Just how many UDP packets *can* I send?

gistfile1.c

#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/time.h>

static double start = 0.0;
static long count = 0;

static double now() {
	struct timeval tv;

	gettimeofday(&tv, NULL);
	double ts = tv.tv_sec;
	ts += tv.tv_usec / 1000000.0;

	return ts;
}

void handle_sigint(int sig) {
	double elapsed = now() - start;
	double rate = count / elapsed;
	printf("Sent %lu message in %f seconds for %f msgs/second", count, elapsed, rate);
	exit(0);
}

int main(int argc, char **argv) {
	struct sockaddr_in sin;
	int s, ret;


	start = now();

	s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
	if (s < 0) {
		perror("socket");
		exit(-1);
	}

	memset(&sin, 0, sizeof(sin));
	sin.sin_family = AF_INET;
	ret = bind(s, (struct sockaddr *)&sin, sizeof(sin));
	if (ret < 0) {
		perror("bind");
		exit(-1);
	}

	signal(SIGINT, handle_sigint);
	sin.sin_port = htons(12345);
	char msg = 'x';
	while (1) {
		ret = sendto(s, &msg, 1, 0, (struct sockaddr *)&sin, sizeof(sin));
		if (ret < 0) {
			perror("sendto");
			exit(-1);
		}	
		count++;
	}


	return 0;
}