ssdp java_SSDP协议 – 实施[通俗易懂]

我正在尝试实现SSDP协议，但我不确定它是如何工作的 . SSDP通过udp发送数据，这很清楚 . 如果控制器连接到网络，它可以搜索具有MSEARCH消息的设备，该消息可以发送到多播地址239.255.255.250:1900 . 每个设备都必须收听此地址并做出响应 . 但我不知道他们是如何回应的 . 我在wireshark中看到他们用单播响应，但我不知道如何确定接收响应的端口 .

编辑 – – – – – – – –

我正在尝试使用spike fuzzing框架编写ssdp fuzzer . 正如我所说，我能够发送正确的数据，但无法收到回复 . 我将尝试粘贴一些尖峰代码并简要说明 . 有Spike结构，它代表要发送的数据(它存储实际数据，大小，协议信息……) . 我删除了一些变量以使其更清晰 .

struct spike {

/*total size of all data*/

unsigned long datasize;

unsigned char *databuf;

unsigned char *endbuf;

int fd; /*for holding socket or file information*/

int proto; /*1 for tcp, 2 for udp*/

struct sockaddr_in *destsockaddr;

};

现在我通过udp发送数据，并希望通过以下功能接收一些响应

spike_connect_udp(target,port);

spike_send();

s_read_packet();

功能实现：

int

spike_connect_udp(char * host, int port)

{

int fd;

/*ahh, having udpstuff.c makes this stuff easy*/

fd=udpconnect(host,port);

if (fd==-1)

{

fprintf(stderr,”Couldn’t udp connect to target\n”);

return (0);

}

current_spike->fd=fd;

current_spike->proto=2; /*UDP*/

return 1;

}

int

udpconnect(const char * host, const unsigned short port )

{

int sfd = -1;

struct sockaddr_in addr;

/* Translate hostname from DNS or IP-address form */

memset(&addr, 0, sizeof(addr));

if (!getHostAddress(host, &addr))

{

hdebug(“can’t resolve host or address.\n”);

return -1;

}

addr.sin_family = AF_INET;

addr.sin_port = ntohs(port);

if ((sfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)

{

hdebug(“Could not create socket!\n”);

return -1;

}

/* Now connect! */

if (connect(sfd, (struct sockaddr *)&addr, sizeof(addr)) < 0)

{

close(sfd);

return -1;

}

return sfd;

}

int

spike_send()

{

int retval;

switch (current_spike->proto)

{

case 1: /*TCP*/

//deleted, doesnt matter, i am sending via udp

case 2: /*UDP*/

//udp_write_data is function from framework

retval=udp_write_data(current_spike->fd, current_spike->destsockaddr, s_get_size(), s_get_databuf());

break;

}

fflush(0);

return retval;

}

这很好，并通过udp发送数据 . 现在我想通过open socket current_spike-> fd收到一些回复 . 函数s_read_packet void

s_read_packet()

{

unsigned char buffer[5000];

int i;

int size;

s_fd_wait();

printf(“Reading packet\n”);

memset(buffer,0x00,sizeof(buffer));

/what alarm and fcntl does?

alarm(1);

fcntl(current_spike->fd, F_SETFL, O_NONBLOCK);

//this read return error -1 and sets errno to 11 service temporarily unavailable

size=read(current_spike->fd,buffer,1500);

fcntl(current_spike->fd, F_SETFL, 0);

alarm(0);

for (i=0; i

{

if (isprint(buffer[i]))

printf(“%c”,buffer[i]);

else

printf(“[%2.2x]”,buffer[i]);

}

printf(“\nDone with read\n”);

}

int

s_fd_wait()

{

/*this function does a select to wait for

input on the fd, and if there

is, returns 1, else 0 */

int fd;

fd_set rfds;

struct timeval tv;

int retval;

fd=current_spike->fd;

/* Watch server_fd (fd 0) to see when it has input. */

FD_ZERO(&rfds);

FD_SET(fd, &rfds);

/* Wait up to zero seconds . will this wait forever? not on linux.*/

/* from man page: timeout is an upper bound on the amount of time

elapsed before select returns. It may be zero, causing select

to return immediately. If timeout is NULL (no timeout), select

can block indefinitely. */

/*wait 2 seconds only*/

tv.tv_sec = TIMEINSECONDS;

tv.tv_usec = TIMEINUSECONDS;

//printf(“Before select %d:%d\n”,TIMEINSECONDS,TIMEINUSECONDS);

retval = select(fd+1, &rfds, NULL, NULL, &tv);

/* Don’t rely on the value of tv now! */

//printf(“After select retval=%d.\n”,retval);

switch (retval)

{

case 0:

/*Timeout – no packet or keypress*/

return(0);

break;

case -1:

/* ignore interrupted system calls */

if (errno != EINTR)

{

/*some kind of weird select error. Die. */

exit(-1);

}

/*otherwise we got interrupted, so just return false*/

return (0);

break;

default:

{

if (FD_ISSET(fd,&rfds))

return (1);

else

return (0);

}

}

}

但是函数s_read_packet没有产生数据……