sourceroute.c

/* include inet_srcrt_init */
#include	"unp.h"
#include	<netinet/in_systm.h>
#include	<netinet/ip.h>

static u_char	*optr;		/* pointer into options being formed */
static u_char	*lenptr;	/* pointer to length byte in SRR option */
static int		ocnt;		/* count of # addresses */

u_char *
inet_srcrt_init(int type)
{
	optr = Malloc(44);		/* NOP, code, len, ptr, up to 10 addresses */
	bzero(optr, 44);		/* guarantees EOLs at end */
	ocnt = 0;
	*optr++ = IPOPT_NOP;	/* NOP for alignment */
	*optr++ = type ? IPOPT_SSRR : IPOPT_LSRR;
	lenptr = optr++;		/* we fill in length later */
	*optr++ = 4;			/* offset to first address */

	return(optr - 4);		/* pointer for setsockopt() */
}
/* end inet_srcrt_init */

/* include inet_srcrt_add */
int
inet_srcrt_add(char *hostptr)
{
	int					len;
	struct addrinfo		*ai;
	struct sockaddr_in	*sin;

	if (ocnt > 9)
		err_quit("too many source routes with: %s", hostptr);

	ai = Host_serv(hostptr, NULL, AF_INET, 0);
	sin = (struct sockaddr_in *) ai->ai_addr;
	memcpy(optr, &sin->sin_addr, sizeof(struct in_addr));
	freeaddrinfo(ai);

	optr += sizeof(struct in_addr);
	ocnt++;
	len = 3 + (ocnt * sizeof(struct in_addr));
	*lenptr = len;
	return(len + 1);	/* size for setsockopt() */
}
/* end inet_srcrt_add */

/* include inet_srcrt_print */
void
inet_srcrt_print(u_char *ptr, int len)
{
	u_char			c;
	char			str[INET_ADDRSTRLEN];
	struct in_addr	hop1;

	memcpy(&hop1, ptr, sizeof(struct in_addr));
	ptr += sizeof(struct in_addr);

	while ( (c = *ptr++) == IPOPT_NOP)
		;		/* skip any leading NOPs */

	if (c == IPOPT_LSRR)
		printf("received LSRR: ");
	else if (c == IPOPT_SSRR)
		printf("received SSRR: ");
	else {
		printf("received option type %d\n", c);
		return;
	}
	printf("%s ", Inet_ntop(AF_INET, &hop1, str, sizeof(str)));

	len = *ptr++ - sizeof(struct in_addr);	/* subtract dest IP addr */
	ptr++;		/* skip over pointer */
	while (len > 0) {
		printf("%s ", Inet_ntop(AF_INET, ptr, str, sizeof(str)));
		ptr += sizeof(struct in_addr);
		len -= sizeof(struct in_addr);
	}
	printf("\n");
}
/* end inet_srcrt_print */