My pleasure, thanks for the quick turnaround! -----Original Message----- From: "David Gwynne" <[email protected]> Sent: Tuesday, 27 August, 2019 4:16am To: "Gerrie Roos" <[email protected]> Cc: "bugs" <[email protected]> Subject: Re: Bad TTL when applying multiple MPLS labels
The fix should be in now. Thanks for the report, and the diff pointing right at the problem. On Tue., 27 Aug. 2019, 01:45 Gerrie Roos, <[email protected]> wrote: > I just tested your patch and it works! I can see the correct TTL. > > -----Original Message----- > From: "David Gwynne" <[email protected]> > Sent: Monday, 26 August, 2019 4:21am > To: "Gerrie Roos" <[email protected]> > Cc: [email protected] > Subject: Re: Bad TTL when applying multiple MPLS labels > > On Fri, Aug 23, 2019 at 10:05:25AM -0500, Gerrie Roos wrote: > > Hi David, > > > > Apologies, I haven't used CVS in a while - here you go. Hope it's useful. > > > > Gerrie > > npz, i can read the attachment fine. > > if someone's carrying a non-ip payload over mpls with a nibble that > makes it look like ip, your diff will cause (very) short payloads > to be dropped when m_pullup can't find bytes to copy into the first > mbuf. > > could you try the following? it uses m_getptr to reach into the right > mbuf and byte offset in that mbuf for the ttl. if the packet is > short, it just returns the default ttl. > > i've attached the diff for your convenience too. > > cheers, > dlg > > Index: mpls_output.c > =================================================================== > RCS file: /cvs/src/sys/netmpls/mpls_output.c,v > retrieving revision 1.26 > diff -u -p -r1.26 mpls_output.c > --- mpls_output.c 2 Dec 2015 08:47:00 -0000 1.26 > +++ mpls_output.c 26 Aug 2019 09:11:08 -0000 > @@ -162,41 +162,39 @@ mpls_do_cksum(struct mbuf *m) > u_int8_t > mpls_getttl(struct mbuf *m, sa_family_t af) > { > - struct shim_hdr *shim; > - struct ip *ip; > -#ifdef INET6 > - struct ip6_hdr *ip6hdr; > -#endif > + struct mbuf *n; > + int loc, off; > u_int8_t ttl = mpls_defttl; > > /* If the AF is MPLS then inherit the TTL from the present label. > */ > - if (af == AF_MPLS) { > - shim = mtod(m, struct shim_hdr *); > - ttl = ntohl(shim->shim_label & MPLS_TTL_MASK); > - return (ttl); > - } > - /* Else extract TTL from the encapsualted packet. */ > - switch (*mtod(m, u_char *) >> 4) { > - case IPVERSION: > - if (!mpls_mapttl_ip) > + if (af == AF_MPLS) > + loc = 3; > + else { > + switch (*mtod(m, uint8_t *) >> 4) { > + case 4: > + if (!mpls_mapttl_ip) > + return (ttl); > + > + loc = offsetof(struct ip, ip_ttl); > break; > - if (m->m_len < sizeof(*ip)) > - break; /* impossible */ > - ip = mtod(m, struct ip *); > - ttl = ip->ip_ttl; > - break; > #ifdef INET6 > - case IPV6_VERSION >> 4: > - if (!mpls_mapttl_ip6) > + case 6: > + if (!mpls_mapttl_ip6) > + break; > + > + loc = offsetof(struct ip6_hdr, ip6_hlim); > break; > - if (m->m_len < sizeof(struct ip6_hdr)) > - break; /* impossible */ > - ip6hdr = mtod(m, struct ip6_hdr *); > - ttl = ip6hdr->ip6_hlim; > - break; > #endif > - default: > - break; > + default: > + return (ttl); > + } > } > + > + n = m_getptr(m, loc, &off); > + if (n == NULL) > + return (ttl); > + > + ttl = *(mtod(n, uint8_t *) + off); > + > return (ttl); > } > > >
