MINOR: proxy: add log_steps struct member

add proxy->conf.log_steps eb32 root tree which will be used to store the
log origin identifiers that should result in haproxy emitting a log as
configured by the user using upcoming "log-steps" proxy keyword.

It was chosen to use eb32 tree instead of simple bitfield because despite
the slight overhead it is more future-proof given that we already
implemented the prerequisites for seamless custom log origins registration
that will also be usable from "log-steps" proxy keyword.

include/haproxy/proxy-t.h

@@ -426,6 +426,7 @@ struct proxy {
 		struct arg_list args;           /* sample arg list that need to be resolved */
 		struct ebpt_node by_name;       /* proxies are stored sorted by name here */
 		struct list lf_checks;          /* list of logformats found in the proxy section that needs to be checked during postparse */
+		struct eb_root log_steps;       /* tree of log origins where log should be generated during request handling */
 		const char *file_prev;          /* file of the previous instance found with the same name, or NULL */
 		int line_prev;                  /* line of the previous instance found with the same name, or 0 */
 		unsigned int refcount;          /* refcount on this proxy (only used for default proxy for now) */

src/proxy.c

@@ -202,6 +202,7 @@ static inline void proxy_free_common(struct proxy *px)
 	struct acl *acl, *aclb;
 	struct logger *log, *logb;
 	struct lf_expr *lf, *lfb;
+	struct eb32_node *node;
 
 	ha_free(&px->id);
 	drop_file_name(&px->conf.file);
@@ -259,6 +260,16 @@ static inline void proxy_free_common(struct proxy *px)
 
 	chunk_destroy(&px->log_tag);
 
+	node = eb32_first(&px->conf.log_steps);
+	while (node) {
+		struct eb32_node *prev_node = node;
+
+		/* log steps directly use the node key as id, they are not encapsulated */
+		node = eb32_next(node);
+		eb32_delete(prev_node);
+		free(prev_node);
+	}
+
 	free_email_alert(px);
 }
 
@@ -1415,6 +1426,7 @@ void init_new_proxy(struct proxy *p)
 	p->conf.used_listener_id = EB_ROOT;
 	p->conf.used_server_id   = EB_ROOT;
 	p->used_server_addr      = EB_ROOT_UNIQUE;
+	p->conf.log_steps        = EB_ROOT_UNIQUE;
 
 	/* Timeouts are defined as -1 */
 	proxy_reset_timeouts(p);
@@ -1644,6 +1656,7 @@ static int proxy_defproxy_cpy(struct proxy *curproxy, const struct proxy *defpro
 {
 	struct logger *tmplogger;
 	char *tmpmsg = NULL;
+	struct eb32_node *node;
 
 	/* set default values from the specified default proxy */
 	srv_settings_cpy(&curproxy->defsrv, &defproxy->defsrv, 0);
@@ -1849,6 +1862,25 @@ static int proxy_defproxy_cpy(struct proxy *curproxy, const struct proxy *defpro
 	curproxy->email_alert.level = defproxy->email_alert.level;
 	curproxy->email_alert.flags = defproxy->email_alert.flags;
 
+	/* defproxy is const pointer, so we need to typecast log_steps to
+	 * drop the const in order to use EB tree API, please note however
+	 * that the operations performed below should theorically be read-only
+	 */
+	node = eb32_first((struct eb_root *)&defproxy->conf.log_steps);
+	while (node) {
+		struct eb32_node *new_node;
+
+		new_node = malloc(sizeof(*new_node));
+		if (!new_node) {
+			memprintf(errmsg, "proxy '%s': out of memory for log_steps option", curproxy->id);
+			return 1;
+		}
+
+		new_node->key = node->key;
+		eb32_insert(&curproxy->conf.log_steps, new_node);
+		node = eb32_next(node);
+	}
+
 	return 0;
 }