pow: catch EOF (#279)

* pow: catch EOF

* Automated commit: update images.

dist/challenge-templates/pwn/challenge/Dockerfile

@@ -18,7 +18,7 @@ RUN /usr/sbin/useradd --no-create-home -u 1000 user
 COPY flag /
 COPY chal /home/user/
 
-FROM gcr.io/kctf-docker/challenge@sha256:e550af5df266cb89a26ace1ba5dcc685981f01d1cb61e45a898cce0c9753de7a
+FROM gcr.io/kctf-docker/challenge@sha256:6dd60da626bc43bf3175d9d7436006db5acc7710d5d1b7006ab53e718fe51e40
 
 COPY --from=chroot / /chroot
 

dist/challenge-templates/web/challenge/Dockerfile

@@ -37,7 +37,7 @@ COPY web-servers /web-servers
 
 COPY flag /
 
-FROM gcr.io/kctf-docker/challenge@sha256:e550af5df266cb89a26ace1ba5dcc685981f01d1cb61e45a898cce0c9753de7a
+FROM gcr.io/kctf-docker/challenge@sha256:6dd60da626bc43bf3175d9d7436006db5acc7710d5d1b7006ab53e718fe51e40
 
 RUN apt-get update \
     && DEBIAN_FRONTEND=noninteractive apt-get install -yq --no-install-recommends tzdata apache2 \

dist/challenge-templates/xss-bot/challenge/Dockerfile

@@ -11,7 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-FROM gcr.io/kctf-docker/challenge@sha256:e550af5df266cb89a26ace1ba5dcc685981f01d1cb61e45a898cce0c9753de7a
+FROM gcr.io/kctf-docker/challenge@sha256:6dd60da626bc43bf3175d9d7436006db5acc7710d5d1b7006ab53e718fe51e40
 
 RUN apt-get update && apt-get install -y gnupg2
 

docker-images/challenge/pow.py

@@ -116,7 +116,12 @@ def main():
         sys.stdout.flush()
         solution = ''
         while not solution:
-            solution = sys.stdin.readline().strip()
+            line = sys.stdin.readline()
+            if not line:
+                sys.stdout.write("EOF")
+                sys.stdout.flush()
+                sys.exit(1)
+            solution = line.strip()
 
         if verify_challenge(challenge, solution):
             sys.stdout.write("Correct\n")