network: Avoid memory leaks on networkBuildDnsmasqArgv

Detected by valgrind. Leaks introduced in commit 973af236.

* src/network/bridge_driver.c: fix memory leaks on failure and successful path.

* How to reproduce?
% make -C tests check TESTS=networkxml2argvtest
% cd tests && valgrind -v --leak-check=full ./networkxml2argvtest

* Actual result:

==2226== 3 bytes in 1 blocks are definitely lost in loss record 1 of 24
==2226==    at 0x4A05FDE: malloc (vg_replace_malloc.c:236)
==2226==    by 0x39CF0FEDE7: __vasprintf_chk (in /lib64/libc-2.12.so)
==2226==    by 0x41DFF7: virVasprintf (stdio2.h:199)
==2226==    by 0x41E0B7: virAsprintf (util.c:1695)
==2226==    by 0x41A2D9: networkBuildDhcpDaemonCommandLine (bridge_driver.c:545)
==2226==    by 0x4145C8: testCompareXMLToArgvHelper (networkxml2argvtest.c:47)
==2226==    by 0x4156A1: virtTestRun (testutils.c:141)
==2226==    by 0x414332: mymain (networkxml2argvtest.c:123)
==2226==    by 0x414D97: virtTestMain (testutils.c:696)
==2226==    by 0x39CF01ECDC: (below main) (in /lib64/libc-2.12.so)
==2226==
==2226== 3 bytes in 1 blocks are definitely lost in loss record 2 of 24
==2226==    at 0x4A05FDE: malloc (vg_replace_malloc.c:236)
==2226==    by 0x39CF0FEDE7: __vasprintf_chk (in /lib64/libc-2.12.so)
==2226==    by 0x41DFF7: virVasprintf (stdio2.h:199)
==2226==    by 0x41E0B7: virAsprintf (util.c:1695)
==2226==    by 0x41A307: networkBuildDhcpDaemonCommandLine (bridge_driver.c:551)
==2226==    by 0x4145C8: testCompareXMLToArgvHelper (networkxml2argvtest.c:47)
==2226==    by 0x4156A1: virtTestRun (testutils.c:141)
==2226==    by 0x414332: mymain (networkxml2argvtest.c:123)
==2226==    by 0x414D97: virtTestMain (testutils.c:696)
==2226==    by 0x39CF01ECDC: (below main) (in /lib64/libc-2.12.so)
==2226==
==2226== 5 bytes in 1 blocks are definitely lost in loss record 4 of 24
==2226==    at 0x4A05FDE: malloc (vg_replace_malloc.c:236)
==2226==    by 0x39CF0FEDE7: __vasprintf_chk (in /lib64/libc-2.12.so)
==2226==    by 0x41DFF7: virVasprintf (stdio2.h:199)
==2226==    by 0x41E0B7: virAsprintf (util.c:1695)
==2226==    by 0x41A2AB: networkBuildDhcpDaemonCommandLine (bridge_driver.c:539)
==2226==    by 0x4145C8: testCompareXMLToArgvHelper (networkxml2argvtest.c:47)
==2226==    by 0x4156A1: virtTestRun (testutils.c:141)
==2226==    by 0x414332: mymain (networkxml2argvtest.c:123)
==2226==    by 0x414D97: virtTestMain (testutils.c:696)
==2226==    by 0x39CF01ECDC: (below main) (in /lib64/libc-2.12.so)
==2226==
==2226== LEAK SUMMARY:
==2226==    definitely lost: 11 bytes in 3 blocks
Signed-off-by: NAlex Jia <ajia@redhat.com>
Signed-off-by: NEric Blake <eblake@redhat.com>

src/network/bridge_driver.c

@@ -459,6 +459,10 @@ networkBuildDnsmasqArgv(virNetworkObjPtr network,
     int r, ret = -1;
     int nbleases = 0;
     int ii;
+    char *record = NULL;
+    char *recordPort = NULL;
+    char *recordWeight = NULL;
+    char *recordPriority = NULL;
     virNetworkIpDefPtr tmpipdef;
 
     /*
@@ -516,24 +520,13 @@ networkBuildDnsmasqArgv(virNetworkObjPtr network,
         int i;
 
         for (i = 0; i < dns->ntxtrecords; i++) {
-            char *record = NULL;
-            if (virAsprintf(&record, "%s,%s",
-                            dns->txtrecords[i].name,
-                            dns->txtrecords[i].value) < 0) {
-                virReportOOMError();
-                goto cleanup;
-            }
-
-            virCommandAddArgPair(cmd, "--txt-record", record);
-            VIR_FREE(record);
+            virCommandAddArg(cmd, "--txt-record");
+            virCommandAddArgFormat(cmd, "%s,%s",
+                                   dns->txtrecords[i].name,
+                                   dns->txtrecords[i].value);
         }
 
         for (i = 0; i < dns->nsrvrecords; i++) {
-            char *record = NULL;
-            char *recordPort = NULL;
-            char *recordPriority = NULL;
-            char *recordWeight = NULL;
-
             if (dns->srvrecords[i].service && dns->srvrecords[i].protocol) {
                 if (dns->srvrecords[i].port) {
                     if (virAsprintf(&recordPort, "%d", dns->srvrecords[i].port) < 0) {
@@ -568,6 +561,9 @@ networkBuildDnsmasqArgv(virNetworkObjPtr network,
 
                 virCommandAddArgPair(cmd, "--srv-host", record);
                 VIR_FREE(record);
+                VIR_FREE(recordPort);
+                VIR_FREE(recordWeight);
+                VIR_FREE(recordPriority);
             }
         }
     }
@@ -671,6 +667,10 @@ networkBuildDnsmasqArgv(virNetworkObjPtr network,
 
     ret = 0;
 cleanup:
+    VIR_FREE(record);
+    VIR_FREE(recordPort);
+    VIR_FREE(recordWeight);
+    VIR_FREE(recordPriority);
     return ret;
 }