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Move binary packet protocols and censoring out of ssh.c.

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sshbpp.h now defines a classoid that encapsulates both directions of
an SSH binary packet protocol - that is, a system for reading a
bufchain of incoming data and turning it into a stream of PktIn, and
another system for taking a PktOut and turning it into data on an
outgoing bufchain.

The state structure in each of those files contains everything that
used to be in the 'rdpkt2_state' structure and its friends, and also
quite a lot of bits and pieces like cipher and MAC states that used to
live in the main Ssh structure.

One minor effect of this layer separation is that I've had to extend
the packet dispatch table by one, because the BPP layer can no longer
directly trigger sending of SSH_MSG_UNIMPLEMENTED for a message too
short to have a type byte. Instead, I extend the PktIn type field to
use an out-of-range value to encode that, and the easiest way to make
that trigger an UNIMPLEMENTED message is to have the dispatch table
contain an entry for it.

(That's a system that may come in useful again - I was also wondering
about inventing a fake type code to indicate network EOF, so that that
could be propagated through the layers and be handled by whichever one
currently knew best how to respond.)

I've also moved the packet-censoring code into its own pair of files,
partly because I was going to want to do that anyway sooner or later,
and mostly because it's called from the BPP code, and the SSH-2
version in particular has to be called from both the main SSH-2 BPP
and the bare unencrypted protocol used for connection sharing. While I
was at it, I took the opportunity to merge the outgoing and incoming
censor functions, so that the parts that were common between them
(e.g. CHANNEL_DATA messages look the same in both directions) didn't
need to be repeated.
This commit is contained in:
Simon Tatham
2018-06-09 09:09:10 +01:00
parent 9e3522a971
commit 679fa90dfe
9 changed files with 1655 additions and 1375 deletions
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24
ssh.h
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@ -129,8 +129,21 @@ typedef enum {
SSH2_PKTCTX_KBDINTER
} Pkt_ACtx;
PktOut *ssh1_pkt_init(int pkt_type);
PktOut *ssh2_pkt_init(int pkt_type);
typedef struct PacketLogSettings {
int omit_passwords, omit_data;
Pkt_KCtx kctx;
Pkt_ACtx actx;
} PacketLogSettings;
#define MAX_BLANKS 4 /* no packet needs more censored sections than this */
int ssh1_censor_packet(
const PacketLogSettings *pls, int type, int sender_is_client,
ptrlen pkt, logblank_t *blanks);
int ssh2_censor_packet(
const PacketLogSettings *pls, int type, int sender_is_client,
ptrlen pkt, logblank_t *blanks);
PktOut *ssh_new_packet(void);
void ssh_unref_packet(PktIn *pkt);
void ssh_free_pktout(PktOut *pkt);
@ -1106,6 +1119,13 @@ void platform_ssh_share_cleanup(const char *name);
#define SSH2_MSG_USERAUTH_GSSAPI_ERRTOK 65
#define SSH2_MSG_USERAUTH_GSSAPI_MIC 66
/* Virtual packet type, for packets too short to even have a type */
#define SSH_MSG_NO_TYPE_CODE 0x100
/* Given that virtual packet types exist, this is how big the dispatch
* table has to be */
#define SSH_MAX_MSG 0x101
/*
* SSH-1 agent messages.
*/