From: Martin Wilck <mwilck@xxxxxxxx>
As a first step towards our state machine, avoid the call to
read_all() via recv_packet_from_client(). handle_client() is now
invoked twice for the same connection. The first time it reads
the command length, and later on it reads the command itself
piece-wise, as sent by the client. This will be just a single
read in most cases, but not always.
Reviewed-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
---
multipathd/uxlsnr.c | 90 +++++++++++++++++++++++++++++++++++++--------
1 file changed, 75 insertions(+), 15 deletions(-)
diff --git a/multipathd/uxlsnr.c b/multipathd/uxlsnr.c
index bfeb30d..eb1c48e 100644
--- a/multipathd/uxlsnr.c
+++ b/multipathd/uxlsnr.c
@@ -292,6 +292,8 @@ static void handle_inotify(int fd, struct watch_descriptors *wds)
condlog(1, "Multipath configuration updated.\nReload multipathd for changes to take effect");
}
+static const struct timespec ts_zero = { .tv_sec = 0, };
+
static int parse_cmd (char *cmd, char **reply, int *len, void *data,
int timeout)
{
@@ -394,23 +396,78 @@ static int uxsock_trigger(char *str, char **reply, int *len,
return r;
}
+static void set_client_state(struct client *c, int state)
+{
+ switch(state)
+ {
+ case CLT_RECV:
+ reset_strbuf(&c->reply);
+ memset(c->cmd, '\0', sizeof(c->cmd));
+ c->expires = ts_zero;
+ /* fallthrough */
+ case CLT_SEND:
+ /* reuse these fields for next data transfer */
+ c->len = c->cmd_len = 0;
+ break;
+ default:
+ break;
+ }
+ c->state = state;
+}
+
static void handle_client(struct client *c, void *trigger_data)
{
int rlen;
- char *inbuf, *reply;
+ char *reply;
+ ssize_t n;
- if (recv_packet_from_client(c->fd, &inbuf, uxsock_timeout) != 0) {
- dead_client(c);
- return;
+ switch (c->state) {
+ case CLT_RECV:
+ if (c->cmd_len == 0) {
+ /*
+ * We got POLLIN; assume that at least the length can
+ * be read immediately.
+ */
+ get_monotonic_time(&c->expires);
+ c->expires.tv_sec += uxsock_timeout / 1000;
+ c->expires.tv_nsec += (uxsock_timeout % 1000) * 1000000;
+ normalize_timespec(&c->expires);
+ n = mpath_recv_reply_len(c->fd, 0);
+ if (n == -1) {
+ condlog(1, "%s: cli[%d]: failed to receive reply len",
+ __func__, c->fd);
+ c->error = -ECONNRESET;
+ } else if (n > _MAX_CMD_LEN) {
+ condlog(1, "%s: cli[%d]: overlong command (%zd bytes)",
+ __func__, c->fd, n);
+ c->error = -ECONNRESET;
+ } else {
+ c->cmd_len = n;
+ condlog(4, "%s: cli[%d]: connected", __func__, c->fd);
+ }
+ /* poll for data */
+ return;
+ } else if (c->len < c->cmd_len) {
+ n = recv(c->fd, c->cmd + c->len, c->cmd_len - c->len, 0);
+ if (n <= 0 && errno != EINTR && errno != EAGAIN) {
+ condlog(1, "%s: cli[%d]: error in recv: %m",
+ __func__, c->fd);
+ c->error = -ECONNRESET;
+ return;
+ }
+ c->len += n;
+ if (c->len < c->cmd_len)
+ /* continue polling */
+ return;
+ set_client_state(c, CLT_PARSE);
+ }
+ break;
+ default:
+ break;
}
- if (!inbuf) {
- condlog(4, "recv_packet_from_client get null request");
- return;
- }
-
- condlog(4, "cli[%d]: Got request [%s]", c->fd, inbuf);
- uxsock_trigger(inbuf, &reply, &rlen,
+ condlog(4, "cli[%d]: Got request [%s]", c->fd, c->cmd);
+ uxsock_trigger(c->cmd, &reply, &rlen,
_socket_client_is_root(c->fd),
trigger_data);
@@ -418,11 +475,12 @@ static void handle_client(struct client *c, void *trigger_data)
if (send_packet(c->fd, reply) != 0)
dead_client(c);
else
- condlog(4, "cli[%d]: Reply [%d bytes]", c->fd, rlen);
- free(reply);
- reply = NULL;
+ condlog(4, "cli[%d]: Reply [%zu bytes]", c->fd,
+ get_strbuf_len(&c->reply) + 1);
+ reset_strbuf(&c->reply);
}
- free(inbuf);
+
+ set_client_state(c, CLT_RECV);
}
/*
@@ -553,6 +611,8 @@ void *uxsock_listen(long ux_sock, void *trigger_data)
continue;
}
handle_client(c, trigger_data);
+ if (c->error == -ECONNRESET)
+ dead_client(c);
}
}
/* see if we got a non-fatal signal */
--
2.33.1
--
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