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dn_comp(3) Library Functions Manual dn_comp(3) NAME dn_comp - Compresses a domain name LIBRARY Standard C Library (libc.a) SYNOPSIS #include <sys/types.h> #include <netinet/in.h> #include <arpa/nameser.h> #include <resolv.h> int dn_comp ( u_char *expanded_name, u_char *compressed_name, int length, u_char **name_ptrs, u_char **end_ptr ); PARAMETERS Points to a domain name. Points to an array containing the compressed domain name. Specifies the size of the array pointed to by the com- pressed_name parameter. Specifies a list of pointers to previously compressed names in the current message. Points to the end of the ar- ray pointed to by the compressed_name parameter. DESCRIPTION The dn_comp() (domain name compression) function compresses the domain name pointed to by the expanded_name parameter and stores it in the area pointed to by the compressed_name parameter. The dn_comp() function inserts labels into the message as the name is compressed. The dn_comp() function also maintains a list of pointers to the message labels. If the value of the name_ptrs parameter is null, the dn_comp() function does not compress any names, but instead translates a domain name from ASCII to internal format without removing suffixes (compressing). Oth- erwise, the name_ptrs parameter is the address of pointers to previ- ously compressed suffixes. If the end_ptr parameter is null, the dn_comp() function does not up- date the list of label pointers. The dn_comp() function is one of a set of subroutines that form the re- solver, a set of functions that resolves domain names. Global informa- tion that is used by the resolver functions is kept in the _res data structure. The /include/resolv.h file contains the _res data struc- ture definition. RETURN VALUES Upon successful completion, the dn_comp() function returns the size of the compressed domain name. Otherwise, a value of -1 is returned. FILES Defines name server and domain name structures, constants, and values. RELATED INFORMATION Functions: res_init(3), res_mkquery(3), res_send(3), dn_expand(3), dn_find(3), _getshort(3), _getlong(3), putshort(3), putlong(3), dn_skipname(3) Commands: named(8) delim off dn_comp(3)