Network Working Group                                     F. Anklesaria
Request for Comments: 1436                                  M. McCahill
                                                            P. Lindner
                                                            D. Johnson
                                                             D. Torrey
                                                            B. Alberti
                                               University of Minnesota
                                                            March 1993


                     The Internet Gopher Protocol
        (a distributed document search and retrieval protocol)

Status of this Memo

  This memo provides information for the Internet community.  It does
  not specify an Internet standard.  Distribution of this memo is
  unlimited.

Abstract

  The Internet Gopher protocol is designed for distributed document
  search and retrieval.  This document describes the protocol, lists
  some of the implementations currently available, and has an overview
  of how to implement new client and server applications.  This
  document is adapted from the basic Internet Gopher protocol document
  first issued by the Microcomputer Center at the University of
  Minnesota in 1991.

Introduction

  gopher  n.  1. Any of various short tailed, burrowing mammals of the
  family Geomyidae, of North America.  2. (Amer. colloq.) Native or
  inhabitant of Minnesota: the Gopher State.  3. (Amer. colloq.) One
  who runs errands, does odd-jobs, fetches or delivers documents for
  office staff.  4. (computer tech.) software following a simple
  protocol for burrowing through a TCP/IP internet.

  The Internet Gopher protocol and software follow a client-server
  model.  This protocol assumes a reliable data stream; TCP is assumed.
  Gopher servers should listen on port 70 (port 70 is assigned to
  Internet Gopher by IANA).  Documents reside on many autonomous
  servers on the Internet.  Users run client software on their desktop
  systems, connecting to a server and sending the server a selector (a
  line of text, which may be empty) via a TCP connection at a well-
  known port.  The server responds with a block of text terminated by a
  period on a line by itself and closes the connection.  No state is
  retained by the server.



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  While documents (and services) reside on many servers, Gopher client
  software presents users with a hierarchy of items and directories
  much like a file system.  The Gopher interface is designed to
  resemble a file system since a file system is a good model for
  organizing documents and services; the user sees what amounts to one
  big networked information system containing primarily document items,
  directory items, and search items (the latter allowing searches for
  documents across subsets of the information base).

  Servers return either directory lists or documents.  Each item in a
  directory is identified by a type (the kind of object the item is),
  user-visible name (used to browse and select from listings), an
  opaque selector string (typically containing a pathname used by the
  destination host to locate the desired object), a host name (which
  host to contact to obtain this item), and an IP port number (the port
  at which the server process listens for connections). The user only
  sees the user-visible name.  The client software can locate and
  retrieve any item by the trio of selector, hostname, and port.

  To use a search item, the client submits a query to a special kind of
  Gopher server: a search server.  In this case, the client sends the
  selector string (if any) and the list of words to be matched. The
  response yields "virtual directory listings" that contain items
  matching the search criteria.

  Gopher servers and clients exist for all popular platforms.  Because
  the protocol is so sparse and simple, writing servers or clients is
  quick and straightforward.

1.  Introduction

  The Internet Gopher protocol is designed primarily to act as a
  distributed document delivery system.  While documents (and services)
  reside on many servers, Gopher client software presents users with a
  hierarchy of items and directories much like a file system.  In fact,
  the Gopher interface is designed to resemble a file system since a
  file system is a good model for locating documents and services.  Why
  model a campus-wide information system after a file system?  Several
  reasons:

     (a) A hierarchical arrangement of information is familiar to many
     users.  Hierarchical directories containing items (such as
     documents, servers, and subdirectories) are widely used in
     electronic bulletin boards and other campus-wide information
     systems. People who access a campus-wide information server will
     expect some sort of hierarchical organization to the information
     presented.




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     (b) A file-system style hierarchy can be expressed in a simple
     syntax.  The syntax used for the internet Gopher protocol is
     easily understandable, and was designed to make debugging servers
     and clients easy.  You can use Telnet to simulate an internet
     Gopher client's requests and observe the responses from a server.
     Special purpose software tools are not required.  By keeping the
     syntax of the pseudo-file system client/server protocol simple, we
     can also achieve better performance for a very common user
     activity: browsing through the directory hierarchy.

     (c) Since Gopher originated in a University setting, one of the
     goals was for departments to have the option of publishing
     information from their inexpensive desktop machines, and since
     much of the information can be presented as simple text files
     arranged in directories, a protocol modeled after a file system
     has immediate utility.  Because there can be a direct mapping from
     the file system on the user's desktop machine to the directory
     structure published via the Gopher protocol, the problem of
     writing server software for slow desktop systems is minimized.

     (d) A file system metaphor is extensible.  By giving a "type"
     attribute to items in the pseudo-file system, it is possible to
     accommodate documents other than simple text documents.  Complex
     database services can be handled as a separate type of item.  A
     file-system metaphor does not rule out search or database-style
     queries for access to documents.  A search-server type is also
     defined in this pseudo-file system.  Such servers return "virtual
     directories" or list of documents matching user specified
     criteria.

2.  The internet Gopher Model

  A detailed BNF rendering of the internet Gopher syntax is available
  in the appendix...but a close reading of the appendix may not be
  necessary to understand the internet Gopher protocol.

  In essence, the Gopher protocol consists of a client connecting to a
  server and sending the server a selector (a line of text, which may
  be empty) via a TCP connection.  The server responds with a block of
  text terminated with a period on a line by itself, and closes the
  connection.  No state is retained by the server between transactions
  with a client. The simple nature of the protocol stems from the need
  to implement servers and clients for the slow, smaller desktop
  computers (1 MB Macs and DOS machines), quickly, and efficiently.

  Below is a simple example of a client/server interaction; more
  complex interactions are dealt with later.  Assume that a "well-
  known" Gopher server (this may be duplicated, details are discussed



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  later) listens at a well known port for the campus (much like a
  domain-name server).  The only configuration information the client
  software retains is this server's name and port number (in this
  example that machine is rawBits.micro.umn.edu and the port 70). In
  the example below the F character denotes the TAB character.

Client:          {Opens connection to rawBits.micro.umn.edu at port 70}

Server:          {Accepts connection but says nothing}

Client: <CR><LF> {Sends an empty line: Meaning "list what you have"}

Server:          {Sends a series of lines, each ending with CR LF}
0About internet GopherFStuff:About usFrawBits.micro.umn.eduF70
1Around University of MinnesotaFZ,5692,AUMFunderdog.micro.umn.eduF70
1Microcomputer News & PricesFPrices/Fpserver.bookstore.umn.eduF70
1Courses, Schedules, CalendarsFFevents.ais.umn.eduF9120
1Student-Staff DirectoriesFFuinfo.ais.umn.eduF70
1Departmental PublicationsFStuff:DP:FrawBits.micro.umn.eduF70
                   {.....etc.....}
.                  {Period on a line by itself}
                   {Server closes connection}


  The first character on each line tells whether the line describes a
  document, directory, or search service (characters '0', '1', '7';
  there are a handful more of these characters described later).  The
  succeeding characters up to the tab form a user display string to be
  shown to the user for use in selecting this document (or directory)
  for retrieval.  The first character of the line is really defining
  the type of item described on this line. In nearly every case, the
  Gopher client software will give the users some sort of idea about
  what type of item this is (by displaying an icon, a short text tag,
  or the like).

  The characters following the tab, up to the next tab form a selector
  string that the client software must send to the server to retrieve
  the document (or directory listing).  The selector string should mean
  nothing to the client software; it should never be modified by the
  client.  In practice, the selector string is often a pathname or
  other file selector used by the server to locate the item desired.
  The next two tab delimited fields denote the domain-name of the host
  that has this document (or directory), and the port at which to
  connect.  If there are yet other tab delimited fields, the basic
  Gopher client should ignore them.  A CR LF denotes the end of the
  item.





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  In the example, line 1 describes a document the user will see as
  "About internet Gopher".  To retrieve this document, the client
  software must send the retrieval string: "Stuff:About us" to
  rawBits.micro.umn.edu at port 70.  If the client does this, the
  server will respond with the contents of the document, terminated by
  a period on a line by itself.  A client might present the user with a
  view of the world something like the following list of items:


     About Internet Gopher
     Around the University of Minnesota...
     Microcomputer News & Prices...
     Courses, Schedules, Calendars...
     Student-Staff Directories...
     Departmental Publications...



  In this case, directories are displayed with an ellipsis and files
  are displayed without any.  However, depending on the platform the
  client is written for and the author's taste, item types could be
  denoted by other text tags or by icons.  For example, the UNIX
  curses-based client displays directories with a slash (/) following
  the name; Macintosh clients display directories alongside an icon of
  a folder.

  The user does not know or care that the items up for selection may
  reside on many different machines anywhere on the Internet.

  Suppose the user selects the line "Microcomputer News & Prices...".
  This appears to be a directory, and so the user expects to see
  contents of the directory upon request that it be fetched.  The
  following lines illustrate the ensuing client-server interaction:


   Client:           (Connects to pserver.bookstore.umn.edu at port 70)
   Server:           (Accepts connection but says nothing)
   Client: Prices/   (Sends the magic string terminated by CRLF)
   Server:           (Sends a series of lines, each ending with CR LF)
   0About PricesFPrices/AboutusFpserver.bookstore.umn.eduF70
   0Macintosh PricesFPrices/MacFpserver.bookstore.umn.eduF70
   0IBM PricesFPrices/IckFpserver.bookstore.umn.eduF70
   0Printer & Peripheral PricesFPrices/PPPFpserver.bookstore.umn.eduF70
                     (.....etc.....)
   .                 (Period on a line by itself)
                     (Server closes connection)





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3. More details

3.1  Locating services

  Documents (or other services that may be viewed ultimately as
  documents, such as a student-staff phonebook) are linked to the
  machine they are on by the trio of selector string, machine domain-
  name, and IP port.  It is assumed that there will be one well-known
  top-level or root server for an institution or campus.  The
  information on this server may be duplicated by one or more other
  servers to avoid a single point of failure and to spread the load
  over several servers.  Departments that wish to put up their own
  departmental servers need to register the machine name and port with
  the administrators of the top-level Gopher server, much the same way
  as they register a machine name with the campus domain-name server.
  An entry which points to the departmental server will then be made at
  the top level server.  This ensures that users will be able to
  navigate their way down what amounts to a virtual hierarchical file
  system with a well known root to any campus server if they desire.

  Note that there is no requirement that a department register
  secondary servers with the central top-level server; they may just
  place a link to the secondary servers in their own primary servers.
  They may indeed place links to any servers they desire in their own
  server, thus creating a customized view of thethe Gopher information
  universe; links can of course point back at the top-level server.
  The virtual (networked) file system is therefore an arbitrary graph
  structure and not necessarily a rooted tree.  The top-level node is
  merely one convenient, well-known point of entry.  A set of Gopher
  servers linked in this manner may function as a campus-wide
  information system.

  Servers may of course point links at other than secondary servers.
  Indeed servers may point at other servers offering useful services
  anywhere on the internet.  Viewed in this manner, Gopher can be seen
  as an Internet-wide information system.

3.2 Server portability and naming

  It is recommended that all registered servers have alias names
  (domain name system CNAME) that are used by Gopher clients to locate
  them.  Links to these servers should use these alias names rather
  than the primary names.  If information needs to be moved from one
  machine to another, a simple change of domain name system alias
  (CNAME) allows this to occur without any reconfiguration of clients
  in the field.  In short, the domain name system may be used to re-map
  a server to a new address.  There is nothing to prevent secondary
  servers or services from running on otherwise named servers or ports



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  other than 70, however these should be reachable via a primary
  server.

3.3 Contacting server administrators

  It is recommended that every server administrator have a document
  called something like: "About Bogus University's Gopher server" as
  the first item in their server's top level directory.  In this
  document should be a short description of what the server holds, as
  well as name, address, phone, and an e-mail address of the person who
  administers the server.  This provides a way for users to get word to
  the administrator of a server that has inaccurate information or is
  not running correctly.  It is also recommended that administrators
  place the date of last update in files for which such information
  matters to the users.

3.4  Modular addition of services

  The first character of each line in a server-supplied directory
  listing indicates whether the item is a file (character '0'), a
  directory (character '1'), or a search (character '7').  This is the
  base set of item types in the Gopher protocol.  It is desirable for
  clients to be able to use different services and speak different
  protocols (simple ones such as finger; others such as CSO phonebook
  service, or Telnet, or X.500 directory service) as needs dictate.
  CSO phonebook service is a client/server phonebook system typically
  used at Universities to publish names, e-mail addresses, and so on.
  The CSO phonebook software was developed at the University of
  Illinois and is also sometimes refered to as ph or qi.  For example,
  if a server-supplied directory listing marks a certain item with type
  character '2', then it means that to use this item, the client must
  speak the CSO protocol.  This removes the need to be able to
  anticipate all future needs and hard-wire them in the basic Internet
  Gopher protocol; it keeps the basic protocol extremely simple.  In
  spite of this simplicity, the scheme has the capability to expand and
  change with the times by adding an agreed upon type-character for a
  new service.  This also allows the client implementations to evolve
  in a modular fashion, simply by dropping in a module (or launching a
  new process) for some new service.  The servers for the new service
  of course have to know nothing about Internet Gopher; they can just
  be off-the shelf CSO, X.500, or other servers.  We do not however,
  encourage arbitrary or machine-specific proliferation of service
  types in the basic Gopher protocol.

  On the other hand, subsets of other document retrieval schemes may be
  mapped onto the Gopher protocol by means of "gateway-servers".
  Examples of such servers include Gopher-to-FTP gateways, Gopher-to-
  archie gateways, Gopher-to-WAIS gateways, etc.  There are a number of



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RFC 1436                         Gopher                       March 1993


  advantages of such mechanisms. First, a relatively powerful server
  machine inherits both the intelligence and work, rather than the more
  modest, inexpensive desktop system that typically runs client
  software or basic server software.  Equally important, clients do not
  have to be modified to take advantage of a new resource.

3.5  Building clients

  A client simply sends the retrieval string to a server if it wants to
  retrieve a document or view the contents of a directory.  Of course,
  each host may have pointers to other hosts, resulting in a "graph"
  (not necessarily a rooted tree) of hosts.  The client software may
  save (or rather "stack") the locations that it has visited in search
  of a document.  The user could therefore back out of the current
  location by unwinding the stack.  Alternatively, a client with
  multiple-window capability might just be able to display more than
  one directory or document at the same time.

  A smart client could cache the contents of visited directories
  (rather than just the directory's item descriptor), thus avoiding
  network transactions if the information has been previously
  retrieved.

  If a client does not understand what a say, type 'B' item (not a core
  item) is, then it may simply ignore the item in the directory
  listing; the user never even has to see it.  Alternatively, the item
  could be displayed as an unknown type.

  Top-level or primary servers for a campus are likely to get more
  traffic than secondary servers, and it would be less tolerable for
  such primary servers to be down for any long time.  So it makes sense
  to "clone" such important servers and construct clients that can
  randomly choose between two such equivalent primary servers when they
  first connect (to balance server load), moving to one if the other
  seems to be down.  In fact, smart client implementations do this
  clone server and load balancing.  Alternatively, it may make sense to
  have the domain name system return one of a set of redundant of
  server's IP address to load balance betwen redundant sets of
  important servers.

3.6  Building ordinary internet Gopher servers

  The retrieval string sent to the server might be a path to a file or
  directory.  It might be the name of a script, an application or even
  a query that generates the document or directory returned.  The basic
  server uses the string it gets up to but not including a CR-LF or a
  TAB, whichever comes first.




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  All intelligence is carried by the server implementation rather than
  the protocol.  What you build into more exotic servers is up to you.
  Server implementations may grow as needs dictate and time allows.

3.7  Special purpose servers

  There are two special server types (beyond the normal Gopher server)
  also discussed below:

     1.  A server directory listing can point at a CSO nameserver (the
     server returns a type character of '2') to allow a campus
     student-staff phonebook lookup service.  This may show up on the
     user's list of choices, perhaps preceded by the icon of a phone-
     book.  If this item is selected, the client software must resort
     to a pure CSO nameserver protocol when it connects to the
     appropriate host.

     2.  A server can also point at a "search server" (returns a first
     character of '7').  Such servers may implement campus network (or
     subnet) wide searching capability.  The most common search servers
     maintain full-text indexes on the contents of text documents held
     by some subset of Gopher servers.  Such a "full-text search
     server" responds to client requests with a list of all documents
     that contain one or more words (the search criteria).  The client
     sends the server the selector string, a tab, and the search string
     (words to search for). If the selector string is empty, the client
     merely sends the search string.  The server returns the equivalent
     of a directory listing for documents matching the search criteria.
     Spaces between words are usually implied Boolean ANDs (although in
     different implementations or search types, this may not
     necessarily be true).

  The CSO addition exists for historical reasons: at time of design,
  the campus phone-book servers at the University of Minnesota used the
  CSO protocol and it seemed simplest to just engulf them.  The index-
  server is however very much a Gopher in spirit, albeit with a slight
  twist in the meaning of the selector-string.  Index servers are a
  natural place to incorperate gateways to WAIS and WHOIS services.

3.7.1  Building CSO-servers

  A CSO Nameserver implementation for UNIX and associated documentation
  is available by anonymous ftp from uxa.cso.uiuc.edu.  We do not
  anticipate implementing it on other machines.







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3.7.2  Building full-text search servers

  A full-text search server is a special-purpose server that knows
  about the Gopher scheme for retrieving documents.  These servers
  maintain a full-text index of the contents of plain text documents on
  Gopher servers in some specified domain.  A Gopher full-text search
  server was implemented using several NeXTstations because it was easy
  to take advantage of the full-text index/search engine built into the
  NeXT system software.  A search server for generic UNIX systems based
  on the public domain WAIS search engine, is also available and
  currently an optional part of the UNIX gopher server.  In addition,
  at least one implementation of the gopher server incorperates a
  gateway to WAIS servers by presenting the WAIS servers to gopherspace
  as full-text search servers.  The gopher<->WAIS gateway servers does
  the work of translating from gopher protocol to WAIS so unmodified
  gopher clients can access WAIS servers via the gateway server.

  By using several index servers (rather than a monolithic index
  server) indexes may be searched in parallel (although the client
  software is not aware of this).  While maintaining full-text indexes
  of documents distributed over many machines may seem a daunting task,
  the task can be broken into smaller pieces (update only a portion of
  the indexes, search several partial indexes in parallel) so that it
  is manageable.  By spreading this task over several small, cheap (and
  fast) workstations it is possible to take advantage of fine-grain
  parallelism.  Again, the client software is not aware of this. Client
  software only needs to know that it can send a search string to an
  index server and will receive a list of documents that contain the
  words in the search string.

3.8  Item type characters

  The client software decides what items are available by looking at
  the first character of each line in a directory listing.  Augmenting
  this list can extend the protocol.  A list of defined item-type
  characters follows:

  0   Item is a file
  1   Item is a directory
  2   Item is a CSO phone-book server
  3   Error
  4   Item is a BinHexed Macintosh file.
  5   Item is DOS binary archive of some sort.
      Client must read until the TCP connection closes.  Beware.
  6   Item is a UNIX uuencoded file.
  7   Item is an Index-Search server.
  8   Item points to a text-based telnet session.
  9   Item is a binary file!



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      Client must read until the TCP connection closes.  Beware.
  +   Item is a redundant server
  T   Item points to a text-based tn3270 session.
  g   Item is a GIF format graphics file.
  I   Item is some kind of image file.  Client decides how to display.

  Characters '0' through 'Z' are reserved.  Local experiments should
  use other characters.  Machine-specific extensions are not
  encouraged.  Note that for type 5 or type 9 the client must be
  prepared to read until the connection closes.  There will be no
  period at the end of the file; the contents of these files are binary
  and the client must decide what to do with them based perhaps on the
  .xxx extension.

3.9  User display strings and server selector strings

  User display strings are intended to be displayed on a line on a
  typical screen for a user's viewing pleasure.  While many screens can
  accommodate 80 character lines, some space is needed to display a tag
  of some sort to tell the user what sort of item this is.  Because of
  this, the user display string should be kept under 70 characters in
  length.  Clients may truncate to a length convenient to them.

4.   Simplicity is intentional

  As far as possible we desire any new features to be carried as new
  protocols that will be hidden behind new document-types.  The
  internet Gopher philosophy is:

     (a) Intelligence is held by the server.  Clients have the option
     of being able to access new document types (different, other types
     of servers) by simply recognizing the document-type character.
     Further intelligence to be borne by the protocol should be
     minimized.

     (b) The well-tempered server ought to send "text" (unless a file
     must be transferred as raw binary).  Should this text include
     tabs, formfeeds, frufru?  Probably not, but rude servers will
     probably send them anyway.  Publishers of documents should be
     given simple tools (filters) that will alert them if there are any
     funny characters in the documents they wish to publish, and give
     them the opportunity to strip the questionable characters out; the
     publisher may well refuse.

     (c) The well-tempered client should do something reasonable with
     funny characters received in text; filter them out, leave them in,
     whatever.




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RFC 1436                         Gopher                       March 1993


Appendix

  Paul's NQBNF (Not Quite BNF) for the Gopher Protocol.

  Note:  This is modified BNF (as used by the Pascal people) with a few
         English modifiers thrown in.  Stuff enclosed in '{}' can be
         repeated zero or more times.  Stuff in '[]' denotes a set of
         items.  The '-' operator denotes set subtraction.


Directory Entity

CR-LF     ::= ASCII Carriage Return Character followed by Line Feed
             character.

Tab       ::= ASCII Tab character.

NUL       ::= ASCII NUL character.

UNASCII   ::= ASCII - [Tab CR-LF NUL].

Lastline  ::= '.'CR-LF.

TextBlock ::= Block of ASCII text not containing Lastline pattern.

Type      ::= UNASCII.

RedType   ::= '+'.

User_Name ::= {UNASCII}.

Selector  ::= {UNASCII}.

Host      ::= {{UNASCII - ['.']} '.'} {UNASCII - ['.']}.

Note: This is a Fully Qualified Domain Name as defined in RFC 1034.
     (e.g., gopher.micro.umn.edu)  Hosts that have a CR-LF
     TAB or NUL in their name get what they deserve.

Digit     ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' .

DigitSeq  ::= digit {digit}.

Port      ::= DigitSeq.

Note: Port corresponds the the TCP Port Number, its value should
     be in the range [0..65535]; port 70 is officially assigned
     to gopher.



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RFC 1436                         Gopher                       March 1993


DirEntity ::= Type User_Name Tab Selector Tab Host Tab Port CR-LF
         {RedType User_Name Tab Selector Tab Host Tab Port CR-LF}



Notes:

  It is *highly* recommended that the User_Name field contain only
  printable characters, since many different clients will be using
  it.  However if eight bit characters are used, the characters
  should conform with the ISO Latin1 Character Set.  The length of
  the User displayable line should be less than 70 Characters; longer
  lines may not fit across some screens.

  The Selector string should be no longer than 255 characters.


Menu Entity

Menu      ::= {DirEntity} Lastline.


Menu Transaction  (Type 1 item)

C: Opens Connection
S: Accepts Connection
C: Sends Selector String
S: Sends Menu Entity

  Connection is closed by either client or server (typically server).


Textfile Entity

TextFile  ::= {TextBlock} Lastline

Note:  Lines beginning with periods must be prepended with an extra
    period to ensure that the transmission is not terminated early.
    The client should strip extra periods at the beginning of the line.


TextFile Transaction (Type 0 item)

C: Opens Connection.
S: Accepts connection
C: Sends Selector String.
S: Sends TextFile Entity.




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RFC 1436                         Gopher                       March 1993


  Connection is closed by either client or server (typically server).

Note:  The client should be prepared for the server closing the
      connection without sending the Lastline.  This allows the
      client to use fingerd servers.


Full-Text Search Transaction (Type 7 item)

Word      ::= {UNASCII - ' '}
BoolOp ::= 'and' | 'or' | 'not' | SPACE
SearchStr ::= Word {{SPACE BoolOp} SPACE Word}

C: Opens Connection.
C: Sends Selector String, Tab, Search String.
S: Sends Menu Entity.

Note:  In absence of 'and', 'or', or 'not' operators, a SPACE is
      regarded as an implied 'and' operator.  Expression is evaluated
      left to right.  Further, not all search engines or search
      gateways currently implemented have the boolean operators
      implemented.

Binary file Transaction (Type 9 or 5 item)

C: Opens Connection.
S: Accepts connection
C: Sends Selector String.
S: Sends a binary file and closes connection when done.


Syntactic Meaning for Directory Entities


The client should interpret the type field as follows:

0   The item is a TextFile Entity.
   Client should use a TextFile Transaction.

1   The item is a Menu Entity.
   Client should use a Menu Transaction.

2   The information applies to a CSO phone book entity.
   Client should talk CSO protocol.

3   Signals an error condition.

4   Item is a Macintosh file encoded in BINHEX format



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RFC 1436                         Gopher                       March 1993


5   Item is PC-DOS binary file of some sort.  Client gets to decide.

6   Item is a uuencoded file.

7   The information applies to a Index Server.
   Client should use a FullText Search transaction.

8   The information applies to a Telnet session.
   Connect to given host at given port. The name to login as at this
   host is in the selector string.

9   Item is a binary file.  Client must decide what to do with it.

+   The information applies to a duplicated server.  The information
   contained within is a duplicate of the primary server.  The primary
   server is defined as the last DirEntity that is has a non-plus
   "Type" field.  The client should use the transaction as defined by
   the primary server Type field.

g   Item is a GIF graphic file.

I   Item is some kind of image file.  Client gets to decide.

T   The information applies to a tn3270 based telnet session.
   Connect to given host at given port. The name to login as at this
   host is in the selector string.

Security Considerations

  Security issues are not discussed in this memo.

Authors' Addresses

  Farhad Anklesaria
  Computer and Information Services, University of Minnesota
  Room 152 Shepherd Labs
  100 Union Street SE
  Minneapolis, MN 55455

  Phone: (612) 625 1300
  EMail: [email protected]










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RFC 1436                         Gopher                       March 1993


  Mark McCahill
  Computer and Information Services, University of Minnesota
  Room 152 Shepherd Labs
  100 Union Street SE
  Minneapolis, MN 55455

  Phone: (612) 625 1300
  EMail: [email protected]


  Paul Lindner
  Computer and Information Services, University of Minnesota
  Room 152 Shepherd Labs
  100 Union Street SE
  Minneapolis, MN 55455

  Phone: (612) 625 1300
  EMail: [email protected]


  David Johnson
  Computer and Information Services, University of Minnesota
  Room 152 Shepherd Labs
  100 Union Street SE
  Minneapolis, MN 55455

  Phone: (612) 625 1300
  EMail: [email protected]


  Daniel Torrey
  Computer and Information Services, University of Minnesota
  Room 152 Shepherd Labs
  100 Union Street SE
  Minneapolis, MN 55455

  Phone: (612) 625 1300
  EMail: [email protected]


  Bob Alberti
  Computer and Information Services, University of Minnesota
  Room 152 Shepherd Labs
  100 Union Street SE
  Minneapolis, MN 55455

  Phone: (612) 625 1300
  EMail: [email protected]



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