tcp to netreceive

[Marc Lavallée]

Dan Neveu wrote:
> > I'm trying to utilize this class which I found (libtcp++)
> > in order to provide tcp client capabilities to my GL code:
> > http://www.sashanet.com/internet/download.html

Then Miller Puckette wrote :
> 
> DO IT!! this is exactly what I'm hoping the
> netsend~/netreceive~ objects will encourage!


I did something similar a couple of weeks ago to drive my openGL app
with PD. I only need udp communication from PD to my app, so I hacked
the source code of u_pdreceive, which is one of Miller's sample
applications that uses the FUDI protocol. I stripped everything not
needed, so it's not as flexible as the original u_pdreceive (no tcp),
but it's simple and it works very well, at least on the same machine.

Here's the source:

/* -- file "u_pd_in.c" -- (sorry, not commented) */

// Maybe some header files are not needed here...
#include <sys/types.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/time.h>

typedef struct _fdpoll
{
    int fdp_fd;
    char *fdp_inbuf;
    int fdp_inhead;
    int fdp_intail;
    int fdp_udp;
} t_fdpoll;

static int maxfd;
static int sockfd;

static void sockerror(char *s);

#define BUFSIZE 1024

char *u_pd_in_argv[25];
int u_pd_in_argc = 0;


int init_u_pd_in() {
    int portno = 3001;
    struct sockaddr_in server;

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0)
    {
    	sockerror("socket()");
    	return(1);
    }
    maxfd = sockfd + 1;
    server.sin_family = AF_INET;
    server.sin_addr.s_addr = INADDR_ANY;

    /* assign client port number */
    server.sin_port = htons((unsigned short)portno);

    /* name the socket */
    if (bind(sockfd, (struct sockaddr *)&server, sizeof(server)) < 0)
    {
        sockerror("bind");
        close(sockfd);
    	return (0);
    }
	return(0);
}


char *check_u_pd_in(void)
{
    fd_set readset;
    struct timeval tv;
    char *buf[BUFSIZE], *command;
	  int retval, ret;
	  
    FD_ZERO(&readset);
    FD_SET(sockfd, &readset);
    
    tv.tv_sec  = 0; tv.tv_usec = 5;       
    retval = select(maxfd+1, &readset, NULL, NULL, &tv);
    
    command = strdup("");
    if (retval > 0) {
    	ret = recv(sockfd, &buf, BUFSIZE, 0);
    	if (ret < 0) {
		    sockerror("recv (udp)");
		    close(sockfd);
		    exit(1);
		  }
      if (ret > 0)
      command = strtok((char *)buf, ";");
    }
    return(command);
}


static void sockerror(char *s)
{
    int err = errno;
    fprintf(stderr, "%s: %s (%d)\n", s, strerror(err), err);
}

/* -- enf of file "u_pd_in.c -- */


In my application main loop, I check if there's new messages from PD, I
split the incoming string in a argv style array, then I parse the
arguments:

void check_u_pd_command(void) {
  int argc = 0;
  char *argv[25], *buffer, *token;
  const char *delims = " ";

// get a new list from PD
  buffer = strdup(check_u_pd_in());
// split the string
  token = strtok(buffer, delims);
  while(token != (char *)NULL) {
    argv[argc] = token;
    argc++;
    token = strtok(NULL, delims);
  }
  free(buffer);
  if (argc == 0) return;

// parse the arguments and do something
  if (!strcmp(argv[0],"test")) {
    printf("test: %s, %s\n", argv[1], argv[2]);
  } else 
....
}

Voilà!

-- 
Marc Lavallée