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@@ -936,3 +936,113 @@ rend_data_client_create(const char *onion_address, const char *desc_id,
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return NULL;
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}
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+/* Length of the 'extended' auth cookie used to encode auth type before
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+ * base64 encoding. */
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+#define REND_DESC_COOKIE_LEN_EXT (REND_DESC_COOKIE_LEN + 1)
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+/* Length of the zero-padded auth cookie when base64 encoded. These two
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+ * padding bytes always (A=) are stripped off of the returned cookie. */
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+#define REND_DESC_COOKIE_LEN_EXT_BASE64 (REND_DESC_COOKIE_LEN_BASE64 + 2)
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+
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+/** Encode a client authorization descriptor cookie.
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+ * The result of this function is suitable for use in the HidServAuth
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+ * option. The trailing padding characters are removed, and the
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+ * auth type is encoded into the cookie.
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+ *
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+ * Returns a new base64-encoded cookie. This function cannot fail.
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+ * The caller is responsible for freeing the returned value.
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+ */
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+char *
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+rend_auth_encode_cookie(const uint8_t *cookie_in, rend_auth_type_t auth_type)
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+{
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+ uint8_t extended_cookie[REND_DESC_COOKIE_LEN_EXT];
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+ char *cookie_out = tor_malloc_zero(REND_DESC_COOKIE_LEN_EXT_BASE64 + 1);
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+ int re;
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+
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+ tor_assert(cookie_in);
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+
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+ memcpy(extended_cookie, cookie_in, REND_DESC_COOKIE_LEN);
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+ extended_cookie[REND_DESC_COOKIE_LEN] = ((int)auth_type - 1) << 4;
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+ re = base64_encode(cookie_out, REND_DESC_COOKIE_LEN_EXT_BASE64 + 1,
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+ (const char *) extended_cookie, REND_DESC_COOKIE_LEN_EXT,
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+ 0);
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+ tor_assert(re == REND_DESC_COOKIE_LEN_EXT_BASE64);
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+
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+ /* Remove the trailing 'A='. Auth type is encoded in the high bits
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+ * of the last byte, so the last base64 character will always be zero
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+ * (A). This is subtly different behavior from base64_encode_nopad. */
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+ cookie_out[REND_DESC_COOKIE_LEN_BASE64] = '\0';
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+ memwipe(extended_cookie, 0, sizeof(extended_cookie));
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+ return cookie_out;
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+}
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+
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+/** Decode a base64-encoded client authorization descriptor cookie.
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+ * The descriptor_cookie can be truncated to REND_DESC_COOKIE_LEN_BASE64
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+ * characters (as given to clients), or may include the two padding
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+ * characters (as stored by the service).
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+ *
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+ * The result is stored in REND_DESC_COOKIE_LEN bytes of cookie_out.
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+ * The rend_auth_type_t decoded from the cookie is stored in the
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+ * optional auth_type_out parameter.
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+ *
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+ * Return 0 on success, or -1 on error. The caller is responsible for
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+ * freeing the returned err_msg.
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+ */
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+int
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+rend_auth_decode_cookie(const char *cookie_in, uint8_t *cookie_out,
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+ rend_auth_type_t *auth_type_out, char **err_msg_out)
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+{
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+ uint8_t descriptor_cookie_decoded[REND_DESC_COOKIE_LEN_EXT + 1] = { 0 };
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+ char descriptor_cookie_base64ext[REND_DESC_COOKIE_LEN_EXT_BASE64 + 1];
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+ const char *descriptor_cookie = cookie_in;
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+ char *err_msg = NULL;
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+ int auth_type_val = 0;
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+ int res = -1;
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+ int decoded_len;
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+
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+ size_t len = strlen(descriptor_cookie);
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+ if (len == REND_DESC_COOKIE_LEN_BASE64) {
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+ /* Add a trailing zero byte to make base64-decoding happy. */
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+ tor_snprintf(descriptor_cookie_base64ext,
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+ sizeof(descriptor_cookie_base64ext),
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+ "%sA=", descriptor_cookie);
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+ descriptor_cookie = descriptor_cookie_base64ext;
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+ } else if (len != REND_DESC_COOKIE_LEN_EXT_BASE64) {
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+ tor_asprintf(&err_msg, "Authorization cookie has wrong length: %s",
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+ escaped(cookie_in));
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+ goto err;
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+ }
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+
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+ decoded_len = base64_decode((char *) descriptor_cookie_decoded,
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+ sizeof(descriptor_cookie_decoded),
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+ descriptor_cookie,
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+ REND_DESC_COOKIE_LEN_EXT_BASE64);
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+ if (decoded_len != REND_DESC_COOKIE_LEN &&
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+ decoded_len != REND_DESC_COOKIE_LEN_EXT) {
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+ tor_asprintf(&err_msg, "Authorization cookie has invalid characters: %s",
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+ escaped(cookie_in));
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+ goto err;
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+ }
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+
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+ if (auth_type_out) {
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+ auth_type_val = (descriptor_cookie_decoded[REND_DESC_COOKIE_LEN] >> 4) + 1;
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+ if (auth_type_val < 1 || auth_type_val > 2) {
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+ tor_asprintf(&err_msg, "Authorization cookie type is unknown: %s",
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+ escaped(cookie_in));
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+ goto err;
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+ }
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+ *auth_type_out = auth_type_val == 1 ? REND_BASIC_AUTH : REND_STEALTH_AUTH;
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+ }
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+
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+ memcpy(cookie_out, descriptor_cookie_decoded, REND_DESC_COOKIE_LEN);
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+ res = 0;
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+ err:
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+ if (err_msg_out) {
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+ *err_msg_out = err_msg;
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+ } else {
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+ tor_free(err_msg);
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+ }
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+ memwipe(descriptor_cookie_decoded, 0, sizeof(descriptor_cookie_decoded));
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+ memwipe(descriptor_cookie_base64ext, 0, sizeof(descriptor_cookie_base64ext));
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+ return res;
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+}
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+
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John Brooks