Jun 30, 2000 lwres_gnba 3 BIND9 lwres_gnbarequest_render lwres_gnbaresponse_render lwres_gnbarequest_parse lwres_gnbaresponse_parse lwres_gnbaresponse_free lwres_gnbarequest_free lightweight resolver getnamebyaddress message handling #include <lwres/lwres.h> lwres_result_t lwres_gnbarequest_render lwres_context_t *ctx lwres_gnbarequest_t *req lwres_lwpacket_t *pkt lwres_buffer_t *b lwres_result_t lwres_gnbaresponse_render lwres_context_t *ctx lwres_gnbaresponse_t *req lwres_lwpacket_t *pkt lwres_buffer_t *b lwres_result_t lwres_gnbarequest_parse lwres_context_t *ctx lwres_buffer_t *b lwres_lwpacket_t *pkt lwres_gnbarequest_t **structp lwres_result_t lwres_gnbaresponse_parse lwres_context_t *ctx lwres_buffer_t *b lwres_lwpacket_t *pkt lwres_gnbaresponse_t **structp void lwres_gnbaresponse_free lwres_context_t *ctx lwres_gnbaresponse_t **structp void lwres_gnbarequest_free lwres_context_t *ctx lwres_gnbarequest_t **structp These are low-level routines for creating and parsing lightweight resolver address-to-name lookup request and response messages. There are four main functions for the getnamebyaddr opcode. One render function converts a getnamebyaddr request structure — lwres_gnbarequest_t — to the lightweight resolver's canonical format. It is complemented by a parse function that converts a packet in this canonical format to a getnamebyaddr request structure. Another render function converts the getnamebyaddr response structure — lwres_gnbaresponse_t to the canonical format. This is complemented by a parse function which converts a packet in canonical format to a getnamebyaddr response structure. These structures are defined in lwres/lwres.h. They are shown below. #define LWRES_OPCODE_GETNAMEBYADDR 0x00010002U typedef struct { lwres_uint32_t flags; lwres_addr_t addr; } lwres_gnbarequest_t; typedef struct { lwres_uint32_t flags; lwres_uint16_t naliases; char *realname; char **aliases; lwres_uint16_t realnamelen; lwres_uint16_t *aliaslen; void *base; size_t baselen; } lwres_gnbaresponse_t; lwres_gnbarequest_render() uses resolver context ctx to convert getnamebyaddr request structure req to canonical format. The packet header structure pkt is initialised and transferred to buffer b. The contents of *req are then appended to the buffer in canonical format. lwres_gnbaresponse_render() performs the same task, except it converts a getnamebyaddr response structure lwres_gnbaresponse_t to the lightweight resolver's canonical format. lwres_gnbarequest_parse() uses context ctx to convert the contents of packet pkt to a lwres_gnbarequest_t structure. Buffer b provides space to be used for storing this structure. When the function succeeds, the resulting lwres_gnbarequest_t is made available through *structp. lwres_gnbaresponse_parse() offers the same semantics as lwres_gnbarequest_parse() except it yields a lwres_gnbaresponse_t structure. lwres_gnbaresponse_free() and lwres_gnbarequest_free() release the memory in resolver context ctx that was allocated to the lwres_gnbaresponse_t or lwres_gnbarequest_t structures referenced via structp. Any memory associated with ancillary buffers and strings for those structures is also discarded. The getnamebyaddr opcode functions lwres_gnbarequest_render(), lwres_gnbaresponse_render() lwres_gnbarequest_parse() and lwres_gnbaresponse_parse() all return LWRES_R_SUCCESS on success. They return LWRES_R_NOMEMORY if memory allocation fails. LWRES_R_UNEXPECTEDEND is returned if the available space in the buffer b is too small to accommodate the packet header or the lwres_gnbarequest_t and lwres_gnbaresponse_t structures. lwres_gnbarequest_parse() and lwres_gnbaresponse_parse() will return LWRES_R_UNEXPECTEDEND if the buffer is not empty after decoding the received packet. These functions will return LWRES_R_FAILURE if pktflags in the packet header structure lwres_lwpacket_t indicate that the packet is not a response to an earlier query. lwres_packet 3 .