--- /dev/null
+/*-
+ * Copyright 2021 Vsevolod Stakhov
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "html_url.hxx"
+#include "libutil/str_util.h"
+#include "libserver/url.h"
+#include "libserver/logger.h"
+
+#include <unicode/idna.h>
+
+namespace rspamd::html {
+
+static auto
+rspamd_url_is_subdomain(std::string_view t1, std::string_view t2) -> bool
+{
+ const auto *p1 = t1.data() + t1.size() - 1;
+ const auto *p2 = t2.data() + t2.size() - 1;
+
+ /* Skip trailing dots */
+ while (p1 > t1.data()) {
+ if (*p1 != '.') {
+ break;
+ }
+
+ p1--;
+ }
+
+ while (p2 > t2.data()) {
+ if (*p2 != '.') {
+ break;
+ }
+
+ p2--;
+ }
+
+ while (p1 > t1.data() && p2 > t2.data()) {
+ if (*p1 != *p2) {
+ break;
+ }
+
+ p1--;
+ p2--;
+ }
+
+ if (p2 == t2.data()) {
+ /* p2 can be subdomain of p1 if *p1 is '.' */
+ if (p1 != t1.data() && *(p1 - 1) == '.') {
+ return true;
+ }
+ }
+ else if (p1 == t1.data()) {
+ if (p2 != t2.data() && *(p2 - 1) == '.') {
+ return true;
+ }
+ }
+
+ return false;
+}
+
+
+static auto
+get_icu_idna_instance(void) -> auto
+{
+ auto uc_err = U_ZERO_ERROR;
+ static auto *udn = icu::IDNA::createUTS46Instance(UIDNA_DEFAULT, uc_err);
+
+ return udn;
+}
+
+static auto
+convert_idna_hostname_maybe(rspamd_mempool_t *pool, struct rspamd_url *url, bool use_tld)
+ -> std::string_view
+{
+ std::string_view ret = use_tld ?
+ std::string_view{rspamd_url_tld_unsafe (url), url->tldlen} :
+ std::string_view {rspamd_url_host_unsafe (url), url->hostlen};
+
+ /* Handle IDN url's */
+ if (ret.size() > 4 &&
+ rspamd_substring_search_caseless(ret.data(), ret.size(), "xn--", 4) != -1) {
+ const auto buf_capacity = ret.size() * 2 + 1;
+ auto *idn_hbuf = (char *)rspamd_mempool_alloc (pool, buf_capacity);
+ icu::CheckedArrayByteSink byte_sink{idn_hbuf, (int)buf_capacity};
+ /* We need to convert it to the normal value first */
+ icu::IDNAInfo info;
+ auto uc_err = U_ZERO_ERROR;
+ auto *udn = get_icu_idna_instance();
+ udn->nameToASCII_UTF8(ret,byte_sink, info, uc_err);
+
+ if (uc_err == U_ZERO_ERROR && !info.hasErrors()) {
+ ret = std::string_view{idn_hbuf, (std::size_t)byte_sink.NumberOfBytesWritten()};
+ }
+ else {
+ msg_err_pool ("cannot convert to IDN: %s (0x%xd)",
+ u_errorName(uc_err), info.getErrors());
+ }
+ }
+
+ return ret;
+};
+
+constexpr auto sv_equals(std::string_view s1, std::string_view s2) -> auto {
+ return (s1.size() == s2.size()) &&
+ std::equal(s1.begin(), s1.end(), s2.begin(), s2.end(),
+ [](const auto c1, const auto c2) {
+ return g_ascii_tolower(c1) == g_ascii_tolower(c2);
+ });
+}
+
+auto
+html_url_is_phished(rspamd_mempool_t *pool,
+ struct rspamd_url *href_url,
+ std::string_view text_data) -> std::optional<rspamd_url *>
+{
+ struct rspamd_url *text_url;
+ std::string_view disp_tok, href_tok;
+ goffset url_pos;
+ gchar *url_str = NULL;
+
+ auto sz = text_data.size();
+ const auto *trimmed = rspamd_string_unicode_trim_inplace(text_data.data(), &sz);
+ text_data = std::string_view(trimmed, sz);
+
+ if (text_data.size() > 4 &&
+ rspamd_url_find(pool, text_data.data(), text_data.size(), &url_str,
+ RSPAMD_URL_FIND_ALL,
+ &url_pos, NULL) && url_str != NULL) {
+
+ text_url = rspamd_mempool_alloc0_type (pool, struct rspamd_url);
+ auto rc = rspamd_url_parse(text_url, url_str, strlen(url_str), pool,
+ RSPAMD_URL_PARSE_TEXT);
+
+ if (rc == URI_ERRNO_OK) {
+ disp_tok = convert_idna_hostname_maybe(pool, text_url, false);
+ href_tok = convert_idna_hostname_maybe(pool, href_url, false);
+
+ if (!sv_equals(disp_tok, href_tok) &&
+ text_url->tldlen > 0 && href_url->tldlen > 0) {
+
+ /* Apply the same logic for TLD */
+ disp_tok = convert_idna_hostname_maybe(pool, text_url, true);
+ href_tok = convert_idna_hostname_maybe(pool, href_url, true);
+
+ if (!sv_equals(disp_tok, href_tok)) {
+ /* Check if one url is a subdomain for another */
+
+ if (!rspamd_url_is_subdomain(disp_tok, href_tok)) {
+ href_url->flags |= RSPAMD_URL_FLAG_PHISHED;
+ href_url->linked_url = text_url;
+ text_url->flags |= RSPAMD_URL_FLAG_HTML_DISPLAYED;
+ }
+ }
+ }
+
+ return text_url;
+ }
+ else {
+ /*
+ * We have found something that looks like an url but it was
+ * not parsed correctly.
+ * Sometimes it means an obfuscation attempt, so we have to check
+ * what's inside of the text
+ */
+ gboolean obfuscation_found = FALSE;
+
+ if (text_data.size() > 4
+ && g_ascii_strncasecmp(text_data.begin(), "http", 4) == 0 &&
+ rspamd_substring_search(text_data.begin(), text_data.size(), "://", 3) != -1) {
+ /* Clearly an obfuscation attempt */
+ obfuscation_found = TRUE;
+ }
+
+ msg_info_pool ("extract of url '%s' failed: %s; obfuscation detected: %s",
+ url_str,
+ rspamd_url_strerror(rc),
+ obfuscation_found ? "yes" : "no");
+
+ if (obfuscation_found) {
+ href_url->flags |= RSPAMD_URL_FLAG_PHISHED | RSPAMD_URL_FLAG_OBSCURED;
+ }
+ }
+ }
+
+ return std::nullopt;
+}
+
+}
\ No newline at end of file
--- /dev/null
+/*-
+ * Copyright 2021 Vsevolod Stakhov
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef RSPAMD_HTML_URL_HXX
+#define RSPAMD_HTML_URL_HXX
+#pragma once
+
+#include "libutil/mem_pool.h"
+#include <string_view>
+#include <optional>
+
+struct rspamd_url; /* Forward declaration */
+
+namespace rspamd::html {
+
+
+/**
+ * Checks if an html url is likely phished by some displayed url
+ * @param pool
+ * @param href_url
+ * @param text_data
+ * @return
+ */
+auto html_url_is_phished(rspamd_mempool_t *pool,
+ struct rspamd_url *href_url,
+ std::string_view text_data) -> std::optional<rspamd_url *>;
+
+
+}
+
+#endif //RSPAMD_HTML_URL_HXX
\ No newline at end of file
projects / rspamd.git / commitdiff