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New centralised binary-data marshalling system.

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I've finally got tired of all the code throughout PuTTY that repeats
the same logic about how to format the SSH binary primitives like
uint32, string, mpint. We've got reasonably organised code in ssh.c
that appends things like that to 'struct Packet'; something similar in
sftp.c which repeats a lot of the work; utility functions in various
places to format an mpint to feed to one or another hash function; and
no end of totally ad-hoc stuff in functions like public key blob
formatters which actually have to _count up_ the size of data
painstakingly, then malloc exactly that much and mess about with
PUT_32BIT.

It's time to bring all of that into one place, and stop repeating
myself in error-prone ways everywhere. The new marshal.h defines a
system in which I centralise all the actual marshalling functions, and
then layer a touch of C macro trickery on top to allow me to (look as
if I) pass a wide range of different types to those functions, as long
as the target type has been set up in the right way to have a write()
function.

This commit adds the new header and source file, and sets up some
general centralised types (strbuf and the various hash-function
contexts like SHA_State), but doesn't use the new calls for anything
yet.

(I've also renamed some internal functions in import.c which were
using the same names that I've just defined macros over. That won't
last long - those functions are going to go away soon, so the changed
names are strictly temporary.)
This commit is contained in:
Simon Tatham
2018-05-24 09:17:13 +01:00
parent bff128fea9
commit 0e3082ee89
14 changed files with 341 additions and 33 deletions
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44
import.c
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@ -274,7 +274,7 @@ static int ber_write_id_len(void *dest, int id, int length, int flags)
return len;
}
static int put_uint32(void *target, unsigned val)
static int write_uint32(void *target, unsigned val)
{
unsigned char *d = (unsigned char *)target;
@ -282,7 +282,7 @@ static int put_uint32(void *target, unsigned val)
return 4;
}
static int put_string(void *target, const void *data, int len)
static int write_string(void *target, const void *data, int len)
{
unsigned char *d = (unsigned char *)target;
@ -291,9 +291,9 @@ static int put_string(void *target, const void *data, int len)
return len+4;
}
static int put_string_z(void *target, const char *string)
static int write_string_z(void *target, const char *string)
{
return put_string(target, string, strlen(string));
return write_string(target, string, strlen(string));
}
static int put_mp(void *target, void *data, int len)
@ -1796,27 +1796,27 @@ int openssh_new_write(const Filename *filename, struct ssh2_userkey *key,
/* Cipher and kdf names, and kdf options. */
if (!passphrase) {
memset(bcrypt_salt, 0, sizeof(bcrypt_salt)); /* prevent warnings */
p += put_string_z(p, "none");
p += put_string_z(p, "none");
p += put_string_z(p, "");
p += write_string_z(p, "none");
p += write_string_z(p, "none");
p += write_string_z(p, "");
} else {
unsigned char *q;
for (i = 0; i < (int)sizeof(bcrypt_salt); i++)
bcrypt_salt[i] = random_byte();
p += put_string_z(p, "aes256-ctr");
p += put_string_z(p, "bcrypt");
p += write_string_z(p, "aes256-ctr");
p += write_string_z(p, "bcrypt");
q = p;
p += 4;
p += put_string(p, bcrypt_salt, sizeof(bcrypt_salt));
p += put_uint32(p, bcrypt_rounds);
p += write_string(p, bcrypt_salt, sizeof(bcrypt_salt));
p += write_uint32(p, bcrypt_rounds);
PUT_32BIT_MSB_FIRST(q, (unsigned)(p - (q+4)));
}
/* Number of keys. */
p += put_uint32(p, 1);
p += write_uint32(p, 1);
/* Public blob. */
p += put_string(p, pubblob, publen);
p += write_string(p, pubblob, publen);
/* Begin private section. */
private_section_length_field = p;
@ -1827,17 +1827,17 @@ int openssh_new_write(const Filename *filename, struct ssh2_userkey *key,
checkint = 0;
for (i = 0; i < 4; i++)
checkint = (checkint << 8) + random_byte();
p += put_uint32(p, checkint);
p += put_uint32(p, checkint);
p += write_uint32(p, checkint);
p += write_uint32(p, checkint);
/* Private key. The main private blob goes inline, with no string
* wrapper. */
p += put_string_z(p, key->alg->name);
p += write_string_z(p, key->alg->name);
memcpy(p, privblob, privlen);
p += privlen;
/* Comment. */
p += put_string_z(p, key->comment);
p += write_string_z(p, key->comment);
/* Pad out the encrypted section. */
padvalue = 1;
@ -2425,11 +2425,11 @@ struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
alg = &ssh_rsa;
pos = 0;
pos += put_string(blob+pos, "ssh-rsa", 7);
pos += write_string(blob+pos, "ssh-rsa", 7);
pos += put_mp(blob+pos, e.start, e.bytes);
pos += put_mp(blob+pos, n.start, n.bytes);
publen = pos;
pos += put_string(blob+pos, d.start, d.bytes);
pos += write_string(blob+pos, d.start, d.bytes);
pos += put_mp(blob+pos, q.start, q.bytes);
pos += put_mp(blob+pos, p.start, p.bytes);
pos += put_mp(blob+pos, u.start, u.bytes);
@ -2456,7 +2456,7 @@ struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
alg = &ssh_dss;
pos = 0;
pos += put_string(blob+pos, "ssh-dss", 7);
pos += write_string(blob+pos, "ssh-dss", 7);
pos += put_mp(blob+pos, p.start, p.bytes);
pos += put_mp(blob+pos, q.start, q.bytes);
pos += put_mp(blob+pos, g.start, g.bytes);
@ -2597,10 +2597,10 @@ int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
pos = 0;
PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4;
pos += 4; /* length field, fill in later */
pos += put_string(outblob+pos, type, strlen(type));
pos += write_string(outblob+pos, type, strlen(type));
{
const char *ciphertype = passphrase ? "3des-cbc" : "none";
pos += put_string(outblob+pos, ciphertype, strlen(ciphertype));
pos += write_string(outblob+pos, ciphertype, strlen(ciphertype));
}
lenpos = pos; /* remember this position */
pos += 4; /* encrypted-blob size */