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Convert '<' back to '&lt;' in factors of the XEP-0115 verification string

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This commit is contained in:
fiaxh 2020-05-14 13:22:25 +02:00
parent cd3a119eff
commit 74b511593d
1 changed files with 28 additions and 11 deletions
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39
xmpp-vala/src/module/xep/0115_entitiy_capabilities.vala
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@ -115,38 +115,46 @@ namespace Xmpp.Xep.EntityCapabilities {
identities.sort(compare_identities);
features.sort();
string s = "";
StringBuilder sb = new StringBuilder();
foreach (ServiceDiscovery.Identity identity in identities) {
string s_identity = identity.category + "/" + identity.type_ + "//";
if (identity.name != null) s_identity += identity.name;
s_identity += "<";
s += s_identity;
sb.append(sanitize(identity.category))
.append("/")
.append(sanitize(identity.type_))
.append("//");
if (identity.name != null) {
sb.append(sanitize(identity.name));
}
sb.append("<");
}
foreach (string feature in features) {
s += feature + "<";
sb.append(sanitize(feature))
.append("<");
}
data_forms.sort(compare_data_forms);
foreach (DataForms.DataForm data_form in data_forms) {
if (data_form.form_type == null) {
// If [..] the FORM_TYPE field is not of type "hidden" or the form does not include a FORM_TYPE field, ignore the form but continue processing. (XEP-0115)
// If [..] the FORM_TYPE field is not of type "hidden" or the form does not include a FORM_TYPE field, ignore the form but continue processing. (XEP-0115 5.4)
continue;
}
s += data_form.form_type + "<";
sb.append(sanitize(data_form.form_type))
.append("<");
data_form.fields.sort(compare_data_fields);
foreach (DataForms.DataForm.Field field in data_form.fields) {
s += field.var + "<";
sb.append(sanitize(field.var))
.append("<");
Gee.List<string> values = field.get_values();
values.sort();
foreach (string value in values) {
s += value + "<";
sb.append(sanitize(value))
.append("<");
}
}
}
Checksum c = new Checksum(ChecksumType.SHA1);
c.update(s.data, -1);
c.update(sb.str.data, -1);
size_t size = 20;
uint8[] buf = new uint8[size];
c.get_digest(buf, ref size);
@ -154,6 +162,15 @@ namespace Xmpp.Xep.EntityCapabilities {
return Base64.encode(buf);
}
/*
* If the four characters '&', 'l', 't', ';' appear consecutively in any of the factors of the verification
* string S [...] then that string of characters MUST be treated as literally '&lt;' and MUST NOT be converted to
* the character '<', because completing such a conversion would open the protocol to trivial attacks. (XEP-0115 5.1)
*/
private static string sanitize(string s) {
return s.replace("<", "&lt;");
}
private static int compare_identities(ServiceDiscovery.Identity a, ServiceDiscovery.Identity b) {
int category_comp = a.category.collate(b.category);
if (category_comp != 0) return category_comp;