Using ioctl() to add an entry to TCPIP routing table

Brian Lindauer — Fri, 12 Dec 2008 19:20:53 GMT

Is anyone familiar with using ioctl() in C to add or delete an entry in the TCPIP routing table? I have the call set as follows:

status = ioctl( sock_id, SIOCADDRT, &rt_entry)

rt_entry is a structure I found in TCPIP$EXAMPLES. I am not sure if it is the correct structure to use since I did not find it anywhere else defined. When I call the ioctl() function I get "Invalid argument". Could someone please tell me what the correct format of the structure is suppose to be. Also is there a way to specify the network mask for the routing IP address in the ioctl function?

Re: Using ioctl() to add an entry to TCPIP routing table

Jim_McKinney — Fri, 12 Dec 2008 21:01:04 GMT

I've not had occasion to have to add an entry to the routing table but it appears that your rt_entry structure should look like the rtentry structure in SYS$COMMON:[SYSHLP.EXAMPLES.TCPIP.LIBPCAP]ROUTE.H. The mask is defined by rt_mask field within this structure.

struct rtentry {
struct radix_node rt_nodes[2]; /* tree glue, and other values */
#define rt_key(r) ((struct sockaddr *)((r)->rt_nodes->rn_key))
#define rt_mask(r) ((struct sockaddr *)((r)->rt_nodes->rn_mask))
struct sockaddr *rt_gateway; /* value */
int rt_flags; /* up/down?, host/net */
int rt_refcnt; /* # held references */
u_long rt_use; /* raw # packets forwarded */
struct ifnet *rt_ifp; /* the answer: interface to use */
struct ifaddr *rt_ifa; /* the answer: interface to use */
struct sockaddr *rt_genmask; /* for generation of cloned routes */
caddr_t rt_llinfo; /* pointer to link level info cache */
struct rt_metrics rt_rmx; /* metrics used by rx'ing protocols */
short rt_idle; /* easy to tell llayer still live */
short rt_aliasid; /* cluster aliasid id of dst */
u_int rt_precedence; /* precedence */
#if SEC_NET
struct tnrh_rem_host *rt_host; /* Remote host structure. */
#endif
struct rtentry *rt_gwroute; /* entry for gateway route */
struct mip6_binding_cache *rt_mip6cache;/* ptr to Mobile IPv6 binding */
u_long rt_reserved[5]; /* reserved for future use */
};

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Using ioctl() to add an entry to TCPIP routing table

Re: Using ioctl() to add an entry to TCPIP routing table