Return NULL if we fail to create a BIO in the demos/quicserver

Strictly speaking the previous code was still correct since BIO_set_fd
is tolerant of a NULL BIO. But this way is more clear.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21950)

5 files changed, 19 insertions, 10 deletions

diff --git a/demos/guide/quic-client-block.c b/demos/guide/quic-client-block.c
index 2c177b4..e6cabfe 100644
--- a/demos/guide/quic-client-block.c
+++ b/demos/guide/quic-client-block.c
@@ -89,10 +89,12 @@ static BIO *create_socket_bio(const char *hostname, const char *port,
     if (sock == -1)
         return NULL;
 
-    /* Create a BIO to wrap the socket*/
+    /* Create a BIO to wrap the socket */
     bio = BIO_new(BIO_s_datagram());
-    if (bio == NULL)
+    if (bio == NULL) {
         BIO_closesocket(sock);
+        return NULL;
+    }
 
     /*
      * Associate the newly created BIO with the underlying socket. By
diff --git a/demos/guide/quic-client-non-block.c b/demos/guide/quic-client-non-block.c
index e1735c0..61d339c 100644
--- a/demos/guide/quic-client-non-block.c
+++ b/demos/guide/quic-client-non-block.c
@@ -90,10 +90,12 @@ static BIO *create_socket_bio(const char *hostname, const char *port,
     if (sock == -1)
         return NULL;
 
-    /* Create a BIO to wrap the socket*/
+    /* Create a BIO to wrap the socket */
     bio = BIO_new(BIO_s_datagram());
-    if (bio == NULL)
+    if (bio == NULL) {
         BIO_closesocket(sock);
+        return NULL;
+    }
 
     /*
      * Associate the newly created BIO with the underlying socket. By
diff --git a/demos/guide/quic-multi-stream.c b/demos/guide/quic-multi-stream.c
index 8b6567a..56db5a9 100644
--- a/demos/guide/quic-multi-stream.c
+++ b/demos/guide/quic-multi-stream.c
@@ -90,11 +90,12 @@ static BIO *create_socket_bio(const char *hostname, const char *port,
     if (sock == -1)
         return NULL;
 
-    /* Create a BIO to wrap the socket*/
+    /* Create a BIO to wrap the socket */
     bio = BIO_new(BIO_s_datagram());
-    if (bio == NULL)
+    if (bio == NULL) {
         BIO_closesocket(sock);
-
+        return NULL;
+    }
     /*
      * Associate the newly created BIO with the underlying socket. By
      * passing BIO_CLOSE here the socket will be automatically closed when
diff --git a/demos/guide/tls-client-block.c b/demos/guide/tls-client-block.c
index b2d2a89..75ce7eb 100644
--- a/demos/guide/tls-client-block.c
+++ b/demos/guide/tls-client-block.c
@@ -76,8 +76,10 @@ static BIO *create_socket_bio(const char *hostname, const char *port)
 
     /* Create a BIO to wrap the socket*/
     bio = BIO_new(BIO_s_socket());
-    if (bio == NULL)
+    if (bio == NULL) {
         BIO_closesocket(sock);
+        return NULL;
+    }
 
     /*
      * Associate the newly created BIO with the underlying socket. By
diff --git a/demos/guide/tls-client-non-block.c b/demos/guide/tls-client-non-block.c
index dc6ee4d..14448c9 100644
--- a/demos/guide/tls-client-non-block.c
+++ b/demos/guide/tls-client-non-block.c
@@ -81,10 +81,12 @@ static BIO *create_socket_bio(const char *hostname, const char *port)
     if (sock == -1)
         return NULL;
 
-    /* Create a BIO to wrap the socket*/
+    /* Create a BIO to wrap the socket */
     bio = BIO_new(BIO_s_socket());
-    if (bio == NULL)
+    if (bio == NULL) {
         BIO_closesocket(sock);
+        return NULL;
+    }
 
     /*
      * Associate the newly created BIO with the underlying socket. By