代码拉取完成，页面将自动刷新
/*
* File: dbus-hostname.c
* Author: Songqing Hua
* email: hengch@163.com
*
* (C) 2023 Songqing Hua.
* https://blog.csdn.net/whowin/
*
* Example of using libdbus to realize the DNS client via calling system service
* Compiled with gcc version 9.4.0 (Ubuntu 9.4.0-1ubuntu1~20.04.1).
* Tested on Linux 5.4.0-139-generic #156-Ubuntu SMP Fri Jan 20 17:27:18 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux.
*
* To compile: $ gcc -Wall -g dbus-hostname.c -o dbus-hostname `pkg-config --libs --cflags dbus-1`
* Usage: $ ./dbus-hostname
*
* Example source code for article 《IPC之十三：使用libdbus通过D-Bus请求系统调用实现域名解析的实例》
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include <ctype.h>
#include <sys/socket.h>
#include <net/if.h>
#include <arpa/inet.h>
#include <dbus/dbus.h>
#define SERVICE_NAME "org.freedesktop.resolve1"
#define OBJECT_PATH "/org/freedesktop/resolve1"
#define INTERFACE_NAME "org.freedesktop.resolve1.Manager"
#define METHOD_NAME "ResolveHostname"
#define REPLY_TIMEOUT 5000
/********************************************************************************
* Function: void print_dbus_error(DBusError *dbus_error_p, char *str)
* Description: Print the error message when involking dbus functions
********************************************************************************/
void print_dbus_error(DBusError *dbus_error_p, char *str) {
printf("%s: %s\n", str, dbus_error_p->message);
dbus_error_free(dbus_error_p);
}
int main(int argc, char **argv) {
DBusError dbus_error;
DBusConnection *conn;
dbus_int32_t ifindex = 0; // means any interface
char *hostname; // domain name
dbus_int32_t afamily = AF_UNSPEC; // Address family. means AF_INET or AF_INET6.
dbus_uint64_t flags = 0; // no use. see specification
if (argc < 2) {
printf("Usage: %s <domain name> [address family]\n", argv[0]);
exit(EXIT_FAILURE);
}
hostname = argv[1];
if (argc > 2) {
if (strcmp(argv[2], "AF_INET") == 0) afamily = AF_INET;
else if (strcmp(argv[2], "AF_INET6") == 0) afamily = AF_INET6;
}
// Step 01: Get bus connection
//=============================
dbus_error_init(&dbus_error);
conn = dbus_bus_get(DBUS_BUS_SYSTEM, &dbus_error);
if (dbus_error_is_set(&dbus_error)) {
print_dbus_error(&dbus_error, "dbus_bus_get()");
exit(EXIT_FAILURE);
}
// Step 02: Construct a DBusMessage for sending request to system service
//========================================================================
DBusMessage *request = dbus_message_new_method_call(SERVICE_NAME,
OBJECT_PATH,
INTERFACE_NAME,
METHOD_NAME);
if (request == NULL) {
printf("Can't construct a new message.\n");
exit(EXIT_FAILURE);
}
// Step 03: Append a string to the message
//==========================================
/*
Will call the 'ResolveHostname' mothod from the service - 'org.freedesktop.resolve1', path - /org/freedesktop/resolve1,
and interface - 'org.freedesktop.resolve1.Manager'.
As per the official specification(https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.resolve1.html),
ResolveHostname(in i ifindex, in s name, in i family, in t flags,
out a(iiay) addresses, out s canonical, out t flags);
*/
if (!dbus_message_append_args(request,
DBUS_TYPE_INT32,
&ifindex,
DBUS_TYPE_STRING,
&hostname,
DBUS_TYPE_INT32,
&afamily,
DBUS_TYPE_UINT64,
&flags,
DBUS_TYPE_INVALID)) {
printf("Can't append the string to the message.\n");
exit(EXIT_FAILURE);
}
// Step 04: Send the request and waiting for reply
//==================================================
DBusMessage *reply;
reply = dbus_connection_send_with_reply_and_block(conn,
request,
REPLY_TIMEOUT,
&dbus_error);
dbus_message_unref(request);
if (dbus_error_is_set(&dbus_error)) {
print_dbus_error(&dbus_error, "dbus_connection_send_with_reply_and_block()");
dbus_error_free(&dbus_error);
exit(EXIT_FAILURE);
}
// Step 05: get the result from the reply
//=========================================
int msg_type = dbus_message_get_type(reply); // message type must be a reply
if (msg_type != DBUS_MESSAGE_TYPE_METHOD_RETURN) {
printf("Wrong message type: %d\n", msg_type);
exit(EXIT_FAILURE);
}
DBusMessageIter iter;
if (!dbus_message_iter_init(reply, &iter)) { // Create a iterator for parsing the args
printf("Can't initial an iterator.\n");
exit(EXIT_FAILURE);
}
// As per the official spcification,
dbus_int32_t ifindex_out; // interface index parsed from the reply
char ifname[IF_NAMESIZE]; // interface name
dbus_int32_t afamily_out; // address family parsed from the reply
char afamily_name[16]; // name of address family
uint8_t ip[16]; // IP address parsed from the reply
char *hostname_out; // canonical hostname parsed from the reply
dbus_uint64_t flags_out; // flags parsed from the reply
//ResolveHostname(..., out a(iiay) addresses, out s canonical, out t flags);
do {
int current_type = dbus_message_iter_get_arg_type(&iter);
if (current_type == DBUS_TYPE_STRING) {
// get the canonical hostname
dbus_message_iter_get_basic(&iter, &hostname_out);
printf("The canonical hostname is %s\n", hostname_out);
goto NEXT_ITEM;
}
if (current_type == DBUS_TYPE_UINT64) {
// get the flags
dbus_message_iter_get_basic(&iter, &flags_out);
printf("The flags is 0x%016lx\n", flags_out);
goto NEXT_ITEM;
}
if (current_type != DBUS_TYPE_ARRAY) {
printf("Expects '%s', but it's '%c'.\n", DBUS_TYPE_ARRAY_AS_STRING, (u_int8_t)current_type);
exit(EXIT_FAILURE);
}
// Address array
// a(iiay) - address, interface index, address family and IP address
// Construct a sub iterator for the array
DBusMessageIter array_iter;
dbus_message_iter_recurse(&iter, &array_iter);
do {
int array_type = dbus_message_iter_get_arg_type(&array_iter);
// The data type must be a structure
if (array_type != DBUS_TYPE_STRUCT) {
printf("Expects '%s', but it's '%c'.\n", DBUS_TYPE_STRUCT_AS_STRING, (u_int8_t)array_type);
exit(EXIT_FAILURE);
}
// Construct a sub iterator for the struct
DBusMessageIter struct_iter;
dbus_message_iter_recurse(&array_iter, &struct_iter);
// The data type of the first element must be an INT32. It is the Interface Index.
int struct_type = dbus_message_iter_get_arg_type(&struct_iter);
if (struct_type != DBUS_TYPE_INT32) {
printf("Expects '%s' for ifname, but it's '%c'.\n", DBUS_TYPE_INT32_AS_STRING, (u_int8_t)struct_type);
exit(EXIT_FAILURE);
}
dbus_message_iter_get_basic(&struct_iter, &ifindex_out);
dbus_message_iter_next(&struct_iter);
// The data type of the second element must be an INT32. It is the address family.
struct_type = dbus_message_iter_get_arg_type(&struct_iter);
if (struct_type != DBUS_TYPE_INT32) {
printf("Expects '%s' for address family, but it's '%c'.\n", DBUS_TYPE_INT32_AS_STRING, (u_int8_t)struct_type);
exit(EXIT_FAILURE);
}
dbus_message_iter_get_basic(&struct_iter, &afamily_out);
dbus_message_iter_next(&struct_iter);
if_indextoname(ifindex_out, ifname);
if (afamily_out == AF_INET) strcpy(afamily_name, "AF_INET");
else if (afamily_out == AF_INET6) strcpy(afamily_name, "AF_INET6");
else strcpy(afamily_name, "UNKNOWN");
printf("Interface name: %s, address family: %s\n", ifname, afamily_name);
// The data type of the third element must be an ARRAY. It is the IP address(IPV4 or IPV6, deponding on address family).
struct_type = dbus_message_iter_get_arg_type(&struct_iter);
if (struct_type != DBUS_TYPE_ARRAY) {
printf("Expects '%s' for address family, but it's '%c'.\n", DBUS_TYPE_ARRAY_AS_STRING, (u_int8_t)struct_type);
exit(EXIT_FAILURE);
}
DBusMessageIter ip_iter;
dbus_message_iter_recurse(&struct_iter, &ip_iter);
int j = 0;
do {
int ip_type = dbus_message_iter_get_arg_type(&ip_iter);
if (ip_type != DBUS_TYPE_BYTE) {
printf("Expects '%s', but it's '%c'.\n", DBUS_TYPE_BYTE_AS_STRING, (u_int8_t)ip_type);
exit(EXIT_FAILURE);
}
dbus_message_iter_get_basic(&ip_iter, &ip[j]);
++j;
} while (dbus_message_iter_next(&ip_iter));
if (afamily_out == AF_INET6) {
char ipv6_addr[INET6_ADDRSTRLEN];
inet_ntop(AF_INET6, (void *)ip, ipv6_addr, INET6_ADDRSTRLEN);
printf("The IPv6 address is %s\n", ipv6_addr);
} else if (afamily_out == AF_INET) {
printf("The IP address is %d.%d.%d.%d\n", ip[0], ip[1], ip[2], ip[3]);
}
} while (dbus_message_iter_next(&array_iter));
NEXT_ITEM:
;
} while (dbus_message_iter_next(&iter));
dbus_message_unref(reply);
return 0;
}
此处可能存在不合适展示的内容，页面不予展示。您可通过相关编辑功能自查并修改。
如您确认内容无涉及 不当用语 / 纯广告导流 / 暴力 / 低俗色情 / 侵权 / 盗版 / 虚假 / 无价值内容或违法国家有关法律法规的内容，可点击提交进行申诉，我们将尽快为您处理。
马建仓 AI 助手