[Qemu-devel] [PATCH] slirp: Allow to disable IPv4 or IPv6

[Samuel Thibault]

Make net=0.0.0.0 disable IPv4 and ip6-net=:: disable IPv6, so the user can
setup IPv4-only and IPv6-only network environments.

Signed-off-by: Samuel Thibault <address@hidden>
---
 net/slirp.c       |  8 +++++---
 qapi-schema.json  |  4 ++--
 qemu-options.hx   |  7 ++++---
 slirp/ip6.h       |  9 +++++++++
 slirp/ip6_icmp.c  | 10 ++++++++++
 slirp/ip6_input.c |  6 ++++++
 slirp/ip_input.c  |  5 +++++
 slirp/slirp.c     |  5 +++++
 8 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/net/slirp.c b/net/slirp.c
index 95239bc..3151d4a 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -244,13 +244,15 @@ static int net_slirp_init(NetClientState *peer, const 
char *model,
 
 #if defined(_WIN32) && (_WIN32_WINNT < 0x0600)
     /* No inet_pton helper before Vista... */
-    if (vprefix6) {
+    if (vprefix6 && strcmp(vprefix6, "::")) {
         /* Unsupported */
         return -1;
     }
     memset(&ip6_prefix, 0, sizeof(ip6_prefix));
-    ip6_prefix.s6_addr[0] = 0xfe;
-    ip6_prefix.s6_addr[1] = 0xc0;
+    if (!vprefix6) {
+        ip6_prefix.s6_addr[0] = 0xfe;
+        ip6_prefix.s6_addr[1] = 0xc0;
+    }
 #else
     if (!vprefix6) {
         vprefix6 = "fec0::";
diff --git a/qapi-schema.json b/qapi-schema.json
index 88f9b81..69eb6e7 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2427,7 +2427,7 @@
 #
 # @ip: #optional legacy parameter, use net= instead
 #
-# @net: #optional IP address and optional netmask
+# @net: #optional IP address and optional netmask. Set to 0.0.0.0 to disable 
IPv4 completely
 #
 # @host: #optional guest-visible address of the host
 #
@@ -2443,7 +2443,7 @@
 # @dnssearch: #optional list of DNS suffixes to search, passed as DHCP option
 #             to the guest
 #
-# @ip6-prefix: #optional IPv6 network prefix (default is fec0::) (since 2.6)
+# @ip6-prefix: #optional IPv6 network prefix. Set to :: to disable IPv6 
completely (default is fec0::) (since 2.6)
 #
 # @ip6-prefixlen: #optional IPv6 network prefix length (default is 64) (since 
2.6)
 #
diff --git a/qemu-options.hx b/qemu-options.hx
index 732ed8c..4938213 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1712,8 +1712,8 @@ Assign symbolic name for use in monitor commands.
 
 @item address@hidden/@var{mask}]
 Set IP network address the guest will see. Optionally specify the netmask,
-either in the form a.b.c.d or as number of valid top-most bits. Default is
-10.0.2.0/24.
+either in the form a.b.c.d or as number of valid top-most bits. Set to 0.0.0.0
+to disable IPv4 completely. Default is 10.0.2.0/24.
 
 @item address@hidden
 Specify the guest-visible address of the host. Default is the 2nd IP in the
@@ -1721,7 +1721,8 @@ guest network, i.e. x.x.x.2.
 
 @item address@hidden/@var{int}]
 Set IPv6 network address the guest will see. Optionally specify the prefix
-size, as number of valid top-most bits. Default is fec0::/64.
+size, as number of valid top-most bits. Set to :: to disable IPv6 completely.
+Default is fec0::/64.
 
 @item address@hidden
 Specify the guest-visible IPv6 address of the host. Default is the 2nd IPv6 in
diff --git a/slirp/ip6.h b/slirp/ip6.h
index 8ddfa24..da23de6 100644
--- a/slirp/ip6.h
+++ b/slirp/ip6.h
@@ -26,6 +26,12 @@
                         0x00, 0x00, 0x00, 0x00,\
                         0x00, 0x00, 0x00, 0x02 } }
 
+#define ZERO_ADDR  { .s6_addr = \
+                        { 0x00, 0x00, 0x00, 0x00,\
+                        0x00, 0x00, 0x00, 0x00,\
+                        0x00, 0x00, 0x00, 0x00,\
+                        0x00, 0x00, 0x00, 0x00 } }
+
 static inline bool in6_equal(const struct in6_addr *a, const struct in6_addr 
*b)
 {
     return memcmp(a, b, sizeof(*a)) == 0;
@@ -84,6 +90,9 @@ static inline bool in6_equal_mach(const struct in6_addr *a,
 #define in6_solicitednode_multicast(a)\
     (in6_equal_net(a, &(struct in6_addr)SOLICITED_NODE_PREFIX, 104))
 
+#define in6_zero(a)\
+    (in6_equal(a, &(struct in6_addr)ZERO_ADDR))
+
 /* Compute emulated host MAC address from its ipv6 address */
 static inline void in6_compute_ethaddr(struct in6_addr ip,
                                        uint8_t eth[ETH_ALEN])
diff --git a/slirp/ip6_icmp.c b/slirp/ip6_icmp.c
index 9d61349..69c0a16 100644
--- a/slirp/ip6_icmp.c
+++ b/slirp/ip6_icmp.c
@@ -24,6 +24,11 @@ static void ra_timer_handler(void *opaque)
 
 void icmp6_init(Slirp *slirp)
 {
+    if (in6_zero(&slirp->vprefix_addr6)) {
+        /* IPv6 is disabled */
+        return;
+    }
+
     slirp->ra_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, ra_timer_handler, 
slirp);
     timer_mod(slirp->ra_timer,
               qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + NDP_Interval);
@@ -31,6 +36,11 @@ void icmp6_init(Slirp *slirp)
 
 void icmp6_cleanup(Slirp *slirp)
 {
+    if (in6_zero(&slirp->vprefix_addr6)) {
+        /* IPv6 is disabled */
+        return;
+    }
+
     timer_del(slirp->ra_timer);
     timer_free(slirp->ra_timer);
 }
diff --git a/slirp/ip6_input.c b/slirp/ip6_input.c
index c0b11e7..7801043 100644
--- a/slirp/ip6_input.c
+++ b/slirp/ip6_input.c
@@ -24,6 +24,12 @@ void ip6_cleanup(Slirp *slirp)
 void ip6_input(struct mbuf *m)
 {
     struct ip6 *ip6;
+    Slirp *slirp = m->slirp;
+
+    if (in6_zero(&slirp->vprefix_addr6)) {
+        /* IPv6 is disabled */
+        goto bad;
+    }
 
     DEBUG_CALL("ip6_input");
     DEBUG_ARG("m = %lx", (long)m);
diff --git a/slirp/ip_input.c b/slirp/ip_input.c
index b464f6b..a519bf6 100644
--- a/slirp/ip_input.c
+++ b/slirp/ip_input.c
@@ -80,6 +80,11 @@ ip_input(struct mbuf *m)
        register struct ip *ip;
        int hlen;
 
+       if (!slirp->vnetwork_addr.s_addr) {
+               /* IPv4 is disabled */
+               goto bad;
+       }
+
        DEBUG_CALL("ip_input");
        DEBUG_ARG("m = %p", m);
        DEBUG_ARG("m_len = %d", m->m_len);
diff --git a/slirp/slirp.c b/slirp/slirp.c
index 9ccf415..4a4c79e 100644
--- a/slirp/slirp.c
+++ b/slirp/slirp.c
@@ -693,6 +693,11 @@ static void arp_input(Slirp *slirp, const uint8_t *pkt, 
int pkt_len)
     int ar_op;
     struct ex_list *ex_ptr;
 
+    if (!slirp->vnetwork_addr.s_addr) {
+        /* IPv4 is disabled */
+        return;
+    }
+
     ar_op = ntohs(ah->ar_op);
     switch(ar_op) {
     case ARPOP_REQUEST:
-- 
2.7.0