lwres_packet

+ + + + + + + +

Name

+ lwres_lwpacket_renderheader, + lwres_lwpacket_parseheader + — lightweight resolver packet handling functions +

Synopsis

#include <lwres/lwpacket.h>

+ + + + + + + + + +

`+lwres_result_t +lwres_lwpacket_renderheader(`	lwres_buffer_t *`b`,
	lwres_lwpacket_t *`pkt)`;

+ + + + + + + + + +

`+lwres_result_t +lwres_lwpacket_parseheader(`	lwres_buffer_t *`b`,
	lwres_lwpacket_t *`pkt)`;

DESCRIPTION

+ +

+ These functions rely on a + struct lwres_lwpacket + which is defined in + lwres/lwpacket.h. +

+ +

+typedef struct lwres_lwpacket lwres_lwpacket_t;
+

+struct lwres_lwpacket {
+        uint32_t          length;
+        uint16_t          version;
+        uint16_t          pktflags;
+        uint32_t          serial;
+        uint32_t          opcode;
+        uint32_t          result;
+        uint32_t          recvlength;
+        uint16_t          authtype;
+        uint16_t          authlength;
+};
+

+ +

+ The elements of this structure are: +

length: +
+ the overall packet length, including the entire packet header. + This field is filled in by the lwres_gabn_*() and lwres_gnba_*() + calls. +
+
version: +
+ the header format. There is currently only one format, + LWRES_LWPACKETVERSION_0. + + This field is filled in by the lwres_gabn_*() and lwres_gnba_*() + calls. +
+
pktflags: +
+ library-defined flags for this packet: for instance whether the + packet + is a request or a reply. Flag values can be set, but not defined + by + the caller. + This field is filled in by the application wit the exception of + the + LWRES_LWPACKETFLAG_RESPONSE bit, which is set by the library in + the + lwres_gabn_*() and lwres_gnba_*() calls. +
+
serial: +
+ is set by the requestor and is returned in all replies. If two + or more + packets from the same source have the same serial number and are + from + the same source, they are assumed to be duplicates and the + latter ones + may be dropped. + This field must be set by the application. +
+
opcode: +
+ indicates the operation. + Opcodes between 0x00000000 and 0x03ffffff are + reserved for use by the lightweight resolver library. Opcodes + between + 0x04000000 and 0xffffffff are application defined. + This field is filled in by the lwres_gabn_*() and lwres_gnba_*() + calls. +
+
result: +
+ is only valid for replies. + Results between 0x04000000 and 0xffffffff are application + defined. + Results between 0x00000000 and 0x03ffffff are reserved for + library use. + This field is filled in by the lwres_gabn_*() and lwres_gnba_*() + calls. +
+
recvlength: +
+ is the maximum buffer size that the receiver can handle on + requests + and the size of the buffer needed to satisfy a request when the + buffer + is too large for replies. + This field is supplied by the application. +
+
authtype: +
+ defines the packet level authentication that is used. + Authorisation types between 0x1000 and 0xffff are application + defined + and types between 0x0000 and 0x0fff are reserved for library + use. + Currently these are not used and must be zero. +
+
authlen: +
+ gives the length of the authentication data. + Since packet authentication is currently not used, this must be + zero. +
+

+ The following opcodes are currently defined: +

NOOP: +
+ Success is always returned and the packet contents are echoed. + The lwres_noop_*() functions should be used for this type. +
+
GETADDRSBYNAME: +
+ returns all known addresses for a given name. + The lwres_gabn_*() functions should be used for this type. +
+
GETNAMEBYADDR: +
+ return the hostname for the given address. + The lwres_gnba_*() functions should be used for this type. +
+

+ +

lwres_lwpacket_renderheader() + transfers the contents of lightweight resolver packet structure + lwres_lwpacket_t *pkt in + network byte order to the lightweight resolver buffer, + *b. +

+ +

lwres_lwpacket_parseheader() + performs the converse operation. It transfers data in network + byte order from buffer *b to resolver + packet *pkt. The contents of the buffer + b should correspond to a + lwres_lwpacket_t. +

+ +

RETURN VALUES

+ +

+ Successful calls to + lwres_lwpacket_renderheader() and + lwres_lwpacket_parseheader() return + LWRES_R_SUCCESS. If there is insufficient + space to copy data between the buffer *b and + lightweight resolver packet *pkt both + functions + return LWRES_R_UNEXPECTEDEND. +

+ +