From ac07692583601db96dc0a655158e78a1cbbbfcfd Mon Sep 17 00:00:00 2001
From: Sebastian Harl <sh@tokkee.org>
Date: Thu, 6 Feb 2014 20:12:38 +0100
Subject: [PATCH] frontend: Send connection-related log messages to the client.

This is done by registering a logging callback which will send all messages
originating from a thread currently handling a connection to the respective
client. For this, the connection object is stored in a thread-specific data
segment.
---
 src/frontend/connection.c         | 88 ++++++++++++++++++++++++++++++-
 src/include/frontend/connection.h | 14 +++++
 src/include/frontend/proto.h      |  4 +-
 src/tools/sysdbd/main.c           |  3 ++
 4 files changed, 107 insertions(+), 2 deletions(-)

diff --git a/src/frontend/connection.c b/src/frontend/connection.c
index 24735de..4ba12dc 100644
--- a/src/frontend/connection.c
+++ b/src/frontend/connection.c
@@ -27,6 +27,7 @@
 
 #include "sysdb.h"
 #include "core/object.h"
+#include "core/plugin.h"
 #include "frontend/connection-private.h"
 #include "utils/error.h"
 #include "utils/strbuf.h"
@@ -38,10 +39,20 @@
 #include <arpa/inet.h>
 #include <fcntl.h>
 
+#include <stdlib.h>
 #include <string.h>
 
+#include <pthread.h>
+
+/*
+ * private variables
+ */
+
+static pthread_key_t conn_ctx_key;
+static _Bool         conn_ctx_key_initialized = 0;
+
 /*
- * private data types
+ * private types
  */
 
 /* name of connection objects */
@@ -145,10 +156,74 @@ static sdb_type_t connection_type = {
 	/* destroy = */ connection_destroy,
 };
 
+/*
+ * private helper functions
+ */
+
+static void
+sdb_conn_ctx_destructor(void *c)
+{
+	sdb_object_t *conn = c;
+
+	if (! conn)
+		return;
+	sdb_object_deref(conn);
+} /* sdb_conn_ctx_destructor */
+
+static void
+sdb_conn_ctx_init(void)
+{
+	if (conn_ctx_key_initialized)
+		return;
+
+	pthread_key_create(&conn_ctx_key, sdb_conn_ctx_destructor);
+	conn_ctx_key_initialized = 1;
+} /* sdb_conn_ctx_init */
+
+static void
+sdb_conn_set_ctx(sdb_conn_t *conn)
+{
+	sdb_conn_ctx_init();
+	if (conn)
+		sdb_object_ref(SDB_OBJ(conn));
+	pthread_setspecific(conn_ctx_key, conn);
+} /* sdb_conn_set_ctx */
+
+static sdb_conn_t *
+sdb_conn_get_ctx(void)
+{
+	if (! conn_ctx_key_initialized)
+		return NULL;
+	return pthread_getspecific(conn_ctx_key);
+} /* sdb_conn_get_ctx */
+
 /*
  * connection handler functions
  */
 
+/*
+ * connection_log:
+ * Send a log message originating from the current thread to the client.
+ */
+static int
+connection_log(int __attribute__((unused)) prio, const char *msg,
+		sdb_object_t __attribute__((unused)) *user_data)
+{
+	sdb_conn_t *conn;
+
+	conn = sdb_conn_get_ctx();
+	/* no connection associated to this thread
+	 * or user not authenticated yet => don't leak any information */
+	if ((! conn) || (! conn->username))
+		return 0;
+
+	/* TODO: Use CONNECTION_LOG_<prio>? */
+	if (sdb_connection_send(conn, CONNECTION_LOG,
+				(uint32_t)strlen(msg), msg) < 0)
+		return -1;
+	return 0;
+} /* connection_log */
+
 static uint32_t
 connection_get_int32(sdb_conn_t *conn, size_t offset)
 {
@@ -303,6 +378,13 @@ connection_read(sdb_conn_t *conn)
  * public API
  */
 
+int
+sdb_connection_enable_logging(void)
+{
+	return sdb_plugin_register_log("connection-logger", connection_log,
+			/* user_data = */ NULL);
+} /* sdb_connection_enable_logging */
+
 sdb_conn_t *
 sdb_connection_accept(int fd)
 {
@@ -326,6 +408,8 @@ sdb_connection_read(sdb_conn_t *conn)
 {
 	ssize_t n = 0;
 
+	sdb_conn_set_ctx(conn);
+
 	while (42) {
 		ssize_t status = connection_read(conn);
 
@@ -341,6 +425,8 @@ sdb_connection_read(sdb_conn_t *conn)
 
 		n += status;
 	}
+
+	sdb_conn_set_ctx(NULL);
 	return n;
 } /* sdb_connection_read */
 
diff --git a/src/include/frontend/connection.h b/src/include/frontend/connection.h
index 45d377e..dc93db6 100644
--- a/src/include/frontend/connection.h
+++ b/src/include/frontend/connection.h
@@ -52,6 +52,20 @@ typedef struct {
 } sdb_conn_node_t;
 #define SDB_CONN_NODE(obj) ((sdb_conn_node_t *)(obj))
 
+/*
+ * sdb_connection_enable_logging:
+ * Enable logging of connection-related messages to the current client
+ * connection. After this function has been called all log messages
+ * originating from the thread handling the current client connection will
+ * also be sent to the client.
+ *
+ * Returns:
+ *  - 0 on success
+ *  - a negative value else
+ */
+int
+sdb_connection_enable_logging(void);
+
 /*
  * sdb_connection_accpet:
  * Accept a new connection on the specified file-descriptor 'fd' and return a
diff --git a/src/include/frontend/proto.h b/src/include/frontend/proto.h
index fd78c26..af336d5 100644
--- a/src/include/frontend/proto.h
+++ b/src/include/frontend/proto.h
@@ -35,7 +35,9 @@ extern "C" {
 /* status codes returned to a client */
 typedef enum {
 	CONNECTION_OK = 0,
-	CONNECTION_ERROR
+	CONNECTION_ERROR,
+
+	CONNECTION_LOG,
 } sdb_conn_status_t;
 
 /* accepted commands / state of the connection */
diff --git a/src/tools/sysdbd/main.c b/src/tools/sysdbd/main.c
index 2e35c16..ca1c50d 100644
--- a/src/tools/sysdbd/main.c
+++ b/src/tools/sysdbd/main.c
@@ -34,6 +34,7 @@
 #include "core/store.h"
 #include "utils/error.h"
 
+#include "frontend/connection.h"
 #include "frontend/sock.h"
 
 #include "tools/sysdbd/configfile.h"
@@ -278,6 +279,8 @@ main(int argc, char **argv)
 			if (sdb_fe_sock_add_listener(sock, listen_addresses[i]))
 				break;
 
+		sdb_connection_enable_logging();
+
 		/* break on error */
 		if (i >= listen_addresses_num)
 			sdb_fe_sock_listen_and_serve(sock, &frontend_main_loop);
-- 
2.30.2