net: add support for specifying port range for forward mode nat

Let users set the port range to be used for forward mode NAT:

...
  <forward mode='nat'>
    <nat>
      <port start='1024' end='65535'/>
    </nat>
  </forward>
...

Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
Signed-off-by: Laine Stump <laine@laine.org>

docs/formatnetwork.html.in

@@ -138,9 +138,11 @@
             0.4.2</span>
 
             <p><span class="since">Since 1.0.3</span> it is possible to
-            specify a public IPv4 address range to be used for the NAT by
+            specify a public IPv4 address and port range to be used for
-            using the <code>&lt;nat&gt;</code> and
+            the NAT by using the <code>&lt;nat&gt;</code> subelement.
-            <code>&lt;address&gt;</code> subelements.
+            The address range is set with the <code>&lt;address&gt;</code>
+            subelements and <code>start</code> and <code>stop</code>
+            attributes:
             <pre>
 ...
   &lt;forward mode='nat'&gt;
@@ -154,6 +156,19 @@
             <code>start</code> and <code>end</code> attributes to
             the same value.
             </p>
+            <p>
+            The port range to be used for the <code>&lt;nat&gt;</code> can
+            be set via the subelement <code>&lt;port&gt;</code>:
+            <pre>
+...
+  &lt;forward mode='nat'&gt;
+    &lt;nat&gt;
+      &lt;port start='500' end='1000'/&gt;
+    &lt;/nat&gt;
+  &lt;/forward&gt;
+...
+            </pre>
+            </p>
           </dd>
 
           <dt><code>route</code></dt>

src/conf/network_conf.c

@@ -1332,7 +1332,8 @@ virNetworkForwardNatDefParseXML(const char *networkName,
 {
     int ret = -1;
     xmlNodePtr *natAddrNodes = NULL;
-    int nNatAddrs;
+    xmlNodePtr *natPortNodes = NULL;
+    int nNatAddrs, nNatPorts;
     char *addrStart = NULL;
     char *addrEnd = NULL;
     xmlNodePtr save = ctxt->node;
@@ -1389,6 +1390,36 @@ virNetworkForwardNatDefParseXML(const char *networkName,
         goto cleanup;
     }
 
+    /* ports for SNAT and MASQUERADE */
+    nNatPorts = virXPathNodeSet("./port", ctxt, &natPortNodes);
+    if (nNatPorts < 0) {
+        virReportError(VIR_ERR_XML_ERROR,
+                       _("invalid <port> element found in <forward> of "
+                         "network %s"), networkName);
+        goto cleanup;
+    } else if (nNatPorts > 1) {
+        virReportError(VIR_ERR_XML_ERROR,
+                       _("Only one <port> element is allowed in <nat> in "
+                         "<forward> in network %s"), networkName);
+        goto cleanup;
+    } else if (nNatPorts == 1) {
+        if (virXPathUInt("string(./port[1]/@start)", ctxt, &def->portStart) < 0
+            || def->portStart > 65535) {
+
+            virReportError(VIR_ERR_XML_DETAIL,
+                           _("Missing or invalid 'start' attribute in <port> "
+                             "in <nat> in <forward> in network %s"),
+                             networkName);
+            goto cleanup;
+        }
+        if (virXPathUInt("string(./port[1]/@end)", ctxt, &def->portEnd) < 0
+            || def->portEnd > 65535 || def->portEnd < def->portStart) {
+            virReportError(VIR_ERR_XML_DETAIL,
+                           _("Missing or invalid 'end' attribute in <port> in "
+                             "<nat> in <forward> in network %s"), networkName);
+            goto cleanup;
+        }
+    }
     ret = 0;
 
 cleanup:
@@ -2193,16 +2224,25 @@ virNetworkForwardNatDefFormat(virBufferPtr buf,
             goto cleanup;
     }
 
-    if (!addrEnd && !addrStart)
+    if (!addrEnd && !addrStart && !fwd->portStart && !fwd->portEnd)
         return 0;
 
     virBufferAddLit(buf, "<nat>\n");
     virBufferAdjustIndent(buf, 2);
 
-    virBufferAsprintf(buf, "<address start='%s'", addrStart);
+    if (addrStart) {
-    if (addrEnd)
+        virBufferAsprintf(buf, "<address start='%s'", addrStart);
-        virBufferAsprintf(buf, " end='%s'", addrEnd);
+        if (addrEnd)
-    virBufferAddLit(buf, "/>\n");
+            virBufferAsprintf(buf, " end='%s'", addrEnd);
+        virBufferAddLit(buf, "/>\n");
+    }
+
+    if (fwd->portStart || fwd->portEnd) {
+        virBufferAsprintf(buf, "<port start='%d'", fwd->portStart);
+        if (fwd->portEnd)
+            virBufferAsprintf(buf, " end='%d'", fwd->portEnd);
+        virBufferAddLit(buf, "/>\n");
+    }
 
     virBufferAdjustIndent(buf, -2);
     virBufferAddLit(buf, "</nat>\n");
@@ -2260,7 +2300,9 @@ virNetworkDefFormatInternal(virBufferPtr buf,
         }
         shortforward = !(def->forward.nifs || def->forward.npfs
                          || VIR_SOCKET_ADDR_VALID(&def->forward.addrStart)
-                         || VIR_SOCKET_ADDR_VALID(&def->forward.addrEnd));
+                         || VIR_SOCKET_ADDR_VALID(&def->forward.addrEnd)
+                         || def->forward.portStart
+                         || def->forward.portEnd);
         virBufferAsprintf(buf, "%s>\n", shortforward ? "/" : "");
         virBufferAdjustIndent(buf, 2);
 

src/conf/network_conf.h

@@ -175,8 +175,9 @@ struct _virNetworkForwardDef {
     size_t nifs;
     virNetworkForwardIfDefPtr ifs;
 
-    /* adresses for SNAT */
+    /* ranges for NAT */
     virSocketAddr addrStart, addrEnd;
+    unsigned int portStart, portEnd;
 };
 
 typedef struct _virPortGroupDef virPortGroupDef;

src/network/bridge_driver.c

@@ -1589,6 +1589,8 @@ networkAddMasqueradingIptablesRules(struct network_driver *driver,
                                      forwardIf,
                                      &network->def->forward.addrStart,
                                      &network->def->forward.addrEnd,
+                                     network->def->forward.portStart,
+                                     network->def->forward.portEnd,
                                      NULL) < 0) {
         virReportError(VIR_ERR_SYSTEM_ERROR,
                        forwardIf ?
@@ -1605,6 +1607,8 @@ networkAddMasqueradingIptablesRules(struct network_driver *driver,
                                      forwardIf,
                                      &network->def->forward.addrStart,
                                      &network->def->forward.addrEnd,
+                                     network->def->forward.portStart,
+                                     network->def->forward.portEnd,
                                      "udp") < 0) {
         virReportError(VIR_ERR_SYSTEM_ERROR,
                        forwardIf ?
@@ -1621,6 +1625,8 @@ networkAddMasqueradingIptablesRules(struct network_driver *driver,
                                      forwardIf,
                                      &network->def->forward.addrStart,
                                      &network->def->forward.addrEnd,
+                                     network->def->forward.portStart,
+                                     network->def->forward.portEnd,
                                      "tcp") < 0) {
         virReportError(VIR_ERR_SYSTEM_ERROR,
                        forwardIf ?
@@ -1639,6 +1645,8 @@ networkAddMasqueradingIptablesRules(struct network_driver *driver,
                                     forwardIf,
                                     &network->def->forward.addrStart,
                                     &network->def->forward.addrEnd,
+                                    network->def->forward.portStart,
+                                    network->def->forward.portEnd,
                                     "udp");
  masqerr4:
     iptablesRemoveForwardMasquerade(driver->iptables,
@@ -1647,6 +1655,8 @@ networkAddMasqueradingIptablesRules(struct network_driver *driver,
                                     forwardIf,
                                     &network->def->forward.addrStart,
                                     &network->def->forward.addrEnd,
+                                    network->def->forward.portStart,
+                                    network->def->forward.portEnd,
                                     NULL);
  masqerr3:
     iptablesRemoveForwardAllowRelatedIn(driver->iptables,
@@ -1679,6 +1689,8 @@ networkRemoveMasqueradingIptablesRules(struct network_driver *driver,
                                         forwardIf,
                                         &network->def->forward.addrStart,
                                         &network->def->forward.addrEnd,
+                                        network->def->forward.portStart,
+                                        network->def->forward.portEnd,
                                         "tcp");
         iptablesRemoveForwardMasquerade(driver->iptables,
                                         &ipdef->address,
@@ -1686,6 +1698,8 @@ networkRemoveMasqueradingIptablesRules(struct network_driver *driver,
                                         forwardIf,
                                         &network->def->forward.addrStart,
                                         &network->def->forward.addrEnd,
+                                        network->def->forward.portStart,
+                                        network->def->forward.portEnd,
                                         "udp");
         iptablesRemoveForwardMasquerade(driver->iptables,
                                         &ipdef->address,
@@ -1693,6 +1707,8 @@ networkRemoveMasqueradingIptablesRules(struct network_driver *driver,
                                         forwardIf,
                                         &network->def->forward.addrStart,
                                         &network->def->forward.addrEnd,
+                                        network->def->forward.portStart,
+                                        network->def->forward.portEnd,
                                         NULL);
 
         iptablesRemoveForwardAllowRelatedIn(driver->iptables,

src/util/viriptables.c

@@ -807,6 +807,8 @@ iptablesForwardMasquerade(iptablesContext *ctx,
                           const char *physdev,
                           virSocketAddr *addrStart,
                           virSocketAddr *addrEnd,
+                          unsigned int portStart,
+                          unsigned int portEnd,
                           const char *protocol,
                           int action)
 {
@@ -814,6 +816,7 @@ iptablesForwardMasquerade(iptablesContext *ctx,
     char *networkstr = NULL;
     char *addrStartStr = NULL;
     char *addrEndStr = NULL;
+    char *portRangeStr = NULL;
     char *natRangeStr = NULL;
     virCommandPtr cmd = NULL;
 
@@ -848,19 +851,34 @@ iptablesForwardMasquerade(iptablesContext *ctx,
     if (physdev && physdev[0])
         virCommandAddArgList(cmd, "--out-interface", physdev, NULL);
 
+    if (protocol && protocol[0]) {
+        if (portStart == 0 && portEnd == 0) {
+            portStart = 1024;
+            portEnd = 65535;
+        }
+
+        if (portStart < portEnd && portEnd < 65536) {
+            if (virAsprintf(&portRangeStr, ":%u-%u", portStart, portEnd) < 0) {
+                virReportOOMError();
+                goto cleanup;
+            }
+        } else {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("Invalid port range '%u-%u'."),
+                           portStart, portEnd);
+        }
+    }
+
     /* Use --jump SNAT if public addr is specified */
     if (addrStartStr && addrStartStr[0]) {
-        const char *portStr = "";
         int r = 0;
 
-        if (protocol && protocol[0])
-            portStr = ":1024-65535";
-
         if (addrEndStr && addrEndStr[0]) {
             r = virAsprintf(&natRangeStr, "%s-%s%s", addrStartStr, addrEndStr,
-                            portStr);
+                            portRangeStr ? portRangeStr : "");
         } else {
-            r = virAsprintf(&natRangeStr, "%s%s", addrStartStr, portStr);
+            r = virAsprintf(&natRangeStr, "%s%s", addrStartStr,
+                            portRangeStr ? portRangeStr : "");
         }
 
         if (r < 0) {
@@ -873,8 +891,8 @@ iptablesForwardMasquerade(iptablesContext *ctx,
      } else {
          virCommandAddArgList(cmd, "--jump", "MASQUERADE", NULL);
 
-         if (protocol && protocol[0])
+         if (portRangeStr && portRangeStr[0])
-             virCommandAddArgList(cmd, "--to-ports", "1024-65535", NULL);
+             virCommandAddArgList(cmd, "--to-ports", &portRangeStr[1], NULL);
      }
 
     ret = virCommandRun(cmd, NULL);
@@ -883,6 +901,7 @@ cleanup:
     VIR_FREE(networkstr);
     VIR_FREE(addrStartStr);
     VIR_FREE(addrEndStr);
+    VIR_FREE(portRangeStr);
     VIR_FREE(natRangeStr);
     return ret;
 }
@@ -907,9 +926,14 @@ iptablesAddForwardMasquerade(iptablesContext *ctx,
                              const char *physdev,
                              virSocketAddr *addrStart,
                              virSocketAddr *addrEnd,
+                             unsigned int portStart,
+                             unsigned int portEnd,
                              const char *protocol)
 {
-    return iptablesForwardMasquerade(ctx, netaddr, prefix, physdev, addrStart, addrEnd, protocol, ADD);
+    return iptablesForwardMasquerade(ctx, netaddr, prefix, physdev,
+                                     addrStart, addrEnd,
+                                     portStart, portEnd,
+                                     protocol, ADD);
 }
 
 /**
@@ -932,9 +956,14 @@ iptablesRemoveForwardMasquerade(iptablesContext *ctx,
                                 const char *physdev,
                                 virSocketAddr *addrStart,
                                 virSocketAddr *addrEnd,
+                                unsigned int portStart,
+                                unsigned int portEnd,
                                 const char *protocol)
 {
-    return iptablesForwardMasquerade(ctx, netaddr, prefix, physdev, addrStart, addrEnd, protocol, REMOVE);
+    return iptablesForwardMasquerade(ctx, netaddr, prefix, physdev,
+                                     addrStart, addrEnd,
+                                     portStart, portEnd,
+                                     protocol, REMOVE);
 }
 
 

src/util/viriptables.h

@@ -109,6 +109,8 @@ int              iptablesAddForwardMasquerade    (iptablesContext *ctx,
                                                   const char *physdev,
                                                   virSocketAddr *addrStart,
                                                   virSocketAddr *addrEnd,
+                                                  unsigned int portStart,
+                                                  unsigned int portEnd,
                                                   const char *protocol);
 int              iptablesRemoveForwardMasquerade (iptablesContext *ctx,
                                                   virSocketAddr *netaddr,
@@ -116,6 +118,8 @@ int              iptablesRemoveForwardMasquerade (iptablesContext *ctx,
                                                   const char *physdev,
                                                   virSocketAddr *addrStart,
                                                   virSocketAddr *addrEnd,
+                                                  unsigned int portStart,
+                                                  unsigned int portEnd,
                                                   const char *protocol);
 int              iptablesAddOutputFixUdpChecksum (iptablesContext *ctx,
                                                   const char *iface,