+enum state {
+ SENDING_GREETING,
+ RECEIVING_USER_QUESTION,
+ SENDING_ANSWER_PREFIX,
+ SENDING_ANSWER,
+ FINISHED
+};
+
+static uint16_t state_flag_map[] = {
+ [SENDING_GREETING] = TEVENT_FD_WRITE,
+ [RECEIVING_USER_QUESTION] = TEVENT_FD_READ,
+ [SENDING_ANSWER_PREFIX] = TEVENT_FD_WRITE,
+ [SENDING_ANSWER] = TEVENT_FD_WRITE,
+ [FINISHED] = 0
+};
+
+struct client {
+ /* What are we doing today, brain? */
+ enum state state;
+ /* Our event info, and the file descriptor. */
+ struct tevent_fd *fde;
+ int fd;
+ /* The question we read from client. */
+ char *question;
+ /* How many bytes of the reply we sent so far. */
+ size_t bytes_sent;
+ /* Our server. */
+ struct oserver *oserver;
+};
+
+struct oserver {
+ /* 5 clients should be enough for anybody! */
+ struct client *clients[5];
+ int fd;
+ struct tevent_fd *fde;
+};
+
+static ssize_t write_string(int fd, const char *str)
+{
+ return write(fd, str, strlen(str));
+}
+
+static ssize_t read_string(int fd, char **buf)
+{
+ ssize_t ret, len, maxlen;
+
+ len = strlen(*buf);
+ maxlen = talloc_array_length(*buf);
+
+ if (maxlen < len + 100) {
+ maxlen += 100;
+ *buf = talloc_realloc(NULL, *buf, char, maxlen);
+ }
+
+ ret = read(fd, *buf + len, maxlen - len - 1);
+ if (ret >= 0)
+ (*buf)[len + ret] = '\0';
+ return ret;
+}
+
+static bool input_finished(const char *str)
+{
+ return strchr(str, '\n');
+}
+
+/* Update state, and set our READ/WRITE flags appropriately. */
+static void set_state(struct client *c, enum state state)
+{
+ c->state = state;
+ tevent_fd_set_flags(c->fde, state_flag_map[state]);
+}
+
+/* Returns false on error, increments state on finishing string. */
+static bool send_string(struct client *c, const char *str)
+{
+ ssize_t len = write_string(c->fd, str + c->bytes_sent);
+ if (len < 0)
+ return false;
+ c->bytes_sent += len;
+ if (c->bytes_sent == strlen(str)) {
+ c->bytes_sent = 0;
+ set_state(c, c->state+1);
+ }
+ return true;
+}
+
+static void service_client(struct tevent_context *ev,
+ struct tevent_fd *fde, uint16_t flags, void *_c)
+{
+ struct client *c = _c;
+ ssize_t len;
+
+ switch (c->state) {
+ case SENDING_GREETING:
+ if (!send_string(c, "Welcome. Please ask your question.\n"))
+ goto fail;
+ break;
+ case RECEIVING_USER_QUESTION:
+ len = read_string(c->fd, &c->question);
+ if (len <= 0)
+ goto fail;
+ if (input_finished(c->question)) {
+ unsigned int i;
+
+ for (i = 0; c->question[i]; i++)
+ c->question[i] = toupper(c->question[i]);
+ set_state(c, SENDING_ANSWER_PREFIX);
+ }
+ break;
+ case SENDING_ANSWER_PREFIX:
+ if (!send_string(c, "Our answer is:\n"))
+ goto fail;
+ break;
+ case SENDING_ANSWER:
+ if (!send_string(c, c->question))
+ goto fail;
+ break;
+ default:
+ goto fail;
+ }
+
+ if (c->state != FINISHED)
+ return;
+
+fail:
+ talloc_free(c);
+}
+
+static int cleanup_client(struct client *client)