Consolidate iptables chain management.

Move creation and management of module iptables chains up into
CommandListener, which gives better visibility into ordering.

Change-Id: If0c94187c6e59a20840b035d7241057f45a0f74b
diff --git a/NetdConstants.cpp b/NetdConstants.cpp
index e57b483..ca869a3 100644
--- a/NetdConstants.cpp
+++ b/NetdConstants.cpp
@@ -14,6 +14,10 @@
  * limitations under the License.
  */
 
+#include <string.h>
+
+#include <cutils/log.h>
+
 #include "NetdConstants.h"
 
 const char * const OEM_SCRIPT_PATH = "/system/bin/oem-iptables-init.sh";
@@ -23,3 +27,71 @@
 const char * const IP_PATH = "/system/bin/ip";
 const char * const ADD = "add";
 const char * const DEL = "del";
+
+static void logExecError(const char* argv[], int res) {
+    const char** argp = argv;
+    std::string args = "";
+    while (*argp) {
+        args += *argp;
+        args += ' ';
+        argp++;
+    }
+    ALOGE("exec() res=%d for %s", res, args.c_str());
+}
+
+static int execIptables(IptablesTarget target, bool silent, va_list args) {
+    /* Read arguments from incoming va_list; we expect the list to be NULL terminated. */
+    std::list<const char*> argsList;
+    argsList.push_back(NULL);
+    const char* arg;
+    do {
+        arg = va_arg(args, const char *);
+        argsList.push_back(arg);
+    } while (arg);
+
+    int i = 0;
+    const char* argv[argsList.size()];
+    std::list<const char*>::iterator it;
+    for (it = argsList.begin(); it != argsList.end(); it++, i++) {
+        argv[i] = *it;
+    }
+
+    int res = 0;
+    if (target == V4 || target == V4V6) {
+        argv[0] = IPTABLES_PATH;
+        int localRes = fork_and_execve(argv[0], argv);
+        if (localRes) {
+            if (!silent) {
+                logExecError(argv, localRes);
+            }
+            res |= localRes;
+        }
+    }
+    if (target == V6 || target == V4V6) {
+        argv[0] = IP6TABLES_PATH;
+        int localRes = fork_and_execve(argv[0], argv);
+        if (localRes) {
+            if (!silent) {
+                logExecError(argv, localRes);
+            }
+            res |= localRes;
+        }
+    }
+    return res;
+}
+
+int execIptables(IptablesTarget target, ...) {
+    va_list args;
+    va_start(args, target);
+    int res = execIptables(target, false, args);
+    va_end(args);
+    return res;
+}
+
+int execIptablesSilently(IptablesTarget target, ...) {
+    va_list args;
+    va_start(args, target);
+    int res = execIptables(target, true, args);
+    va_end(args);
+    return res;
+}