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namespace Xmpp.Sasl {
private const string NS_URI = "urn:ietf:params:xml:ns:xmpp-sasl";
public class Flag : XmppStreamFlag {
public static FlagIdentity<Flag> IDENTITY = new FlagIdentity<Flag>(NS_URI, "sasl");
public string mechanism;
public string name;
public string password;
public string client_nonce;
public uint8[] server_signature;
public bool finished = false;
public override string get_ns() { return NS_URI; }
public override string get_id() { return IDENTITY.id; }
}
namespace Mechanism {
public const string PLAIN = "PLAIN";
public const string SCRAM_SHA_1 = "SCRAM-SHA-1";
public const string SCRAM_SHA_1_PLUS = "SCRAM-SHA-1-PLUS";
}
public class Module : XmppStreamNegotiationModule {
public static ModuleIdentity<Module> IDENTITY = new ModuleIdentity<Module>(NS_URI, "sasl");
public string name { get; set; }
public string password { get; set; }
public bool use_full_name = false;
public signal void received_auth_failure(XmppStream stream, StanzaNode node);
public Module(string name, string password) {
this.name = name;
this.password = password;
}
public override void attach(XmppStream stream) {
stream.received_features_node.connect(this.received_features_node);
stream.received_nonza.connect(this.received_nonza);
}
public override void detach(XmppStream stream) {
stream.received_features_node.disconnect(this.received_features_node);
stream.received_nonza.disconnect(this.received_nonza);
}
private static size_t SHA1_SIZE = 20;
private static uint8[] sha1(uint8[] data) {
Checksum checksum = new Checksum(ChecksumType.SHA1);
checksum.update(data, data.length);
uint8[] res = new uint8[SHA1_SIZE];
checksum.get_digest(res, ref SHA1_SIZE);
return res;
}
private static uint8[] hmac_sha1(uint8[] key, uint8[] data) {
Hmac hmac = new Hmac(ChecksumType.SHA1, key);
hmac.update(data);
uint8[] res = new uint8[SHA1_SIZE];
hmac.get_digest(res, ref SHA1_SIZE);
return res;
}
private static uint8[] pbkdf2_sha1(string password, uint8[] salt, uint iterations) {
uint8[] res = new uint8[SHA1_SIZE];
uint8[] last = new uint8[salt.length + 4];
for(int i = 0; i < salt.length; i++) {
last[i] = salt[i];
}
last[salt.length + 3] = 1;
for(int i = 0; i < iterations; i++) {
last = hmac_sha1((uint8[]) password.to_utf8(), last);
xor_inplace(res, last);
}
return res;
}
private static void xor_inplace(uint8[] mix, uint8[] a2) {
for(int i = 0; i < mix.length; i++) {
mix[i] = mix[i] ^ a2[i];
}
}
private static uint8[] xor(uint8[] a1, uint8[] a2) {
uint8[] mix = new uint8[a1.length];
for(int i = 0; i < a1.length; i++) {
mix[i] = a1[i] ^ a2[i];
}
return mix;
}
public void received_nonza(XmppStream stream, StanzaNode node) {
if (node.ns_uri == NS_URI) {
if (node.name == "success") {
Flag flag = stream.get_flag(Flag.IDENTITY);
if (flag.mechanism == Mechanism.SCRAM_SHA_1) {
string confirm = (string) Base64.decode(node.get_string_content());
uint8[] server_signature = null;
foreach(string c in confirm.split(",")) {
string[] split = c.split("=", 2);
if (split.length != 2) continue;
switch(split[0]) {
case "v": server_signature = Base64.decode(split[1]); break;
}
}
if (server_signature == null) return;
if (server_signature.length != flag.server_signature.length) return;
for(int i = 0; i < server_signature.length; i++) {
if (server_signature[i] != flag.server_signature[i]) return;
}
}
stream.require_setup();
flag.password = null; // Remove password from memory
flag.finished = true;
} else if (node.name == "failure") {
stream.remove_flag(stream.get_flag(Flag.IDENTITY));
received_auth_failure(stream, node);
} else if (node.name == "challenge" && stream.has_flag(Flag.IDENTITY)) {
Flag flag = stream.get_flag(Flag.IDENTITY);
if (flag.mechanism == Mechanism.SCRAM_SHA_1) {
string challenge = (string) Base64.decode(node.get_string_content());
string? server_nonce = null;
uint8[] salt = null;
uint iterations = 0;
foreach(string c in challenge.split(",")) {
string[] split = c.split("=", 2);
if (split.length != 2) continue;
switch(split[0]) {
case "r": server_nonce = split[1]; break;
case "s": salt = Base64.decode(split[1]); break;
case "i": iterations = int.parse(split[1]); break;
}
}
if (server_nonce == null || salt == null || iterations == 0) return;
if (!server_nonce.has_prefix(flag.client_nonce)) return;
string client_final_message_bare = @"c=biws,r=$server_nonce";
uint8[] salted_password = pbkdf2_sha1(flag.password, salt, iterations);
uint8[] client_key = hmac_sha1(salted_password, (uint8[]) "Client Key".to_utf8());
uint8[] stored_key = sha1(client_key);
string auth_message = @"n=$(flag.name),r=$(flag.client_nonce),$challenge,$client_final_message_bare";
uint8[] client_signature = hmac_sha1(stored_key, (uint8[]) auth_message.to_utf8());
uint8[] client_proof = xor(client_key, client_signature);
uint8[] server_key = hmac_sha1(salted_password, (uint8[]) "Server Key".to_utf8());
flag.server_signature = hmac_sha1(server_key, (uint8[]) auth_message.to_utf8());
string client_final_message = @"$client_final_message_bare,p=$(Base64.encode(client_proof))";
stream.write(new StanzaNode.build("response", NS_URI).add_self_xmlns()
.put_node(new StanzaNode.text(Base64.encode((uchar[]) (client_final_message).to_utf8()))));
}
}
}
}
public void received_features_node(XmppStream stream) {
if (stream.has_flag(Flag.IDENTITY)) return;
if (stream.is_setup_needed()) return;
var mechanisms = stream.features.get_subnode("mechanisms", NS_URI);
string[] supported_mechanisms = {};
foreach (var mechanism in mechanisms.sub_nodes) {
if (mechanism.name != "mechanism" || mechanism.ns_uri != NS_URI) continue;
supported_mechanisms += mechanism.get_string_content();
}
if (!name.contains("@")) {
name = "%s@%s".printf(name, stream.remote_name.to_string());
}
if (!use_full_name && name.contains("@")) {
var split = name.split("@");
if (split[1] == stream.remote_name.to_string()) {
name = split[0];
} else {
use_full_name = true;
}
}
string name = this.name;
if (!use_full_name && name.contains("@")) {
var split = name.split("@");
if (split[1] == stream.remote_name.to_string()) {
name = split[0];
}
}
if (Mechanism.SCRAM_SHA_1 in supported_mechanisms) {
string normalized_password = password.normalize(-1, NormalizeMode.NFKC);
string client_nonce = Random.next_int().to_string("%.8x") + Random.next_int().to_string("%.8x") + Random.next_int().to_string("%.8x");
string initial_message = @"n=$name,r=$client_nonce";
stream.write(new StanzaNode.build("auth", NS_URI).add_self_xmlns()
.put_attribute("mechanism", Mechanism.SCRAM_SHA_1)
.put_node(new StanzaNode.text(Base64.encode((uchar[]) ("n,,"+initial_message).to_utf8()))));
var flag = new Flag();
flag.mechanism = Mechanism.SCRAM_SHA_1;
flag.name = name;
flag.password = normalized_password;
flag.client_nonce = client_nonce;
stream.add_flag(flag);
} else if (Mechanism.PLAIN in supported_mechanisms) {
stream.write(new StanzaNode.build("auth", NS_URI).add_self_xmlns()
.put_attribute("mechanism", Mechanism.PLAIN)
.put_node(new StanzaNode.text(Base64.encode(get_plain_bytes(name, password)))));
var flag = new Flag();
flag.mechanism = Mechanism.PLAIN;
flag.name = name;
stream.add_flag(flag);
} else {
stderr.printf("No supported mechanism provided by server at %s\n", stream.remote_name.to_string());
return;
}
}
private static uchar[] get_plain_bytes(string name_s, string password_s) {
var name = name_s.to_utf8();
var password = password_s.to_utf8();
uchar[] res = new uchar[name.length + password.length + 2];
res[0] = 0;
res[name.length + 1] = 0;
for(int i = 0; i < name.length; i++) { res[i + 1] = (uchar) name[i]; }
for(int i = 0; i < password.length; i++) { res[i + name.length + 2] = (uchar) password[i]; }
return res;
}
public override bool mandatory_outstanding(XmppStream stream) {
return !stream.has_flag(Flag.IDENTITY) || !stream.get_flag(Flag.IDENTITY).finished;
}
public override bool negotiation_active(XmppStream stream) {
return stream.has_flag(Flag.IDENTITY) && !stream.get_flag(Flag.IDENTITY).finished;
}
public override string get_ns() { return NS_URI; }
public override string get_id() { return IDENTITY.id; }
}
}
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