[7/8] export: Add fsidd

Commit Message

Richard Weinberger April 18, 2023, 9:33 a.m. UTC

The fsidnum daemon offers a local UNIX domain socket interface
for all NFS userspace to query the reexport database.
Currently fsidd just uses the SQlite backend.

fsidd serves also as an example on how to implement more complex
backends for the load balancing use case.

Signed-off-by: Richard Weinberger <[e-mail]>
---
 support/reexport/Makefile.am |  12 +++
 support/reexport/fsidd.c     | 198 +++++++++++++++++++++++++++++++++++
 2 files changed, 210 insertions(+)
 create mode 100644 support/reexport/fsidd.c

Patch

diff --git a/support/reexport/Makefile.am b/support/reexport/Makefile.am
index 9d544a8f..fbd66a20 100644
--- a/support/reexport/Makefile.am
+++ b/support/reexport/Makefile.am
@@ -3,4 +3,16 @@ 
 noinst_LIBRARIES = libreexport.a
 libreexport_a_SOURCES = reexport.c
 
+sbin_PROGRAMS	= fsidd
+
+fsidd_SOURCES = fsidd.c backend_sqlite.c
+
+fsidd_LDADD = ../../support/misc/libmisc.a \
+	      ../../support/nfs/libnfs.la \
+	       $(LIBPTHREAD) $(LIBEVENT) $(LIBSQLITE) \
+	       $(OPTLIBS)
+
+fsidd_CPPFLAGS = $(AM_CPPFLAGS) $(CPPFLAGS) \
+		  -I$(top_builddir)/support/include
+
 MAINTAINERCLEANFILES = Makefile.in
diff --git a/support/reexport/fsidd.c b/support/reexport/fsidd.c
new file mode 100644
index 00000000..410b3a37
--- /dev/null
+++ b/support/reexport/fsidd.c
@@ -0,0 +1,198 @@ 
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <assert.h>
+#include <dlfcn.h>
+#include <event2/event.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <sys/random.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <sys/vfs.h>
+#include <unistd.h>
+
+#include "conffile.h"
+#include "reexport_backend.h"
+#include "xcommon.h"
+#include "xlog.h"
+
+#define FSID_SOCKET_NAME "fsid.sock"
+
+static struct event_base *evbase;
+static struct reexpdb_backend_plugin *dbbackend = &sqlite_plug_ops;
+
+static void client_cb(evutil_socket_t cl, short ev, void *d)
+{
+	struct event *me = d;
+	char buf[PATH_MAX * 2];
+	int n;
+
+	(void)ev;
+
+	n = recv(cl, buf, sizeof(buf) - 1, 0);
+	if (n <= 0) {
+		event_del(me);
+		event_free(me);
+		close(cl);
+		return;
+	}
+
+	buf[n] = '\0';
+
+	if (strncmp(buf, "get_fsidnum ", strlen("get_fsidnum ")) == 0) {
+		char *req_path = buf + strlen("get_fsidnum ");
+		uint32_t fsidnum;
+		char *answer = NULL;
+		bool found;
+
+		assert(req_path < buf + n );
+
+		printf("client asks for %s\n", req_path);
+
+		if (dbbackend->fsidnum_by_path(req_path, &fsidnum, false, &found)) {
+			if (found)
+				assert(asprintf(&answer, "+ %u", fsidnum) != -1);
+			else
+				assert(asprintf(&answer, "+ ") != -1);
+		
+		} else {
+			assert(asprintf(&answer, "- %s", "Command failed") != -1);
+		}
+
+		(void)send(cl, answer, strlen(answer), 0);
+
+		free(answer);
+	} else if (strncmp(buf, "get_or_create_fsidnum ", strlen("get_or_create_fsidnum ")) == 0) {
+		char *req_path = buf + strlen("get_or_create_fsidnum ");
+		uint32_t fsidnum;
+		char *answer = NULL;
+		bool found;
+
+		assert(req_path < buf + n );
+
+
+		if (dbbackend->fsidnum_by_path(req_path, &fsidnum, true, &found)) {
+			if (found) {
+				assert(asprintf(&answer, "+ %u", fsidnum) != -1);
+			} else {
+				assert(asprintf(&answer, "+ ") != -1);
+			}
+		
+		} else {
+			assert(asprintf(&answer, "- %s", "Command failed") != -1);
+		}
+
+		(void)send(cl, answer, strlen(answer), 0);
+
+		free(answer);
+	} else if (strncmp(buf, "get_path ", strlen("get_path ")) == 0) {
+		char *req_fsidnum = buf + strlen("get_path ");
+		char *path = NULL, *answer = NULL, *endp;
+		bool bad_input = true;
+		uint32_t fsidnum;
+		bool found;
+
+		assert(req_fsidnum < buf + n );
+
+		errno = 0;
+		fsidnum = strtoul(req_fsidnum, &endp, 10);
+		if (errno == 0 && *endp == '\0') {
+			bad_input = false;
+		}
+
+		if (bad_input) {
+			assert(asprintf(&answer, "- %s", "Command failed: Bad input") != -1);
+		} else {
+			if (dbbackend->path_by_fsidnum(fsidnum, &path, &found)) {
+				if (found)
+					assert(asprintf(&answer, "+ %s", path) != -1);
+				else
+					assert(asprintf(&answer, "+ ") != -1);
+			} else {
+				assert(asprintf(&answer, "+ ") != -1);
+			}
+		}
+
+		(void)send(cl, answer, strlen(answer), 0);
+
+		free(path);
+		free(answer);
+	} else if (strcmp(buf, "version") == 0) {
+		char answer[] = "+ 1";
+
+		(void)send(cl, answer, strlen(answer), 0);
+	} else {
+		char *answer = NULL;
+
+		assert(asprintf(&answer, "- bad command") != -1);
+		(void)send(cl, answer, strlen(answer), 0);
+
+		free(answer);
+	}
+}
+
+static void srv_cb(evutil_socket_t fd, short ev, void *d)
+{
+	int cl = accept4(fd, NULL, NULL, SOCK_NONBLOCK);
+	struct event *client_ev;
+	
+	(void)ev;
+	(void)d;
+
+	client_ev = event_new(evbase, cl, EV_READ | EV_PERSIST | EV_CLOSED, client_cb, event_self_cbarg());
+	event_add(client_ev, NULL);
+}
+
+int main(void)
+{
+	struct event *srv_ev;
+	struct sockaddr_un addr;
+	char *sock_file;
+	int srv;
+
+	conf_init_file(NFS_CONFFILE);
+
+	if (!dbbackend->initdb()) {
+		return 1;
+	}
+
+	sock_file = conf_get_str_with_def("reexport", "fsidd_socket", FSID_SOCKET_NAME);
+
+	unlink(sock_file);
+
+	memset(&addr, 0, sizeof(struct sockaddr_un));
+	addr.sun_family = AF_UNIX;
+	strncpy(addr.sun_path, sock_file, sizeof(addr.sun_path) - 1);
+
+	srv = socket(AF_UNIX, SOCK_SEQPACKET | SOCK_NONBLOCK, 0);
+	if (srv == -1) {
+		xlog(L_WARNING, "Unable to create AF_UNIX socket for %s: %m\n", sock_file);
+		return 1;
+	}
+
+	if (bind(srv, (const struct sockaddr *)&addr, sizeof(struct sockaddr_un)) == -1) {
+		xlog(L_WARNING, "Unable to bind %s: %m\n", sock_file);
+		return 1;
+	}
+
+	if (listen(srv, 5) == -1) {
+		xlog(L_WARNING, "Unable to listen on %s: %m\n", sock_file);
+		return 1;
+	}
+
+	evbase = event_base_new();
+
+	srv_ev = event_new(evbase, srv, EV_READ | EV_PERSIST, srv_cb, NULL);
+	event_add(srv_ev, NULL);
+
+	event_base_dispatch(evbase);
+
+	dbbackend->destroydb();
+
+	return 0;
+}