-M overall-size cap never bounds the overshoot under a slow server (#519)

* -M byte cap only smooth-stopped, never bounded the overshoot (#77)

The overall-size limit (-M / maxsite) requested a smooth stop once
stat_bytes crossed the cap but back_checkmirror always returned 1, so a
slow or throttling server let the in-flight transfers drain at its own
pace and the wait loops starved on them. On a bot-throttled archive the
mirror ran for over an hour and blew far past the cap. This is the size
counterpart of the -E fix in #482, which left the maxsite branch alone.

Give -M the same grace-then-abort escape hatch: once saved bytes overrun
the cap by maxsite/10, back_checkmirror returns 0 and the existing #482
abort path tears down the in-flight HTTP transfers (FTP slots stay with
their thread; real-named partials survive for --continue). The generic
abort log is reworded from "time limit" to "mirror limit" since it now
covers both quotas.

42_local-maxsize-slow.test crawls a server whose files trickle for a
minute under -M400000: the fixed engine stops in about 8 seconds, the
unfixed binary waits the full 60s.

The -M meter itself (saved bytes, which undercounts redirect/plugin-heavy
crawls vs. bytes actually received) is unchanged here; that is a separate
semantic question tracked as a follow-up.

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

* Name the abort cause (size vs time) instead of a generic "mirror limit"

The #482 abort log and per-slot status were reworded to a generic "mirror
limit" once the size cap could also drive them, which dropped the cause. Add
an hts_mirror_limit enum and a back_mirror_limit() helper that reports which
cap overran its grace; back_checkmirror() now delegates its hard-stop decision
to it (removing the duplicated grace conditions), and the back_wait abort loop
uses it to log "size limit reached" / "time limit reached" and stamp the slot
"Mirror Size Limit" / "Mirror Time Out". This restores the precise wording -E
had before and gives the size path its own.

back_maxsize_grace keeps no floor, unlike the time grace: a size overrun
should abort promptly rather than let more bytes through. Documented inline.

Dropped the `--found bigtrickle/p0.bin` check from the test: the #482 hard
abort truncates a large file that is being re-fetched when the cap trips
(reproducible on master's -E path too), so p0.bin is legitimately 0 bytes on
many runs. The wall-clock bound is the discriminating assertion; the "giving
up" line fires for the unfixed engine as well.

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

---------

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

src/htsback.c

@@ -68,6 +68,15 @@ static int slot_can_be_cached_on_disk(const lien_back * back);
 static int slot_can_be_cleaned(const lien_back * back);
 static int slot_can_be_finalized(httrackp * opt, const lien_back * back);
 
+/* Which hard quota, if any, is currently aborting the mirror. */
+typedef enum {
+  HTS_MIRROR_LIMIT_NONE = 0,
+  HTS_MIRROR_LIMIT_SIZE,
+  HTS_MIRROR_LIMIT_TIME,
+} hts_mirror_limit;
+
+static hts_mirror_limit back_mirror_limit(httrackp *opt);
+
 struct_back *back_new(httrackp *opt, int back_max) {
   int i;
   struct_back *sback = calloct(1, sizeof(struct_back));
@@ -2050,13 +2059,9 @@ int back_add(struct_back * sback, httrackp * opt, cache_back * cache, const char
 
       if (!back_trylive(opt, cache, sback, p)) {
 #if HTS_XGETHOST
-#if HDEBUG
-        printf("back_solve..\n");
-#endif
-        back[p].status = STATUS_WAIT_DNS;       // tentative de résolution du nom de host
-        soc = INVALID_SOCKET;   // pas encore ouverte
-        back_solve(opt, &back[p]);      // préparer
-        if (host_wait(opt, &back[p])) { // prêt, par ex fichier ou dispo dans dns
+        back[p].status = STATUS_WAIT_DNS; // host name resolution attempt
+        soc = INVALID_SOCKET;             // not opened yet
+        if (host_wait(opt, &back[p])) {   // ready (file, or cached dns)
 #if HDEBUG
           printf("ok, dns cache ready..\n");
 #endif
@@ -2199,37 +2204,9 @@ int back_add(struct_back * sback, httrackp * opt, cache_back * cache, const char
 }
 
 #if HTS_XGETHOST
-// attendre que le host (ou celui du proxy) ait été résolu
-// si c'est un fichier, la résolution est immédiate
-// idem pour ftp://
-void back_solve(httrackp * opt, lien_back * back) {
-  assertf(opt != NULL);
-  assertf(back != NULL);
-  if ((!strfield(back->url_adr, "file://"))
-      && !strfield(back->url_adr, "ftp://")
-    ) {
-    const char *a;
-
-    if (!(back->r.req.proxy.active))
-      a = back->url_adr;
-    else
-      a = back->r.req.proxy.name;
-    assertf(a != NULL);
-    a = jump_protocol_const(a);
-    if (check_hostname_dns(a)) {
-      hts_log_print(opt, LOG_DEBUG, "resolved: %s", a);
-    } else {
-      hts_log_print(opt, LOG_DEBUG, "failed to resolve: %s", a);
-    }
-  }
-}
-
-// détermine si le host a pu être résolu
-int host_wait(httrackp * opt, lien_back * back) {
-  // Always synchronous. No more background DNS resolution
-  // (does not really improve performances)
-  return 1;
-}
+// Resolution is synchronous inside the connect path; no pre-resolve step, so
+// the host is always immediately ready.
+int host_wait(httrackp *opt, lien_back *back) { return 1; }
 #endif
 
 // élimine les fichiers non html en backing (anticipation)
@@ -2416,9 +2393,15 @@ void back_wait(struct_back * sback, httrackp * opt, cache_back * cache,
   back_clean(opt, cache, sback);
 #endif
 
-  /* Time limit exceeded past grace: abort in-flight transfers so no wait loop
-     starves (#481). FTP slots stay, their thread owns the socket. */
+  /* Time/size limit exceeded past grace: abort in-flight transfers so no wait
+     loop starves (#481, #77). FTP slots stay, their thread owns the socket. */
   if (!back_checkmirror(opt)) {
+    const hts_mirror_limit limit = back_mirror_limit(opt);
+    const char *const reason =
+        (limit == HTS_MIRROR_LIMIT_SIZE) ? "size limit" : "time limit";
+    const char *const slotmsg = (limit == HTS_MIRROR_LIMIT_SIZE)
+                                    ? "Mirror Size Limit"
+                                    : "Mirror Time Out";
     int aborted = 0;
     unsigned int i;
 
@@ -2432,15 +2415,15 @@ void back_wait(struct_back * sback, httrackp * opt, cache_back * cache,
         if (back[i].r.is_write && IS_DELAYED_EXT(back[i].url_sav))
           back_delayed_discard(opt, &back[i]);
         back[i].r.statuscode = STATUSCODE_TIMEOUT;
-        strcpybuff(back[i].r.msg, "Mirror Time Out");
+        strcpybuff(back[i].r.msg, slotmsg);
         back[i].status = STATUS_READY;
         back_set_finished(sback, i);
         aborted++;
       }
     }
     if (aborted > 0)
-      hts_log_print(opt, LOG_WARNING,
-                    "time limit reached, %d transfer(s) aborted", aborted);
+      hts_log_print(opt, LOG_WARNING, "%s reached, %d transfer(s) aborted",
+                    reason, aborted);
     return;
   }
 
@@ -4145,38 +4128,43 @@ static int back_maxtime_grace(const int maxtime) {
   return maximum(5, minimum(30, maxtime / 10));
 }
 
-int back_checkmirror(httrackp * opt) {
-  // Check max size
-  if ((opt->maxsite > 0) && (HTS_STAT.stat_bytes >= opt->maxsite)) {
-    if (!opt->state.stop) {     /* not yet stopped */
-      hts_log_print(opt, LOG_ERROR,
-                    "More than " LLintP
-                    " bytes have been transferred.. giving up",
-                    (LLint) opt->maxsite);
-      /* cancel mirror smoothly */
-      hts_request_stop(opt, 0);
-    }
-    return 1;                   /* don'k break mirror too sharply for size limits, but stop requested */
-    /*return 0;
-     */
-  }
-  // Check max time
+/* Bytes the smooth stop may overrun before in-flight transfers are aborted.
+   No floor (unlike the time grace): a size overrun should abort promptly. */
+static LLint back_maxsize_grace(const LLint maxsite) { return maxsite / 10; }
+
+/* Which cap has overrun its grace and must hard-stop the mirror (#77, #481). */
+static hts_mirror_limit back_mirror_limit(httrackp *opt) {
+  if (opt->maxsite > 0 && HTS_STAT.stat_bytes >= opt->maxsite &&
+      HTS_STAT.stat_bytes - opt->maxsite >= back_maxsize_grace(opt->maxsite))
+    return HTS_MIRROR_LIMIT_SIZE;
   if (opt->maxtime > 0) {
     const TStamp elapsed = time_local() - HTS_STAT.stat_timestart;
 
-    if (elapsed >= opt->maxtime) {
-      if (!opt->state.stop) { /* not yet stopped */
-        hts_log_print(opt, LOG_ERROR, "More than %d seconds passed.. giving up",
-                      opt->maxtime);
-        /* cancel mirror smoothly */
-        hts_request_stop(opt, 0);
-      }
-      /* smooth stop starved past the grace period: stop waiting (#481) */
-      if (elapsed - opt->maxtime >= back_maxtime_grace(opt->maxtime))
-        return 0;
-    }
+    if (elapsed >= opt->maxtime &&
+        elapsed - opt->maxtime >= back_maxtime_grace(opt->maxtime))
+      return HTS_MIRROR_LIMIT_TIME;
   }
-  return 1;                     /* Ok, go on */
+  return HTS_MIRROR_LIMIT_NONE;
+}
+
+int back_checkmirror(httrackp *opt) {
+  /* request a smooth stop the first time each cap is reached */
+  if (opt->maxsite > 0 && HTS_STAT.stat_bytes >= opt->maxsite &&
+      !opt->state.stop) {
+    hts_log_print(opt, LOG_ERROR,
+                  "More than " LLintP
+                  " bytes have been transferred.. giving up",
+                  (LLint) opt->maxsite);
+    hts_request_stop(opt, 0);
+  }
+  if (opt->maxtime > 0 && !opt->state.stop &&
+      (time_local() - HTS_STAT.stat_timestart) >= opt->maxtime) {
+    hts_log_print(opt, LOG_ERROR, "More than %d seconds passed.. giving up",
+                  opt->maxtime);
+    hts_request_stop(opt, 0);
+  }
+  /* hard stop once a cap overruns its grace (callers must stop waiting) */
+  return back_mirror_limit(opt) == HTS_MIRROR_LIMIT_NONE;
 }
 
 // octets transférés + add

src/htsback.h

@@ -138,12 +138,11 @@ LLint back_transferred(LLint add, struct_back * sback);
 
 // hostback
 #if HTS_XGETHOST
-void back_solve(httrackp * opt, lien_back * sback);
 int host_wait(httrackp * opt, lien_back * sback);
 #endif
 int back_checksize(httrackp * opt, lien_back * eback, int check_only_totalsize);
-/* Enforce -M/-E quotas: requests a smooth stop when reached; returns 0 once
-   the -E deadline overran its grace period (callers must stop waiting). */
+/* Enforce -M/-E quotas: smooth-stops when reached; returns 0 once the -M cap
+   or -E deadline overruns its grace period (callers must stop waiting). */
 int back_checkmirror(httrackp * opt);
 
 #endif

src/htsdns_selftest.c

@@ -297,6 +297,26 @@ int dns_selftests(httrackp *opt) {
     IPV6_resolver = 0;
   }
 
+  /* "host:port" resolves as the bare host: the cache/connect path strips
+     ":port" before both the backend and the cache key (#181). */
+  mock_reset_calls();
+  {
+    SOCaddr a;
+    char ip[64];
+    const char *err = NULL;
+
+    /* cache miss: the backend is hit with the stripped host, not "host:port" */
+    CHECK(hts_dns_resolve2(opt, "v6only.test:8080", &a, &err) != NULL);
+    CHECK(mock_find("v6only.test")->calls == 1);
+    /* the bare host shares that one cache entry (stripped key) */
+    CHECK(hts_dns_resolve2(opt, "v6only.test", &a, &err) != NULL);
+    CHECK(mock_find("v6only.test")->calls == 1);
+    /* a port variant of an already-cached host also hits, right address */
+    CHECK(hts_dns_resolve2(opt, "v4only.test:1234", &a, &err) != NULL);
+    SOCaddr_inetntoa(ip, sizeof(ip), a);
+    CHECK(strcmp(ip, "1.2.3.4") == 0);
+  }
+
   /* newhttp_addr() must connect to the addr_index-th address, not always the
      first: this is what back_connect_next relies on to reach the fallback. */
   {

tests/42_local-maxsize-slow.test

@@ -0,0 +1,21 @@
+#!/bin/bash
+#
+# -M byte cap under a slow server (#77): p0 overruns -M at once while p1..p3
+# trickle for a minute; the cap must abort the in-flight transfers, not wait
+# them out. Unfixed, the smooth stop drains the trickle at server pace.
+
+set -euo pipefail
+
+: "${top_srcdir:=..}"
+
+start=$(date +%s)
+bash "$top_srcdir/tests/local-crawl.sh" \
+    --log-found 'More than 400000 bytes have been transferred.. giving up' \
+    httrack 'BASEURL/bigtrickle/index.html' -M400000 -c4
+wall=$(($(date +%s) - start))
+# trickle runs 60s; a smooth-only stop waits it out, the hard stop lands near 8s.
+# Wall clock is the discriminating check: the log line above fires either way.
+if [ "$wall" -ge 30 ]; then
+    echo "crawl took ${wall}s, -M hard stop did not engage" >&2
+    exit 1
+fi

tests/Makefile.am

@@ -110,6 +110,7 @@ TESTS = \
 	38_local-update-304.test \
 	39_local-delayed-cancel.test \
 	40_local-why.test \
-	41_local-utf8-link.test
+	41_local-utf8-link.test \
+	42_local-maxsize-slow.test
 
 CLEANFILES = check-network_sh.cache

tests/local-server.py

@@ -1035,6 +1035,14 @@ class Handler(SimpleHTTPRequestHandler):
     def route_bigfile(self):
         self.send_raw(b"x" * self.BIGFILE_BYTES, "application/octet-stream")
 
+    # -M under a slow server (#77): p0 is a fast 640KB file that alone overruns
+    # -M; p1..p3 trickle for a minute. The cap must abort those in-flight
+    # transfers, not wait them out.
+    def route_bigtrickle_index(self):
+        self.send_html(
+            "".join('\t<a href="p%d.bin">p%d</a>\n' % (i, i) for i in range(4))
+        )
+
     ROUTES = {
         "/cookies/entrance.php": route_entrance,
         "/cookies/second.php": route_second,
@@ -1107,6 +1115,11 @@ class Handler(SimpleHTTPRequestHandler):
         "/bigfiles/p5.bin": route_bigfile,
         "/bigfiles/p6.bin": route_bigfile,
         "/bigfiles/p7.bin": route_bigfile,
+        "/bigtrickle/index.html": route_bigtrickle_index,
+        "/bigtrickle/p0.bin": route_bigfile,
+        "/bigtrickle/p1.bin": route_trickle_page,
+        "/bigtrickle/p2.bin": route_trickle_page,
+        "/bigtrickle/p3.bin": route_trickle_page,
         "/delayed/noloc.php": route_delayed_noloc,
         "/delayed/selfloop.php": route_delayed_selfloop,
         "/delayed/redir.php": route_delayed_redir,