summaryrefslogtreecommitdiff
path: root/source4/libcli/resolve
diff options
context:
space:
mode:
authorAndrew Tridgell <tridge@samba.org>2005-01-22 00:52:54 +0000
committerGerald (Jerry) Carter <jerry@samba.org>2007-10-10 13:09:05 -0500
commitb9a1e9a6677613865474c3c66b443b1c9e54c408 (patch)
tree2938bd729b62812084a221fa9d1a2b4eaca3e168 /source4/libcli/resolve
parent79ef4f216bbf26db69560acffa8d075ac704d654 (diff)
downloadsamba-b9a1e9a6677613865474c3c66b443b1c9e54c408.tar.gz
samba-b9a1e9a6677613865474c3c66b443b1c9e54c408.tar.bz2
samba-b9a1e9a6677613865474c3c66b443b1c9e54c408.zip
r4916: added "host" name resolution using fork() per gethostbyname()
comments welcome, but please think about the alternatives first :-) (This used to be commit 3d40b479907226be349137117e0d2bd718efa1a8)
Diffstat (limited to 'source4/libcli/resolve')
-rw-r--r--source4/libcli/resolve/host.c233
-rw-r--r--source4/libcli/resolve/resolve.c51
2 files changed, 268 insertions, 16 deletions
diff --git a/source4/libcli/resolve/host.c b/source4/libcli/resolve/host.c
new file mode 100644
index 0000000000..2cc0c1705f
--- /dev/null
+++ b/source4/libcli/resolve/host.c
@@ -0,0 +1,233 @@
+/*
+ Unix SMB/CIFS implementation.
+
+ async gethostbyname() name resolution module
+
+ Copyright (C) Andrew Tridgell 2005
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+/*
+ this module uses a fork() per gethostbyname() call. At first that
+ might seem crazy, but it is actually very fast, and solves many of
+ the tricky problems of keeping a child hanging around in a library
+ (like what happens when the parent forks). We use a talloc
+ destructor to ensure that the child is cleaned up when we have
+ finished with this name resolution.
+*/
+
+#include "includes.h"
+#include "events.h"
+#include "system/network.h"
+#include "libcli/raw/libcliraw.h"
+#include "libcli/composite/composite.h"
+
+struct host_state {
+ struct nbt_name name;
+ const char *reply_addr;
+ pid_t child;
+ int child_fd;
+ struct fd_event *fde;
+ struct event_context *event_ctx;
+};
+
+
+/*
+ kill off a wayward child if needed. This allows us to stop an async
+ name resolution without leaving a potentially blocking call running
+ in a child
+*/
+static int host_destructor(void *ptr)
+{
+ struct host_state *state = talloc_get_type(ptr, struct host_state);
+ close(state->child_fd);
+ if (state->child != (pid_t)-1) {
+ kill(state->child, SIGTERM);
+ }
+ if (state->fde) {
+ event_remove_fd(state->event_ctx, state->fde);
+ }
+ return 0;
+}
+
+/*
+ the blocking child
+*/
+static void run_child(struct smbcli_composite *c, int fd)
+{
+ struct host_state *state = talloc_get_type(c->private, struct host_state);
+ struct ipv4_addr ip;
+ const char *address;
+
+ /* this is the blocking call we are going to lots of trouble
+ to avoid in the parent */
+ ip = interpret_addr2(state->name.name);
+
+ address = sys_inet_ntoa(ip);
+ if (address != NULL) {
+ write(fd, address, strlen(address)+1);
+ }
+}
+
+/*
+ handle a read event on the pipe
+*/
+static void pipe_handler(struct event_context *ev, struct fd_event *fde,
+ struct timeval t, uint16_t flags)
+{
+ struct smbcli_composite *c = talloc_get_type(fde->private, struct smbcli_composite);
+ struct host_state *state = talloc_get_type(c->private, struct host_state);
+ char address[128];
+ int ret;
+
+ /* if we get any event from the child then we know that we
+ won't need to kill it off */
+ state->child = (pid_t)-1;
+
+ /* yes, we don't care about EAGAIN or other niceities
+ here. They just can't happen with this parent/child
+ relationship, and even if they did then giving an error is
+ the right thing to do */
+ ret = read(state->child_fd, address, sizeof(address)-1);
+ if (ret <= 0) goto failed;
+
+ /* enusre the address looks good */
+ address[ret] = 0;
+ if (strcmp(address, "0.0.0.0") == 0 ||
+ sys_inet_addr(address) == INADDR_NONE) {
+ goto failed;
+ }
+
+ state->reply_addr = talloc_strdup(state, address);
+ if (state->reply_addr == NULL) goto failed;
+
+ c->status = NT_STATUS_OK;
+ c->state = SMBCLI_REQUEST_DONE;
+ if (c->async.fn) {
+ c->async.fn(c);
+ }
+ return;
+
+failed:
+ c->status = NT_STATUS_BAD_NETWORK_NAME;
+ c->state = SMBCLI_REQUEST_ERROR;
+ if (c->async.fn) {
+ c->async.fn(c);
+ }
+}
+
+/*
+ gethostbyname name resolution method - async send
+ */
+struct smbcli_composite *resolve_name_host_send(struct nbt_name *name,
+ struct event_context *event_ctx)
+{
+ struct smbcli_composite *c;
+ struct host_state *state;
+ NTSTATUS status;
+ int fd[2] = { -1, -1 };
+ struct fd_event fde;
+ int ret;
+
+ c = talloc_zero(NULL, struct smbcli_composite);
+ if (c == NULL) goto failed;
+
+ state = talloc(c, struct host_state);
+ if (state == NULL) goto failed;
+
+ status = nbt_name_dup(state, name, &state->name);
+ if (!NT_STATUS_IS_OK(status)) goto failed;
+
+ c->state = SMBCLI_REQUEST_SEND;
+ c->private = state;
+ c->event_ctx = talloc_reference(c, event_ctx);
+
+ /* setup a pipe to chat to our child */
+ ret = pipe(fd);
+ if (ret == -1) goto failed;
+
+ state->child_fd = fd[0];
+ state->event_ctx = c->event_ctx;
+
+ /* we need to put the child in our event context so
+ we know when the gethostbyname() has finished */
+ fde.fd = state->child_fd;
+ fde.flags = EVENT_FD_READ;
+ fde.handler = pipe_handler;
+ fde.private = c;
+ state->fde = event_add_fd(c->event_ctx, &fde);
+ if (state->fde == NULL) {
+ close(fd[0]);
+ close(fd[1]);
+ goto failed;
+ }
+
+ /* signal handling in posix really sucks - doing this in a library
+ affects the whole app, but what else to do?? */
+ signal(SIGCHLD, SIG_IGN);
+
+ state->child = fork();
+ if (state->child == (pid_t)-1) {
+ goto failed;
+ }
+
+ if (state->child == 0) {
+ close(fd[0]);
+ run_child(c, fd[1]);
+ _exit(0);
+ }
+ close(fd[1]);
+
+ /* cleanup wayward children */
+ talloc_set_destructor(state, host_destructor);
+
+ return c;
+
+failed:
+ talloc_free(c);
+ return NULL;
+}
+
+/*
+ gethostbyname name resolution method - recv side
+*/
+NTSTATUS resolve_name_host_recv(struct smbcli_composite *c,
+ TALLOC_CTX *mem_ctx, const char **reply_addr)
+{
+ NTSTATUS status;
+
+ status = smb_composite_wait(c);
+
+ if (NT_STATUS_IS_OK(status)) {
+ struct host_state *state = talloc_get_type(c->private, struct host_state);
+ *reply_addr = talloc_steal(mem_ctx, state->reply_addr);
+ }
+
+ talloc_free(c);
+ return status;
+}
+
+/*
+ gethostbyname name resolution method - sync call
+ */
+NTSTATUS resolve_name_host(struct nbt_name *name,
+ TALLOC_CTX *mem_ctx,
+ const char **reply_addr)
+{
+ struct smbcli_composite *c = resolve_name_host_send(name, NULL);
+ return resolve_name_host_recv(c, mem_ctx, reply_addr);
+}
+
diff --git a/source4/libcli/resolve/resolve.c b/source4/libcli/resolve/resolve.c
index b36d6e8ee6..013403fd9c 100644
--- a/source4/libcli/resolve/resolve.c
+++ b/source4/libcli/resolve/resolve.c
@@ -33,6 +33,33 @@ struct resolve_state {
static struct smbcli_composite *setup_next_method(struct smbcli_composite *c);
+/* pointers to the resolver backends */
+static const struct resolve_method {
+ const char *name;
+ struct smbcli_composite *(*send_fn)(struct nbt_name *, struct event_context *);
+ NTSTATUS (*recv_fn)(struct smbcli_composite *, TALLOC_CTX *, const char **);
+} methods[] = {
+ { "bcast", resolve_name_bcast_send, resolve_name_bcast_recv },
+ { "wins", resolve_name_wins_send, resolve_name_wins_recv },
+ { "host", resolve_name_host_send, resolve_name_host_recv }
+};
+
+
+/*
+ find a matching backend
+*/
+static const struct resolve_method *find_method(const char *name)
+{
+ int i;
+ if (name == NULL) return NULL;
+ for (i=0;i<ARRAY_SIZE(methods);i++) {
+ if (strcasecmp(name, methods[i].name) == 0) {
+ return &methods[i];
+ }
+ }
+ return NULL;
+}
+
/*
handle completion of one name resolve method
*/
@@ -40,15 +67,9 @@ static void resolve_handler(struct smbcli_composite *req)
{
struct smbcli_composite *c = req->async.private;
struct resolve_state *state = talloc_get_type(c->private, struct resolve_state);
- const char *method = state->methods[0];
+ const struct resolve_method *method = find_method(state->methods[0]);
- if (strcasecmp(method, "bcast")) {
- c->status = resolve_name_bcast_recv(req, state, &state->reply_addr);
- } else if (strcasecmp(method, "wins")) {
- c->status = resolve_name_wins_recv(req, state, &state->reply_addr);
- } else {
- c->status = NT_STATUS_INTERNAL_ERROR;
- }
+ c->status = method->recv_fn(req, state, &state->reply_addr);
if (!NT_STATUS_IS_OK(c->status)) {
state->methods++;
@@ -72,18 +93,16 @@ static void resolve_handler(struct smbcli_composite *req)
static struct smbcli_composite *setup_next_method(struct smbcli_composite *c)
{
struct resolve_state *state = talloc_get_type(c->private, struct resolve_state);
- const char *method;
struct smbcli_composite *req = NULL;
do {
- method = state->methods[0];
- if (method == NULL) break;
- if (strcasecmp(method, "bcast")) {
- req = resolve_name_bcast_send(&state->name, c->event_ctx);
- } else if (strcasecmp(method, "wins")) {
- req = resolve_name_wins_send(&state->name, c->event_ctx);
+ const struct resolve_method *method = find_method(state->methods[0]);
+ if (method) {
+ req = method->send_fn(&state->name, c->event_ctx);
+ if (req == NULL) {
+ state->methods++;
+ }
}
- if (req == NULL) state->methods++;
} while (!req && state->methods[0]);
if (req) {