dbus-message.c

dbus-message.c

//  linuxthor
//
//  Showing how to open a socket connection to dbus and do 'raw' messages (i.e. just sending
//  some bytes and not worrying about weird stuff like Dict of{String, Variant} or whatever 
//  for the moment..) 
// 
//  Started off fun but the whole thing is surprisingly bulky & annoying tbh

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <ctype.h>
#include <poll.h>
#include <signal.h>
#include <sys/un.h>
#include <sys/types.h>
#include <sys/socket.h>

#include "hexdump.h"

int main(void)
{
    int x,y;
    struct sockaddr_un *sock;
    struct msghdr *mhdr;
    struct msghdr *rxmhdr;
    struct iovec iov[2];
    struct iovec rxv[2];
    char take[1024];
    socklen_t *socklen;
    struct pollfd fds;
    char *dbus_path = "/run/user/1000/bus";               // <-- 'session bus' for uid 1000 
    char *auth_string = "AUTH EXTERNAL 31303030\r\n";     // <-- other methods per docs but only seen this
    char *dbus_hello  = "l\1\0\1\0\0\0\0\1\0\0\0n\0\0\0\1\1o\0\25\0\0\0/org/freedesktop/DBus\0\0\0\6\1s\0\24\0\0\0\
org.freedesktop.DBus\0\0\0\0\2\1s\0\24\0\0\0org.freedesktop.DBus\0\0\0\0\3\1s\0\5\0\0\0Hello\0\0\0";
    char *dbus_mesg = "l\1\0\1\0\0\0\0\2\0\0\0h\0\0\0\1\1o\0\20\0\0\0/org/freedesktop\0\0\0\0\0\0\0\0\2\1s\0\17\0\0\0\
org.freedesktop\0\3\1s\0\7\0\0\0attempt\0\6\1s\0\27\0\0\0org.freedesktop.attempt\0";
    sock = malloc(sizeof(struct sockaddr_un));    
    mhdr = (struct msghdr *)malloc(sizeof(struct msghdr)); 
    rxmhdr = (struct msghdr *)malloc(sizeof(struct msghdr)); 
    socklen = malloc(sizeof (socklen_t));
    sock->sun_family = AF_UNIX; 
    strncpy(sock->sun_path, dbus_path, sizeof(sock->sun_path) - 1);
    socklen[0] = 256;

    // preamble.. (you MUST do the poll() dance or nothing happens)
    x = socket(AF_UNIX, SOCK_STREAM, 0);
    fds.fd = x; 
    fds.events = POLLOUT; 
    printf("Connecting. .\n");
    connect(x, (struct sockaddr *)sock, 20);
    fcntl(x, F_GETFL);
    fcntl(x, F_SETFL, O_RDWR|O_NONBLOCK); 
    poll(&fds, 1, 0);
    fds.events = POLLIN;  
    printf("Sending null. .\n");
    sendto(x, "\0", 1, MSG_NOSIGNAL, NULL, 0);
    printf("Sending auth. .\n");
    sendto(x, auth_string, strlen(auth_string), MSG_NOSIGNAL, NULL, 0);
    poll(&fds, 1, -1);
    read(x, take, 1024); 
    printf("Server replies: %s\n",take);
    sendto(x, "NEGOTIATE_UNIX_FD\r\n", 19, MSG_NOSIGNAL, NULL, 0); 
    poll(&fds, 1, -1);
    read(x, take, 1024); 
    printf("Server replies: %s\n",take);
    sendto(x, "BEGIN\r\n", 7, MSG_NOSIGNAL, NULL, 0);    
    fds.events = POLLIN|POLLOUT;  
    poll(&fds, 1, -1);

    // tx vectors (like writev/readv)
    iov[0].iov_base = dbus_hello; 
    iov[0].iov_len  = 128; 
    iov[1].iov_base = 0;
    iov[1].iov_len  = 0;
    mhdr->msg_iov = iov; 
    mhdr->msg_iovlen = 2; 

    // rx vectors
    rxv[0].iov_base = take; 
    rxv[0].iov_len  = 1024; 
    rxv[1].iov_base = 0;
    rxv[1].iov_len  = 0;
    rxmhdr->msg_namelen = 0; 
    rxmhdr->msg_iov = rxv; 
    rxmhdr->msg_iovlen = 2; 

    // switch to sendmsg / recvmsg and do hello - should check the response here
    printf("Sending hello\n");
    y = sendmsg(x, mhdr, MSG_NOSIGNAL);  
    hexdump(iov[0].iov_base, y);
    fds.events = POLLIN;  
    poll(&fds, 1, 2500);
    printf("Server replies\n");
    y = recvmsg(x, rxmhdr, MSG_CMSG_CLOEXEC); 
    hexdump(rxv[0].iov_base,y);

    // end of preamble.. now prepare the actual message
    iov[0].iov_base = dbus_mesg; 
    iov[0].iov_len  = 120; 
    iov[1].iov_base = 0;
    iov[1].iov_len  = 0;
    mhdr->msg_iov = iov; 
    mhdr->msg_iovlen = 2;

    // and send it.. 
    printf("Sending message\n");
    y = sendmsg(x, mhdr, MSG_NOSIGNAL);  
    hexdump(iov[0].iov_base, y);
    fds.events = POLLIN;  
    poll(&fds, 1, 2500);
    printf("Server replies\n");
    y = recvmsg(x, rxmhdr, MSG_CMSG_CLOEXEC); 
    hexdump(rxv[0].iov_base,y);

    return 0;
}