BUG/MINOR: quic: Possible crash when verifying certificates

This verification is done by ssl_sock_bind_verifycbk() which is set at different
locations in the ssl_sock.c code . About QUIC connections, there are a lot of chances
the connection object is not initialized when entering this function. What must
be accessed is the SSL object to retrieve the connection or quic_conn objects,
then the bind_conf object of the listener. If the connection object is not found,
we try to find the quic_conn object.

Modify ssl_sock_dump_errors() interface which takes a connection object as parameter
to also passed a quic_conn object as parameter. Again this function try first
to access the connection object if not NULL or the quic_conn object if not.

There is a remaining thing to do for QUIC: store the certificate verification error
code as it is currently stored in the connection object. This error code is at least
used by the "bc_err" and "fc_err" sample fetches.

There are chances this bug is in relation with GH #1851. Thank you to @tasavis
for the report.

Must be merged into 2.6.
diff --git a/src/ssl_sock.c b/src/ssl_sock.c
index 0edad3b..caf41eb 100644
--- a/src/ssl_sock.c
+++ b/src/ssl_sock.c
@@ -638,7 +638,8 @@
  * if the debug mode and the verbose mode are activated. It dump all
  * the SSL error until the stack was empty.
  */
-static forceinline void ssl_sock_dump_errors(struct connection *conn)
+static forceinline void ssl_sock_dump_errors(struct connection *conn,
+                                             struct quic_conn *qc)
 {
 	unsigned long ret;
 
@@ -650,9 +651,18 @@
 			ret = ERR_get_error();
 			if (ret == 0)
 				return;
-			fprintf(stderr, "fd[%#x] OpenSSL error[0x%lx] %s: %s\n",
-			        conn_fd(conn), ret,
-			        func, ERR_reason_error_string(ret));
+			if (conn) {
+				fprintf(stderr, "fd[%#x] OpenSSL error[0x%lx] %s: %s\n",
+				        conn_fd(conn), ret,
+				        func, ERR_reason_error_string(ret));
+			}
+#ifdef USE_QUIC
+			else {
+				/* TODO: we are not sure <conn> is always initialized for QUIC connections */
+				fprintf(stderr, "qc @%p OpenSSL error[0x%lx] %s: %s\n", qc, ret,
+				        func, ERR_reason_error_string(ret));
+			}
+#endif
 		}
 	}
 }
@@ -1699,16 +1709,36 @@
 {
 	SSL *ssl;
 	struct connection *conn;
-	struct ssl_sock_ctx *ctx;
+	struct ssl_sock_ctx *ctx = NULL;
 	int err, depth;
 	X509 *client_crt;
 	STACK_OF(X509) *certs;
+	struct bind_conf *bind_conf;
+	struct quic_conn *qc = NULL;
 
 	ssl = X509_STORE_CTX_get_ex_data(x_store, SSL_get_ex_data_X509_STORE_CTX_idx());
 	conn = SSL_get_ex_data(ssl, ssl_app_data_index);
 	client_crt = SSL_get_ex_data(ssl, ssl_client_crt_ref_index);
 
+	if (conn) {
+		bind_conf = __objt_listener(conn->target)->bind_conf;
+		ctx = __conn_get_ssl_sock_ctx(conn);
+	}
+#ifdef USE_QUIC
+	else {
+		qc = SSL_get_ex_data(ssl, ssl_qc_app_data_index);
+		if (qc) {
+			bind_conf = qc->li->bind_conf;
+			ctx = qc->xprt_ctx;
+		}
+	}
+#endif
+
+	if (!ctx || !bind_conf) {
+		/* Must never happen */
+		ABORT_NOW();
+	}
+
-	ctx = __conn_get_ssl_sock_ctx(conn);
 	ctx->xprt_st |= SSL_SOCK_ST_FL_VERIFY_DONE;
 
 	depth = X509_STORE_CTX_get_error_depth(x_store);
@@ -1751,13 +1781,12 @@
 			ctx->xprt_st |= SSL_SOCK_CAEDEPTH_TO_ST(depth);
 		}
 
-		if (err < 64 && __objt_listener(conn->target)->bind_conf->ca_ignerr & (1ULL << err)) {
-			ssl_sock_dump_errors(conn);
-			ERR_clear_error();
-			return 1;
-		}
+		if (err < 64 && bind_conf->ca_ignerr & (1ULL << err))
+			goto err_ignored;
 
-		conn->err_code = CO_ER_SSL_CA_FAIL;
+		/* TODO: for QUIC connection, this error code is lost */
+		if (conn)
+			conn->err_code = CO_ER_SSL_CA_FAIL;
 		return 0;
 	}
 
@@ -1765,14 +1794,18 @@
 		ctx->xprt_st |= SSL_SOCK_CRTERROR_TO_ST(err);
 
 	/* check if certificate error needs to be ignored */
-	if (err < 64 && __objt_listener(conn->target)->bind_conf->crt_ignerr & (1ULL << err)) {
-		ssl_sock_dump_errors(conn);
-		ERR_clear_error();
-		return 1;
-	}
+	if (err < 64 && bind_conf->crt_ignerr & (1ULL << err))
+		goto err_ignored;
 
-	conn->err_code = CO_ER_SSL_CRT_FAIL;
+	/* TODO: for QUIC connection, this error code is lost */
+	if (conn)
+		conn->err_code = CO_ER_SSL_CRT_FAIL;
 	return 0;
+
+ err_ignored:
+	ssl_sock_dump_errors(conn, qc);
+	ERR_clear_error();
+	return 1;
 }
 
 #ifdef TLS1_RT_HEARTBEAT
@@ -6229,7 +6262,7 @@
 
  out_error:
 	/* Clear openssl global errors stack */
-	ssl_sock_dump_errors(conn);
+	ssl_sock_dump_errors(conn, NULL);
 	ERR_clear_error();
 
 	/* free resumed session if exists */
@@ -6594,7 +6627,7 @@
 
  clear_ssl_error:
 	/* Clear openssl global errors stack */
-	ssl_sock_dump_errors(conn);
+	ssl_sock_dump_errors(conn, NULL);
 	ERR_clear_error();
  read0:
 	conn_sock_read0(conn);
@@ -6603,7 +6636,7 @@
  out_error:
 	conn->flags |= CO_FL_ERROR;
 	/* Clear openssl global errors stack */
-	ssl_sock_dump_errors(conn);
+	ssl_sock_dump_errors(conn, NULL);
 	ERR_clear_error();
 	goto leave;
 }
@@ -6759,7 +6792,7 @@
 
  out_error:
 	/* Clear openssl global errors stack */
-	ssl_sock_dump_errors(conn);
+	ssl_sock_dump_errors(conn, NULL);
 	ERR_clear_error();
 
 	conn->flags |= CO_FL_ERROR;
@@ -6858,7 +6891,7 @@
 	/* no handshake was in progress, try a clean ssl shutdown */
 	if (SSL_shutdown(ctx->ssl) <= 0) {
 		/* Clear openssl global errors stack */
-		ssl_sock_dump_errors(conn);
+		ssl_sock_dump_errors(conn, NULL);
 		ERR_clear_error();
 	}
 }