From: Andrew Oates <aoa...@google.com>
On Linux, SOCK_DGRAM+IPPROTO_ICMP sockets give only the ICMP packet when
read from. On macOS, however, the socket acts like a SOCK_RAW socket
and includes the IP header as well.
This change strips the extra IP header from the received packet on macOS
before sending it to the guest.
Signed-off-by: Andrew Oates <aoa...@google.com>
---
v2: check validity of inner_hlen and update len appropriately
slirp/ip_icmp.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/slirp/ip_icmp.c b/slirp/ip_icmp.c
index 0b667a429a..76c6d54b11 100644
--- a/slirp/ip_icmp.c
+++ b/slirp/ip_icmp.c
@@ -420,7 +420,21 @@ void icmp_receive(struct socket *so)
icp = mtod(m, struct icmp *);
id = icp->icmp_id;
- len = qemu_recv(so->s, icp, m->m_len, 0);
+ len = qemu_recv(so->s, icp, M_ROOM(m), 0);
+#ifdef CONFIG_DARWIN
+ if (len > 0) {
+ /* Skip the IP header that OS X (unlike Linux) includes. */
+ struct ip *inner_ip = mtod(m, struct ip *);
+ int inner_hlen = inner_ip->ip_hl << 2;
+ if (inner_hlen > len) {
+ len = -1;
+ errno = -EINVAL;
+ } else {
+ len -= inner_hlen;
+ memmove(icp, (unsigned char *)icp + inner_hlen, len);
+ }
+ }
+#endif
icp->icmp_id = id;
m->m_data -= hlen;
--
2.17.0
