[Qemu-devel] [PATCH] slirp: Fix migration from older versions of QEMU to the current one

[Thomas Huth <thuth@redhat.com>]

While adding the IPv6 support, the commit eae303ff23f51259eddc8856c71453d8
("slirp: Make Socket structure IPv6 compatible") changed the format of
the migration stream, without taking into account that we might still
receive an old migration stream layout when upgrading from QEMU version
2.5 (or older) to QEMU 2.6. Currently, QEMU bails out when doing a
migration from QEMU 2.5 to the recent master version when it has
been started with a "-net user,guestfwd=..." network. So let's fix
this by checking the version ID of the migration stream and by using
the old behavior if we've detected version 3 or less.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 slirp/slirp.c | 44 ++++++++++++++++++++++++++------------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/slirp/slirp.c b/slirp/slirp.c
index 3481fcc..998f278 100644
--- a/slirp/slirp.c
+++ b/slirp/slirp.c
@@ -1233,31 +1233,39 @@ static int slirp_sbuf_load(QEMUFile *f, struct sbuf *sbuf)
     return 0;
 }
 
-static int slirp_socket_load(QEMUFile *f, struct socket *so)
+static int slirp_socket_load(QEMUFile *f, struct socket *so, int version_id)
 {
     if (tcp_attach(so) < 0)
         return -ENOMEM;
 
     so->so_urgc = qemu_get_be32(f);
-    so->so_ffamily = qemu_get_be16(f);
-    switch (so->so_ffamily) {
-    case AF_INET:
+    if (version_id <= 3) {
+        so->so_ffamily = AF_INET;
         so->so_faddr.s_addr = qemu_get_be32(f);
-        so->so_fport = qemu_get_be16(f);
-        break;
-    default:
-        error_report(
-                "so_ffamily unknown, unable to restore so_faddr and so_lport\n");
-    }
-    so->so_lfamily = qemu_get_be16(f);
-    switch (so->so_lfamily) {
-    case AF_INET:
         so->so_laddr.s_addr = qemu_get_be32(f);
+        so->so_fport = qemu_get_be16(f);
         so->so_lport = qemu_get_be16(f);
-        break;
-    default:
-        error_report(
-                "so_ffamily unknown, unable to restore so_laddr and so_lport\n");
+    } else {
+        so->so_ffamily = qemu_get_be16(f);
+        switch (so->so_ffamily) {
+        case AF_INET:
+            so->so_faddr.s_addr = qemu_get_be32(f);
+            so->so_fport = qemu_get_be16(f);
+            break;
+        default:
+            error_report(
+                "so_ffamily unknown, unable to restore so_faddr and so_lport");
+        }
+        so->so_lfamily = qemu_get_be16(f);
+        switch (so->so_lfamily) {
+        case AF_INET:
+            so->so_laddr.s_addr = qemu_get_be32(f);
+            so->so_lport = qemu_get_be16(f);
+            break;
+        default:
+            error_report(
+                "so_ffamily unknown, unable to restore so_laddr and so_lport");
+        }
     }
     so->so_iptos = qemu_get_byte(f);
     so->so_emu = qemu_get_byte(f);
@@ -1294,7 +1302,7 @@ static int slirp_state_load(QEMUFile *f, void *opaque, int version_id)
         if (!so)
             return -ENOMEM;
 
-        ret = slirp_socket_load(f, so);
+        ret = slirp_socket_load(f, so, version_id);
 
         if (ret < 0)
             return ret;
-- 
1.8.3.1