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ctdb-common: Add sock_client abstraction
This sets up boilerplate required for a client code connecting to a server over unix domain socket. The communication between client and server is "request" from client to server and "reply" from server to client. Signed-off-by: Amitay Isaacs <amitay@gmail.com> Reviewed-by: Martin Schwenke <martin@meltin.net>
This commit is contained in:
Amitay Isaacs
Martin Schwenke
parent
dfa87862fb
commit
dcc1eaf542
332
ctdb/common/sock_client.c
Normal file
332
ctdb/common/sock_client.c
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@ -0,0 +1,332 @@
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/*
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A client based on unix domain socket
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Copyright (C) Amitay Isaacs 2017
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "replace.h"
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#include "system/filesys.h"
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#include "system/network.h"
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#include <talloc.h>
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#include <tevent.h>
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#include "lib/util/debug.h"
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#include "lib/util/time.h"
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#include "lib/util/tevent_unix.h"
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#include "common/logging.h"
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#include "common/reqid.h"
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#include "common/comm.h"
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#include "common/sock_client.h"
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struct sock_client_context {
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struct sock_client_proto_funcs *funcs;
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void *private_data;
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void (*disconnect_callback)(void *private_data);
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void *disconnect_data;
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int fd;
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struct comm_context *comm;
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struct reqid_context *idr;
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};
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/*
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* connect to a unix domain socket
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*/
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static int socket_connect(const char *sockpath)
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{
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struct sockaddr_un addr;
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size_t len;
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int fd, ret;
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memset(&addr, 0, sizeof(addr));
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addr.sun_family = AF_UNIX;
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len = strlcpy(addr.sun_path, sockpath, sizeof(addr.sun_path));
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if (len >= sizeof(addr.sun_path)) {
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D_ERR("socket path too long: %s\n", sockpath);
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return -1;
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}
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fd = socket(AF_UNIX, SOCK_STREAM, 0);
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if (fd == -1) {
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D_ERR("socket create failed - %s\n", sockpath);
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return -1;
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}
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ret = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
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if (ret != 0) {
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D_ERR("socket connect failed - %s\n", sockpath);
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close(fd);
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return -1;
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}
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return fd;
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}
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/*
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* Socket client
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*/
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static int sock_client_context_destructor(struct sock_client_context *sockc);
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static void sock_client_read_handler(uint8_t *buf, size_t buflen,
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void *private_data);
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static void sock_client_dead_handler(void *private_data);
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static void sock_client_msg_reply(struct sock_client_context *sockc,
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uint8_t *buf, size_t buflen);
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int sock_client_setup(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
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const char *sockpath,
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struct sock_client_proto_funcs *funcs,
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void *private_data,
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struct sock_client_context **result)
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{
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struct sock_client_context *sockc;
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int ret;
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if (sockpath == NULL) {
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return EINVAL;
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}
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if (funcs == NULL || funcs->request_push == NULL ||
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funcs->reply_pull == NULL || funcs->reply_reqid == NULL) {
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return EINVAL;
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}
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sockc = talloc_zero(mem_ctx, struct sock_client_context);
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if (sockc == NULL) {
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return ENOMEM;
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}
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sockc->funcs = funcs;
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sockc->private_data = private_data;
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sockc->fd = socket_connect(sockpath);
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if (sockc->fd == -1) {
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talloc_free(sockc);
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return EIO;
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}
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ret = comm_setup(sockc, ev, sockc->fd,
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sock_client_read_handler, sockc,
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sock_client_dead_handler, sockc,
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&sockc->comm);
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if (ret != 0) {
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D_ERR("comm_setup() failed, ret=%d\n", ret);
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close(sockc->fd);
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talloc_free(sockc);
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return ret;
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}
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ret = reqid_init(sockc, INT_MAX-200, &sockc->idr);
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if (ret != 0) {
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D_ERR("reqid_init() failed, ret=%d\n", ret);
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close(sockc->fd);
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talloc_free(sockc);
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return ret;
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}
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talloc_set_destructor(sockc, sock_client_context_destructor);
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*result = sockc;
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return 0;
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}
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static int sock_client_context_destructor(struct sock_client_context *sockc)
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{
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TALLOC_FREE(sockc->comm);
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if (sockc->fd != -1) {
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close(sockc->fd);
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sockc->fd = -1;
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}
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return 0;
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}
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static void sock_client_read_handler(uint8_t *buf, size_t buflen,
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void *private_data)
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{
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struct sock_client_context *sockc = talloc_get_type_abort(
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private_data, struct sock_client_context);
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sock_client_msg_reply(sockc, buf, buflen);
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}
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static void sock_client_dead_handler(void *private_data)
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{
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struct sock_client_context *sockc = talloc_get_type_abort(
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private_data, struct sock_client_context);
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if (sockc->disconnect_callback != NULL) {
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sockc->disconnect_callback(sockc->disconnect_data);
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talloc_free(sockc);
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return;
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}
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D_NOTICE("connection to daemon closed, exiting\n");
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exit(1);
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}
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void sock_client_set_disconnect_callback(struct sock_client_context *sockc,
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sock_client_callback_func_t callback,
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void *private_data)
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{
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sockc->disconnect_callback = callback;
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sockc->disconnect_data = private_data;
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}
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struct sock_client_msg_state {
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struct sock_client_context *sockc;
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uint32_t reqid;
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struct tevent_req *req;
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void *reply;
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};
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static int sock_client_msg_state_destructor(
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struct sock_client_msg_state *state);
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static void sock_client_msg_done(struct tevent_req *subreq);
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struct tevent_req *sock_client_msg_send(TALLOC_CTX *mem_ctx,
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struct tevent_context *ev,
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struct sock_client_context *sockc,
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struct timeval timeout,
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void *request)
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{
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struct tevent_req *req, *subreq;
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struct sock_client_msg_state *state;
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uint8_t *buf;
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size_t buflen;
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int ret;
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req = tevent_req_create(mem_ctx, &state, struct sock_client_msg_state);
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if (req == NULL) {
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return NULL;
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}
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state->sockc = sockc;
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state->reqid = reqid_new(sockc->idr, state);
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if (state->reqid == REQID_INVALID) {
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talloc_free(req);
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return NULL;
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}
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state->req = req;
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talloc_set_destructor(state, sock_client_msg_state_destructor);
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ret = sockc->funcs->request_push(request, state->reqid, state,
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&buf, &buflen, sockc->private_data);
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if (ret != 0) {
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tevent_req_error(req, ret);
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return tevent_req_post(req, ev);
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}
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subreq = comm_write_send(state, ev, sockc->comm, buf, buflen);
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if (tevent_req_nomem(subreq, req)) {
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return tevent_req_post(req, ev);
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}
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tevent_req_set_callback(subreq, sock_client_msg_done, req);
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if (! timeval_is_zero(&timeout)) {
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tevent_req_set_endtime(req, ev, timeout);
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}
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return req;
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}
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static int sock_client_msg_state_destructor(
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struct sock_client_msg_state *state)
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{
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reqid_remove(state->sockc->idr, state->reqid);
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return 0;
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}
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static void sock_client_msg_done(struct tevent_req *subreq)
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{
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struct tevent_req *req = tevent_req_callback_data(
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subreq, struct tevent_req);
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int ret;
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bool status;
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status = comm_write_recv(subreq, &ret);
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TALLOC_FREE(subreq);
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if (! status) {
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tevent_req_error(req, ret);
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return;
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}
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/* wait for the reply or timeout */
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}
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static void sock_client_msg_reply(struct sock_client_context *sockc,
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uint8_t *buf, size_t buflen)
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{
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struct sock_client_msg_state *state;
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uint32_t reqid;
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int ret;
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ret = sockc->funcs->reply_reqid(buf, buflen, &reqid,
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sockc->private_data);
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if (ret != 0) {
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D_WARNING("Invalid packet received, ret=%d\n", ret);
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return;
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}
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state = reqid_find(sockc->idr, reqid, struct sock_client_msg_state);
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if (state == NULL) {
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return;
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}
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if (reqid != state->reqid) {
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return;
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}
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ret = sockc->funcs->reply_pull(buf, buflen, state, &state->reply,
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sockc->private_data);
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if (ret != 0) {
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tevent_req_error(state->req, ret);
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return;
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}
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tevent_req_done(state->req);
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}
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bool sock_client_msg_recv(struct tevent_req *req, int *perr,
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TALLOC_CTX *mem_ctx, void **reply)
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{
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struct sock_client_msg_state *state = tevent_req_data(
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req, struct sock_client_msg_state);
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int ret;
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if (tevent_req_is_unix_error(req, &ret)) {
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if (perr != NULL) {
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*perr = ret;
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}
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return false;
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}
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if (reply != NULL) {
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*reply = talloc_steal(mem_ctx, state->reply);
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}
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return true;
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}
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129
ctdb/common/sock_client.h
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129
ctdb/common/sock_client.h
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@ -0,0 +1,129 @@
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/*
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A client based on unix domain socket
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Copyright (C) Amitay Isaacs 2017
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __CTDB_SOCK_CLIENT_H__
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#define __CTDB_SOCK_CLIENT_H__
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#include <talloc.h>
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#include <tevent.h>
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/**
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* @file sock_client.h
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*
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* @brief A framework for a client based on unix-domain sockets.
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*
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* This abstraction allows to build clients that communicate using
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* unix-domain sockets. It takes care of the common boilerplate.
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*/
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/**
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* @brief The abstract socket daemon context
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*/
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struct sock_client_context;
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/**
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* @brief callback function
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*
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* This function can be registered to be called in case daemon goes away.
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*/
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typedef void (*sock_client_callback_func_t)(void *private_data);
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/**
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* @brief Protocol marshalling functions
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*
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* The typical protocol packet will have a header and a payload.
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* Header will contain at least 2 fields: length and reqid
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*
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* request_push() is called when the request packet needs to be marshalled
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*
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* reply_pull() is called to unmarshall data into a reply packet
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*
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* reply_reqid() is called to extract request id from a reply packet
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*/
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struct sock_client_proto_funcs {
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int (*request_push)(void *request, uint32_t reqid,
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TALLOC_CTX *mem_ctx,
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uint8_t **buf, size_t *buflen,
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void *private_data);
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int (*reply_pull)(uint8_t *buf, size_t buflen,
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TALLOC_CTX *mem_ctx, void **reply,
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void *private_data);
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int (*reply_reqid)(uint8_t *buf, size_t buflen,
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uint32_t *reqid, void *private_data);
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};
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/**
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* @brief Create a new socket client
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*
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* @param[in] mem_ctx Talloc memory context
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* @param[in] ev Tevent context
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* @param[in] sockpath Unix domain socket path
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* @param[in] funcs Protocol marshalling functions
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* @param[in] private_data Private data for protocol functions
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* @param[out] result New socket client context
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* @return 0 on success, errno on failure
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*/
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int sock_client_setup(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
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const char *sockpath,
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struct sock_client_proto_funcs *funcs,
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void *private_data,
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struct sock_client_context **result);
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/**
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* @brief Register a callback in case of client disconnection
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*
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* @param[in] sockc Socket client context
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* @param[in] callback Callback function
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* @param[in] private_data Private data for callback function
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*/
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void sock_client_set_disconnect_callback(struct sock_client_context *sockc,
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sock_client_callback_func_t callback,
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void *private_data);
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/**
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* @brief Async computation to send data to the daemon
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*
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* @param[in] mem_ctx Talloc memory context
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* @param[in] ev Tevent context
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* @param[in] sockc The socket client context
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* @param[in] timeout How long to wait for
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* @param[in] request Requeset packet to be sent
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* @return new tevent request, or NULL on failure
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*/
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struct tevent_req *sock_client_msg_send(TALLOC_CTX *mem_ctx,
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struct tevent_context *ev,
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struct sock_client_context *sockc,
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struct timeval timeout,
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void *request);
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/**
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* @brief Async computation end to send data to the daemon
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*
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* @param[in] req Tevent request
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* @param[out] perr errno in case of failure
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* @param[in] mem_ctx Talloc memory context
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* @param[out] reply Reply received from server
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* @return true on success, false on failure
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*/
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bool sock_client_msg_recv(struct tevent_req *req, int *perr,
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TALLOC_CTX *mem_ctx, void **reply);
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#endif /* __CTDB_SOCK_CLIENT_H__ */
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@ -385,7 +385,8 @@ def build(bld):
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pkt_read.c pkt_write.c comm.c
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logging.c rb_tree.c tunable.c
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pidfile.c run_proc.c
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hash_count.c run_event.c'''),
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hash_count.c run_event.c
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sock_client.c'''),
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deps='''samba-util sys_rw tevent-util
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replace talloc tevent tdb''')
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