extern int open_cutthrough_connection( address_item * addr );
-extern uschar *parse_extract_address(uschar *, uschar **, int *, int *, int *,
+extern uschar *parse_extract_address(const uschar *, uschar **, int *, int *, int *,
BOOL);
extern int parse_forward_list(uschar *, int, address_item **, uschar **,
const uschar *, uschar *, error_block **);
extern uschar *parse_find_address_end(uschar *, BOOL);
-extern uschar *parse_find_at(uschar *);
+extern const uschar *parse_find_at(const uschar *);
extern const uschar *parse_fix_phrase(const uschar *, int);
-extern uschar *parse_message_id(uschar *, uschar **, uschar **);
+extern const uschar *parse_message_id(const uschar *, uschar **, uschar **);
extern const uschar *parse_quote_2047(const uschar *, int, uschar *, BOOL);
-extern uschar *parse_date_time(uschar *str, time_t *t);
+extern const uschar *parse_date_time(const uschar *str, time_t *t);
extern int vaguely_random_number(int);
#ifndef DISABLE_TLS
extern int vaguely_random_number_fallback(int);
extern uschar *readconf_find_option(void *);
extern void readconf_main(BOOL);
extern void readconf_options_from_list(optionlist *, unsigned, const uschar *, uschar *);
-extern BOOL readconf_print(uschar *, uschar *, BOOL);
+extern BOOL readconf_print(const uschar *, uschar *, BOOL);
extern uschar *readconf_printtime(int);
extern uschar *readconf_readname(uschar *, int, uschar *);
extern int readconf_readtime(const uschar *, int, BOOL);
extern BOOL retry_ultimate_address_timeout(uschar *, const uschar *,
dbdata_retry *, time_t);
extern void retry_update(address_item **, address_item **, address_item **);
-extern uschar *rewrite_address(uschar *, BOOL, BOOL, rewrite_rule *, int);
-extern uschar *rewrite_address_qualify(uschar *, BOOL);
+extern const uschar *rewrite_address(const uschar *, BOOL, BOOL, rewrite_rule *, int);
+extern const uschar *rewrite_address_qualify(const uschar *, BOOL);
extern header_line *rewrite_header(header_line *,
const uschar *, const uschar *,
rewrite_rule *, int, BOOL);
-extern uschar *rewrite_one(uschar *, int, BOOL *, BOOL, uschar *,
+extern const uschar *rewrite_one(const uschar *, int, BOOL *, BOOL, uschar *,
rewrite_rule *);
-extern void rewrite_test(uschar *);
+extern void rewrite_test(const uschar *);
extern uschar *rfc2047_decode2(uschar *, BOOL, uschar *, int, int *, int *,
uschar **);
extern int route_address(address_item *, address_item **, address_item **,
BOOL (*)(transport_ctx *, uschar *, int));
extern gstring * transport_show_supported(gstring *);
extern BOOL transport_write_message(transport_ctx *, int);
-extern void tree_add_duplicate(uschar *, address_item *);
-extern void tree_add_nonrecipient(uschar *);
-extern void tree_add_unusable(host_item *);
+extern void tree_add_duplicate(const uschar *, address_item *);
+extern void tree_add_nonrecipient(const uschar *);
+extern void tree_add_unusable(const host_item *);
extern void tree_dup(tree_node **, tree_node *);
extern int tree_insertnode(tree_node **, tree_node *);
extern tree_node *tree_search(tree_node *, const uschar *);