[MEDIUM] add support for configuration keyword registration

Any module which needs configuration keywords may now dynamically
register a keyword in a given section, and associate it with a
configuration parsing function using cfg_register_keywords() from
a constructor function. This makes the configuration parser more
modular because it is not required anymore to touch cfg_parse.c.
Example :

static int parse_global_blah(char **args, int section_type, struct proxy *curpx,
                             struct proxy *defpx, char *err, int errlen)
{
	printf("parsing blah in global section\n");
	return 0;
}

static int parse_listen_blah(char **args, int section_type, struct proxy *curpx,
		      struct proxy *defpx, char *err, int errlen)
{
	printf("parsing blah in listen section\n");
	if (*args[1]) {
		snprintf(err, errlen, "missing arg for listen_blah!!!");
		return -1;
	}
	return 0;
}

static struct cfg_kw_list cfg_kws = {{ },{
	{ CFG_GLOBAL, "blah", parse_global_blah },
	{ CFG_LISTEN, "blah", parse_listen_blah },
	{ 0, NULL, NULL },
}};

__attribute__((constructor))
static void __module_init(void)
{
	cfg_register_keywords(&cfg_kws);
}

include/common/cfgparse.h

@@ -2,7 +2,7 @@
   include/common/cfgparse.h
   Configuration parsing functions.
 
-  Copyright (C) 2000-2006 Willy Tarreau - w@1wt.eu
+  Copyright (C) 2000-2008 Willy Tarreau - w@1wt.eu
   
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
@@ -22,20 +22,47 @@
 #ifndef _COMMON_CFGPARSE_H
 #define _COMMON_CFGPARSE_H
 
+#include <common/compat.h>
 #include <common/config.h>
+#include <common/mini-clist.h>
+
+#include <types/proxy.h>
 
 /* configuration sections */
 #define CFG_NONE	0
 #define CFG_GLOBAL	1
 #define CFG_LISTEN	2
 
+struct cfg_keyword {
+	int section;                            /* section type for this keyword */
+	const char *kw;                         /* the keyword itself */
+	int (*parse)(char **args,               /* command line and arguments */
+		     int section_type,          /* current section CFG_{GLOBAL|LISTEN} */
+		     struct proxy *curpx,       /* current proxy (NULL in GLOBAL) */
+		     struct proxy *defpx,       /* default proxy (NULL in GLOBAL) */
+		     char *err,                 /* error message buffer (do not add '\n') */
+		     int errlen);               /* error buffer size, '\0' included */
+};
+
+/* A keyword list. It is a NULL-terminated array of keywords. It embeds a
+ * struct list in order to be linked to other lists, allowing it to easily
+ * be declared where it is needed, and linked without duplicating data nor
+ * allocating memory.
+ */
+struct cfg_kw_list {
+	struct list list;
+	struct cfg_keyword kw[VAR_ARRAY];
+};
+
+
 extern int cfg_maxpconn;
 extern int cfg_maxconn;
 
 int cfg_parse_global(const char *file, int linenum, char **args, int inv);
 int cfg_parse_listen(const char *file, int linenum, char **args, int inv);
 int readcfgfile(const char *file);
-
+void cfg_register_keywords(struct cfg_kw_list *kwl);
+void cfg_unregister_keywords(struct cfg_kw_list *kwl);
 
 #endif /* _COMMON_CFGPARSE_H */
 

src/cfgparse.c

@@ -121,6 +121,11 @@ static struct proxy defproxy;		/* fake proxy used to assign default values on al
 int cfg_maxpconn = DEFAULT_MAXCONN;	/* # of simultaneous connections per proxy (-N) */
 int cfg_maxconn = 0;		/* # of simultaneous connections, (-n) */
 
+/* List head of all known configuration keywords */
+static struct cfg_kw_list cfg_keywords = {
+	.list = LIST_HEAD_INIT(cfg_keywords.list)
+};
+
 /*
  * converts <str> to a list of listeners which are dynamically allocated.
  * The format is "{addr|'*'}:port[-end][,{addr|'*'}:port[-end]]*", where :
@@ -501,6 +506,26 @@ int cfg_parse_global(const char *file, int linenum, char **args, int inv)
 		}
 	}
 	else {
+		struct cfg_kw_list *kwl;
+		int index;
+
+		list_for_each_entry(kwl, &cfg_keywords.list, list) {
+			for (index = 0; kwl->kw[index].kw != NULL; index++) {
+				if (kwl->kw[index].section != CFG_GLOBAL)
+					continue;
+				if (strcmp(kwl->kw[index].kw, args[0]) == 0) {
+					/* prepare error message just in case */
+					snprintf(trash, sizeof(trash),
+						 "error near '%s' in '%s' section", args[0], "global");
+					if (kwl->kw[index].parse(args, CFG_GLOBAL, NULL, NULL, trash, sizeof(trash)) < 0) {
+						Alert("parsing [%s:%d] : %s\n", file, linenum, trash);
+						return -1;
+					}
+					return 0;
+				}
+			}
+		}
+		
 		Alert("parsing [%s:%d] : unknown keyword '%s' in '%s' section\n", file, linenum, args[0], "global");
 		return -1;
 	}
@@ -2651,6 +2676,26 @@ int cfg_parse_listen(const char *file, int linenum, char **args, int inv)
 		}
 	}
 	else {
+		struct cfg_kw_list *kwl;
+		int index;
+
+		list_for_each_entry(kwl, &cfg_keywords.list, list) {
+			for (index = 0; kwl->kw[index].kw != NULL; index++) {
+				if (kwl->kw[index].section != CFG_LISTEN)
+					continue;
+				if (strcmp(kwl->kw[index].kw, args[0]) == 0) {
+					/* prepare error message just in case */
+					snprintf(trash, sizeof(trash),
+						 "error near '%s' in %s section", args[0], cursection);
+					if (kwl->kw[index].parse(args, CFG_LISTEN, curproxy, &defproxy, trash, sizeof(trash)) < 0) {
+						Alert("parsing [%s:%d] : %s\n", file, linenum, trash);
+						return -1;
+					}
+					return 0;
+				}
+			}
+		}
+		
 		Alert("parsing [%s:%d] : unknown keyword '%s' in '%s' section\n", file, linenum, args[0], cursection);
 		return -1;
 	}
@@ -3232,7 +3277,23 @@ int readcfgfile(const char *file)
 	return -1;
 }
 
+/*
+ * Registers the CFG keyword list <kwl> as a list of valid keywords for next
+ * parsing sessions.
+ */
+void cfg_register_keywords(struct cfg_kw_list *kwl)
+{
+	LIST_ADDQ(&cfg_keywords.list, &kwl->list);
+}
 
+/*
+ * Unregisters the CFG keyword list <kwl> from the list of valid keywords.
+ */
+void cfg_unregister_keywords(struct cfg_kw_list *kwl)
+{
+	LIST_DEL(&kwl->list);
+	LIST_INIT(&kwl->list);
+}
 
 /*
  * Local variables: