[Freeipa-devel] [PATCH 0064] Create ipa-otp-decrement 389DS plugin
Nathaniel McCallum
npmccallum at redhat.com
Mon Sep 29 18:30:53 UTC 2014
On Mon, 2014-09-22 at 09:32 -0400, Simo Sorce wrote:
> On Sun, 21 Sep 2014 22:33:47 -0400
> Nathaniel McCallum <npmccallum at redhat.com> wrote:
>
> Comments inline.
>
> > +
> > +#define ch_malloc(type) \
> > + (type*) slapi_ch_malloc(sizeof(type))
> > +#define ch_calloc(count, type) \
> > + (type*) slapi_ch_calloc(count, sizeof(type))
> > +#define ch_free(p) \
> > + slapi_ch_free((void**) &(p))
>
> please do not redefine slapi functions, it just makes it harder to know
> what you used.
>
>
> > +typedef struct {
> > + bool exists;
> > + long long value;
> > +} counter;
>
>
> please no typedefs of structures, use "struct counter { ... };" and
> reference it as "struct counter" in the code.
>
> Btw, FWIW you could use a value of -1 to indicate non-existence of the
> counter value, given counters can only be positive, this would avoid
> the need for a struct.
>
> > +static int
> > +send_error(Slapi_PBlock *pb, int rc, char *template, ...)
> > +{
> > + va_list ap;
> > + int res;
> > +
> > + va_start(ap, template);
> > + res = vsnprintf(NULL, 0, template, ap);
> > + va_end(ap);
> > +
> > + if (res > 0) {
> > + char str[res + 1];
> > +
> > + va_start(ap, template);
> > + res = vsnprintf(str, sizeof(str), template, ap);
> > + va_end(ap);
> > +
> > + if (res > 0)
> > + slapi_send_ldap_result(pb, rc, NULL, str, 0, NULL);
> > + }
> > +
> > + if (res <= 0)
> > + slapi_send_ldap_result(pb, rc, NULL, NULL, 0, NULL);
> > +
> > + slapi_pblock_set(pb, SLAPI_RESULT_CODE, &rc);
> > + return rc;
> > +}
>
> This function seem not really useful, you use send_error() only at the
> end of one single function where you could have the classic scheme of
> using a done: label and just use directly slapi_ch_smprintf. This would
> remove the need to use vsnprintf and all the va_ machinery which is
> more than 50% of this function.
>
>
> > +static long long
> > +get_value(const LDAPMod *mod, long long def)
> > +{
> > + const struct berval *bv;
> > + long long val;
> > +
> > + if (mod == NULL)
> > + return def;
> > +
> > + if (mod->mod_vals.modv_bvals == NULL)
> > + return def;
> > +
> > + bv = mod->mod_vals.modv_bvals[0];
> > + if (bv == NULL)
> > + return def;
>
> In general (here and elsewhere) I prefer to always use {} in if clauses.
> I have been bitten enough time by people adding an instruction that
> should be in the braces but forgot to add braces (defensive programming
> style). But up to you.
>
> > + char buf[bv->bv_len + 1];
> > + memcpy(buf, bv->bv_val, bv->bv_len);
> > + buf[sizeof(buf)-1] = '\0';
> > +
> > + val = strtoll(buf, NULL, 10);
> > + if (val == LLONG_MIN || val == LLONG_MAX)
> > + return def;
> > +
> > + return val;
> > +}
> > +
> > +static struct berval **
> > +make_berval_array(long long value)
> > +{
> > + struct berval **bvs;
> > +
> > + bvs = ch_calloc(2, struct berval*);
> > + bvs[0] = ch_malloc(struct berval);
> > + bvs[0]->bv_val = slapi_ch_smprintf("%lld", value);
> > + bvs[0]->bv_len = strlen(bvs[0]->bv_val);
> > +
> > + return bvs;
> > +}
> > +
> > +static LDAPMod *
> > +make_ldapmod(int op, const char *attr, long long value)
> > +{
> > + LDAPMod *mod;
> > +
> > + mod = (LDAPMod*) slapi_ch_calloc(1, sizeof(LDAPMod));
> > + mod->mod_op = op | LDAP_MOD_BVALUES;
> > + mod->mod_type = slapi_ch_strdup(attr);
> > + mod->mod_bvalues = make_berval_array(value);
> > +
> > + return mod;
> > +}
> > +
> > +static void
> > +convert_ldapmod_to_bval(LDAPMod *mod)
> > +{
> > + if (mod == NULL || (mod->mod_op & LDAP_MOD_BVALUES))
> > + return;
> > +
> > + mod->mod_op |= LDAP_MOD_BVALUES;
> > +
> > + if (mod->mod_values == NULL) {
> > + mod->mod_bvalues = NULL;
> > + return;
> > + }
> > +
> > + for (size_t i = 0; mod->mod_values[i] != NULL; i++) {
> > + struct berval *bv = ch_malloc(struct berval);
> > + bv->bv_val = mod->mod_values[i];
> > + bv->bv_len = strlen(bv->bv_val);
> > + mod->mod_bvalues[i] = bv;
> > + }
> > +}
> > +
> > +static counter
> > +get_counter(Slapi_Entry *entry, const char *attr)
> > +{
> > + Slapi_Attr *sattr = NULL;
> > +
> > + return (counter) {
> > + slapi_entry_attr_find(entry, attr, &sattr) == 0,
> > + slapi_entry_attr_get_longlong(entry, attr)
> > + };
> > +}
> > +
> > +static void
> > +berval_free_array(struct berval ***bvals)
> > +{
> > + for (size_t i = 0; (*bvals)[i] != NULL; i++) {
> > + ch_free((*bvals)[i]->bv_val);
> > + ch_free((*bvals)[i]);
> > + }
> > +
> > + slapi_ch_free((void**) bvals);
> > +}
> > +
> > +static bool
> > +is_replication(Slapi_PBlock *pb)
> > +{
> > + int repl = 0;
> > + slapi_pblock_get(pb, SLAPI_IS_REPLICATED_OPERATION, &repl);
> > + return repl != 0;
> > +}
> > +
> > +static const char *
> > +get_attribute(Slapi_Entry *entry)
> > +{
> > + static struct {
> > + const char *clss;
> > + const char *attr;
> > + } table[] = {
> > + { "ipatokenHOTP", "ipatokenHOTPcounter" },
> > + { "ipatokenTOTP", "ipatokenTOTPwatermark" },
> > + { NULL, NULL }
> > + };
> > +
> > + const char *attr = NULL;
> > + char **clsses = NULL;
> > +
> > + clsses = slapi_entry_attr_get_charray(entry, "objectClass");
> > + if (clsses == NULL)
> > + return NULL;
> > +
> > + for (size_t i = 0; attr == NULL && clsses[i] != NULL; i++) {
> > + for (size_t j = 0; attr == NULL && table[j].clss != NULL;
> > j++) {
> > + if (PL_strcasecmp(table[j].clss, clsses[i]) == 0)
> > + attr = table[j].attr;
> > + }
> > + }
> > +
> > + slapi_ch_array_free(clsses);
> > + return attr;
> > +}
>
> Can you put a comment here that explains what you are going to do in
> each cases in plain English ? This will help people in future figuring
> out if/how to modify the code or why something happens a specific way.
> It will also help the reviewer follow what is going on.
>
>
> > +static int
> > +preop_mod(Slapi_PBlock *pb)
> > +{
> > + size_t count = 0, attrs = 0, extras = 0;
> > + Slapi_Entry *entry = NULL;
> > + const char *attr = NULL;
> > + LDAPMod **inmods = NULL;
> > + LDAPMod **mods = NULL;
> > + counter ctr, orig;
> > +
> > + /* Get the input values. */
> > + slapi_pblock_get(pb, SLAPI_ENTRY_PRE_OP, &entry);
> > + slapi_pblock_get(pb, SLAPI_MODIFY_MODS, &inmods);
> > + if (entry == NULL || inmods == NULL)
> > + return 0;
> > +
> > + /* Get the attribute name. */
> > + attr = get_attribute(entry);
> > + if (attr == NULL)
> > + return 0; /* Not a token. */
> > +
> > + /* Count items. */
> > + while (inmods != NULL && inmods[count] != NULL) {
>
> ^^ this one would read much better as:
> for (count = 0; inmods[count] != NULL; count++) {
>
> You do not need to check for insmods != NULL as you already check for
> it and return 0 a few lines above.
>
> > + LDAPMod *mod = inmods[count++];
> > +
> > + if (PL_strcasecmp(mod->mod_type, attr) != 0)
> > + continue;
> > +
> > + attrs++;
> > + switch (mod->mod_op & LDAP_MOD_OP) {
> > + case LDAP_MOD_REPLACE:
> > + case LDAP_MOD_INCREMENT:
> > + extras++;
> > + break;
> > + }
> > + }
> > +
> > + /* Not operating on the counter/watermark. */
> > + if (attrs == 0)
> > + return 0;
> > +
> > + /* Get the counter. */
> > + orig = ctr = get_counter(entry, attr);
> > +
> > + /* Filter the modify operations. */
> > + mods = ch_calloc(count + extras + 1, LDAPMod*);
> > + for (size_t i = 0, j = 0; inmods != NULL && inmods[i] != NULL;
> > mods[j++] = inmods[i++]) {
>
> Please remove check for insmods != NULL, it is useless, and removing it
> will bring back the line under 80columns
>
> > + LDAPMod *mod = inmods[i];
> > +
> > + if (PL_strcasecmp(mod->mod_type, attr) != 0)
> > + continue;
> > +
> > + convert_ldapmod_to_bval(mod);
> > +
> > + switch (mod->mod_op & LDAP_MOD_OP) {
> > + case LDAP_MOD_DELETE:
> > + ctr.exists = false;
> > + if (mod->mod_bvalues != NULL && mod->mod_bvalues[0] ==
> > NULL)
> > + berval_free_array(&mod->mod_bvalues);
> > +
> > + if (is_replication(pb))
> > + berval_free_array(&mod->mod_bvalues);
> > +
> > + if (mod->mod_bvalues == NULL)
> > + mod->mod_bvalues = make_berval_array(ctr.value);
> > + break;
>
> I am not sure I understand this segment, why are you touching the
> delete operation outside of a replication event ?
> Doesn't this defeat and admin tool trying to correctly delete/add to
> avoid races ?
>
> > + case LDAP_MOD_INCREMENT:
> > + mods[j++] = make_ldapmod(LDAP_MOD_DELETE, attr,
> > ctr.value); +
> > + ctr.value += get_value(mod, 1);
>
> uhmmm if you had an ADD followed by INCREMENT operation, would this
> cause the value to become value*2+1 instead of just value+1 ?
>
> > + berval_free_array(&mod->mod_bvalues);
> > + mod->mod_op &= ~LDAP_MOD_OP;
> > + mod->mod_op |= LDAP_MOD_ADD;
> > + mod->mod_bvalues = make_berval_array(ctr.value);
> > + break;
>
> uhmm why are you converting mod_increment in all cases ? (including
> replication)
>
> > + case LDAP_MOD_REPLACE:
> > + if (ctr.exists)
> > + mods[j++] = make_ldapmod(LDAP_MOD_DELETE, attr,
> > ctr.value); +
> > + mod->mod_op &= ~LDAP_MOD_OP;
> > + mod->mod_op |= LDAP_MOD_ADD;
>
> same question here, why are you converting a replace coming from
> replication into a delete/add ?
>
> > + case LDAP_MOD_ADD:
> > + ctr.value = get_value(mod, 0);
> > + ctr.exists = true;
> > + break;
> > + }
> > + }
> > +
> > + /* Set the modified operations. */
> > + slapi_pblock_set(pb, SLAPI_MODIFY_MODS, mods);
> > + ch_free(inmods);
> > +
> > + /* Ensure we aren't deleting the counter. */
> > + if (orig.exists && !ctr.exists)
> > + return send_error(pb, LDAP_UNWILLING_TO_PERFORM,
> > + "Will not delete %s", attr);
> > +
> > + /* Ensure we aren't rolling back the counter. */
> > + if (orig.value > ctr.value)
> > + return send_error(pb, LDAP_UNWILLING_TO_PERFORM,
> > + "Will not decrement %s", attr);
> > +
> > + return 0;
> > +}
>
>
> see above about send_error().
>
> I think what is needed most is the comment that explains the process
> at the to of the main function.
>
> Simo.
All of the above are fixed.
Also, I have addressed Thierry's concern about putting the plugin in
betxnpreoperation by splitting the plugin into two phases: modification
and validation. Now all modifications occur in bepreoperation and all
validation occurs in betxnpreoperation.
Additionally, I have new code to trigger a new replication in the case
where a validation error occurs and we are in a replication transaction.
Thus, when A attempts to push an old counter value to B, B will now
replicate the latest value back to A.
Nathaniel
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