| Message ID | 20140514004420.GV6302@type.youpi.perso.aquilenet.fr |
|---|---|
| State | New |
| Headers | show |
On Wed, May 14, 2014 at 02:44:20AM +0200, Samuel Thibault wrote: > Edgar E. Iglesias, le Wed 14 May 2014 00:30:09 +0000, a écrit : > > > At best I could think of using the patch below, which avoids registering > > > anything for 0.0.0.0, and use a broadcast to answer a guest which > > > would have used 0.0.0.0 as a source for whatever reason. I don't find > > > anything else reasonable. What would be preferred? > > > > Specs are not super clear on this but rfc1700 says that 0.0.0.0 is a source only address. > > I agree. > > > What I was trying to suggest was a mix between your two versions. > > Removing the assert in table_search and avoid adding 0.0.0.0/32 to the cache > > in table_add. We might need to complement with something that drops datagrams > > destined to 0.0.0.0 in upper layers so we dont keep trying, not sure. > > Does something like that make sense? > > So that would be this. > > Samuel This looks good to me. Minor nit, the comment in if_encap should say "0.0.0.0 can not be a destination address..." Cheers, Edgar > > > Do not special-case addresses with zero host part, as we do not > necessarily know how big it is, and the guest can fake them anyway. > Silently avoiding having 0.0.0.0 as a destination, however. > > Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org> > --- > > diff --git a/slirp/arp_table.c b/slirp/arp_table.c > index ecdb0ba..bcaeb44 100644 > --- a/slirp/arp_table.c > +++ b/slirp/arp_table.c > @@ -37,12 +37,7 @@ void arp_table_add(Slirp *slirp, uint32_t ip_addr, uint8_t ethaddr[ETH_ALEN]) > ethaddr[0], ethaddr[1], ethaddr[2], > ethaddr[3], ethaddr[4], ethaddr[5])); > > - /* Check 0.0.0.0/8 invalid source-only addresses */ > - if ((ip_addr & htonl(~(0xfU << 28))) == 0) { > - return; > - } > - > - if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) { > + if (ip_addr == 0 || ip_addr == 0xffffffff || ip_addr == broadcast_addr) { > /* Do not register broadcast addresses */ > return; > } > @@ -73,9 +68,6 @@ bool arp_table_search(Slirp *slirp, uint32_t ip_addr, > DEBUG_CALL("arp_table_search"); > DEBUG_ARG("ip = 0x%x", ip_addr); > > - /* Check 0.0.0.0/8 invalid source-only addresses */ > - assert((ip_addr & htonl(~(0xfU << 28))) != 0); > - > /* If broadcast address */ > if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) { > /* return Ethernet broadcast address */ > diff --git a/slirp/slirp.c b/slirp/slirp.c > index 3fb48a4..2f189e0 100644 > --- a/slirp/slirp.c > +++ b/slirp/slirp.c > @@ -778,6 +778,11 @@ int if_encap(Slirp *slirp, struct mbuf *ifm) > return 1; > } > > + if (!iph->ip_dst.s_addr) { > + /* 0.0.0.0 can not be a source address, something went wrong, avoid > + * making it worse */ > + return 1; > + } > if (!arp_table_search(slirp, iph->ip_dst.s_addr, ethaddr)) { > uint8_t arp_req[ETH_HLEN + sizeof(struct arphdr)]; > struct ethhdr *reh = (struct ethhdr *)arp_req; > diff --git a/slirp/arp_table.c b/slirp/arp_table.c > index ecdb0ba..bcaeb44 100644 > --- a/slirp/arp_table.c > +++ b/slirp/arp_table.c > @@ -37,12 +37,7 @@ void arp_table_add(Slirp *slirp, uint32_t ip_addr, uint8_t ethaddr[ETH_ALEN]) > ethaddr[0], ethaddr[1], ethaddr[2], > ethaddr[3], ethaddr[4], ethaddr[5])); > > - /* Check 0.0.0.0/8 invalid source-only addresses */ > - if ((ip_addr & htonl(~(0xfU << 28))) == 0) { > - return; > - } > - > - if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) { > + if (ip_addr == 0 || ip_addr == 0xffffffff || ip_addr == broadcast_addr) { > /* Do not register broadcast addresses */ > return; > } > @@ -73,9 +68,6 @@ bool arp_table_search(Slirp *slirp, uint32_t ip_addr, > DEBUG_CALL("arp_table_search"); > DEBUG_ARG("ip = 0x%x", ip_addr); > > - /* Check 0.0.0.0/8 invalid source-only addresses */ > - assert((ip_addr & htonl(~(0xfU << 28))) != 0); > - > /* If broadcast address */ > if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) { > /* return Ethernet broadcast address */ > diff --git a/slirp/slirp.c b/slirp/slirp.c > index 3fb48a4..2f189e0 100644 > --- a/slirp/slirp.c > +++ b/slirp/slirp.c > @@ -778,6 +778,11 @@ int if_encap(Slirp *slirp, struct mbuf *ifm) > return 1; > } > > + if (!iph->ip_dst.s_addr) { > + /* 0.0.0.0 can not a a source address, something went wrong, avoid > + * making it it worse */ > + return 1; > + } > if (!arp_table_search(slirp, iph->ip_dst.s_addr, ethaddr)) { > uint8_t arp_req[ETH_HLEN + sizeof(struct arphdr)]; > struct ethhdr *reh = (struct ethhdr *)arp_req;
Edgar E. Iglesias, le Wed 14 May 2014 00:54:50 +0000, a écrit : > Minor nit, the comment in if_encap should say > "0.0.0.0 can not be a destination address..." D'oh :) Samuel
diff --git a/slirp/arp_table.c b/slirp/arp_table.c index ecdb0ba..bcaeb44 100644 --- a/slirp/arp_table.c +++ b/slirp/arp_table.c @@ -37,12 +37,7 @@ void arp_table_add(Slirp *slirp, uint32_t ip_addr, uint8_t ethaddr[ETH_ALEN]) ethaddr[0], ethaddr[1], ethaddr[2], ethaddr[3], ethaddr[4], ethaddr[5])); - /* Check 0.0.0.0/8 invalid source-only addresses */ - if ((ip_addr & htonl(~(0xfU << 28))) == 0) { - return; - } - - if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) { + if (ip_addr == 0 || ip_addr == 0xffffffff || ip_addr == broadcast_addr) { /* Do not register broadcast addresses */ return; } @@ -73,9 +68,6 @@ bool arp_table_search(Slirp *slirp, uint32_t ip_addr, DEBUG_CALL("arp_table_search"); DEBUG_ARG("ip = 0x%x", ip_addr); - /* Check 0.0.0.0/8 invalid source-only addresses */ - assert((ip_addr & htonl(~(0xfU << 28))) != 0); - /* If broadcast address */ if (ip_addr == 0xffffffff || ip_addr == broadcast_addr) { /* return Ethernet broadcast address */ diff --git a/slirp/slirp.c b/slirp/slirp.c index 3fb48a4..2f189e0 100644 --- a/slirp/slirp.c +++ b/slirp/slirp.c @@ -778,6 +778,11 @@ int if_encap(Slirp *slirp, struct mbuf *ifm) return 1; } + if (!iph->ip_dst.s_addr) { + /* 0.0.0.0 can not be a source address, something went wrong, avoid + * making it worse */ + return 1; + } if (!arp_table_search(slirp, iph->ip_dst.s_addr, ethaddr)) { uint8_t arp_req[ETH_HLEN + sizeof(struct arphdr)]; struct ethhdr *reh = (struct ethhdr *)arp_req;