#undef NDEBUG#include <assert.h>#include <errno.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <sys/ioctl.h>#include <sys/socket.h>#include <netinet/in.h>#include <net/gen/in.h>#include <net/gen/udp.h>#include <net/gen/udp_hdr.h>#include <net/gen/udp_io.h>#define DEBUG 0static ssize_t _udp_sendto(int socket, const void *message, size_t length,	int flags, const struct sockaddr *dest_addr, socklen_t dest_len,	nwio_udpopt_t *udpoptp);ssize_t sendto(int socket, const void *message, size_t length, int flags,	const struct sockaddr *dest_addr, socklen_t dest_len){	int r;	nwio_udpopt_t udpopt;	r= ioctl(socket, NWIOGUDPOPT, &udpopt);	if (r != -1 || (errno != ENOTTY && errno != EBADIOCTL))	{		if (r == -1)			return r;		return _udp_sendto(socket, message, length, flags,			dest_addr, dest_len, &udpopt);	}#if DEBUG	fprintf(stderr, "sendto: not implemented for fd %d\n", socket);#endif	errno= ENOSYS;	return -1;}static ssize_t _udp_sendto(int socket, const void *message, size_t length,	int flags, const struct sockaddr *dest_addr, socklen_t dest_len,	nwio_udpopt_t *udpoptp){	int r, t_errno;	size_t buflen;	void *buf;	struct sockaddr_in *sinp;	udp_io_hdr_t *io_hdrp;	if (flags)	{#if DEBUG		fprintf(stderr, "sendto(udp): flags not implemented\n");#endif		errno= ENOSYS;		return -1;	}	if (udpoptp->nwuo_flags & NWUO_RWDATONLY)		return write(socket, message, length);	if ((udpoptp->nwuo_flags & NWUO_RP_ANY) ||		(udpoptp->nwuo_flags & NWUO_RA_ANY))	{		/* Check destination address */		if (dest_len < sizeof(*sinp))		{			errno= EINVAL;			return -1;		}		sinp= (struct sockaddr_in *)dest_addr;		if (sinp->sin_family != AF_INET)		{			errno= EAFNOSUPPORT;			return -1;		}	}	buflen= sizeof(*io_hdrp) + length;	if (buflen < length)	{			/* Overflow */		errno= EMSGSIZE;		return -1;	}	buf= malloc(buflen);	if (buf == NULL)		return -1;	io_hdrp= buf;	io_hdrp->uih_src_addr= 0;	/* Unused */	io_hdrp->uih_src_port= 0;	/* Will cause error if NWUO_LP_ANY */	if (udpoptp->nwuo_flags & NWUO_RA_ANY)		io_hdrp->uih_dst_addr= sinp->sin_addr.s_addr;	else		io_hdrp->uih_dst_addr= 0;	if (udpoptp->nwuo_flags & NWUO_RP_ANY)		io_hdrp->uih_dst_port= sinp->sin_port;	else		io_hdrp->uih_dst_port= 0;	io_hdrp->uih_ip_opt_len= 0;	io_hdrp->uih_data_len= 0;	memcpy(&io_hdrp[1], message, length);	r= write(socket, buf, buflen);	if (r == -1)	{		t_errno= errno;		free(buf);		errno= t_errno;		return -1;	}	assert(r == buflen);	free(buf);	return length;}