commit ddb34755fb54882b3ece8d4919593e26a2c1cfcb
author Selim Gurun <sgurun@google.com> Mon Feb 27 16:01:42 2012 -0800
committer Selim Gurun <sgurun@google.com> Thu Mar 01 14:09:13 2012 -0800
tree 1ae60c84acdf766466ed437ed03c663b627f25c1
parent c2b26cb83d9bf3f91e986625efcc40fc8eb79a13

Prevent potential stall on dns proxy operations.

Update wire protocol to return and process error code first. This
will make sure dns proxy operations do not stall when an internal
error happens.

Change-Id: I65595abb0638722ccd877f69057bd435ca06e524

DnsProxyListener.cpp

diff --git a/DnsProxyListener.cpp b/DnsProxyListener.cpp
index 2e2a013..6c09e69 100644
--- a/DnsProxyListener.cpp
+++ b/DnsProxyListener.cpp
@@ -32,6 +32,7 @@
 #include <sysutils/SocketClient.h>
 
 #include "DnsProxyListener.h"
+#include "ResponseCode.h"
 
 DnsProxyListener::DnsProxyListener() :
                  FrameworkListener("dnsproxyd") {
@@ -72,9 +73,12 @@
     }
 
     struct addrinfo* result = NULL;
-    int rv = getaddrinfo(mHost, mService, mHints, &result);
-    bool success = (mClient->sendData(&rv, sizeof(rv)) == 0);
-    if (rv == 0) {
+    uint32_t rv = getaddrinfo(mHost, mService, mHints, &result);
+    if (rv) {
+        // getaddrinfo failed
+        mClient->sendBinaryMsg(ResponseCode::DnsProxyOperationFailed, &rv, sizeof(rv));
+    } else {
+        bool success = !mClient->sendCode(ResponseCode::DnsProxyQueryResult);
         struct addrinfo* ai = result;
         while (ai && success) {
             success = sendLenAndData(mClient, sizeof(struct addrinfo), ai)
@@ -85,13 +89,13 @@
             ai = ai->ai_next;
         }
         success = success && sendLenAndData(mClient, 0, "");
+        if (!success) {
+            ALOGW("Error writing DNS result to client");
+        }
     }
     if (result) {
         freeaddrinfo(result);
     }
-    if (!success) {
-        ALOGW("Error writing DNS result to client");
-    }
     mClient->decRef();
 }
 
@@ -107,8 +111,11 @@
         }
     }
     if (argc != 7) {
-        ALOGW("Invalid number of arguments to getaddrinfo: %i", argc);
-        sendLenAndData(cli, 0, NULL);
+        char* msg = NULL;
+        asprintf( &msg, "Invalid number of arguments to getaddrinfo: %i", argc);
+        ALOGW("%s", msg);
+        cli->sendMsg(ResponseCode::CommandParameterError, msg, false);
+        free(msg);
         return -1;
     }
 
@@ -168,9 +175,13 @@
             ALOGD("argv[%i]=%s", i, argv[i]);
         }
     }
+
     if (argc != 4) {
-        ALOGW("Invalid number of arguments to gethostbyaddr: %i", argc);
-        sendLenAndData(cli, 0, NULL);
+        char* msg = NULL;
+        asprintf(&msg, "Invalid number of arguments to gethostbyaddr: %i", argc);
+        ALOGW("%s", msg);
+        cli->sendMsg(ResponseCode::CommandParameterError, msg, false);
+        free(msg);
         return -1;
     }
 
@@ -182,9 +193,12 @@
     errno = 0;
     int result = inet_pton(addrFamily, addrStr, addr);
     if (result <= 0) {
-        ALOGW("inet_pton(\"%s\") failed %s", addrStr, strerror(errno));
+        char* msg = NULL;
+        asprintf(&msg, "inet_pton(\"%s\") failed %s", addrStr, strerror(errno));
+        ALOGW("%s", msg);
+        cli->sendMsg(ResponseCode::OperationFailed, msg, false);
         free(addr);
-        sendLenAndData(cli, 0, NULL);
+        free(msg);
         return -1;
     }
 
@@ -230,10 +244,18 @@
                 (hp && hp->h_name) ? strlen(hp->h_name)+ 1 : 0);
     }
 
-    bool success = sendLenAndData(mClient, (hp && hp->h_name) ? strlen(hp->h_name)+ 1 : 0,
-            (hp && hp->h_name) ? hp->h_name : "");
+    bool failed = true;
+    if (hp) {
+        failed = mClient->sendBinaryMsg(ResponseCode::DnsProxyQueryResult,
+                                        hp->h_name ? hp->h_name : "",
+                                        hp->h_name ? strlen(hp->h_name)+ 1 : 0);
+    } else {
+        uint32_t error = h_errno;
+        failed = mClient->sendBinaryMsg(ResponseCode::DnsProxyOperationFailed,
+                                        &error, sizeof(error));
+    }
 
-    if (!success) {
+    if (failed) {
         ALOGW("GetHostByAddrHandler: Error writing DNS result to client\n");
     }
     mClient->decRef();

ResponseCode.h

diff --git a/ResponseCode.h b/ResponseCode.h
index b01c141..04a6644 100644
--- a/ResponseCode.h
+++ b/ResponseCode.h
@@ -44,10 +44,12 @@
     static const int InterfaceTxThrottleResult = 219;
     static const int QuotaCounterResult        = 220;
     static const int TetheringStatsResult      = 221;
+    static const int DnsProxyQueryResult       = 222;
 
     // 400 series - The command was accepted but the requested action
     // did not take place.
-    static const int OperationFailed = 400;
+    static const int OperationFailed           = 400;
+    static const int DnsProxyOperationFailed   = 401;
 
     // 500 series - The command was not accepted and the requested
     // action did not take place.