Date: Mon, 14 Feb 2000 14:45:38 -0800 From: Nathan <nboeger@getrelevant.com> To: rbg@pmr.com, "freebsd-net@FreeBSD.ORG" <freebsd-net@FreeBSD.ORG> Subject: Re: HELP ! programing routes ?? Message-ID: <38A88592.8F1B94E7@getrelevant.com> References: R01YxZF
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rbg@pmr.com wrote:
> ----- ORIGINAL INTERNET MAIL FOLLOWS 02/14/2000 02:26 PM PST -----
> From: rbg@pmr.com
> To: nboeger
>
> Nath..
>
> I don't see were l is getting set to the size you're
> writing to the socket...
>
> ----- Original Message -----
> From: "Nathan" <nboeger@getrelevant.com>
> To: <freebsd-net@FreeBSD.ORG>
> Sent: Monday, February 14, 2000 4:07 PM
> Subject: HELP ! programing routes ??
>
> > Sorry if this is a repeat !
> >
> >
> > I have a question, I need to write a small program that sets the default
> >
> > gw. It is written in C and I have looked at several way to do it. One
> > way is using ioctl but that way seems a little "old" and not very well
> > documented. Here is a simple snippet of my code, now when I run it I get
> >
> > an error "error 22" invalid arg. Does anyone have experience with this
> > and can point out what I am doing wrong ? I did have it to where it
> > would work but the kernel never added my netmask to the routing table.
> > So the route would kinda "hang" their and not do anything. I did tell it
> >
> > that it was being sent but..... also the flags never where set proper on
> >
> > the route (when doing route -dvn flush )
> >
> >
> > Any help would be great ! (oh if this looks familiar, I learned this
> > from reading both ruote.c and netstat.c. )
> >
> > struct rt_data_msg{
> > struct rt_msghdr add_rtm;
> > union{
> > struct sockaddr sa;
> > struct sockaddr_in sin;
> > struct sockaddr_dl sdl;
> > }rt_dst, rt_gate, rt_mask;
> > };
> >
> > int set_droute(char *gw){
> >
> > int sockfd, i, err = 0;
> > int flags = 0, r_addrs = 0;
> > u_long inits;
> > char t_gw[32];
> > register int l;
> > struct rt_data_msg add_rt;
> > pid_t pid;
> >
> > /* check to see if we have a gateway address or quit */
> > if(!gw){
> > ERR("set_droute: FREEBSD no route sent ! %d");
> > return(BAD);
> > }
> > else{
> > /* convet this address if not valid quit */
> > if((inet_aton(gw, &so_gate.sin.sin_addr)) < 0){
> > ERR("set_droute: FREEBSD route not valid ! %d");
> >
> > return(BAD);
> > }
> > }
> >
> > memset(&add_rt, 0, sizeof(struct rt_data_msg));
> >
> > /* check to see if thier is an existing route or not make an
> > entry from scratch */
> > if( (i = get_droute(t_gw)) == BAD){
> >
> > /* make the address and netmasks */
> >
> > if((inet_aton("0.0.0.0", &add_rt.rt_mask.sin.sin_addr))
> > < 0){ err++; }
> > if((inet_aton("0.0.0.0", &add_rt.rt_dst.sin.sin_addr)) <
> >
> > 0) { err++; }
> > if((inet_aton(gw, &add_rt.rt_gate.sin.sin_addr)) < 0){
> > err++; }
> > if(err > 0){
> > ERR("get_droute: FREEBSD cannot set mask or dst
> > or gw invalid addresses %d");
> > return(BAD);
> > }
> >
> > inits = RTV_EXPIRE;
> > inits |= RTV_RPIPE;
> > inits |= RTV_SPIPE;
> > inits |= RTV_SSTHRESH;
> >
> > r_addrs = RTAX_DST;
> > r_addrs |= RTAX_GATEWAY;
> > r_addrs |= RTAX_NETMASK;
> >
> > flags = RTF_UP;
> > flags |= RTF_GATEWAY;
> > flags |= RTF_STATIC;
> > flags |= RTF_PRCLONING;
> >
> > /* add thier size */
> > #define ADD_SIZE(w) l = ROUNDUP(w.sa.sa_len)
> > #define ROUNDUP(a) ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1)))
> > : sizeof(long));
> >
> > ADD_SIZE(add_rt.rt_dst);
> > ADD_SIZE(add_rt.rt_gate);
> > ADD_SIZE(add_rt.rt_mask);
> >
> > /* add their address family */
> > #define ADD_FAM(x) x.sin.sin_family = AF_INET;
> > ADD_FAM(add_rt.rt_dst);
> > ADD_FAM(add_rt.rt_gate);
> > ADD_FAM(add_rt.rt_mask);
> > ADD_FAM(add_rt.rt_genmask);
> >
> > /* set up all of the flags and tables */
> > #define RD add_rt.add_rtm
> > RD.rtm_msglen = l;
> > RD.rtm_version = RTM_VERSION;
> > RD.rtm_type = RTM_ADD;
> > RD.rtm_flags = flags;
> > RD.rtm_addrs = rtm_addrs;
> > RD.rtm_inits = RTF_GATEWAY;
> > RD.rtm_pid = pid = getpid();
> > RD.rtm_seq = ++SEQ;
> >
> > if( (sockfd = socket(PF_ROUTE, SOCK_RAW, 0)) < 0){
> > ERR("set_droute: FREEBSD cannot open socket
> > %d");
> > }
> > /* send it to the kernel */
> > i = write(sockfd, (char *)&add_rt, l);
> > syslog(LOG_ERR, "errno = %d ", errno);
> > }
> > else{
> > /* get a buffer for the data */
> > ERR("get_droute returned ok %d ");
> > }
> >
> > return(GOOD);
> > }
> >
> >
> > Thank you
> >
> > nathan
> >
> >
> >
> > To Unsubscribe: send mail to majordomo@FreeBSD.org
> > with "unsubscribe freebsd-net" in the body of the message
> >
Good point !
this is an older copy, but the size I have fixed that and it receives a size
of 128,. Now the problem I think is that the sizeof the struct rt_msghdr is
92, now that would be followed by my 3 sockaddr_in structs which are 16 each
so total is 140 ?
now the size of 128 is the size that the actual route.c sends and the
difference is that they make a struct with a rt_msghdr, and a char buf of 512
and then he formats that without the popen numbers and only writes the fist
128.
Now what I need to know if that is the case then what exactly needs to follow
the rt_msghdr the doc's that I have found say that it needs in order:
sockaddr dst /* destination rt_msghdr == 92 + this == 108*/
sockaddr gtw /* gateway current 108 + 16 == 124*/
sockaddr ntmsl /* net mask current 124 + 16 == 140 ? */
so does it really need the first destination or is that implied when you send
the netmask ? or is their a location that is inside the struct rt_msghdr that
you need to fill-in besides the obvious ?
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