FreeLists / openbeosnetteam / [openbeosnetteam] Re: DHCP Status + Help Needed

[Ingo Weinhold <bonefish@xxxxxxxxxxxxxxx>]

On 2004-10-12 at 23:56:04 [+0200], David Enderson wrote:
> Networking Team,
> 
> I'm into my second week of unpaid vacation and have spent part of the
> time working on the Haiku DHCP implementation as promised.  I've got a
> nearly complete understanding of the RFC and I've enough of the client
> together for some test messages with a DHCP server.
> 
> (This is where the "Help Needed" part comes in)
> 
> What I'm lacking is the ability to broadcast a UDP packet.  I have
> googled for numerous examples and have been thoroughly frustrated.  I
> think I can send a UDP packet, but I can't get broadcast to work.  I
> implemented a working sockets implementation for an open source game a
> while back, so I think I can do this, I just need the...rosetta
> stone...if you will for UDP.
> 
> Can anyone point me towards excellent, simple, and COMPILEABLE examples?

I just very recently learned how to do broadcasting myself. Attached is my 
test app. It's definitely simple and compiles and runs under R5. About the 
`excellent' part I don't know.

Note that POSIX defines the socket option SO_BROADCAST, that -- if I 
understand it correctly -- has to be set (via setsockopt()) for both the 
socket of the sender and the receiver. Since R5 doesn't know this option, I 
can't set it. Don't know, if it is required for BONE/our stack.

CU, Ingo

// broadcast-test.cpp

#include <errno.h>
#include <socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// client
static
status_t
client(unsigned short port)
{
        printf("client(): port: %hu\n", port);
        // create a socket
        int fd = socket(AF_INET, SOCK_DGRAM, 0);
        if (fd < 0)
                return errno;
        // bind it to the port
        sockaddr_in addr;
        addr.sin_family = AF_INET;
        addr.sin_port = htons(port);
        addr.sin_addr.s_addr = INADDR_ANY;
        if (bind(fd, (sockaddr*)&addr, sizeof(addr)) < 0) {
                printf("binding failed: %s\n", strerror(errno));
                closesocket(fd);
                return errno;
        }
        // receive
        addr.sin_family = AF_INET;
        addr.sin_port = htons(port);
        addr.sin_addr.s_addr = INADDR_BROADCAST;
        int addrSize = sizeof(addr);
        char buffer[1024];
        ssize_t bytesRead = recvfrom(fd, buffer, sizeof(buffer), 0,
                         (sockaddr*)&addr, &addrSize);
        if (bytesRead >= 0)
                printf("received %ld bytes\n", bytesRead);
        else
                printf("recvfrom failed: %s\n", strerror(errno));
        closesocket(fd);
        return B_OK;
}

// server
static
status_t
server(unsigned short port)
{
        printf("server(): port: %hu\n", port);
        // create a socket
        int fd = socket(AF_INET, SOCK_DGRAM, 0);
        if (fd < 0)
                return errno;
        // send
        sockaddr_in addr;
        addr.sin_family = AF_INET;
        addr.sin_port = htons(port);
        addr.sin_addr.s_addr = INADDR_BROADCAST;
        int addrSize = sizeof(addr);
        char buffer[1024];
        ssize_t bytesSent = sendto(fd, buffer, 29, 0,
                         (sockaddr*)&addr, addrSize);
        if (bytesSent >= 0)
                printf("sent %ld bytes\n", bytesSent);
        else
                printf("send failed: %s\n", strerror(errno));
        closesocket(fd);
        return B_OK;
}

// main
int
main(int argc, char** argv)
{
        if (argc <= 2) {
                fprintf(stderr, "Usage: %s client|server <port>\n", argv[0]);
                return 1;
        }
        int port = atoi(argv[2]);
        if (strcmp(argv[1], "client") == 0)
                client(port);
        else
                server(port);
        return 0;
}