libubus: implement file descriptor passing support

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

libubus-internal.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2012 Felix Fietkau <nbd@openwrt.org>
+ * Copyright (C) 2011-2014 Felix Fietkau <nbd@openwrt.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License version 2.1
@@ -22,12 +22,12 @@ extern const struct ubus_method watch_method;
 struct blob_attr **ubus_parse_msg(struct blob_attr *msg);
 void ubus_handle_data(struct uloop_fd *u, unsigned int events);
 int ubus_send_msg(struct ubus_context *ctx, uint32_t seq,
-		  struct blob_attr *msg, int cmd, uint32_t peer);
+		  struct blob_attr *msg, int cmd, uint32_t peer, int fd);
-void ubus_process_msg(struct ubus_context *ctx, struct ubus_msghdr *hdr);
+void ubus_process_msg(struct ubus_context *ctx, struct ubus_msghdr *hdr, int fd);
 int __hidden ubus_start_request(struct ubus_context *ctx, struct ubus_request *req,
 				struct blob_attr *msg, int cmd, uint32_t peer);
 void ubus_process_obj_msg(struct ubus_context*ctx, struct ubus_msghdr *hdr);
-void ubus_process_req_msg(struct ubus_context *ctx, struct ubus_msghdr *hdr);
+void ubus_process_req_msg(struct ubus_context *ctx, struct ubus_msghdr *hdr, int fd);
 void ubus_process_pending_msg(struct ubus_context *ctx);
 
 #endif

libubus-io.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2012 Felix Fietkau <nbd@openwrt.org>
+ * Copyright (C) 2011-2014 Felix Fietkau <nbd@openwrt.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License version 2.1
@@ -54,12 +54,37 @@ static void wait_data(int fd, bool write)
 	poll(&pfd, 1, 0);
 }
 
-static int writev_retry(int fd, struct iovec *iov, int iov_len)
+static int writev_retry(int fd, struct iovec *iov, int iov_len, int sock_fd)
 {
+	static struct {
+		struct cmsghdr h;
+		int fd;
+	} fd_buf = {
+		.h = {
+			.cmsg_len = sizeof(fd_buf),
+			.cmsg_level = SOL_SOCKET,
+			.cmsg_type = SCM_RIGHTS,
+		}
+	};
+	struct msghdr msghdr = {
+		.msg_iov = iov,
+		.msg_iovlen = iov_len,
+		.msg_control = &fd_buf,
+		.msg_controllen = sizeof(fd_buf),
+	};
 	int len = 0;
 
 	do {
-		int cur_len = writev(fd, iov, iov_len);
+		int cur_len;
+
+		if (sock_fd < 0) {
+			msghdr.msg_control = NULL;
+			msghdr.msg_controllen = 0;
+		} else {
+			fd_buf.fd = sock_fd;
+		}
+
+		cur_len = sendmsg(fd, &msghdr, 0);
 		if (cur_len < 0) {
 			switch(errno) {
 			case EAGAIN:
@@ -72,6 +97,10 @@ static int writev_retry(int fd, struct iovec *iov, int iov_len)
 			}
 			continue;
 		}
+
+		if (len > 0)
+			sock_fd = -1;
+
 		len += cur_len;
 		while (cur_len >= iov->iov_len) {
 			cur_len -= iov->iov_len;
@@ -88,7 +117,7 @@ static int writev_retry(int fd, struct iovec *iov, int iov_len)
 }
 
 int __hidden ubus_send_msg(struct ubus_context *ctx, uint32_t seq,
-			   struct blob_attr *msg, int cmd, uint32_t peer)
+			   struct blob_attr *msg, int cmd, uint32_t peer, int fd)
 {
 	struct ubus_msghdr hdr;
 	struct iovec iov[2] = {
@@ -109,22 +138,45 @@ int __hidden ubus_send_msg(struct ubus_context *ctx, uint32_t seq,
 	iov[1].iov_base = (char *) msg;
 	iov[1].iov_len = blob_raw_len(msg);
 
-	ret = writev_retry(ctx->sock.fd, iov, ARRAY_SIZE(iov));
+	ret = writev_retry(ctx->sock.fd, iov, ARRAY_SIZE(iov), fd);
 	if (ret < 0)
 		ctx->sock.eof = true;
 
 	return ret;
 }
 
-static int recv_retry(int fd, struct iovec *iov, bool wait)
+static int recv_retry(int fd, struct iovec *iov, bool wait, int *recv_fd)
 {
 	int bytes, total = 0;
+	static struct {
+		struct cmsghdr h;
+		int fd;
+	} fd_buf = {
+		.h = {
+			.cmsg_type = SCM_RIGHTS,
+			.cmsg_level = SOL_SOCKET,
+			.cmsg_len = sizeof(fd_buf),
+		},
+	};
+	struct msghdr msghdr = {
+		.msg_iov = iov,
+		.msg_iovlen = 1,
+	};
 
 	while (iov->iov_len > 0) {
 		if (wait)
 			wait_data(fd, false);
 
-		bytes = read(fd, iov->iov_base, iov->iov_len);
+		if (recv_fd) {
+			msghdr.msg_control = &fd_buf;
+			msghdr.msg_controllen = sizeof(fd_buf);
+		} else {
+			msghdr.msg_control = NULL;
+			msghdr.msg_controllen = 0;
+		}
+
+		fd_buf.fd = -1;
+		bytes = recvmsg(fd, &msghdr, 0);
 		if (!bytes)
 			return -1;
 
@@ -141,6 +193,11 @@ static int recv_retry(int fd, struct iovec *iov, bool wait)
 		if (!wait && !bytes)
 			return 0;
 
+		if (recv_fd)
+			*recv_fd = fd_buf.fd;
+
+		recv_fd = NULL;
+
 		wait = true;
 		iov->iov_len -= bytes;
 		iov->iov_base += bytes;
@@ -166,14 +223,14 @@ static bool ubus_validate_hdr(struct ubus_msghdr *hdr)
 	return true;
 }
 
-static bool get_next_msg(struct ubus_context *ctx)
+static bool get_next_msg(struct ubus_context *ctx, int *recv_fd)
 {
 	struct iovec iov = STATIC_IOV(ctx->msgbuf.hdr);
 	int r;
 
 	/* receive header + start attribute */
 	iov.iov_len += sizeof(struct blob_attr);
-	r = recv_retry(ctx->sock.fd, &iov, false);
+	r = recv_retry(ctx->sock.fd, &iov, false, recv_fd);
 	if (r <= 0) {
 		if (r < 0)
 			ctx->sock.eof = true;
@@ -182,7 +239,7 @@ static bool get_next_msg(struct ubus_context *ctx)
 	}
 
 	iov.iov_len = blob_len(ubus_msghdr_data(&ctx->msgbuf.hdr));
-	if (iov.iov_len > 0 && !recv_retry(ctx->sock.fd, &iov, true))
+	if (iov.iov_len > 0 && !recv_retry(ctx->sock.fd, &iov, true, NULL))
 		return false;
 
 	return ubus_validate_hdr(&ctx->msgbuf.hdr);
@@ -192,9 +249,10 @@ void __hidden ubus_handle_data(struct uloop_fd *u, unsigned int events)
 {
 	struct ubus_context *ctx = container_of(u, struct ubus_context, sock);
 	struct ubus_msghdr *hdr = &ctx->msgbuf.hdr;
+	int recv_fd = -1;
 
-	while (get_next_msg(ctx)) {
+	while (get_next_msg(ctx, &recv_fd)) {
-		ubus_process_msg(ctx, hdr);
+		ubus_process_msg(ctx, hdr, recv_fd);
 		if (uloop_cancelled)
 			break;
 	}

libubus-obj.c

@@ -46,7 +46,9 @@ static void
 ubus_process_invoke(struct ubus_context *ctx, struct ubus_msghdr *hdr,
 		    struct ubus_object *obj, struct blob_attr **attrbuf)
 {
-	struct ubus_request_data req = {};
+	struct ubus_request_data req = {
+		.fd = -1,
+	};
 	int method;
 	int ret;
 	bool no_reply = false;

libubus-req.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2012 Felix Fietkau <nbd@openwrt.org>
+ * Copyright (C) 2011-2014 Felix Fietkau <nbd@openwrt.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License version 2.1
@@ -11,6 +11,7 @@
  * GNU General Public License for more details.
  */
 
+#include <unistd.h>
 #include "libubus.h"
 #include "libubus-internal.h"
 
@@ -61,7 +62,7 @@ int __hidden ubus_start_request(struct ubus_context *ctx, struct ubus_request *r
 	req->ctx = ctx;
 	req->peer = peer;
 	req->seq = ++ctx->request_seq;
-	return ubus_send_msg(ctx, req->seq, msg, cmd, peer);
+	return ubus_send_msg(ctx, req->seq, msg, cmd, peer, -1);
 }
 
 void ubus_abort_request(struct ubus_context *ctx, struct ubus_request *req)
@@ -184,7 +185,7 @@ void ubus_complete_deferred_request(struct ubus_context *ctx, struct ubus_reques
 	blob_buf_init(&b, 0);
 	blob_put_int32(&b, UBUS_ATTR_STATUS, ret);
 	blob_put_int32(&b, UBUS_ATTR_OBJID, req->object);
-	ubus_send_msg(ctx, req->seq, b.head, UBUS_MSG_STATUS, req->peer);
+	ubus_send_msg(ctx, req->seq, b.head, UBUS_MSG_STATUS, req->peer, req->fd);
 }
 
 int ubus_send_reply(struct ubus_context *ctx, struct ubus_request_data *req,
@@ -195,7 +196,7 @@ int ubus_send_reply(struct ubus_context *ctx, struct ubus_request_data *req,
 	blob_buf_init(&b, 0);
 	blob_put_int32(&b, UBUS_ATTR_OBJID, req->object);
 	blob_put(&b, UBUS_ATTR_DATA, blob_data(msg), blob_len(msg));
-	ret = ubus_send_msg(ctx, req->seq, b.head, UBUS_MSG_DATA, req->peer);
+	ret = ubus_send_msg(ctx, req->seq, b.head, UBUS_MSG_DATA, req->peer, -1);
 	if (ret < 0)
 		return UBUS_STATUS_NO_DATA;
 
@@ -428,7 +429,7 @@ static void ubus_process_notify_status(struct ubus_request *req, int id, struct
 		ubus_set_req_status(req, 0);
 }
 
-void __hidden ubus_process_req_msg(struct ubus_context *ctx, struct ubus_msghdr *hdr)
+void __hidden ubus_process_req_msg(struct ubus_context *ctx, struct ubus_msghdr *hdr, int fd)
 {
 	struct ubus_request *req;
 	int id = -1;
@@ -439,6 +440,13 @@ void __hidden ubus_process_req_msg(struct ubus_context *ctx, struct ubus_msghdr
 		if (!req)
 			break;
 
+		if (fd >= 0) {
+			if (req->fd_cb)
+				req->fd_cb(req, fd);
+			else
+				close(fd);
+		}
+
 		if (id >= 0)
 			ubus_process_notify_status(req, id, hdr);
 		else

libubus.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2012 Felix Fietkau <nbd@openwrt.org>
+ * Copyright (C) 2011-2014 Felix Fietkau <nbd@openwrt.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License version 2.1
@@ -84,13 +84,13 @@ ubus_queue_msg(struct ubus_context *ctx, struct ubus_msghdr *hdr)
 }
 
 void __hidden
-ubus_process_msg(struct ubus_context *ctx, struct ubus_msghdr *hdr)
+ubus_process_msg(struct ubus_context *ctx, struct ubus_msghdr *hdr, int fd)
 {
 
 	switch(hdr->type) {
 	case UBUS_MSG_STATUS:
 	case UBUS_MSG_DATA:
-		ubus_process_req_msg(ctx, hdr);
+		ubus_process_req_msg(ctx, hdr, fd);
 		break;
 
 	case UBUS_MSG_INVOKE:
@@ -113,7 +113,7 @@ void __hidden ubus_process_pending_msg(struct ubus_context *ctx)
 	while (!list_empty(&ctx->pending)) {
 		pending = list_first_entry(&ctx->pending, struct ubus_pending_msg, list);
 		list_del(&pending->list);
-		ubus_process_msg(ctx, &pending->hdr);
+		ubus_process_msg(ctx, &pending->hdr, -1);
 		free(pending);
 		if (ctx->stack_depth > 2)
 			break;

libubus.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011-2012 Felix Fietkau <nbd@openwrt.org>
+ * Copyright (C) 2011-2014 Felix Fietkau <nbd@openwrt.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License version 2.1
@@ -53,6 +53,7 @@ typedef void (*ubus_event_handler_t)(struct ubus_context *ctx, struct ubus_event
 				     const char *type, struct blob_attr *msg);
 typedef void (*ubus_data_handler_t)(struct ubus_request *req,
 				    int type, struct blob_attr *msg);
+typedef void (*ubus_fd_handler_t)(struct ubus_request *req, int fd);
 typedef void (*ubus_complete_handler_t)(struct ubus_request *req, int ret);
 typedef void (*ubus_notify_complete_handler_t)(struct ubus_notify_request *req,
 					       int idx, int ret);
@@ -155,7 +156,10 @@ struct ubus_request_data {
 	uint32_t object;
 	uint32_t peer;
 	uint16_t seq;
+
+	/* internal use */
 	bool deferred;
+	int fd;
 };
 
 struct ubus_request {
@@ -173,6 +177,7 @@ struct ubus_request {
 
 	ubus_data_handler_t raw_data_cb;
 	ubus_data_handler_t data_cb;
+	ubus_fd_handler_t fd_cb;
 	ubus_complete_handler_t complete_cb;
 
 	struct ubus_context *ctx;
@@ -275,6 +280,12 @@ static inline void ubus_defer_request(struct ubus_context *ctx,
     req->deferred = true;
 }
 
+static inline void ubus_request_set_fd(struct ubus_context *ctx,
+				       struct ubus_request_data *req, int fd)
+{
+    req->fd = fd;
+}
+
 void ubus_complete_deferred_request(struct ubus_context *ctx,
 				    struct ubus_request_data *req, int ret);