pss->len - 1);
+  json[pss->len - 1] = '\0';
+
+  json_object *obj = json_tokener_parse(json);
+  struct json_object *o = NULL;
+
+  if (!json_object_object_get_ex(obj, "columns", &o)) {
+    lwsl_err("columns field not exists, json: %s\n", json);
+    return false;
+  }
+  *cols = json_object_get_int(o);
+  if (!json_object_object_get_ex(obj, "rows", &o)) {
+    lwsl_err("rows field not exists, json: %s\n", json);
+    return false;
+  }
+  *rows = json_object_get_int(o);
+  json_object_put(obj);
+
+  return true;
+}
+
+static bool check_host_origin(struct lws *wsi) {
+  int origin_length = lws_hdr_total_length(wsi, WSI_TOKEN_ORIGIN);
+  char buf[origin_length + 1];
+  memset(buf, 0, sizeof(buf));
+  int len = lws_hdr_copy(wsi, buf, sizeof(buf), WSI_TOKEN_ORIGIN);
+  if (len <= 0) {
+    return false;
+  }
+
+  const char *prot, *address, *path;
+  int port;
+  if (lws_parse_uri(buf, &prot, &address, &port, &path)) return false;
+  if (port == 80 || port == 443) {
+    sprintf(buf, "%s", address);
+  } else {
+    sprintf(buf, "%s:%d", address, port);
+  }
+
+  int host_length = lws_hdr_total_length(wsi, WSI_TOKEN_HOST);
+  if (host_length != strlen(buf)) return false;
+  char host_buf[host_length + 1];
+  memset(host_buf, 0, sizeof(host_buf));
+  len = lws_hdr_copy(wsi, host_buf, sizeof(host_buf), WSI_TOKEN_HOST);
+
+  return len > 0 && strcasecmp(buf, host_buf) == 0;
+}
+
+static void close_cb(uv_handle_t *handle) {
+  struct pty_proc *proc = container_of((uv_pipe_t *)handle, struct pty_proc, pipe);
+  free(proc);
+}
+
+static void pty_proc_free(struct pty_proc *proc) {
+  uv_read_stop((uv_stream_t *)&proc->pipe);
+  close(proc->pty);
+  if (proc->pty_buffer != NULL) {
+    free(proc->pty_buffer);
+    proc->pty_buffer = NULL;
+  }
+  for (int i = 0; i < proc->argc; i++) {
+    free(proc->args[i]);
+  }
+  uv_close((uv_handle_t *)&proc->pipe, close_cb);
+}
+
+static void alloc_cb(uv_handle_t *handle, size_t suggested_size, uv_buf_t *buf) {
+  buf->base = xmalloc(suggested_size);
+  buf->len = suggested_size;
+}
+
+static void read_cb(uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf) {
+  struct pss_tty *pss = (struct pss_tty *)stream->data;
+  struct pty_proc *proc = pss->proc;
+  proc->pty_len = nread;
+
+  uv_read_stop(stream);
+
+  if (nread == UV_ENOBUFS || nread == 0) return;
+  if (nread > 0) {
+    proc->pty_buffer = xmalloc(LWS_PRE + 1 + (size_t)nread);
+    memcpy(proc->pty_buffer + LWS_PRE + 1, buf->base, (size_t)nread);
+  } else {
+    proc->pty_buffer = NULL;
+    if (nread != UV_EOF) {
+      proc->err_count++;
+      lwsl_err("read_cb: %s (%s)\n", uv_err_name(nread), uv_strerror(nread));
+    }
+  }
+  free(buf->base);
+
+  lws_callback_on_writable(pss->wsi);
+}
+
+static void child_cb(uv_signal_t *handle, int signum) {
+  pid_t pid;
+  int stat;
+
+  struct pty_proc *proc;
+  LIST_HEAD(proc, pty_proc) *procs = handle->data;
+  LIST_FOREACH(proc, procs, entry) {
+    do
+      pid = waitpid(proc->pid, &stat, WNOHANG);
+    while (pid == -1 && errno == EINTR);
+
+    if (pid <= 0) continue;
+
+    if (WIFEXITED(stat)) {
+      proc->status = WEXITSTATUS(stat);
+      lwsl_notice("process exited with code %d, pid: %d\n", proc->status, proc->pid);
+    } else if (WIFSIGNALED(stat)) {
+      int sig = WTERMSIG(stat);
+      char sig_name[20];
+
+      proc->status = 128 + sig;
+      get_sig_name(sig, sig_name, sizeof(sig_name));
+      lwsl_notice("process killed with signal %d (%s), pid: %d\n", sig, sig_name, proc->pid);
+    }
+
+    LIST_REMOVE(proc, entry);
+    if (proc->state == STATE_KILL) {
+      pty_proc_free(proc);
+    } else {
+      proc->state = STATE_EXIT;
+    }
+  }
+}
+
+static int spawn_process(struct pss_tty *pss) {
+  struct pty_proc *proc = pss->proc;
+  // append url args to arguments
+  char *argv[server->argc + proc->argc + 1];
+  int i, n = 0;
+  for (i = 0; i < server->argc; i++) {
+    argv[n++] = server->argv[i];
+  }
+  for (i = 0; i < proc->argc; i++) {
+    argv[n++] = proc->args[i];
+  }
+  argv[n] = NULL;
+
+  uv_signal_start(&server->watcher, child_cb, SIGCHLD);
+
+  // ensure the lws socket fd close-on-exec
+  fd_set_cloexec(lws_get_socket_fd(pss->wsi));
+
+  // create process with pseudo-tty
+  proc->pid = pty_fork(&proc->pty, argv[0], argv, server->terminal_type);
+  if (proc->pid < 0) {
+    lwsl_err("pty_fork: %d (%s)\n", errno, strerror(errno));
+    return 1;
+  }
+
+  lwsl_notice("started process, pid: %d\n", proc->pid);
+
+  proc->pipe.data = pss;
+  uv_pipe_open(&proc->pipe, proc->pty);
+
+  lws_callback_on_writable(pss->wsi);
+
+  return 0;
+}
+
+static void kill_process(struct pty_proc *proc) {
+  if (proc->pid <= 0) return;
+
+  pid_t pid = proc->pid;
+  int sig = server->sig_code;
+  char *sig_name = server->sig_name;
+
+  lwsl_notice("killing process %d with signal: %d (%s)\n", pid, sig, sig_name);
+  int pgid = getpgid(pid);
+  if (uv_kill(pgid > 0 ? -pgid : pid, sig) != 0) {
+    lwsl_err("kill: %d, errno: %d (%s)\n", pid, errno, strerror(errno));
+  }
+}
+
+static void write_cb(uv_write_t *req, int status) {
+  if (status != 0) lwsl_warn("uv_write callback returned status: %d\n", status);
+  free(req->data);
+  free(req);
+}
+
+int callback_tty(struct lws *wsi, enum lws_callback_reasons reason, void *user, void *in,
+                 size_t len) {
+  struct pss_tty *pss = (struct pss_tty *)user;
+  struct pty_proc *proc;
+  char buf[256];
+  size_t n = 0;
+
+  switch (reason) {
+    case LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION:
+      if (server->once && server->client_count > 0) {
+        lwsl_warn("refuse to serve WS client due to the --once option.\n");
+        return 1;
+      }
+      if (server->max_clients > 0 && server->client_count == server->max_clients) {
+        lwsl_warn("refuse to serve WS client due to the --max-clients option.\n");
+        return 1;
+      }
+
+      n = lws_hdr_copy(wsi, pss->path, sizeof(pss->path), WSI_TOKEN_GET_URI);
+#if defined(LWS_ROLE_H2)
+      if (n <= 0) n = lws_hdr_copy(wsi, pss->path, sizeof(pss->path), WSI_TOKEN_HTTP_COLON_PATH);
+#endif
+      if (strncmp(pss->path, endpoints.ws, n) != 0) {
+        lwsl_warn("refuse to serve WS client for illegal ws path: %s\n", buf);
+        return 1;
+      }
+
+      if (server->check_origin && !check_host_origin(wsi)) {
+        lwsl_warn(
+            "refuse to serve WS client from different origin due to the "
+            "--check-origin option.\n");
+        return 1;
+      }
+      break;
+
+    case LWS_CALLBACK_ESTABLISHED:
+      pss->initialized = false;
+      pss->initial_cmd_index = 0;
+      pss->authenticated = false;
+      pss->wsi = wsi;
+      pss->buffer = NULL;
+
+      pss->proc = proc = xmalloc(sizeof(struct pty_proc));
+      memset(proc, 0, sizeof(struct pty_proc));
+      proc->status = -1;
+      proc->state = STATE_INIT;
+      uv_pipe_init(server->loop, &proc->pipe, 0);
+
+      if (server->url_arg) {
+        while (lws_hdr_copy_fragment(wsi, buf, sizeof(buf), WSI_TOKEN_HTTP_URI_ARGS, n++) > 0) {
+          if (strncmp(buf, "arg=", 4) == 0) {
+            proc->args = xrealloc(proc->args, (proc->argc + 1) * sizeof(char *));
+            proc->args[proc->argc] = strdup(&buf[4]);
+            proc->argc++;
+          }
+        }
+      }
+
+      LIST_INSERT_HEAD(&server->procs, proc, entry);
+      server->client_count++;
+
+#if LWS_LIBRARY_VERSION_NUMBER >= 2004000
+      lws_get_peer_simple(lws_get_network_wsi(wsi), pss->address, sizeof(pss->address));
+#else
+      char name[100];
+      lws_get_peer_addresses(wsi, lws_get_socket_fd(wsi), name, sizeof(name), pss->address,
+                             sizeof(pss->address));
+#endif
+      lwsl_notice("WS   %s - %s, clients: %d\n", pss->path, pss->address, server->client_count);
+      break;
+
+    case LWS_CALLBACK_SERVER_WRITEABLE:
+      proc = pss->proc;
+      if (!pss->initialized) {
+        if (pss->initial_cmd_index == sizeof(initial_cmds)) {
+          pss->initialized = true;
+          uv_read_start((uv_stream_t *)&proc->pipe, alloc_cb, read_cb);
+          break;
+        }
+        if (send_initial_message(wsi, pss->initial_cmd_index) < 0) {
+          lwsl_err("failed to send initial message, index: %d\n", pss->initial_cmd_index);
+          lws_close_reason(wsi, LWS_CLOSE_STATUS_UNEXPECTED_CONDITION, NULL, 0);
+          return -1;
+        }
+        pss->initial_cmd_index++;
+        lws_callback_on_writable(wsi);
+        break;
+      }
+
+      // read error or client exited, close connection
+      if (proc->status == 0 || proc->pty_len == UV_EOF) {
+        lws_close_reason(wsi, LWS_CLOSE_STATUS_NORMAL, NULL, 0);
+        return 1;
+      } else if (proc->status > 0 || (proc->pty_len < 0 && proc->err_count == MAX_READ_RETRY)) {
+        lws_close_reason(wsi, LWS_CLOSE_STATUS_UNEXPECTED_CONDITION, NULL, 0);
+        return -1;
+      }
+
+      if (proc->pty_buffer != NULL && proc->pty_len > 0) {
+        proc->pty_buffer[LWS_PRE] = OUTPUT;
+        n = (size_t)(proc->pty_len + 1);
+        if (lws_write(wsi, (unsigned char *)proc->pty_buffer + LWS_PRE, n, LWS_WRITE_BINARY) < n) {
+          lwsl_err("write OUTPUT to WS\n");
+        }
+        free(proc->pty_buffer);
+        proc->pty_buffer = NULL;
+      }
+
+      uv_read_start((uv_stream_t *)&proc->pipe, alloc_cb, read_cb);
+      break;
+
+    case LWS_CALLBACK_RECEIVE:
+      if (pss->buffer == NULL) {
+        pss->buffer = xmalloc(len);
+        pss->len = len;
+        memcpy(pss->buffer, in, len);
+      } else {
+        pss->buffer = xrealloc(pss->buffer, pss->len + len);
+        memcpy(pss->buffer + pss->len, in, len);
+        pss->len += len;
+      }
+
+      const char command = pss->buffer[0];
+
+      // check auth
+      if (server->credential != NULL && !pss->authenticated && command != JSON_DATA) {
+        lwsl_warn("WS client not authenticated\n");
+        return 1;
+      }
+
+      // check if there are more fragmented messages
+      if (lws_remaining_packet_payload(wsi) > 0 || !lws_is_final_fragment(wsi)) {
+        return 0;
+      }
+
+      proc = pss->proc;
+      switch (command) {
+        case INPUT:
+          if (proc->pty == 0) break;
+          if (server->readonly) break;
+
+          char *data = xmalloc(pss->len - 1);
+          memcpy(data, pss->buffer + 1, pss->len - 1);
+
+          uv_buf_t b = {data, pss->len - 1};
+          uv_write_t *req = xmalloc(sizeof(uv_write_t));
+          req->data = data;
+
+          int err = uv_write(req, (uv_stream_t *)&proc->pipe, &b, 1, write_cb);
+          if (err) {
+            lwsl_err("uv_write: %s (%s)\n", uv_err_name(err), uv_strerror(err));
+            return -1;
+          }
+          break;
+        case RESIZE_TERMINAL: {
+          int cols, rows;
+          if (parse_window_size(pss, &cols, &rows)) {
+            if (pty_resize(proc->pty, cols, rows) < 0) {
+              lwsl_err("pty_resize: %d (%s)\n", errno, strerror(errno));
+            }
+          }
+        } break;
+        case PAUSE:
+          if (proc->state == STATE_INIT) {
+            uv_read_stop((uv_stream_t *)&proc->pipe);
+            proc->state = STATE_PAUSE;
+          }
+          break;
+        case RESUME:
+          if (proc->state == STATE_PAUSE) {
+            uv_read_start((uv_stream_t *)&proc->pipe, alloc_cb, read_cb);
+            proc->state = STATE_INIT;
+          }
+          break;
+        case JSON_DATA:
+          if (proc->pid > 0) break;
+          if (server->credential != NULL) {
+            json_object *obj = json_tokener_parse(pss->buffer);
+            struct json_object *o = NULL;
+            if (json_object_object_get_ex(obj, "AuthToken", &o)) {
+              const char *token = json_object_get_string(o);
+              if (token != NULL && !strcmp(token, server->credential))
+                pss->authenticated = true;
+              else
+                lwsl_warn("WS authentication failed with token: %s\n", token);
+            }
+            if (!pss->authenticated) {
+              lws_close_reason(wsi, LWS_CLOSE_STATUS_POLICY_VIOLATION, NULL, 0);
+              return -1;
+            }
+          }
+          if (spawn_process(pss) != 0) return 1;
+          break;
+        default:
+          lwsl_warn("ignored unknown message type: %c\n", command);
+          break;
+      }
+
+      if (pss->buffer != NULL) {
+        free(pss->buffer);
+        pss->buffer = NULL;
+      }
+      break;
+
+    case LWS_CALLBACK_CLOSED:
+      if (pss->wsi == NULL) break;
+
+      server->client_count--;
+      lwsl_notice("WS closed from %s, clients: %d\n", pss->address, server->client_count);
+      if (pss->buffer != NULL) {
+        free(pss->buffer);
+      }
+
+      proc = pss->proc;
+      if (proc->state == STATE_EXIT) {
+        pty_proc_free(proc);
+      } else {
+        proc->state = STATE_KILL;
+        uv_read_stop((uv_stream_t *)&proc->pipe);
+        kill_process(proc);
+      }
+
+      if (server->once && server->client_count == 0) {
+        lwsl_notice("exiting due to the --once option.\n");
+        force_exit = true;
+        lws_cancel_service(context);
+        exit(0);
+      }
+      break;
+
+    default:
+      break;
+  }
+
+  return 0;
+}