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authorailin-nemui <ailin-nemui@users.noreply.github.com>2016-09-26 16:43:33 +0200
committerGitHub <noreply@github.com>2016-09-26 16:43:33 +0200
commit8d4d313cc9853a62a2901d99b7c555e5c0d730b7 (patch)
tree09e5d709fff8669b11b9c21cec7abc4bac7975bb /src
parent2216ed19da3dd6cd72ed93f212acee2fe08bcc2f (diff)
parent60d9ec621ff81ac68b9d2066fb77eaefc8d02ccb (diff)
downloadirssi-8d4d313cc9853a62a2901d99b7c555e5c0d730b7.zip
Merge pull request #506 from kruton/sasl-400-byte-chunk
SASL: handle fragmentation
Diffstat (limited to 'src')
-rw-r--r--src/irc/core/irc-servers.c2
-rw-r--r--src/irc/core/irc-servers.h3
-rw-r--r--src/irc/core/sasl.c172
3 files changed, 154 insertions, 23 deletions
diff --git a/src/irc/core/irc-servers.c b/src/irc/core/irc-servers.c
index 8148997b..79aeb227 100644
--- a/src/irc/core/irc-servers.c
+++ b/src/irc/core/irc-servers.c
@@ -446,6 +446,8 @@ static void sig_disconnected(IRC_SERVER_REC *server)
gslist_free_full(server->cap_queue, (GDestroyNotify) g_free);
server->cap_queue = NULL;
+ g_free_and_null(server->sasl_buffer);
+
/* these are dynamically allocated only if isupport was sent */
g_hash_table_foreach(server->isupport,
(GHFunc) isupport_destroy_hash, server);
diff --git a/src/irc/core/irc-servers.h b/src/irc/core/irc-servers.h
index 41c4b9c2..ecf65ac2 100644
--- a/src/irc/core/irc-servers.h
+++ b/src/irc/core/irc-servers.h
@@ -78,7 +78,8 @@ struct _IRC_SERVER_REC {
GSList *cap_queue; /* A list of caps to request on connection */
int cap_complete:1; /* We've done the initial CAP negotiation */
- guint sasl_timeout; /* Holds the source id of the running timeout */
+ GString *sasl_buffer; /* Buffer used to reassemble a fragmented SASL payload */
+ guint sasl_timeout; /* Holds the source id of the running timeout */
/* Command sending queue */
int cmdcount; /* number of commands in `cmdqueue'. Can be more than
diff --git a/src/irc/core/sasl.c b/src/irc/core/sasl.c
index f080ae59..a1c16cdd 100644
--- a/src/irc/core/sasl.c
+++ b/src/irc/core/sasl.c
@@ -26,6 +26,19 @@
#include "irc-servers.h"
#include "sasl.h"
+/*
+ * Based on IRCv3 SASL Extension Specification:
+ * http://ircv3.net/specs/extensions/sasl-3.1.html
+ */
+#define AUTHENTICATE_CHUNK_SIZE 400 // bytes
+
+/*
+ * Maximum size to allow the buffer to grow to before the next fragment comes in. Note that
+ * due to the way fragmentation works, the maximum message size will actually be:
+ * floor(AUTHENTICATE_MAX_SIZE / AUTHENTICATE_CHUNK_SIZE) + AUTHENTICATE_CHUNK_SIZE - 1
+ */
+#define AUTHENTICATE_MAX_SIZE 8192 // bytes
+
#define SASL_TIMEOUT (20 * 1000) // ms
static gboolean sasl_timeout(IRC_SERVER_REC *server)
@@ -105,19 +118,106 @@ static void sasl_success(IRC_SERVER_REC *server, const char *data, const char *f
cap_finish_negotiation(server);
}
-static void sasl_step(IRC_SERVER_REC *server, const char *data, const char *from)
+/*
+ * Responsible for reassembling incoming SASL requests. SASL requests must be split
+ * into 400 byte requests to stay below the IRC command length limit of 512 bytes.
+ * The spec says that if there is 400 bytes, then there is expected to be a
+ * continuation in the next chunk. If a message is exactly a multiple of 400 bytes,
+ * there must be a blank message of "AUTHENTICATE +" to indicate the end.
+ *
+ * This function returns the fully reassembled and decoded AUTHENTICATION message if
+ * completed or NULL if there are more messages expected.
+ */
+static gboolean sasl_reassemble_incoming(IRC_SERVER_REC *server, const char *fragment, GString **decoded)
{
- IRC_SERVER_CONNECT_REC *conn;
- GString *req;
- char *enc_req;
+ GString *enc_req;
+ gsize fragment_len;
+
+ fragment_len = strlen(fragment);
+
+ /* Check if there is an existing fragment to prepend. */
+ if (server->sasl_buffer != NULL) {
+ if (g_strcmp0("+", fragment) == 0) {
+ enc_req = server->sasl_buffer;
+ } else {
+ enc_req = g_string_append_len(server->sasl_buffer, fragment, fragment_len);
+ }
+ server->sasl_buffer = NULL;
+ } else {
+ enc_req = g_string_new_len(fragment, fragment_len);
+ }
- conn = server->connrec;
+ /*
+ * Fail authentication with this server. They have sent too much data.
+ */
+ if (enc_req->len > AUTHENTICATE_MAX_SIZE) {
+ return FALSE;
+ }
- /* Stop the timer */
- if (server->sasl_timeout != 0) {
- g_source_remove(server->sasl_timeout);
- server->sasl_timeout = 0;
+ /*
+ * If the the request is exactly the chunk size, this is a fragment
+ * and more data is expected.
+ */
+ if (fragment_len == AUTHENTICATE_CHUNK_SIZE) {
+ server->sasl_buffer = enc_req;
+ return TRUE;
+ }
+
+ if (enc_req->len == 1 && *enc_req->str == '+') {
+ *decoded = g_string_new_len("", 0);
+ } else {
+ gsize dec_len;
+ gchar *tmp;
+
+ tmp = (gchar *) g_base64_decode(enc_req->str, &dec_len);
+ *decoded = g_string_new_len(tmp, dec_len);
+ }
+
+ g_string_free(enc_req, TRUE);
+ return TRUE;
+}
+
+/*
+ * Splits the response into appropriately sized chunks for the AUTHENTICATION
+ * command to be sent to the IRC server. If |response| is NULL, then the empty
+ * response is sent to the server.
+ */
+void sasl_send_response(IRC_SERVER_REC *server, GString *response)
+{
+ char *enc;
+ size_t offset, enc_len, chunk_len;
+
+ if (response == NULL) {
+ irc_send_cmdv(server, "AUTHENTICATE +");
+ return;
+ }
+
+ enc = g_base64_encode((guchar *) response->str, response->len);
+ enc_len = strlen(enc);
+
+ for (offset = 0; offset < enc_len; offset += AUTHENTICATE_CHUNK_SIZE) {
+ chunk_len = enc_len - offset;
+ if (chunk_len > AUTHENTICATE_CHUNK_SIZE)
+ chunk_len = AUTHENTICATE_CHUNK_SIZE;
+
+ irc_send_cmdv(server, "AUTHENTICATE %.*s", (int) chunk_len, enc + offset);
+ }
+
+ if (offset == enc_len) {
+ irc_send_cmdv(server, "AUTHENTICATE +");
}
+ g_free(enc);
+}
+
+/*
+ * Called when the incoming SASL request is completely received.
+ */
+static void sasl_step_complete(IRC_SERVER_REC *server, GString *data)
+{
+ IRC_SERVER_CONNECT_REC *conn;
+ GString *resp;
+
+ conn = server->connrec;
switch (conn->sasl_mechanism) {
case SASL_MECHANISM_PLAIN:
@@ -125,29 +225,57 @@ static void sasl_step(IRC_SERVER_REC *server, const char *data, const char *from
* The PLAIN mechanism expects a NULL-separated string composed by the authorization identity, the
* authentication identity and the password.
* The authorization identity field is explicitly set to the user provided username.
- * The whole request is then encoded in base64. */
-
- req = g_string_new(NULL);
+ */
- g_string_append(req, conn->sasl_username);
- g_string_append_c(req, '\0');
- g_string_append(req, conn->sasl_username);
- g_string_append_c(req, '\0');
- g_string_append(req, conn->sasl_password);
+ resp = g_string_new(NULL);
- enc_req = g_base64_encode((const guchar *)req->str, req->len);
+ g_string_append(resp, conn->sasl_username);
+ g_string_append_c(resp, '\0');
+ g_string_append(resp, conn->sasl_username);
+ g_string_append_c(resp, '\0');
+ g_string_append(resp, conn->sasl_password);
- irc_send_cmdv(server, "AUTHENTICATE %s", enc_req);
+ sasl_send_response(server, resp);
+ g_string_free(resp, TRUE);
- g_free(enc_req);
- g_string_free(req, TRUE);
break;
case SASL_MECHANISM_EXTERNAL:
/* Empty response */
- irc_send_cmdv(server, "AUTHENTICATE +");
+ sasl_send_response(server, NULL);
break;
}
+}
+
+static void sasl_step_fail(IRC_SERVER_REC *server)
+{
+ irc_send_cmd_now(server, "AUTHENTICATE *");
+ cap_finish_negotiation(server);
+
+ server->sasl_timeout = 0;
+
+ signal_emit("server sasl failure", 2, server, "The server sent an invalid payload");
+}
+
+static void sasl_step(IRC_SERVER_REC *server, const char *data, const char *from)
+{
+ GString *req = NULL;
+
+ /* Stop the timer */
+ if (server->sasl_timeout != 0) {
+ g_source_remove(server->sasl_timeout);
+ server->sasl_timeout = 0;
+ }
+
+ if (!sasl_reassemble_incoming(server, data, &req)) {
+ sasl_step_fail(server);
+ return;
+ }
+
+ if (req != NULL) {
+ sasl_step_complete(server, req);
+ g_string_free(req, TRUE);
+ }
/* We expect a response within a reasonable time */
server->sasl_timeout = g_timeout_add(SASL_TIMEOUT, (GSourceFunc) sasl_timeout, server);