ubus客户端向服务器请求信息的例子

openwrt用户空间进中通信常用的通信方式是使用ubus通信，下面给出一个例子，是客户端向服务器请求ap的个数。

 

服务器端代码

 

#include <unistd.h>#include <signal.h>#include "libubus.h"static struct ubus_context *ctx;static struct blob_buf b;enum {REQ_STATION_COUNT,REQ_AP_NAME,__REQ_MAX};/* 接收的解析格式， client发送过来的调用是 blobmsg_add_u32(&b, "getcnt", ap_index); */static const struct blobmsg_policy fun2_message_parse_policy[__REQ_MAX] = {[REQ_STATION_COUNT] = { .name = "getcnt", .type = BLOBMSG_TYPE_INT32 },[REQ_STATION_COUNT] = { .name = "apname", .type = BLOBMSG_TYPE_STRING },};static int fun2_handler(struct ubus_context *ctx, struct ubus_object *obj,      struct ubus_request_data *req, const char *method,      struct blob_attr *msg){struct blob_attr *tb[__REQ_MAX];//模拟ap数组中station的个数int ap_array[] = {-1, 11111,22222,33333};int ap_index;blobmsg_parse(fun2_message_parse_policy, __REQ_MAX, tb, blob_data(msg), blob_len(msg));if (!tb[REQ_STATION_COUNT])return UBUS_STATUS_INVALID_ARGUMENT;ap_index = blobmsg_get_u32(tb[REQ_STATION_COUNT]);fprintf(stdout, "someone ask the ap[%d]' info \n", ap_index);if (ap_index > (sizeof(ap_array) / sizeof(int)))ap_index = 0;blob_buf_init(&b, 0);//返回客户端请求的station个数blobmsg_add_u32(&b, "stacnt", ap_array[ap_index]);//发送ubus_send_reply(ctx, req, b.head);return 0;}static const struct ubus_method test_methods[] = {UBUS_METHOD("fun2", fun2_handler, fun2_message_parse_policy),};static struct ubus_object_type test_object_type =UBUS_OBJECT_TYPE("server_fun", test_methods);//定义一个ubus 对象。//其他进程通过调用相应字符串给执行对应的回调函数//注册成功后可以通过命令ubus list -v 查看到obj//' server_fun' @79a8beac// "fun2" : {"getcnt":"Iterger","apname":"String"}static struct ubus_object test_object = {.name = "server_fun",.type = &test_object_type,.methods = test_methods,.n_methods = ARRAY_SIZE(test_methods),};static void server_main(void){int ret;//向ubusd新增一个对象，之后test_object在ubusd中有一个id号，其他进程通过该id号来向test_object发送消息。ret = ubus_add_object(ctx, &test_object);if (ret)fprintf(stderr, "Failed to add object: %s\n", ubus_strerror(ret));uloop_run();}int main(int argc, char **argv){const char *ubus_socket = NULL;int ch;while ((ch = getopt(argc, argv, "cs:")) != -1) {switch (ch) {case 's':ubus_socket = optarg;break;default:break;}}argc -= optind;argv += optind;uloop_init();signal(SIGPIPE, SIG_IGN);ctx = ubus_connect(ubus_socket);if (!ctx) {fprintf(stderr, "Failed to connect to ubus\n");return -1;}ubus_add_uloop(ctx);server_main();ubus_free(ctx);uloop_done();return 0;}

 

客户端代码

 

#include <sys/time.h>#include <unistd.h>#include "libubus.h"static struct ubus_context *ctx;static struct blob_buf b;enum {RETURN_CODE,__RETURN_MAX,};static const struct blobmsg_policy return_policy[__RETURN_MAX] = {[RETURN_CODE] = { .name = "stacnt", .type = BLOBMSG_TYPE_INT32 },};static void get_result_data_cb(struct ubus_request *req,    int type, struct blob_attr *msg){struct blob_attr *tb[__RETURN_MAX];int rc;//返回的数据也是有tlv格式的，按照return_policy格式进行解析。blobmsg_parse(return_policy, __RETURN_MAX, tb, blob_data(msg), blob_len(msg));if (!tb[RETURN_CODE]) {fprintf(stderr, "No return code received from server\n");return;}rc = blobmsg_get_u32(tb[RETURN_CODE]);fprintf(stderr, "get station number is %d \n", rc);}static void client_main(void){static struct ubus_request req;uint32_t id;int ret;int ap_index=2;//查找ubusd上的server_fun对象。该对象由server端注册if (ubus_lookup_id(ctx, "server_fun", &id)) {fprintf(stderr, "Failed to look up test object\n");return;}//b 为全局变量，初始化blob_buf_init(&b, 0);//添加发送buffer的tlv，格式由server_main.c的fun2_message_parse_policy定义blobmsg_add_u32(&b, "getcnt", ap_index);//触发server端注册的函数，并接收返回值，处理函数为get_result_data_cbubus_invoke(ctx, id, "fun2", b.head, get_result_data_cb, NULL, 3000);}int main(int argc, char **argv){const char *ubus_socket = NULL;int ch;while ((ch = getopt(argc, argv, "cs:")) != -1) {switch (ch) {case 's':ubus_socket = optarg;break;default:break;}}argc -= optind;argv += optind;uloop_init();ctx = ubus_connect(ubus_socket);if (!ctx) {fprintf(stderr, "Failed to connect to ubus\n");return -1;}ubus_add_uloop(ctx);client_main();ubus_free(ctx);uloop_done();return 0;}

以上代码：服务器端向ubusd注册了个server_fun的服务器对象，客户端通过server_fun ubus对象与服务器端通信。