putty-source/utils/nullkey.c

#include "misc.h"
#include "ssh.h"

unsigned nullkey_supported_flags(const ssh_keyalg *self)
{
    return 0;
}

const char *nullkey_alternate_ssh_id(const ssh_keyalg *self, unsigned flags)
{
    /* There are no alternate ids */
    return self->ssh_id;
}
ssh_keyalg: new method 'alternate_ssh_id'. Previously, the fact that "ssh-rsa" sometimes comes with two subtypes "rsa-sha2-256" and "rsa-sha2-512" was known to three different parts of the code - two in userauth and one in transport. Now the knowledge of what those ids are, which one goes with which signing flags, and which key types have subtypes at all, is centralised into a method of the key algorithm, and all those locations just query it. This will enable the introduction of further key algorithms that have a parallel upgrade system. 2022-04-19 16:27:54 +00:00			`#include "misc.h"`
Make ssh_keyalg's supported_flags a method. It's a class method rather than an object method, so it doesn't allow keys with the same algorithm to make different choices about what flags they support. But that's not what I wanted it for: the real purpose is to allow one key algorithm to delegate supported_flags to another, by having its method implementation call the one from the delegate class. (If only C's compile/link model permitted me to initialise a field of one global const struct variable to be a copy of that of another, I wouldn't need the runtime overhead of this method! But object file formats don't let you even specify that.) Most key algorithms support no flags at all, so they all want to use the same implementation of this method. So I've started a file of stubs utils/nullkey.c to contain the common stub version. 2022-04-19 16:05:36 +00:00			`#include "ssh.h"`

			`unsigned nullkey_supported_flags(const ssh_keyalg *self)`
			`{`
			`return 0;`
			`}`
ssh_keyalg: new method 'alternate_ssh_id'. Previously, the fact that "ssh-rsa" sometimes comes with two subtypes "rsa-sha2-256" and "rsa-sha2-512" was known to three different parts of the code - two in userauth and one in transport. Now the knowledge of what those ids are, which one goes with which signing flags, and which key types have subtypes at all, is centralised into a method of the key algorithm, and all those locations just query it. This will enable the introduction of further key algorithms that have a parallel upgrade system. 2022-04-19 16:27:54 +00:00
			`const char nullkey_alternate_ssh_id(const ssh_keyalg self, unsigned flags)`
			`{`
			`/* There are no alternate ids */`
			`return self->ssh_id;`
			`}`