Fix crash is sptps_logger().

Unfortunately, sptps_logger() cannot know if s->handle is pointing to a
connection_t or a node_t. But it needs to print name and hostname in
both cases. So make sure both types have name and hostname fields at the
start with the same offset.

src/connection.h

@@ -59,9 +59,9 @@ typedef struct connection_status_t {
 
 typedef struct connection_t {
 	char *name;                     /* name he claims to have */
+	char *hostname;                 /* the hostname of its real ip */
 
 	union sockaddr_t address;       /* his real (internet) ip */
-	char *hostname;                 /* the hostname of its real ip */
 	int protocol_major;             /* used protocol */
 	int protocol_minor;             /* used protocol */
 

src/logger.c

@@ -127,6 +127,8 @@ static void sptps_logger(sptps_t *s, int s_errno, const char *format, va_list ap
 		if(message[len - 1] == '\n')
 			message[--len] = 0;
 
+		// WARNING: s->handle can point to a connection_t or a node_t,
+		// but both types have the name and hostname fields at the same offsets.
 		connection_t *c = s->handle;
 		if(c)
 			snprintf(message + len, sizeof message - len, " from %s (%s)", c->name, c->hostname);

src/node.h

@@ -45,12 +45,12 @@ typedef struct node_status_t {
 
 typedef struct node_t {
 	char *name;                             /* name of this node */
+	char *hostname;                         /* the hostname of its real ip */
 	node_id_t id;                           /* unique node ID (name hash) */
 	uint32_t options;                       /* options turned on for this node */
 
 	int sock;                               /* Socket to use for outgoing UDP packets */
 	sockaddr_t address;                     /* his real (internet) ip to send UDP packets to */
-	char *hostname;                         /* the hostname of its real ip */
 
 	node_status_t status;
 	time_t last_state_change;