Ladder Diagrams » History » Version 8
laforge, 04/21/2022 05:36 PM
| 1 | 1 | laforge | h1. Ladder Diagrams |
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| 2 | |||
| 3 | 5 | laforge | Some ladder diagrams about the proposed OCTOI protocol. |
| 4 | |||
| 5 | 7 | laforge | h2. Initial connection setup (success without redirect) |
| 6 | |||
| 7 | 4 | laforge | Note: we might want to do something for DoS mitigation at the very initial step? |
| 8 | |||
| 9 | 1 | laforge | {{mscgen_link() |
| 10 | msc { |
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| 11 | hscale=2; |
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| 12 | 7 | laforge | client [label="Client"], server [label="Server (main port)"], hlr [label="HLR (database)"]; |
| 13 | |||; |
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| 14 | --- [label="Initial connection attempt from client to well-known server/port"]; |
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| 15 | |||; |
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| 16 | client => server [label="SERVICE_REQ (user_id)"]; |
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| 17 | server <=> hlr [label="Obtain auth vectors"]; |
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| 18 | client <= server [label="AUTH_REQ (rand, autn)"]; |
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| 19 | client => server [label="AUTH_RESP (res)"]; |
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| 20 | server box server [label="Verify res == xres?"]; |
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| 21 | client <= server [label="SERVICE_ACK"]; |
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| 22 | ...; |
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| 23 | client <=> server [label="TDMoIP"]; |
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| 24 | ...; |
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| 25 | } |
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| 26 | }} |
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| 27 | |||
| 28 | h2. Initial connection setup (success with redirect) |
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| 29 | |||
| 30 | Note: we might want to do something for DoS mitigation at the very initial step? |
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| 31 | |||
| 32 | {{mscgen_link() |
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| 33 | msc { |
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| 34 | hscale=2; |
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| 35 | 1 | laforge | client [label="Client"], server [label="Server (main port)"], worker [label="Server (worker port)"], hlr [label="HLR (database)"]; |
| 36 | |||; |
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| 37 | --- [label="Initial connection attempt from client to well-known server/port"]; |
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| 38 | |||; |
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| 39 | 6 | laforge | client => server [label="SERVICE_REQ (user_id)"]; |
| 40 | 1 | laforge | server <=> hlr [label="Obtain auth vectors"]; |
| 41 | client <= server [label="AUTH_REQ (rand, autn)"]; |
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| 42 | client => server [label="AUTH_RESP (res)"]; |
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| 43 | server box server [label="Verify res == xres?"]; |
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| 44 | server => worker [label="Create worker socket"]; |
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| 45 | server note server [label="Server accepts client + redirects to worker IP+Port"]; |
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| 46 | 6 | laforge | client <= server [label="REDIR_CMD (worker IP:Port, token)"]; |
| 47 | 1 | laforge | ...; |
| 48 | 6 | laforge | client => worker [label="SERVICE_REQ (user_id, token)"]; |
| 49 | worker box worker [label="Verify user_id + token, or\nperform AUTH_REQ/AUTH_CMD again"]; |
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| 50 | client <= worker [label="SERVICE_ACK"]; |
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| 51 | 1 | laforge | ...; |
| 52 | client <=> worker [label="TDMoIP"]; |
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| 53 | 2 | laforge | ...; |
| 54 | 3 | laforge | } |
| 55 | }} |
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| 56 | |||
| 57 | 1 | laforge | Both sides operate timeouts, if those occur, the entire procedure is aborted. |
| 58 | 7 | laforge | |
| 59 | h2. Initial connection setup (failure) |
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| 60 | |||
| 61 | Note: we might want to do something for DoS mitigation at the very initial step? |
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| 62 | |||
| 63 | {{mscgen_link() |
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| 64 | msc { |
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| 65 | hscale=2; |
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| 66 | client [label="Client"], server [label="Server (main port)"], hlr [label="HLR (database)"]; |
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| 67 | |||; |
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| 68 | --- [label="Initial connection attempt from client to well-known server/port"]; |
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| 69 | |||; |
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| 70 | client => server [label="SERVICE_REQ (user_id)"]; |
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| 71 | server <=> hlr [label="Obtain auth vectors"]; |
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| 72 | client <= server [label="AUTH_REQ (rand, autn)"]; |
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| 73 | client => server [label="AUTH_RESP (res)"]; |
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| 74 | server box server [label="Verify res == xres?"]; |
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| 75 | client <= server [label="SERVICE_REJ"]; |
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| 76 | ...; |
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| 77 | } |
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| 78 | }} |
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| 79 | 4 | laforge | |
| 80 | 3 | laforge | h2. subsequent re-authentication |
| 81 | |||
| 82 | {{mscgen_link() |
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| 83 | msc { |
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| 84 | hscale=2; |
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| 85 | client [label="Client"], server [label="Server (main port)"], worker [label="Server (worker port)"], hlr [label="HLR (database)"]; |
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| 86 | |||; |
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| 87 | 2 | laforge | --- [label="At any later point in time, whenever the server wants"]; |
| 88 | worker <=> hlr [label="Obtain auth vectors"]; |
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| 89 | client <= worker [label="AUTH_REQ (rand, autn)"]; |
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| 90 | client => worker [label="AUTH_RESP (res)"]; |
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| 91 | 1 | laforge | worker box worker [label="Verify res == xres?"]; |
| 92 | } |
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| 93 | }} |
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| 94 | 4 | laforge | |
| 95 | If there is no response to the AUTH_REQ within a timeout, up to three re-transmissions are attempted, before declaring the link as dead. |
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| 96 | |||
| 97 | h2. dead peer detection |
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| 98 | |||
| 99 | Procedure operates on on both sides: |
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| 100 | |||
| 101 | * Every time a packet is received, a timer is re-started. If the timer expires, the link is declared dead, and no further TDMoIP packets are transmitted. |
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| 102 | ** On the server side, a dead link means the worker port is closed. |
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| 103 | ** On the client side, a dead link means the client needs to start like in an initial connection attempt by contacting the well-known server port with a HELLO_REQ. |
