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Regarding proffered official ICP (RFC0143)

IP.com Disclosure Number: IPCOM000002257D
Original Publication Date: 1971-May-03
Included in the Prior Art Database: 2000-Sep-12
Document File: 3 page(s) / 7K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

W. Naylor: AUTHOR [+4]

Abstract

We should like to comment on a race condition discovered in the ICP as proposed in NWG/RFC #123. The problem arises when the server attempts to initiate a second connection to the user's receive socket and the first connection is not yet closed. Using a similar notation to that of NWG/RFC #123 the following table illustrates the sequence of events in the proferred and proposed ICP. The last two columns indicate which actions must be completed before the current action may be initiated. User and Server are third level programs, and UNCP and SNCP are the users NCP and Servers NCP respectively. Allocates have not been included since they add nothing to the argument.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 45% of the total text.

Network Working Group W. Naylor

Request for Comments #143 J. Wong

NIC #6728 C. Kline

Categories: D.1, D.3 J. Postel

Obsoletes: None UCLA - NMC

Updates: 123, 145 3 May 1971

Regarding Proferred Official ICP

We should like to comment on a race condition discovered in the ICP as

proposed in NWG/RFC #123. The problem arises when the server attempts

to initiate a second connection to the user's receive socket and the

first connection is not yet closed. Using a similar notation to that of

NWG/RFC #123 the following table illustrates the sequence of events in

the proferred and proposed ICP. The last two columns indicate which

actions must be completed before the current action may be initiated.

User and Server are third level programs, and UNCP and SNCP are the

users NCP and Servers NCP respectively. Allocates have not been

included since they add nothing to the argument.

Required Predecessors

---------------------

Reference # Action Initiator "Proferred" Proposed

----------- ------ --------- ----------- --------

1 Listen(L,32) Server -- --

2 Init(U,L,32) User -- --

3 RTS(U,L,'l') UNCP 2 2

4 STR(L,U,32) SNCP 1 and 3 1 and 3

5 Send(L,S) Server 4 4

6 SEND('l',S) SNCP 5 5

7 RECEIVE('l',S) UNCP 6 6

8 Receive(U,S) User 7 7

9 Close(L) Server 5 5

10 CLS(L,U) SNCP 9 and 7 9 and 7

11 Close(U) User 8 not used

12 CLS(U,L) UNCP 11 10

NWG Regarding Proferred Official ICP RFC 143

Required Predecessors

---------------------

Reference # Action Initiator "Proferred" Proposed

----------- ------ --------- ----------- --------

13 Init(S,U+1,B ) Server 9 9

u

14 RTS(S,U+1,'l' ) SNCP 13 13

2

15 Init(S+1,U,B ) Server 13 14 and 18

s

16 STR(S+1,U,B ) SNCP 15 15

s

17 Init(U+1,S,B ) User 11 12

u

...