NetworkPkg: Code logic optimization for DnsDxe and HttpDxe driver

Revise some errors which may lead NULL pointer be dereferenced:
* DnsDhcp.c: Paralist may be used without any initialized
* DnsHeader and RcvString may be null but be dereferenced
* HttpDriver.c: revise an if judgment
* HttpImpl.c: add a judgment to avoid null dereferenced

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: fanwang2 <fan.wang@intel.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>
Reviewed-by: Jiaxin Wu <jiaxin.wu@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17923 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 1 insertions, 1 deletions

diff --git a/NetworkPkg/HttpDxe/HttpDriver.c b/NetworkPkg/HttpDxe/HttpDriver.c
index b65607a4cb..43f42e29bf 100644
--- a/NetworkPkg/HttpDxe/HttpDriver.c
+++ b/NetworkPkg/HttpDxe/HttpDriver.c
@@ -79,7 +79,7 @@ HttpCleanService (
   IN HTTP_SERVICE     *HttpService

   )

 {

-  if (HttpService != NULL) {

+  if (HttpService == NULL) {

     return ;

   }