Network Working Group S. Williamson Request for Comments: 2167 M. Kosters Obsoletes: RFC 1714 D. Blacka Category: Informational J. Singh K. Zeilstra Network Solutions, Inc. June 1997 Referral Whois (RWhois) Protocol V1.5 Status of this Memo This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Abstract This memo describes Version 1.5 of the client/server interaction of RWhois. RWhois provides a distributed system for the discovery, retrieval, and maintenance of directory information. This system is primarily hierarchical by design. It allows for the deterministic routing of a query based on hierarchical tags, referring the user closer to the maintainer of the information. While RWhois can be considered a generic directory services protocol, it distinguishes itself from other protocols by providing an integrated, hierarchical architecture and query routing mechanism. 1. Introduction Early in the development of the ARPANET, the SRI-NIC established a centralized Whois database that provided host and network information about the systems connected to the network and the electronic mail (email) addresses of the users on those systems [RFC 954]. The ARPANET experiment evolved into a global network, the Internet, with countless people and hundreds of thousands of end systems. The sheer size and effort needed to maintain a centralized database necessitates an alternate, decentralized approach to storing and retrieving this information.
The original Whois function was to be a central directory of resources and people on ARPANET. However, it could not adequately meet the needs of the expanded Internet. RWhois extends and enhances the Whois concept in a hierarchical and scaleable fashion. In accordance with this, RWhois focuses primarily on the distribution of "network objects", or the data representing Internet resources or people, and uses the inherently hierarchical nature of these network objects (domain names, Internet Protocol (IP) networks, email addresses) to more accurately discover the requested information. RWhois synthesizes concepts from other, established Internet protocols. The RWhois protocol and architecture derive a great deal of structure from the Domain Name System (DNS) [RFC 1034] and borrow directory service concepts from other directory service efforts, primarily [X.500]. The protocol is also influenced by earlier established Internet protocols, such as the Simple Mail Transport Protocol (SMTP) [RFC 821]. This RWhois specification defines both a directory access protocol and a directory architecture. The directory access protocol specifically describes the syntax of the client/server interaction. It describes how an RWhois client can search for data on an RWhois server, or how the client can modify data on the server. It also describes how the server is to interpret input from the client, and how the client should interpret the results returned by the server. The architecture portion of this document describes the conceptual framework behind the RWhois protocol. It details the concepts upon which the protocol is based and describes its structural elements. The protocol implements the architecture. This document uses language like SHOULD and SHALL that have special meaning as specified in "Key words for use in RFCs to Indicate Requirement Levels". [RFC2119]
2. Architecture 2.1 Overview As a directory service, RWhois is a distributed database, where data is split across multiple servers to keep database sizes manageable. The architecture portion of this document details the concepts upon which the protocol is based and describes its structural elements. Specifically, the architecture is concerned with how the data is split across the different servers. The basis of this splitting is the lexically hierarchical label (or tag), which is a text string whose position in a hierarchy can be determined from the structure of the string itself. All data can follow some sort of hierarchy, even if the hierarchy seems somewhat arbitrary. For example, person names can be arranged into hierarchical groups via geography. If all the people in particular towns are grouped into town groups, then all of the town groups can be grouped into state (or province) groups, and then all of the state groups can be grouped into a country group. Then, a particular name would belong in a town group, a state group, and a country group. However, just given a name, it would be impossible to determine where in the hierarchy it belongs. Therefore, a person name is not lexically hierarchical. However, there are certain types of data whose position in the hierarchy can be determined by deciphering the data itself, for example, phone numbers. A phone number is grouped according to country code, area code, local exchange, and local extension. By looking at a phone number, it is possible to determine to which of all these groups the number belongs: 1-303-555-2367 is in country code 1, area code 303, local exchange 555, and has a local extension of 2367. Therefore, a phone number is lexically hierarchical. On the Internet, two such types of data are widely used: domain names and IP networks. Domain names are organized via a label-dot system, reading from a more specific label to a more general label left to right; for example, war.west.netsol.com is a part of west.netsol.com, which is a part of netsol.com, which is a part of com. IP networks are also lexically hierarchical labels using the Classless Inter- Domain Routing (CIDR) notation, but their hierarchy is not easily determined with simple text manipulation; for example, 126.96.36.199/22 is a part of 188.8.131.52/16, which is a part of 184.108.40.206/15. Instead, an IP network's hierarchy is determined by converting the network to binary notation and applying successively shorter bit masks.
It is important to note that, while very little real data is lexically hierarchical in nature, people often create label systems (or namespaces) to help manage the data and provide an element of uniqueness, for example, Social Security Numbers, ISBNs, or the Dewey Decimal System. RWhois leverages lexically hierarchical labels, domain names and IP networks, for its data splitting using the concepts of authority areas and referrals. An authority area is associated with an RWhois server and a lexically hierarchical label, which is considered to be its name. An authority area is a piece of the distributed database that speaks with authority about its assigned part of the hierarchy. All data associated with a particular lexically hierarchical tag should be located within that authority area's database. Authority areas are further explained in Section 2.4. RWhois directs clients toward the appropriate authority area by generating referrals. Referrals are pointers to other servers that are presumed to be closer to the desired data. The client uses this referral to contact the next server and ask the same question. The next server may respond with data, an error, or another referral (or referrals). By following this chain of referrals, the client will eventually reach the server with the appropriate authority area. In the RWhois architecture, referrals are generated by identifying a lexically hierarchical label and deciphering the label to determine the next server. Referrals are further explained in Section 2.5. When a number of RWhois servers containing authority areas are brought on line and informed about each other, they form an RWhois tree. The tree has a root authority area, which is the group that contains all other groups. The root authority area must keep pointers to the servers and authority areas that form the first level of the hierarchy. The authority areas in the first level of the hierarchy are then responsible for keeping pointers to the authority areas below them and for keeping a pointer to the root. 2.2 Design Philosophy The design goals for the RWhois protocol are as follows. * It should be a directory access protocol. The server should be able to access and update the data residing on it. * It should facilitate query routing. An unresolved query should be redirected to a server that is presumed to be closer to the desired data. * It should enable data replication. The server should be able to duplicate its data on another server. * The server should be lightweight and delegate more functions to the client.
The concepts used to achieve these design goals are explained in the remaining document. 2.3 Schema Model As a directory service, RWhois uses various database schema to store and represent data. Schema, in this document, has two definitions. First, it refers to the entire structure of a database, all the tables and fields forming a complete database. When schema is used in this context, it is called the "database schema". Database schema consists of attributes, classes, and objects. Schema may also refer to a single piece of the database, a single table with fields. When schema is used in this context, it is just called "schema" or it is preceded by the name of the particular piece: contact schema or domain schema, for example. In this usage, schema is equivalent to "class", defined below. There is no standard database schema in the RWhois architecture. Each authority area is presumed to be able to define its own local schema. However, an authority area that is part of a larger RWhois tree is expected to have some part of its schema pertain to the lexically hierarchical label upon which the RWhois tree is based. An authority area schema may not change throughout much of an RWhois tree. 2.3.1 Attributes An attribute is a named field and is the smallest typed unit in the database schema. It is equivalent to a relational database's field. An attribute is not considered to be data by itself; it is simply used to give data a type. When a piece of data has been typed by an attribute, it is typically referred to as a value and is represented as an attribute-value pair. The RWhois syntax for the attribute-value pair is to separate them with a colon, for example: First-Name:Bill Attributes have a number of properties, some mandated by the RWhois protocol and some that are implementation dependent. These properties are usually a reflection of the database system used by the server. The following is a list of the protocol-mandated properties and their descriptions. Attribute This is the name of the attribute. Description This is a natural language description of the attribute.
Type This is a parameter that broadly indicates the use of the attribute to the protocol. There are three standard types: TEXT, ID, and SEE-ALSO. The default is TEXT, which indicates that the value is a text string. ID indicates that the attribute contains the ID of another RWhois object. This type of attribute is used for database normalization. SEE-ALSO indicates that the attribute contains a pointer (a Uniform Resource Identifier (URI)) to some other kind of external data; for example, a World Wide Web page or FTP site. Format This is an interpretable string that describes the acceptance format of the value. The server (and optionally the client) should match the value to the format string to determine if the value is acceptable. The format of this property is a keyword indicating the syntax of the format string, followed by a colon, followed by the format string itself. Currently, the only keyword recognized is "re" for POSIX.2 extended regular expressions. Indexed This is a true or false flag indicating that this attribute should be indexed (and therefore able to be searched). Required This is a true or false flag indicating that this attribute must have a value in an instance of the class. Multi-Line This is a true or false flag indicating that this attribute may have multiple instances in a class, but all of the instances are to be considered as multiple lines of the same attribute instance. This allows normal line terminators to terminate values. Repeatable This is a true or false flag indicating that there may be multiple instances of this attribute in a class and each instance is to be interpreted as a separate instance (in contrast to Multi-Line). This flag is mutually exclusive with Multi-Line: if Multi-Line is true, then Repeatable must be false and vice versa.
Primary This is a true or false flag that indicates that this attribute is a primary key. If more than one attribute in a class is marked as primary, then these attributes together form a single primary key. The primary key is intended to be used to force uniqueness among class instances. Therefore, there can be only one instance of a primary key in a database. The Primary flag implies that the attribute is also required. Hierarchical This is a true or false flag that indicates that this attribute is lexically hierarchical. Private This is a true or false flag that indicates whether or not this attribute is private (that is, publicly not viewable). It defaults to false. If it is true, then only the clients that satisfy the authentication/encryption requirements of a guardian (described below) are able to view the attribute-value pair. 2.3.2 Class A class is a collection of attributes; it is a structure, not data. The concept is equivalent to that of a relational database table. It is also equivalent to the second definition of schema, above. A class also has some properties that are sometimes referred to as its "meta" information. These properties are listed below. Version This is a time/date stamp that is used to quickly detect when a class definition has been changed. Description This is a natural language description of the class. 2.3.3 Object An object is an instance of a class. It is data with a type of <class>. 2.3.4 Base Class While RWhois does not have or advocate using a specific, standardized schema, it does impose a few requirements. It requires that all defined classes inherit attributes from a particular base class (or base schema). The RWhois specification does not require the actual implementation of inheritance. Instead, all classes must include the attributes defined in the base class.
The base class has the following attributes. Class-Name This attribute contains the name of the class to which the object belongs. It is the type of the object itself. It is of type TEXT and is required. Auth-Area This attribute contains the name of the authority area to which the object belongs. It, along with Class- Name, definitively defines the type of the object. It is of type TEXT and is required. ID This attribute is a universal identifier for the object. It is formed by choosing a string that is unique within an authority area and appending the authority area to it, separating the local string from the authority area name with a period. The only restrictions on the local string are that it must be unique within the authority area and not contain the period character. This attribute is hierarchical in nature. It is always generated by the server (for example, during a register operation). It is of type TEXT and is required. Updated This attribute is a time/date stamp that indicates the time of last modification of the object. It is both informational and a form of record locking. It prevents two clients from modifying the same object at the same time. It is of type TEXT and is required. Guardian This attribute is a link to a guardian object (described below). Its value is the ID of a guardian object. It is of type ID and is optional. It is repeatable, since an object may have multiple guardians. Private This attribute is a true or false flag that indicates whether or not an object is private (that is, publicly not viewable). It defaults to false. If it is true, then only the clients that satisfy the authentication/encryption requirements of one of the object's guardians are able to view the object. If the object is publicly viewable, then the Private attribute property of each of its attributes still applies.
TTL This attribute is the "time-to-live" of a given object. It is included only if an object has a different time-to-live than the default given in the Start of Authority information. Its value is specified in seconds. It is of type TEXT and is optional. The RWhois specification defines two standard classes that should be included in all implementations: the referral and guardian classes. 2.3.5 Referral Class The referral class is defined to hold referral information (typically for link referrals). It consists of attributes defined as part of the base class, the protocol-specific attributes described below, and any installation-specific attributes. Referred-Auth-Area This attribute contains the name of the authority area to which the referral points. It is used as a search key during the query routing. It is of type TEXT and is required. It is repeatable, since referrals can point to servers hosting more than one authority area. Referral This attribute contains the referral itself. It is an RWhois URL. It is of type TEXT and is required. It is repeatable, since more than one server can host a Referred-Auth-Area. 2.3.6 Guardian Class The guardian class is defined to hold security information. The fundamental concept behind the guardian class is that an object (or another structure) is "guarded" by containing a pointer to a guardian object [Guardian]. To modify, delete, or possibly view the guarded object, the authentication (or encryption, or both) scheme must be satisfied. Guardians are intended to not have rank: if an object is guarded by more than one guardian object, satisfying any one of those guardians is sufficient. A guardian object that does not have any Guardian attribute linking it to other guardians guards itself. That is, the authentication scheme in the guardian object itself must be satisfied to modify, delete, or possibly view it. Guardian objects are typically linked to actual database objects with the Guardian attribute found in the base class. However, a guardian may also be linked to an entire authority area, in which case the guardian becomes implicitly linked to all of the objects contained within the authority area.
The guardian class consists of the base class, the protocol-specific attributes described below, and any installation-specific attributes. Guard-Scheme This attribute contains a keyword indicating the authentication methodology. Its value must be understood by both the client and server, and its value dictates the contents of the Guard-Info attribute. It is of type TEXT and is required. Guard-Info This attribute contains that data that is used by the Guard-Scheme to verify the authentication. Its actual format is dictated by the Guard-Scheme, for example, it could contain a password or Pretty Good Privacy (PGP) public key id [RFC 1991]. For security reasons, it should not be displayed, and its Private attribute property should be set to true. It is of type TEXT and is required. 2.4 Authority Areas The concept of authority areas is pivotal to the RWhois architecture. When an RWhois tree is created for a particular lexically hierarchical namespace, the different pieces of the hierarchy are mapped to authority areas. The most important concept behind an authority area is the ability for a portion of the RWhois tree to definitively control that portion of the hierarchy. This means that an authority area is able to state whether or not a hierarchical tag is in the whole RWhois tree. It does this either by returning the object containing this tag, returning a referral to a sub-authority area, or returning a response indicating that no objects were found. This structure enables efficient routing of queries based on the hierarchical label to the piece of the hierarchy responsible for it. For example, in the domain name namespace as served by RWhois, the root of the tree would be an authority area named ".", which would delegate a "us" sub-authority area, which would delegate "va", "co", "md", and "ca" authority areas, and so forth. When the server with the "va.us" authority area is asked about "loudoun.va.us", it will be able to authoritatively state that either no "loudoun.va.us" exists or it will provide an object for or a referral to "loudoun.va.us". Further, if the server is asked about "howard.md.us", it cannot answer authoritatively, so it must provide a referral to its hierarchical parent ("us" or the root). This use of authority area strongly indicates where data should be stored within an RWhois tree. Because RWhois uses a specific query routing model, data needs to be placed under the proper authority area. It is certainly possible to place a piece of data under the
wrong authority area, for example, putting an object for "howard.md.us" under the "va.us" authority area. In such cases, the data is considered to be misplaced and unable to be found within the RWhois tree. However, while data should be placed under the lowest (most specific) authority area, it is also possible that it could be placed in a higher (least specific) authority area, for example, putting an object for "loudoun.va.us" under the "us" authority. This may be acceptable since, in most cases, the data would be able to be found. In addition to controlling a part of an RWhois hierarchy, an authority area is considered to be autonomous. Each authority area is treated as a separate database by the protocol. However, it is recommended that an authority area share some core schema with the rest of the RWhois tree for interoperability reasons. Each authority area, however, is not bound by the database schema of its hierarchical parent or by any of its sub-authority areas. 2.5 Query Routing RWhois is not only a directory access protocol but it can also route queries. Routing a query involves redirecting the query to another server that is presumed to be closer to the desired data. To route a query, the server first determines the location of the next server. It then either forwards the query to that server and returns the result to the client or returns the location of that server to the client. The location of the server must contain its host name (or IP address), port number, and authority area. The location of the server to which a query is routed is called a referral. There are two types of referrals: punt and link referrals. A punt referral is a pointer to a server that is further up an RWhois tree, and a link referral is a pointer to a server that is further down the tree. For example, in Figure 1, when the server for the "va.us" authority area routes a query up to the server for the "us" authority area, it generates a punt referral. Alternatively, when it routes a query down to the server for the "loudon.va.us" authority area, it generates a link referral. Query routing depends on whether or not the search value in a query is lexically hierarchical. If the search value is hierarchical, the server can generate punt or link referrals using the association of authority areas with lexically hierarchical labels. Otherwise, the server may send the query to a special index server that gathers the indexing information for both hierarchical and non-hierarchical data from the directory servers and returns referrals to these servers [CIP]. If the server receives one or more referrals from the index server, it should return them to the client.
It is important to note that the server may route a query whether it could resolve the query or not. Even if a query has been resolved locally, the server may also return referrals to the client by sending the query to the index server. For example, if the server for the "com" authority area receives the "domain Org-Name=IBM" query, it may return all the domain objects for IBM within the "com" authority area. In addition, it may also return referrals to the server for the "nl" authority area if that server contains domain objects for IBM in the Netherlands and has fed the corresponding indexing information to the index server. This way the client can get back information for both "ibm.com" and "ibm.nl" domains. 2.5.1 Query Routing Rules An RWhois server routes a query based on certain rules. The objective is to determine the location of a server to which to route the query. A query may contain one or more query terms. The query routing rules are applied on each query term until a referral is found. The rules are listed below. * Is the search value in the query term hierarchical? If not, go to the next query term. * Parse the hierarchical portion of the search value. Is it is within one of the authority areas? If not, go to the next query term. * Does the found authority area have any referral objects (instances of the referral class)? If not, return the "230 No objects found" error to the client. * Is the hierarchical portion of the search value within the Referred-Auth-Area attribute of one of the referral objects? If it is, return the value of the Referral attribute of the found referral object as a link referral to the client. * Are the search values of some of the query terms hierarchical but not within any of the authority areas? If they are, return a punt referral to the client. * Are the search values of all the query terms non-hierarchical? If they are, send the query to a special index server that gathers the indexing information for both hierarchical and non- hierarchical data from the directory servers and returns referrals to these servers. If the server receives one or more referrals from the index server, return them to the client. Note that there can be more than one referral returned to the client. These referrals may point to servers serving different authority areas. The client may follow them in any order.
The pseudo code for the above rules is: for each query term in the query if the search value in the query term is hierarchical if the search value is within one of the authority areas if the search value is within one of the referred authority areas the server sends link referral(s) else the server sends a "230 No objects found" error endif endif endif endfor if the search values of some of the query terms are hierarchical but not within any of the authority areas the server sends Punt referral(s) endif if the search values of all the query terms are non-hierarchical the server sends Referral(s) from an index server endif 2.6 Data Replication An RWhois server can replicate (duplicate) data from another RWhois server on a per-authority area basis. Data replication makes the RWhois service more reliable. Further, it increases throughput by distributing queries to more than one server. There can be two types of servers serving an authority area: a master server and a slave server. A master server is where data is registered for an authority area. It answers authoritatively to queries in that authority area. There must be one and only one master server for an authority area. A master server is also called a primary server. A slave server is where data is replicated from the master server for an authority area. It also answers authoritatively to queries in that authority area. There may be one or more slave servers for an authority area. A slave server is also called a secondary server. Note that a slave server must not register data for an authority area. It is recommended that the master and slave servers for an authority area be geographically separate. Therefore, network unreachability at one site will not completely shut down the RWhois service for that authority area.
2.6.1 Data to Replicate In RWhois, data is replicated on a per-authority area basis. The smallest type of data a slave server can replicate is an attribute of a class. Therefore, a slave server can replicate data for all the classes, some classes, or some attributes of some classes. The amount of data a slave server can replicate each time is either all of the data or the data that has changed since the last replication. The process of replicating all of the data is called complete replication. The process of replicating the data that has changed since the last replication is called incremental replication. 2.6.2 Start Of Authority Variables Each authority area has some administrative variables, defined at the master server, to control data replication. These variables are called the Start Of Authority (SOA) variables. They are listed below. Serial-Number This is the serial number of the data in an authority area. The master server should update this variable whenever the data in the authority area is changed. Its value is a time/date stamp. Refresh-Interval This is the time interval before a slave server checks for complete replication. Its value is specified in seconds. Increment-IntervalThis is the time interval before a slave server checks for incremental replication. Its value is specified in seconds. Retry-Interval This is the time interval before a slave server tries again to connect to a master server that appears to be out-of-service. Its value is specified in seconds. Time-To-Live This is the default time to live for the data in an authority area at a slave server. The slave server should not answer authoritatively to queries for such stale data. Its value is specified in seconds. Admin-Contact This is the email address of an individual or a role account responsible for the data integrity in an authority area at the master server.
Tech-Contact This is the email address of an individual or a role account responsible for the operation of the master server for an authority area. Hostmaster This is the email address of an individual or a role account to whom email messages to update the data in an authority area at the master server are sent. Primary-Server This is the location of the master server for an authority area. Its value must contain both the host name (or IP address) and port number of the master server. 3. Protocol 3.1 Overview The above sections describe the directory service architecture based on the RWhois protocol. The remaining sections describe the syntax of the protocol; the sequence and syntax of the information exchanged between a server and a client. There are five types of information that may be exchanged during a client/server session: directive, response, query, result, and info. 3.1.1 Directive A directive is a command that a client sends to a server to set a control parameter for the session, get the meta-information (class definitions and SOA information) about an authority area, or get the data in an authority area. The first character of a directive must be a "-". The server must support the "-rwhois" directive; all other directives are optional. The server must indicate in the banner which directives are implemented (see Section 3.1.9). 3.1.2 Response A response is the information that a server returns to a client for a directive. It is comprised of one or more lines, and the last line always indicates the success or failure of the directive. The first character of each response line must be a "%". If a server runs a directive successfully, the last response line must be "%ok". Otherwise, it must be "%error <error-code> <error-text>". A line with the string "%ok" or "%error" in the first position must occur only once in a server response and must always be the last line. The server may send the "%info" response for special messages.
A client must understand the "%ok", "%error", and "%info" responses. The client must also understand directive specific responses, if it uses the related directives to communicate with the server. For example, if the client sends the "-schema" directive to the server, the client must understand the "%schema" response. 3.1.3 Query A query is a command that a client sends to a server to access the data in an authority area. The first character of a query must not be a "-", since the server checks the first character of each command from a client to determine whether it is a directive or a query. 3.1.4 Result A result is the information that a server returns to a client for a query. It can be either the accessed data or referrals to other servers. It is comprised of one or more lines, and the last line always indicates the success or failure of the query. If a server returns either data or referrals for a query, the last result line must be "%ok". Otherwise, it must be "%error <error-code> <error- text>". 3.1.5 Info An info message contains miscellaneous information that a server sends to a client. The server may use it to send special messages, for example a "message of the day" (MOTD), to the client. The first info line must be "%info on", and the last info line must be "%info off". 3.1.6 Client/Server Session A typical RWhois client/server session has the following sequence of messages. * The client connects to the server. * The server returns a banner identifying its protocol versions and capabilities. * The client sends one or more directives to the server. * The server returns the response to each directive. * The client finally sends a query to the server. * The server returns the query results. * The server closes the connection, unless the client has directed it not to close the connection.
3.1.7 Examples This section gives some common examples of the client/server interaction. The notation in the examples uses a prefix to indicate from where the information comes. A "C" indicates that the client sends the data to the server. An "S" indicates that the server sends the data to the client. The line is a comment when "#" is used. The space after the prefix is not part of the data. The following example illustrates a successful query. # The client connects to the server. # The server returns a banner identifying its protocol versions and # capabilities. S %rwhois V-1.5:00ffff:00 master.rwhois.net (Network Solutions V-1.5) # The client sends a directive to limit the number of search hits # to 20. C -limit 20 # The server returns a successful response. S %ok # The client sends a query to search for rwhois.net domain. C domain rwhois.net # The server returns the data for rwhois.net domain. S domain:ID:dom-1.rwhois.net S domain:Auth-Area:rwhois.net S domain:Class-Name:domain S domain:Updated:19970107201111000 S domain:Domain:rwhois.net S domain:Server;I:hst-1.rwhois.net S domain:Server;I:hst-2.rwhois.net S S %ok # The server closes the connection. The following example illustrates the link and punt referrals. # The client connects to the server. # The server returns a banner identifying its protocol versions and # capabilities. S %rwhois V-1.5:00ffff:00 master.rwhois.net (Network Solutions V-1.5) # The client sends a directive to hold the connection until it sends # a directive to close the connection. C -holdconnect on # The server returns a successful response. S %ok # The client sends a query to search for a.b.rwhois.net domain. C domain a.b.rwhois.net # The server returns a link referral to a server serving the
# b.rwhois.net authority area. S %referral rwhois://master.b.rwhois.net:4321/auth-area=b.rwhois.net S %ok # The client sends a query to search for internic.net domain. C domain internic.net # The server returns a punt referral to a server serving the root # authority area. S %referral rwhois://rs.internic.net:4321/auth-area=. S %ok # The client sends a directive to close the connection. C -quit S %ok # The server closes the connection. The following example illustrates a query error. # The client connects to the server. # The server returns a banner identifying its protocol versions and # capabilities. S %rwhois V-1.5:00ffff:00 master.rwhois.net (Network Solutions V-1.5) # The client sends a query to search for c.rwhois.net domain. C domain c.rwhois.net # The server returns an error, since neither data nor referrals for # c.rwhois.net domain are found within the rwhois.net authority area. S %error 230 No objects found # The server closes the connection. 3.1.8 Notation The following sections use the Augmented Backus-Naur Form (ABNF) notation to describe the syntax of the protocol. For further information, see Section 2 of [RFC822]. The notation in the examples uses a prefix to indicate from where the information comes. A "C" indicates that the client sends the data to the server. An "S" indicates that the server sends the data to the client. The line is a comment when "#" is used. The space after the prefix is not part of the data. 3.1.9 General ABNF definitions Lexical Tokens alpha = "a".."z" / "A".."Z" digit = "0".."9" hex-digit = digit / "a".."f" / "A".. "F" id-char = alpha / digit / "_" / "-" any-char = <ASCII 1..255, except LF (linefeed) and CR (carriage return)>
dns-char = alpha / digit / "-" email-char = <see [RFC 822]> space = " " tab = <ASCII TAB (tab)> lf = <ASCII LF (linefeed)> cr = <ASCII CR (carriage return)> crlf = cr lf Grammar year = 4digit month = 2digit day = 2digit hour = 2digit minute = 2digit second = 2digit milli-second = 3digit host-name = dns-char *(dns-char / ".") ip-address = 1*3digit "." 1*3digit "." 1*3digit "." 1*3digit email = 1*email-char "@" host-name authority-area = (dns-char / ".") *(dns-char / "." / "/") object-id = 1*id-char "." authority-area host-port = (host-name / ip-address) ":" 1*5digit class-name = 1*id-char attribute-name = 1*id-char attribute-value = 1*any-char time-stamp = year month day hour minute second milli-second on-off = "on" / "off" Note that the time-stamp must be in the Greenwich Mean Time (GMT) time zone. Also note that since in the above any-char is 1..255 ASCII that the RWhois protocol is an 8 bit protocol. Response The general response for every directive and query is either "%ok" or "%error". In addition, a "%info" response may be sent. response = ok-response crlf / error-response crlf / info-response ok-response = "%ok" error-response = "%error" space error-code space error-text error-code = 3digit error-text = 1*any-char info-response = "%info" space "on" crlf *(*any-char crlf) "%info" space "off" crlf
Banner The server must send a banner to the client when the connection is opened. The banner contains the version(s) of the protocol the server supports and a capability ID of encoded bit flags that indicates which directives are implemented. If the server supports more than one version of the protocol, the lowest-numbered version must be specified first. The bits in extra-id are reserved for future use. The end of the banner should contain a free-form string indicating the name of the server implementation. A server must support at least one version of the protocol, and may accept more versions for compatibility reasons. rwhois-banner = "%rwhois" space version-list space host-name [space implementation] crlf version-list = version *("," version) version = version-number [":" capability-id] / "V-1.5" ":" capability-id version-number = "V-" 1*digit "." 1*digit capability-id = response-id ":" extra-id response-id = 6hex-digit extra-id = 2hex-digit implementation = 1*any-char Protocol The entire RWhois protocol can be defined as a series of directives, responses, queries, and results. rwhois-protocol = client-sends / server-returns client-sends = *(directives / rwhois-query) server-returns = *(responses / rwhois-query-result) 3.2 Required Directives The server must implement the following directives.
3.2.1 rwhois Description The "-rwhois" directive may be issued by the client at the start of every session . It tells the server which version of the protocol the client can handle. The server must respond with a banner containing the protocol version and directives it implements. This banner is the same banner that is sent by the server when the connection is opened, except that the server must indicate only one version number. The banner issued when opening a connection may contain more than one version number. The directive flags are encoded into three octets, which are described in Appendix D. ABNF rwhois-dir = "-rwhois" space version-number [space implementation] crlf rwhois-response = "%rwhois" space version space host-name [space implementation] crlf Errors 300 Not compatible with version 338 Invalid directive syntax Examples # When a connection is opened, the server issues the banner. S %rwhois V-1.0,V-1.5:00ffff:00 rs.internic.net (NSI Server 1.5.4) # The client sends the rwhois directive. C -rwhois V-1.5 NSI Client 1.2.3 S %rwhois V-1.5:00ffff:00 rs.internic.net (NSI Server 1.5.4) S %ok 3.3 Optional Directives The server should implement the following directives.
3.3.1 class Description The "-class" directive can be used by the client to get the meta- information for one or more classes in an authority area. The response must contain the description and version number of each specified class and may be expanded in the future with additional attributes. When no class name is given, the server must return the meta-information for all the classes in the authority area. Every class record must end with an empty "%class" line. ABNF class-dir = "-class" space authority-area *(space class-name) crlf class-response = *class-record response class-record = *class-line "%class" crlf class-line = "%class" space class-name ":" "description" ":" 1*any-char crlf / "%class" space class-name ":" "version" ":" time-stamp crlf / "%class" space class-name ":" meta-field ":" meta-value crlf meta-field = 1*id-char meta-value = 1*any-char The following fields are required. meta-field meta-value Description description 1*any-char Class description. Time/date stamp indicating version of class, version time-stamp must be updated after class definition is changed. Errors 338 Invalid directive syntax 340 Invalid authority area 341 Invalid class 400 Directive not available 401 Not authorized for directive Examples C -class rwhois.net domain host S %class domain:description:Domain information S %class domain:version:19970103101232000 S %class
S %class host:description:Host information S %class host:version:19970214213241000 S %class S %ok 3.3.2 directive Description The "-directive" directive can be used by the client to get information about the directives that the server supports. The response must contain the name and description of each specified directive and may be expanded in the future with additional attributes. When no directive name is given, the server must return information about all the directives. Every directive record must end with an empty "%directive" line. ABNF directive-dir = "-directive" *(space directive-name) crlf directive-name = 1*id-char directive-response = *directive-record response directive-record = "%directive" space "directive" ":" directive-name crlf *directive-line "%directive" crlf directive-line = "%directive" space "description" ":" 1*any-char crlf / "%directive" space attribute-name ":" attribute-value crlf Errors 338 Invalid directive syntax 400 Directive not available 401 Not authorized for directive Examples Without parameters: C -directive S %directive directive:rwhois S %directive description:RWhois directive S %directive S %directive directive:quit S %directive description:Quit connection S %directive S %ok
With parameters: C -directive quit S %directive directive:quit S %directive description:Quit connection S %directive S %ok 3.3.3 display Description By default, the server uses the dump format for the output of a query result. The output format can be changed with the "-display" directive. When no parameter is given, the server must list all the display formats it supports. Every display record must end with an empty "%display" line. Currently, only the dump format is standard and must be supported by the server. Other output formats may be added in the future. See Section 3.4 for the definition of the dump format. ABNF display-dir = "-display" crlf / "-display" space display-name crlf display-name = 1*id-char display-response = *(display-record) response display-record = "%display" space "name" ":" display-name crlf *display-line "%display" crlf display-line = "%display" space attribute-name ":" attribute-value crlf Errors 338 Invalid directive syntax 400 Directive not available 401 Not authorized for directive 436 Invalid display format Examples # Get the available display formats. C -display S %display name:dump S %display S %ok
# Change the active display format. C -display dump S %ok 3.3.4 forward Description The "-forward" directive instructs the server to follow all the referrals and return the results to the client. This directive can be used to run an RWhois server as a proxy server. The default value must be "off". When the value is set to "on", the server must not return referrals. ABNF forward-dir = "-forward" space on-off crlf forward-response = response Errors 338 Invalid directive syntax 400 Directive not available 401 Not authorized for directive Examples C -forward on S %ok C -forward off S %ok 3.3.5 holdconnect Description Normally, the server closes the connection after each query. This behavior is controlled by the holdconnect state, which can be changed with the "-holdconnect" directive. When the holdconnect state is set to "off", the server must close the connection after a query; when it is set to "on", the server must not close the connection after a query. By default, the holdconnect state must be set to "off" for each connection.
ABNF holdconnect-dir = "-holdconnect" space on-off crlf holdconnect-response = response Errors 338 Invalid directive syntax 400 Directive not available 401 Not authorized for directive Examples C -holdconnect on S %ok C -holdconnect off S %ok 3.3.6 limit Description When returning a query result, the server should limit the number of objects returned to the client. The "-limit" directive changes this limit. The default and maximum limit is server-dependent. The client can get the current limit by using the "-status" directive (see Section 3.3.13). ABNF limit-dir = "-limit" space 1*digit crlf limit-response = response Errors 331 Invalid limit 338 Invalid directive syntax 400 Directive not available 401 Not authorized for directive Examples C -limit 100 S %ok