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Diffstat (limited to 'src/libserver/css/css_util.cxx')
| -rw-r--r-- | src/libserver/css/css_util.cxx | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/src/libserver/css/css_util.cxx b/src/libserver/css/css_util.cxx new file mode 100644 index 0000000..07f8722 --- /dev/null +++ b/src/libserver/css/css_util.cxx @@ -0,0 +1,157 @@ +/*- + * 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 "css_util.hxx" +#include "css.hxx" +#include <unicode/utf8.h> + +namespace rspamd::css { + +std::string_view unescape_css(rspamd_mempool_t *pool, + const std::string_view &sv) +{ + auto *nspace = reinterpret_cast<char *>(rspamd_mempool_alloc(pool, sv.length())); + auto *d = nspace; + auto nleft = sv.length(); + + enum { + normal = 0, + quoted, + escape, + skip_spaces, + } state = normal; + + char quote_char, prev_c = 0; + auto escape_offset = 0, i = 0; + +#define MAYBE_CONSUME_CHAR(c) \ + do { \ + if ((c) == '"' || (c) == '\'') { \ + state = quoted; \ + quote_char = (c); \ + nleft--; \ + *d++ = (c); \ + } \ + else if ((c) == '\\') { \ + escape_offset = i; \ + state = escape; \ + } \ + else { \ + state = normal; \ + nleft--; \ + *d++ = g_ascii_tolower(c); \ + } \ + } while (0) + + for (const auto c: sv) { + if (nleft == 0) { + msg_err_css("cannot unescape css: truncated buffer of size %d", + (int) sv.length()); + break; + } + switch (state) { + case normal: + MAYBE_CONSUME_CHAR(c); + break; + case quoted: + if (c == quote_char) { + if (prev_c != '\\') { + state = normal; + } + } + prev_c = c; + nleft--; + *d++ = c; + break; + case escape: + if (!g_ascii_isxdigit(c)) { + if (i > escape_offset + 1) { + /* Try to decode an escape */ + const auto *escape_start = &sv[escape_offset + 1]; + unsigned long val; + + if (!rspamd_xstrtoul(escape_start, i - escape_offset - 1, &val)) { + msg_debug_css("invalid broken escape found at pos %d", + escape_offset); + } + else { + if (val < 0x80) { + /* Trivial case: ascii character */ + *d++ = (unsigned char) g_ascii_tolower(val); + nleft--; + } + else { + UChar32 uc = val; + auto off = 0; + UTF8_APPEND_CHAR_SAFE((uint8_t *) d, off, + sv.length(), u_tolower(uc)); + d += off; + nleft -= off; + } + } + } + else { + /* Empty escape, ignore it */ + msg_debug_css("invalid empty escape found at pos %d", + escape_offset); + } + + if (nleft <= 0) { + msg_err_css("cannot unescape css: truncated buffer of size %d", + (int) sv.length()); + } + else { + /* Escape is done, advance forward */ + if (g_ascii_isspace(c)) { + state = skip_spaces; + } + else { + MAYBE_CONSUME_CHAR(c); + } + } + } + break; + case skip_spaces: + if (!g_ascii_isspace(c)) { + MAYBE_CONSUME_CHAR(c); + } + /* Ignore spaces */ + break; + } + + i++; + } + + return std::string_view{nspace, sv.size() - nleft}; +} + +}// namespace rspamd::css + +/* C API */ +const gchar *rspamd_css_unescape(rspamd_mempool_t *pool, + const guchar *begin, + gsize len, + gsize *outlen) +{ + auto sv = rspamd::css::unescape_css(pool, {(const char *) begin, len}); + const auto *v = sv.begin(); + + if (outlen) { + *outlen = sv.size(); + } + + return v; +}
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