1 files changed, 225 insertions, 0 deletions
diff --git a/source4/libcli/resolve/host.c b/source4/libcli/resolve/host.c
new file mode 100644
index 0000000000..1a695432ee
--- /dev/null
+++ b/source4/libcli/resolve/host.c
@@ -0,0 +1,225 @@
+/* 
+   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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+  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 "lib/events/events.h"
+#include "system/network.h"
+#include "system/filesys.h"
+#include "libcli/composite/composite.h"
+#include "librpc/gen_ndr/ndr_nbt.h"
+#include "libcli/resolve/resolve.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(struct host_state *state)
+{
+	close(state->child_fd);
+	if (state->child != (pid_t)-1) {
+		kill(state->child, SIGTERM);
+	}
+	return 0;
+}
+
+/*
+  the blocking child
+*/
+static void run_child(struct composite_context *c, int fd)
+{
+	struct host_state *state = talloc_get_type(c->private_data, struct host_state);
+	struct in_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 = inet_ntoa(ip);
+	if (address != NULL) {
+		write(fd, address, strlen(address)+1);
+	}
+	close(fd);
+}
+
+/*
+  handle a read event on the pipe
+*/
+static void pipe_handler(struct event_context *ev, struct fd_event *fde, 
+			 uint16_t flags, void *private_data)
+{
+	struct composite_context *c = talloc_get_type(private_data, struct composite_context);
+	struct host_state *state = talloc_get_type(c->private_data, 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) {
+		composite_error(c, NT_STATUS_OBJECT_NAME_NOT_FOUND);
+		return;
+	}
+
+	/* enusre the address looks good */
+	address[ret] = 0;
+	if (strcmp(address, "0.0.0.0") == 0 ||
+	    inet_addr(address) == INADDR_NONE) {
+		composite_error(c, NT_STATUS_OBJECT_NAME_NOT_FOUND);
+		return;
+	}
+
+	state->reply_addr = talloc_strdup(state, address);
+	if (composite_nomem(state->reply_addr, c)) return;
+
+	composite_done(c);
+}
+
+/*
+  gethostbyname name resolution method - async send
+ */
+struct composite_context *resolve_name_host_send(TALLOC_CTX *mem_ctx,
+						 struct event_context *event_ctx,
+						 void *privdata,
+						 struct nbt_name *name)
+{
+	struct composite_context *c;
+	struct host_state *state;
+	int fd[2] = { -1, -1 };
+	int ret;
+
+	c = composite_create(mem_ctx, event_ctx);
+	if (c == NULL) return NULL;
+
+	if (composite_nomem(c->event_ctx, c)) return c;
+
+	state = talloc(c, struct host_state);
+	if (composite_nomem(state, c)) return c;
+	c->private_data = state;
+
+	c->status = nbt_name_dup(state, name, &state->name);
+	if (!composite_is_ok(c)) return c;
+
+	/* setup a pipe to chat to our child */
+	ret = pipe(fd);
+	if (ret == -1) {
+		composite_error(c, map_nt_error_from_unix(errno));
+		return c;
+	}
+
+	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 */
+	state->fde = event_add_fd(c->event_ctx, c, state->child_fd, EVENT_FD_READ, 
+				  pipe_handler, c);
+	if (composite_nomem(state->fde, c)) {
+		close(fd[0]);
+		close(fd[1]);
+		return c;
+	}
+
+	/* 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) {
+		composite_error(c, map_nt_error_from_unix(errno));
+		return c;
+	}
+
+
+	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;
+}
+
+/*
+  gethostbyname name resolution method - recv side
+*/
+NTSTATUS resolve_name_host_recv(struct composite_context *c, 
+				TALLOC_CTX *mem_ctx, const char **reply_addr)
+{
+	NTSTATUS status;
+
+	status = composite_wait(c);
+
+	if (NT_STATUS_IS_OK(status)) {
+		struct host_state *state = talloc_get_type(c->private_data, 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 composite_context *c = resolve_name_host_send(mem_ctx, NULL, NULL, name);
+	return resolve_name_host_recv(c, mem_ctx, reply_addr);
+}
+
+bool resolve_context_add_host_method(struct resolve_context *ctx)
+{
+	return resolve_context_add_method(ctx, resolve_name_host_send, resolve_name_host_recv,
+					  NULL);
+}