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ssh: Rewrite a function for better maintainability

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* agent/command-ssh.c (ssh_signature_encoder_dsa): Rewrite.
--

Using es_fopenmem instead of a preallocated buffer is safer and easier
to read.
(cherry picked from commit f76a0312c3)
This commit is contained in:
Werner Koch 2012-12-11 14:50:34 +01:00
parent 9011625791
commit cf7f930327
1 changed files with 41 additions and 40 deletions
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81
agent/command-ssh.c
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@ -1190,65 +1190,51 @@ ssh_signature_encoder_dsa (estream_t signature_blob, gcry_mpi_t *mpis)
by the KEY_SPEC, SECRET, MPIS and COMMENT, which is to be stored in
*SEXP. Returns usual error code. */
static gpg_error_t
sexp_key_construct (gcry_sexp_t *sexp,
sexp_key_construct (gcry_sexp_t *r_sexp,
ssh_key_type_spec_t key_spec, int secret,
gcry_mpi_t *mpis, const char *comment)
{
const char *key_identifier[] = { "public-key", "private-key" };
gcry_sexp_t sexp_new;
char *sexp_template;
size_t sexp_template_n;
gpg_error_t err;
gcry_sexp_t sexp_new = NULL;
char *formatbuf = NULL;
void **arg_list = NULL;
int arg_idx;
estream_t format;
const char *elems;
size_t elems_n;
unsigned int i;
unsigned int j;
void **arg_list;
unsigned int i, j;
err = 0;
sexp_new = NULL;
arg_list = NULL;
if (secret)
elems = key_spec.elems_sexp_order;
else
elems = key_spec.elems_key_public;
elems_n = strlen (elems);
/*
Calculate size for sexp_template_n:
"(%s(%s<mpis>)(comment%s))" -> 20 + sizeof (<mpis>).
mpi: (X%m) -> 5.
*/
sexp_template_n = 20 + (elems_n * 5);
sexp_template = xtrymalloc (sexp_template_n);
if (! sexp_template)
format = es_fopenmem (0, "a+b");
if (!format)
{
err = gpg_error_from_syserror ();
goto out;
}
/* Key identifier, algorithm identifier, mpis, comment. */
arg_list = xtrymalloc (sizeof (*arg_list) * (2 + elems_n + 1));
if (! arg_list)
/* Key identifier, algorithm identifier, mpis, comment, and a NULL
as a safeguard. */
arg_list = xtrymalloc (sizeof (*arg_list) * (2 + elems_n + 1 + 1));
if (!arg_list)
{
err = gpg_error_from_syserror ();
goto out;
}
arg_idx = 0;
i = 0;
arg_list[i++] = &key_identifier[secret];
arg_list[i++] = &key_spec.identifier;
es_fputs ("(%s(%s", format);
arg_list[arg_idx++] = &key_identifier[secret];
arg_list[arg_idx++] = &key_spec.identifier;
*sexp_template = 0;
sexp_template_n = 0;
sexp_template_n = sprintf (sexp_template + sexp_template_n, "(%%s(%%s");
for (i = 0; i < elems_n; i++)
{
sexp_template_n += sprintf (sexp_template + sexp_template_n, "(%c%%m)",
elems[i]);
es_fprintf (format, "(%c%%m)", elems[i]);
if (secret)
{
for (j = 0; j < elems_n; j++)
@ -1257,27 +1243,42 @@ sexp_key_construct (gcry_sexp_t *sexp,
}
else
j = i;
arg_list[i + 2] = &mpis[j];
arg_list[arg_idx++] = &mpis[j];
}
sexp_template_n += sprintf (sexp_template + sexp_template_n,
")(comment%%s))");
es_fputs (")(comment%s))", format);
arg_list[arg_idx++] = &comment;
arg_list[arg_idx] = NULL;
arg_list[i + 2] = &comment;
es_putc (0, format);
if (es_ferror (format))
{
err = gpg_error_from_syserror ();
goto out;
}
if (es_fclose_snatch (format, &formatbuf, NULL))
{
err = gpg_error_from_syserror ();
goto out;
}
format = NULL;
err = gcry_sexp_build_array (&sexp_new, NULL, sexp_template, arg_list);
log_debug ("sexp formatbuf='%s' nargs=%d\n", formatbuf, arg_idx);
err = gcry_sexp_build_array (&sexp_new, NULL, formatbuf, arg_list);
if (err)
goto out;
*sexp = sexp_new;
*r_sexp = sexp_new;
err = 0;
out:
es_fclose (format);
xfree (arg_list);
xfree (sexp_template);
xfree (formatbuf);
return err;
}
/* This functions breaks up the key contained in the S-Expression SEXP
according to KEY_SPEC. The MPIs are bundled in a newly create
list, which is to be stored in MPIS; a newly allocated string