| 1 | #include "includes.h" |
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| 2 | #include "ssh.h" |
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| 3 | #include "emulate.h" |
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| 4 | |
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| 5 | unsigned long emulation_information = 0; |
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| 6 | |
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| 7 | /* check_emulation: take the remote party's version number as |
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| 8 | arguments and return our possibly modified version number back |
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| 9 | (relevant only for clients). |
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| 10 | |
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| 11 | Return values: |
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| 12 | EMULATE_VERSION_OK means we can work together |
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| 13 | |
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| 14 | EMULATE_VERSION_TOO_OLD if the other party has too old version |
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| 15 | which we cannot emulate, |
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| 16 | |
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| 17 | EMULATE_MAJOR_VERSION_MISMATCH if the other party has different |
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| 18 | major version and thus will probably not understand anything we |
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| 19 | say, and |
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| 20 | |
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| 21 | EMULATE_VERSION_NEWER if the other party has never code than we |
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| 22 | have. |
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| 23 | |
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| 24 | */ |
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| 25 | |
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| 26 | int check_emulation(int remote_major, int remote_minor, |
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| 27 | int *return_major, int *return_minor) |
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| 28 | { |
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| 29 | if (return_major) |
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| 30 | *return_major = PROTOCOL_MAJOR; |
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| 31 | if (return_minor) |
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| 32 | { |
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| 33 | if (remote_minor < PROTOCOL_MINOR) |
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| 34 | *return_minor = remote_minor; |
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| 35 | else |
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| 36 | *return_minor = PROTOCOL_MINOR; |
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| 37 | } |
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| 38 | |
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| 39 | if (remote_major < PROTOCOL_MAJOR) |
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| 40 | return EMULATE_MAJOR_VERSION_MISMATCH; |
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| 41 | |
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| 42 | if (remote_major == 1 && remote_minor == 0) |
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| 43 | return EMULATE_VERSION_TOO_OLD; /* We no longer support 1.0. */ |
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| 44 | |
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| 45 | if (remote_major == 1 && remote_minor <= 3) |
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| 46 | { |
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| 47 | debug("Old channel code will be emulated."); |
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| 48 | emulation_information |= EMULATE_OLD_CHANNEL_CODE; |
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| 49 | } |
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| 50 | |
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| 51 | if (remote_major == 1 && remote_minor <= 4) |
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| 52 | { |
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| 53 | emulation_information |= EMULATE_OLD_AGENT_BUG; |
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| 54 | debug("Agent forwarding disabled (remote protocol too old)"); |
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| 55 | } |
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| 56 | |
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| 57 | if (remote_major > PROTOCOL_MAJOR || |
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| 58 | (remote_major == PROTOCOL_MAJOR && remote_minor > PROTOCOL_MINOR)) |
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| 59 | { |
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| 60 | /* The remote software is newer than we. If we are the client, |
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| 61 | no matter - the server will decide. If we are the server, we |
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| 62 | cannot emulate a newer client and decide to stop. */ |
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| 63 | return EMULATE_VERSION_NEWER; |
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| 64 | } |
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| 65 | |
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| 66 | return EMULATE_VERSION_OK; |
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| 67 | } |
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