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Turn SSH-2 MACs into a classoid.

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This piece of tidying-up has come out particularly well in terms of
saving tedious repetition and boilerplate. I've managed to remove
three pointless methods from every MAC implementation by means of
writing them once centrally in terms of the implementation-specific
methods; another method (hmacmd5_sink) vanished because I was able to
make the interface type 'ssh2_mac' be directly usable as a BinarySink
by way of a new delegation system; and because all the method
implementations can now find their own vtable, I was even able to
merge a lot of keying and output functions that had previously
differed only in length parameters by having them look up the lengths
in whatever vtable they were passed.
This commit is contained in:
Simon Tatham
2018-09-13 16:15:17 +01:00
parent 229af2b5bf
commit 853bd8b284
12 changed files with 294 additions and 397 deletions
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61
ssh.h
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@ -374,11 +374,12 @@ void MD5Init(struct MD5Context *context);
void MD5Final(unsigned char digest[16], struct MD5Context *context);
void MD5Simple(void const *p, unsigned len, unsigned char output[16]);
void *hmacmd5_make_context(ssh2_cipher *);
void hmacmd5_free_context(void *handle);
void hmacmd5_key(void *handle, void const *key, int len);
void hmacmd5_do_hmac(void *handle, unsigned char const *blk, int len,
unsigned char *hmac);
struct hmacmd5_context;
struct hmacmd5_context *hmacmd5_make_context(void);
void hmacmd5_free_context(struct hmacmd5_context *ctx);
void hmacmd5_key(struct hmacmd5_context *ctx, void const *key, int len);
void hmacmd5_do_hmac(struct hmacmd5_context *ctx,
unsigned char const *blk, int len, unsigned char *hmac);
int supports_sha_ni(void);
@ -476,7 +477,7 @@ struct ssh2_cipheralg {
#define SSH_CIPHER_SEPARATE_LENGTH 2
const char *text_name;
/* If set, this takes priority over other MAC. */
const struct ssh_mac *required_mac;
const struct ssh2_macalg *required_mac;
};
#define ssh2_cipher_new(alg) ((alg)->new(alg))
@ -496,24 +497,36 @@ struct ssh2_ciphers {
const struct ssh2_cipheralg *const *list;
};
struct ssh_mac {
struct ssh2_macalg;
typedef struct ssh2_mac {
const struct ssh2_macalg *vt;
BinarySink_DELEGATE_IMPLEMENTATION;
} ssh2_mac;
struct ssh2_macalg {
/* Passes in the cipher context */
void *(*make_context)(ssh2_cipher *);
void (*free_context)(void *);
void (*setkey) (void *, const void *key);
/* whole-packet operations */
void (*generate) (void *, void *blk, int len, unsigned long seq);
int (*verify) (void *, const void *blk, int len, unsigned long seq);
/* partial-packet operations */
void (*start) (void *);
BinarySink *(*sink) (void *);
void (*genresult) (void *, unsigned char *);
int (*verresult) (void *, unsigned char const *);
ssh2_mac *(*new)(const struct ssh2_macalg *alg, ssh2_cipher *cipher);
void (*free)(ssh2_mac *);
void (*setkey)(ssh2_mac *, const void *key);
void (*start)(ssh2_mac *);
void (*genresult)(ssh2_mac *, unsigned char *);
const char *name, *etm_name;
int len, keylen;
const char *text_name;
};
#define ssh2_mac_new(alg, cipher) ((alg)->new(alg, cipher))
#define ssh2_mac_free(ctx) ((ctx)->vt->free(ctx))
#define ssh2_mac_setkey(ctx, key) ((ctx)->vt->free(ctx, key))
#define ssh2_mac_start(ctx) ((ctx)->vt->start(ctx))
#define ssh2_mac_genresult(ctx, out) ((ctx)->vt->genresult(ctx, out))
#define ssh2_mac_alg(ctx) ((ctx)->vt)
/* Centralised 'methods' for ssh2_mac, defined in sshmac.c */
int ssh2_mac_verresult(ssh2_mac *, const void *);
void ssh2_mac_generate(ssh2_mac *, void *, int, unsigned long seq);
int ssh2_mac_verify(ssh2_mac *, const void *, int, unsigned long seq);
struct ssh_hash {
void *(*init)(void); /* also allocates context */
void *(*copy)(const void *);
@ -628,12 +641,12 @@ extern const ssh_keyalg ssh_ecdsa_ed25519;
extern const ssh_keyalg ssh_ecdsa_nistp256;
extern const ssh_keyalg ssh_ecdsa_nistp384;
extern const ssh_keyalg ssh_ecdsa_nistp521;
extern const struct ssh_mac ssh_hmac_md5;
extern const struct ssh_mac ssh_hmac_sha1;
extern const struct ssh_mac ssh_hmac_sha1_buggy;
extern const struct ssh_mac ssh_hmac_sha1_96;
extern const struct ssh_mac ssh_hmac_sha1_96_buggy;
extern const struct ssh_mac ssh_hmac_sha256;
extern const struct ssh2_macalg ssh_hmac_md5;
extern const struct ssh2_macalg ssh_hmac_sha1;
extern const struct ssh2_macalg ssh_hmac_sha1_buggy;
extern const struct ssh2_macalg ssh_hmac_sha1_96;
extern const struct ssh2_macalg ssh_hmac_sha1_96_buggy;
extern const struct ssh2_macalg ssh_hmac_sha256;
typedef struct AESContext AESContext;
AESContext *aes_make_context(void);