Bound the cookie default-domain copy against a hostile over-long host

treathead seeds each Set-Cookie's default domain from the request host with a
strcpybuff into domain[256]. A 256+ byte host, reachable via a redirect
Location (sized HTS_URLMAXSIZE), overflows the fail-safe copy and aborts the
whole mirror. Drop such a Set-Cookie instead, matching the existing too-long
handling of the explicit domain= attribute.

Adds a cookies self-test driving treathead with a 599-byte host (aborts
without the guard) plus a normal-host control.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>

src/htslib.c

@@ -1708,6 +1708,9 @@ void treathead(t_cookie * cookie, const char *adr, const char *fil, htsblk * ret
 #if DEBUG_COOK
     printf("set-cookie detected\n");
 #endif
+    /* Over-long host overflows the fail-safe domain[] copy (abort); drop it. */
+    if (adr && strlen(jump_identification_const(adr)) >= sizeof(domain))
+      return;
     while(*a) {
       char *token_st, *token_end;
       char *value_st, *value_end;

src/htsselftest.c

@@ -1816,6 +1816,27 @@ static int st_cookies(httrackp *opt, int argc, char **argv) {
   http_cookie_header(&cookie, dom, "/", hdr, sizeof(hdr));
   if (strcmp(hdr, expected) != 0)
     err = 1;
+
+  /* A hostile over-long request host must not overflow domain[256] in
+     treathead's default-domain copy (that would abort the mirror). */
+  {
+    static t_cookie ck2;
+    htsblk r;
+    char host[600];
+
+    memset(&r, 0, sizeof(r));
+    memset(host, 'a', sizeof(host) - 1);
+    host[sizeof(host) - 1] = '\0';
+    ck2.max_len = (int) sizeof(ck2.data);
+    ck2.data[0] = '\0';
+    treathead(&ck2, host, "/", &r, "Set-Cookie: SID=1; path=/");
+    if (strnotempty(ck2.data)) // oversize-host cookie was not dropped
+      err = 1;
+    /* control: a normal host still yields a cookie through treathead */
+    treathead(&ck2, dom, "/", &r, "Set-Cookie: SID=1; path=/");
+    if (strstr(ck2.data, "SID") == NULL) // guard wrongly dropped a valid cookie
+      err = 1;
+  }
   if (strstr(hdr, "$Version") != NULL || strstr(hdr, "$Path") != NULL)
     err = 1;
   if (strstr(hdr, "junk") != NULL) // wrong-domain cookie leaked