Test the relative-link engine; collapse ../ in file:// URLs

The ../-handling tickets #137 (embedded ../ in a URL) and #162 (cross-host
"too many ../") do not reproduce on master or the released 3.49.x: the engine
has resolved embedded, cross-host, out-of-scope and above-root ../ correctly
since the 2012 import, and the released binary behaves identically. #137's
actual breakage was a JS-generated iframe URL (httrack can't rewrite
dynamically-built links); #162 is a long-gone Windows path quirk.

The area was nearly untested, though, despite feeding both link rewriting and
crawl-scope decisions: two trivial lienrelatif asserts, none for
ident_url_relatif. Add a wide regression net via two hidden debug probes
(-#l lienrelatif, -#i ident_url_relatif, mirroring -#1 fil_simplifie) driving
tens of cases in tests/01_engine-relative.test (embedded/cross-host/sibling/
ancestor/above-root ../, query stripping, scheme handling), plus the missing
fil_simplifie edge cases (absolute paths, root clamp, query freeze) in
01_engine-simplify.test. Expected values are computed by hand, not echoed.

While covering it, fixed one real gap: the file:// branch of
ident_url_absolute skipped the fil_simplifie its http sibling runs, so file://
URLs kept their ../ in adrfil->fil while the save path was already collapsed
(htsname.c:1343). Collapsing it matches the other schemes, contains traversal
at the file:// root, and dedups a/../b against b.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>

src/htscoremain.c

@@ -2787,6 +2787,47 @@ static int hts_main_internal(int argc, char **argv, httrackp * opt) {
                   return 0;
                 }
                 break;
+              case 'l': /* lienrelatif: relative link from curr_fil to link */
+                if (na + 2 >= argc) {
+                  HTS_PANIC_PRINTF(
+                      "Option #l needs a link and a current-file path");
+                  printf(
+                      "Example: '-#l' 'host/dir/img.gif' 'host/dir/p.html'\n");
+                  htsmain_free();
+                  return -1;
+                } else {
+                  char s[HTS_URLMAXSIZE * 2];
+
+                  if (lienrelatif(s, sizeof(s), argv[na + 1], argv[na + 2]) ==
+                      0)
+                    printf("relative=%s\n", s);
+                  else
+                    printf("relative=<ERROR>\n");
+                  htsmain_free();
+                  return 0;
+                }
+                break;
+              case 'i': /* ident_url_relatif: resolve a link -> adr/fil */
+                if (na + 3 >= argc) {
+                  HTS_PANIC_PRINTF(
+                      "Option #i needs a link, an origin address and file");
+                  printf("Example: '-#i' '../img.gif' 'www.foo.com' "
+                         "'/d/p.html'\n");
+                  htsmain_free();
+                  return -1;
+                } else {
+                  lien_adrfil af;
+                  const int r = ident_url_relatif(argv[na + 1], argv[na + 2],
+                                                  argv[na + 3], &af);
+
+                  if (r == 0)
+                    printf("adr=%s fil=%s\n", af.adr, af.fil);
+                  else
+                    printf("error=%d\n", r);
+                  htsmain_free();
+                  return 0;
+                }
+                break;
               case '2':        // mimedefs
                 if (na + 1 >= argc) {
                   HTS_PANIC_PRINTF("Option #2 needs to be followed by an URL");

src/htslib.c

@@ -2605,6 +2605,8 @@ int ident_url_absolute(const char *url, lien_adrfil *adrfil) {
     for(i = 0; adrfil->fil[i] != '\0'; i++)
       if (adrfil->fil[i] == '\\')
         adrfil->fil[i] = '/';
+    // collapse ../ like the http branch above (path-traversal safety)
+    fil_simplifie(adrfil->fil);
   }
 
   // no hostname

src/htsparse.c

@@ -317,6 +317,27 @@ static int is_http_method(const char *s, size_t len) {
   return 0;
 }
 
+/* Percent-encode '(' and ')' in a link emitted into an unquoted url(...) (CSS
+   or JS): a literal ')' closes the token early and the UA mis-parses the value
+   (#163). The UA decodes %28/%29 back to the saved-on-disk name. */
+static void escape_url_parens(char *const s, const size_t size) {
+  char BIGSTK buff[HTS_URLMAXSIZE * 2];
+  size_t i, j;
+
+  for (i = 0, j = 0; s[i] != '\0' && j + 3 < size && j + 3 < sizeof(buff);
+       i++) {
+    if (s[i] == '(' || s[i] == ')') {
+      buff[j++] = '%';
+      buff[j++] = '2';
+      buff[j++] = s[i] == '(' ? '8' : '9';
+    } else {
+      buff[j++] = s[i];
+    }
+  }
+  buff[j] = '\0';
+  strlcpybuff(s, buff, size);
+}
+
 /* Main parser */
 int htsparse(htsmoduleStruct * str, htsmoduleStructExtended * stre) {
   char catbuff[CATBUFF_SIZE];
@@ -3027,6 +3048,10 @@ int htsparse(htsmoduleStruct * str, htsmoduleStructExtended * stre) {
                           /* Never escape high-chars (we don't know the encoding!!) */
                           inplace_escape_uri_utf(tempo, sizeof(tempo));
 
+                          // unquoted url() (CSS/JS): keep parens escaped
+                          if (ending_p == ')')
+                            escape_url_parens(tempo, sizeof(tempo));
+
                           //if (!no_esc_utf)
                           //  escape_uri(tempo);     // escape with %xx
                           //else {

tests/01_engine-parse.test

@@ -264,4 +264,63 @@ grep -Fq 'window.open("winopen.gif")' "$saved7" ||
 ! grep -Fq 'window.open("file://' "$saved7" ||
     ! echo "FAIL #218: window.open URL left absolute (not rewritten)" || exit 1
 
+# Parens in an unquoted url(...) (#163): the source %28/%29 decode to literal
+# '(' ')' in the saved name, but a literal ')' in the rewritten url() closes the
+# token early, so they must stay encoded. Negative control: without the fix the
+# %281%29 greps fail (parens are RFC2396 "mark" chars the escaper leaves alone).
+site8="$tmp/cssparens"
+mkdir -p "$site8"
+for f in 'img (1).gif' 'a(b)c(1).gif' 'q (4).gif'; do gif "$site8/$f"; done
+cat >"$site8/style.css" <<'EOF'
+.a { background: url(img%20%281%29.gif); }
+.b { background: url(a%28b%29c%281%29.gif); }
+.c { background: url("q%20%284%29.gif"); }
+EOF
+out8="$tmp/cssparens-out"
+crawl "$site8/style.css" "$out8"
+found "img (1).gif" "$out8"
+found "a(b)c(1).gif" "$out8"
+found "q (4).gif" "$out8"
+css8=$(find "$out8" -type f -path '*/file/*' -name style.css -print -quit)
+test -n "$css8" || ! echo "FAIL: saved style.css not found" || exit 1
+grep -Fq 'url(img%20%281%29.gif)' "$css8" ||
+    ! echo "FAIL #163: parens in unquoted url() not percent-encoded on rewrite" || exit 1
+grep -Fq 'url(a%28b%29c%281%29.gif)' "$css8" ||
+    ! echo "FAIL #163: not every paren in a url() was percent-encoded" || exit 1
+grep -Fq 'url("q%20%284%29.gif")' "$css8" ||
+    ! echo "FAIL #163: quoted url() altered or parens left literal on rewrite" || exit 1
+
+# The url() detector is not CSS-specific: <script> and inline style= get the
+# same encoding, but ordinary href/src (ending_p is the quote, not ')') keep
+# literal parens -- the attribute checks guard the gate against over-firing.
+site9="$tmp/urlparens"
+mkdir -p "$site9"
+for f in 'js (1).gif' 'inl (2).gif' 'asrc (3).gif' 'ahref (4).gif'; do gif "$site9/$f"; done
+cat >"$site9/index.html" <<EOF
+<html><body>
+<script>var bg = "url(js%20%281%29.gif)";</script>
+<div style="background-image:url(inl%20%282%29.gif)"></div>
+<img src="asrc%20%283%29.gif">
+<a href="ahref%20%284%29.gif">link</a>
+</body></html>
+EOF
+out9="$tmp/urlparens-out"
+crawl "$site9/index.html" "$out9"
+saved9=$(savedhtml "$out9")
+test -n "$saved9" || ! echo "FAIL: saved urlparens page not found" || exit 1
+# rewrite-only: the JS-string asset is not queued for download
+grep -Fq 'url(js%20%281%29.gif)' "$saved9" ||
+    ! echo "FAIL #163: parens in <script> url() not percent-encoded" || exit 1
+found "inl (2).gif" "$out9"
+grep -Fq 'url(inl%20%282%29.gif)' "$saved9" ||
+    ! echo "FAIL #163: parens in inline style url() not percent-encoded" || exit 1
+found "asrc (3).gif" "$out9"
+found "ahref (4).gif" "$out9"
+grep -Fq 'src="asrc%20(3).gif"' "$saved9" ||
+    ! echo "FAIL #163: parens in a plain src attribute were wrongly encoded" || exit 1
+grep -Fq 'href="ahref%20(4).gif"' "$saved9" ||
+    ! echo "FAIL #163: parens in a plain href attribute were wrongly encoded" || exit 1
+! grep -Eq '(src|href)="[^"]*%28' "$saved9" ||
+    ! echo "FAIL #163: gate over-fired onto a non-url() attribute link" || exit 1
+
 exit 0

tests/01_engine-relative.test

@@ -0,0 +1,62 @@
+#!/bin/bash
+#
+# lienrelatif (build relative path) + ident_url_relatif (resolve a link, collapse
+# ./ and ../). Regression net for #137/#162; expected values hand-computed.
+
+set -euo pipefail
+
+# relative path from <curr>'s directory to <link>
+rel() {
+	local got
+	got=$(httrack -O /dev/null -#l "$1" "$2")
+	test "$got" == "relative=$3" ||
+		{ echo "FAIL rel($1, $2): got '$got' want 'relative=$3'"; exit 1; }
+}
+
+# resolve <link> against origin <adr>/<fil> -> adr=.. fil=..
+ident() {
+	local got
+	got=$(httrack -O /dev/null -#i "$1" "$2" "$3")
+	test "$got" == "$4" ||
+		{ echo "FAIL ident($1, $2, $3): got '$got' want '$4'"; exit 1; }
+}
+
+### lienrelatif
+
+rel 'dir/page.html'        'dir/index.html'        'page.html'
+rel 'dir/page.html'        'dir/page.html'         'page.html'   # self-link
+rel 'a.html'               'dir/index.html'        '../a.html'
+rel 'x.html'               'a/b/c/index.html'      '../../../x.html'
+rel 'h/a/x.jpg'            'h/a/sub/page.html'     '../x.jpg'
+rel 'a/b/c/x.html'         'index.html'            'a/b/c/x.html'
+rel 'h/sub/x.jpg'          'h/page.html'           'sub/x.jpg'
+rel 'h/dir2/x.jpg'         'h/dir1/page.html'      '../dir2/x.jpg'   # sibling dir
+rel 'h/bc/x.jpg'           'h/b/page.html'         '../bc/x.jpg'     # b/bc prefix trap
+rel 'h/b/x.jpg'            'h/bc/page.html'        '../b/x.jpg'
+rel 'h2/img/x.jpg'         'h1/p/page.html'        '../../h2/img/x.jpg'   # cross-host
+rel 'img.cdn/photo.jpg'    'www.site/articles/2020/post.html' '../../../img.cdn/photo.jpg'
+rel 'h/a/'                 'h/a/sub/page.html'     '../'             # link is ancestor dir
+rel 'x.html'               'page.html'             'x.html'
+rel 'dir/page.html?x=1'    'dir/index.html?y=2'    'page.html'       # ? stripped
+
+### ident_url_relatif
+
+ident 'img.gif'      'www.foo.com' '/dir/page.html'     'adr=www.foo.com fil=/dir/img.gif'
+ident 'sub/img.gif'  'www.foo.com' '/dir/page.html'     'adr=www.foo.com fil=/dir/sub/img.gif'
+ident '/img.gif'     'www.foo.com' '/dir/page.html'     'adr=www.foo.com fil=/img.gif'
+# embedded ../ collapses (#137)
+ident '../img.gif'             'www.foo.com' '/dir/sub/page.html'        'adr=www.foo.com fil=/dir/img.gif'
+ident 'sub/../logo.png'        'www.foo.com' '/articles/2020/post.html' 'adr=www.foo.com fil=/articles/2020/logo.png'
+ident '../../pix/sub/../logo.png' 'www.foo.com' '/articles/2020/post.html' 'adr=www.foo.com fil=/pix/logo.png'
+ident '../../../../x.gif'      'www.foo.com' '/a/b/page.html'           'adr=www.foo.com fil=/x.gif'   # above-root clamp
+ident '?page=2'      'www.foo.com' '/dir/index.html?old=1' 'adr=www.foo.com fil=/dir/index.html?page=2'
+ident 'http://other.com/a/b/../c/index.html' 'www.foo.com' '/p.html' 'adr=other.com fil=/a/c/index.html'
+# file:// collapses ../ like the other schemes; traversal contained, // authority kept
+ident 'file:///var/data/pix/sub/../logo.png' 'www.foo.com' '/p.html' 'adr=file:// fil=/var/data/pix/logo.png'
+ident 'file:///a/b/c/../../d/e.gif'          'www.foo.com' '/p.html' 'adr=file:// fil=/a/d/e.gif'
+ident 'file:///a/../../b'        'www.foo.com' '/p.html' 'adr=file:// fil=/b'
+ident 'file://srv/share/../x'    'www.foo.com' '/p.html' 'adr=file:// fil=//srv/x'
+ident 'mailto:foo@bar.com'   'www.foo.com' '/p.html'    'error=-1'   # unsupported scheme
+ident 'javascript:void(0)'   'www.foo.com' '/p.html'    'error=-1'
+
+echo "OK"

tests/01_engine-simplify.test

@@ -26,3 +26,17 @@ simp './a/../../b' 'b'
 
 # empty segments ('//') are not dot-segments and are preserved, per RFC 3986
 simp 'a//b' 'a//b'
+simp 'a//b/../c' 'a//c'
+
+# absolute paths keep the leading '/'; above-root '..' is clamped to it
+simp '/a/../b' '/b'
+simp '/a/../../b' '/b'
+simp '/../x' '/x'
+
+# collapses to nothing -> './' (relative) or '/' (absolute)
+simp '..' './'
+simp 'a/..' './'
+simp '/' '/'
+
+simp 'a/b/..' 'a/'              # trailing bare '..'
+simp 'a/../b?x=../y' 'b?x=../y' # '?' freezes simplification

tests/Makefile.am

@@ -35,6 +35,7 @@ TESTS = \
 	01_engine-mime.test \
 	01_engine-parse.test \
 	01_engine-rcfile.test \
+	01_engine-relative.test \
 	01_engine-simplify.test \
 	01_engine-strsafe.test \
 	02_manpage-regen.test \