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[libvirt] [PATCH] net: support set public ip for forward mode nat



Support setting which public ip to use for NAT via attribute
publicaddr. This will construct an iptables line using '-j SNAT
--to-source <publicaddr>' instead of '-j MASQUERADE'.

Signed-off-by: Natanael Copa <ncopa alpinelinux org>
---
This depends on previous sent iptables refactor patch.
http://www.mail-archive.com/libvir-list redhat com/msg66788.html

The validation of the publicaddr is very basic, but at least it is a
start.

Please let me know if you have a better suggestion for the attribute
name 'publicaddr' and I'll resend the patch.

Thanks!

 docs/formatnetwork.html.in  |  4 +++-
 src/conf/network_conf.c     | 33 +++++++++++++++++++++++++++++++++
 src/conf/network_conf.h     |  1 +
 src/network/bridge_driver.c | 24 ++++++++++++++++--------
 src/util/iptables.c         | 31 ++++++++++++++++++++++++-------
 src/util/iptables.h         |  6 ++++--
 6 files changed, 81 insertions(+), 18 deletions(-)

diff --git a/docs/formatnetwork.html.in b/docs/formatnetwork.html.in
index 49206dd..07f9783 100644
--- a/docs/formatnetwork.html.in
+++ b/docs/formatnetwork.html.in
@@ -125,7 +125,9 @@
             other network device whether ethernet, wireless, dialup,
             or VPN. If the <code>dev</code> attribute is set, the
             firewall rules will restrict forwarding to the named
-            device only. Inbound connections from other networks are
+            device only. If the <code>publicaddr</code> attribute is set,
+	    the given source address will be used with iptables' SNAT
+	    target. Inbound connections from other networks are
             all prohibited; all connections between guests on the same
             network, and to/from the host to the guests, are
             unrestricted and not NATed.<span class="since">Since
diff --git a/src/conf/network_conf.c b/src/conf/network_conf.c
index 6ce2e63..36128ac 100644
--- a/src/conf/network_conf.c
+++ b/src/conf/network_conf.c
@@ -174,6 +174,7 @@ void virNetworkDefFree(virNetworkDefPtr def)
     VIR_FREE(def->name);
     VIR_FREE(def->bridge);
     VIR_FREE(def->domain);
+    VIR_FREE(def->publicaddr);
 
     for (ii = 0 ; ii < def->nForwardPfs && def->forwardPfs ; ii++) {
         virNetworkForwardPfDefClear(&def->forwardPfs[ii]);
@@ -1211,6 +1212,22 @@ error:
     return result;
 }
 
+static  int
+virValidPublicaddr(const char *publicaddr)
+{
+    /* only check for max len and valid chars for now */
+    const int maxlen = sizeof("123.123.123.123-123.123.123.123:65535-65534")-1;
+    int len = strlen(publicaddr);
+
+    if (len > maxlen)
+        return 0;
+
+    if (strspn(publicaddr, "0123456789.-:") < len)
+        return 0;
+
+    return 1;
+}
+
 static virNetworkDefPtr
 virNetworkDefParseXML(xmlXPathContextPtr ctxt)
 {
@@ -1387,6 +1404,21 @@ virNetworkDefParseXML(xmlXPathContextPtr ctxt)
                 def->managed = 1;
         }
 
+        def->publicaddr = virXPathString("string(./@publicaddr)", ctxt);
+	if (def->publicaddr != NULL) {
+	    char *errstr = NULL;
+            if (def->forwardType != VIR_NETWORK_FORWARD_NAT) {
+	        errstr = "Attribute 'publicaddr' is only valid with mode='nat'";
+	    } else if (!virValidPublicaddr(def->publicaddr)) {
+	        errstr = "Attribute 'publicaddr' must be in the format: ipaddr[-ipaddr][:port[-port]]";
+	    }
+
+	    if (errstr != NULL) {
+                virReportError(VIR_ERR_XML_ERROR, "%s", _(errstr));
+                goto error;
+	    }
+	}
+
         /* all of these modes can use a pool of physical interfaces */
         nForwardIfs = virXPathNodeSet("./interface", ctxt, &forwardIfNodes);
         nForwardPfs = virXPathNodeSet("./pf", ctxt, &forwardPfNodes);
@@ -1861,6 +1893,7 @@ char *virNetworkDefFormat(const virNetworkDefPtr def, unsigned int flags)
         }
         virBufferAddLit(&buf, "<forward");
         virBufferEscapeString(&buf, " dev='%s'", dev);
+        virBufferEscapeString(&buf, " publicaddr='%s'", def->publicaddr);
         virBufferAsprintf(&buf, " mode='%s'", mode);
         if (def->forwardType == VIR_NETWORK_FORWARD_HOSTDEV) {
             if (def->managed == 1)
diff --git a/src/conf/network_conf.h b/src/conf/network_conf.h
index 3e46304..76fb591 100644
--- a/src/conf/network_conf.h
+++ b/src/conf/network_conf.h
@@ -206,6 +206,7 @@ struct _virNetworkDef {
     virPortGroupDefPtr portGroups;
     virNetDevBandwidthPtr bandwidth;
     virNetDevVlan vlan;
+    char *publicaddr;
 };
 
 typedef struct _virNetworkObj virNetworkObj;
diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
index 75f3c3a..04f178b 100644
--- a/src/network/bridge_driver.c
+++ b/src/network/bridge_driver.c
@@ -1438,7 +1438,8 @@ networkAddMasqueradingIptablesRules(struct network_driver *driver,
                                      &ipdef->address,
                                      prefix,
                                      forwardIf,
-                                     NULL) < 0) {
+                                     NULL,
+				     network->def->publicaddr) < 0) {
         virReportError(VIR_ERR_SYSTEM_ERROR,
                        forwardIf ?
                        _("failed to add iptables rule to enable masquerading to %s") :
@@ -1452,7 +1453,8 @@ networkAddMasqueradingIptablesRules(struct network_driver *driver,
                                      &ipdef->address,
                                      prefix,
                                      forwardIf,
-                                     "udp") < 0) {
+                                     "udp",
+				     network->def->publicaddr) < 0) {
         virReportError(VIR_ERR_SYSTEM_ERROR,
                        forwardIf ?
                        _("failed to add iptables rule to enable UDP masquerading to %s") :
@@ -1466,7 +1468,8 @@ networkAddMasqueradingIptablesRules(struct network_driver *driver,
                                      &ipdef->address,
                                      prefix,
                                      forwardIf,
-                                     "tcp") < 0) {
+                                     "tcp",
+				     network->def->publicaddr) < 0) {
         virReportError(VIR_ERR_SYSTEM_ERROR,
                        forwardIf ?
                        _("failed to add iptables rule to enable TCP masquerading to %s") :
@@ -1482,13 +1485,15 @@ networkAddMasqueradingIptablesRules(struct network_driver *driver,
                                     &ipdef->address,
                                     prefix,
                                     forwardIf,
-                                    "udp");
+                                    "udp",
+				    network->def->publicaddr);
  masqerr4:
     iptablesRemoveForwardMasquerade(driver->iptables,
                                     &ipdef->address,
                                     prefix,
                                     forwardIf,
-                                    NULL);
+                                    NULL,
+				    network->def->publicaddr);
  masqerr3:
     iptablesRemoveForwardAllowRelatedIn(driver->iptables,
                                         &ipdef->address,
@@ -1518,17 +1523,20 @@ networkRemoveMasqueradingIptablesRules(struct network_driver *driver,
                                         &ipdef->address,
                                         prefix,
                                         forwardIf,
-                                        "tcp");
+                                        "tcp",
+					network->def->publicaddr);
         iptablesRemoveForwardMasquerade(driver->iptables,
                                         &ipdef->address,
                                         prefix,
                                         forwardIf,
-                                        "udp");
+                                        "udp",
+					network->def->publicaddr);
         iptablesRemoveForwardMasquerade(driver->iptables,
                                         &ipdef->address,
                                         prefix,
                                         forwardIf,
-                                        NULL);
+					NULL,
+					network->def->publicaddr);
 
         iptablesRemoveForwardAllowRelatedIn(driver->iptables,
                                             &ipdef->address,
diff --git a/src/util/iptables.c b/src/util/iptables.c
index 407ca3a..4a89673 100644
--- a/src/util/iptables.c
+++ b/src/util/iptables.c
@@ -804,6 +804,7 @@ iptablesForwardMasquerade(iptablesContext *ctx,
                           unsigned int prefix,
                           const char *physdev,
                           const char *protocol,
+			  const char *publicaddr,
                           int action)
 {
     int ret;
@@ -833,10 +834,24 @@ iptablesForwardMasquerade(iptablesContext *ctx,
     if (physdev && physdev[0])
         virCommandAddArgList(cmd, "--out-interface", physdev, NULL);
 
-    virCommandAddArgList(cmd, "--jump", "MASQUERADE", NULL);
+    /* Use --jump SNAT if public addr is specified */
+    if (publicaddr && publicaddr[0]) {
+        char tmpstr[sizeof("123.123.123.123-123.123.123.123:65535-65535")];
+	const char *portstr = "";
 
-    if (protocol && protocol[0])
-        virCommandAddArgList(cmd, "--to-ports", "1024-65535", NULL);
+	memset(tmpstr, 0, sizeof(tmpstr));
+        if (protocol && protocol[0] && (strchr(publicaddr, ':') == NULL))
+	    portstr = ":1024-65535";
+	snprintf(tmpstr, sizeof(tmpstr), "%s%s", publicaddr, portstr);
+
+        virCommandAddArgList(cmd, "--jump", "SNAT",
+	                          "--to-source", tmpstr, NULL);
+    } else {
+        virCommandAddArgList(cmd, "--jump", "MASQUERADE", NULL);
+
+        if (protocol && protocol[0])
+            virCommandAddArgList(cmd, "--to-ports", "1024-65535", NULL);
+    }
 
     ret = iptablesCommandRunAndFree(cmd);
     VIR_FREE(networkstr);
@@ -861,9 +876,10 @@ iptablesAddForwardMasquerade(iptablesContext *ctx,
                              virSocketAddr *netaddr,
                              unsigned int prefix,
                              const char *physdev,
-                             const char *protocol)
+                             const char *protocol,
+			     const char *publicaddr)
 {
-    return iptablesForwardMasquerade(ctx, netaddr, prefix, physdev, protocol, ADD);
+    return iptablesForwardMasquerade(ctx, netaddr, prefix, physdev, protocol, publicaddr, ADD);
 }
 
 /**
@@ -884,9 +900,10 @@ iptablesRemoveForwardMasquerade(iptablesContext *ctx,
                                 virSocketAddr *netaddr,
                                 unsigned int prefix,
                                 const char *physdev,
-                                const char *protocol)
+                                const char *protocol,
+			        const char *publicaddr)
 {
-    return iptablesForwardMasquerade(ctx, netaddr, prefix, physdev, protocol, REMOVE);
+    return iptablesForwardMasquerade(ctx, netaddr, prefix, physdev, protocol, publicaddr, REMOVE);
 }
 
 
diff --git a/src/util/iptables.h b/src/util/iptables.h
index e54f8b1..a9d2772 100644
--- a/src/util/iptables.h
+++ b/src/util/iptables.h
@@ -105,12 +105,14 @@ int              iptablesAddForwardMasquerade    (iptablesContext *ctx,
                                                   virSocketAddr *netaddr,
                                                   unsigned int prefix,
                                                   const char *physdev,
-                                                  const char *protocol);
+                                                  const char *protocol,
+						  const char *publicaddr);
 int              iptablesRemoveForwardMasquerade (iptablesContext *ctx,
                                                   virSocketAddr *netaddr,
                                                   unsigned int prefix,
                                                   const char *physdev,
-                                                  const char *protocol);
+                                                  const char *protocol,
+						  const char *publicaddr);
 int              iptablesAddOutputFixUdpChecksum (iptablesContext *ctx,
                                                   const char *iface,
                                                   int port);
-- 
1.8.0.1


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