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async_req: fix non-blocking connect()

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According to Stevens UNIX Network Programming and various other sources,
the correct handling for non-blocking connect() is:

- when the initial connect() return -1/EINPROGRESS polling the socket
  for *writeability*

- in the poll handler call getsocktopt() with SO_ERROR to get the
  finished connect() return value

Simply calling connect() a second time without error checking is
probably wrong and not portable. For a successfull connect() Linux
returns 0, but Solaris will return EISCONN:

24254:   0.0336  0.0002 connect(4, 0xFEFFECAC, 16, SOV_DEFAULT) Err#150 EINPROGRESS
24254:          AF_INET  name = 10.10.10.143  port = 1024
24254:   0.0349  0.0001 port_associate(3, 4, 0x00000004, 0x0000001D,0x080648A8) = 0
24254:   0.0495  0.0146 port_getn(3, 0xFEFFEB50, 1, 1, 0xFEFFEB60) = 1 [0]
24254:   0.0497  0.0002 connect(4, 0x080646E4, 16, SOV_DEFAULT) Err#133 EISCONN
24254:          AF_INET  name = 10.10.10.143  port = 1024

Bug: https://bugzilla.samba.org/show_bug.cgi?id=11564

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
(cherry picked from commit 05d4dbda8357712cb81008e0d611fdb0e7239587)
This commit is contained in:
Ralph Boehme 2015-10-18 22:21:10 +02:00 committed by Karolin Seeger
parent 536733fb9d
commit 374a288022
1 changed files with 25 additions and 27 deletions
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52
lib/async_req/async_sock.c
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@ -127,24 +127,17 @@ struct tevent_req *async_connect_send(
return tevent_req_post(req, ev);
}
/**
* A number of error messages show that something good is progressing
* and that we have to wait for readability.
*
* If none of them are present, bail out.
/*
* The only errno indicating that the connect is still in
* flight is EINPROGRESS, everything else is an error
*/
if (!(errno == EINPROGRESS || errno == EALREADY ||
#ifdef EISCONN
errno == EISCONN ||
#endif
errno == EAGAIN || errno == EINTR)) {
if (errno != EINPROGRESS) {
tevent_req_error(req, errno);
return tevent_req_post(req, ev);
}
state->fde = tevent_add_fd(ev, state, fd,
TEVENT_FD_READ | TEVENT_FD_WRITE,
state->fde = tevent_add_fd(ev, state, fd, TEVENT_FD_WRITE,
async_connect_connected, req);
if (state->fde == NULL) {
tevent_req_error(req, ENOMEM);
@ -189,27 +182,32 @@ static void async_connect_connected(struct tevent_context *ev,
struct async_connect_state *state =
tevent_req_data(req, struct async_connect_state);
int ret;
int socket_error = 0;
socklen_t slen = sizeof(socket_error);
if (state->before_connect != NULL) {
state->before_connect(state->private_data);
}
ret = getsockopt(state->fd, SOL_SOCKET, SO_ERROR,
&socket_error, &slen);
ret = connect(state->fd, (struct sockaddr *)(void *)&state->address,
state->address_len);
if (state->after_connect != NULL) {
state->after_connect(state->private_data);
}
if (ret == 0) {
tevent_req_done(req);
if (ret != 0) {
/*
* According to Stevens this is the Solaris behaviour
* in case the connection encountered an error:
* getsockopt() fails, error is in errno
*/
tevent_req_error(req, errno);
return;
}
if (errno == EINPROGRESS) {
/* Try again later, leave the fde around */
if (socket_error != 0) {
/*
* Berkeley derived implementations (including) Linux
* return the pending error via socket_error.
*/
tevent_req_error(req, socket_error);
return;
}
tevent_req_error(req, errno);
tevent_req_done(req);
return;
}