Mirror probe: guard failures under set -e, reject HTTP errors

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QKxGW1raAWaqeU8WdHsMsp

cn/lib/mirror.sh

@@ -24,23 +24,27 @@ cn_mirror_ids_by_region() {
 # Probe one mirror: prints "<speed_bytes_s> <ttfb_s> <sync_age_s|stale|unknown>"
 cn_mirror_probe() {
   local url="$1"
-  local speed ttfb lastsync age now
+  local out speed=0 ttfb=0 lastsync age="unknown" now
 
-  read -r speed ttfb < <(curl -sS -o /dev/null -m 12 --connect-timeout 5 \
-    -w '%{speed_download} %{time_starttransfer}\n' \
-    "$url/core/os/x86_64/core.db" 2>/dev/null) || true
+  if out=$(curl -sSf -o /dev/null -m 12 --connect-timeout 5 \
+    -w '%{speed_download} %{time_starttransfer}' \
+    "$url/core/os/x86_64/core.db" 2>/dev/null); then
+    read -r speed ttfb <<<"$out"
     speed="${speed%%.*}"
-  [[ -z $speed ]] && speed=0
+  fi
 
-  age="unknown"
-  lastsync=$(curl -sS -m 5 --connect-timeout 5 "$url/lastsync" 2>/dev/null | tr -cd '0-9')
+  if lastsync=$(curl -sSf -m 5 --connect-timeout 5 "$url/lastsync" 2>/dev/null); then
+    lastsync=$(tr -cd '0-9' <<<"$lastsync")
     if [[ -n $lastsync ]]; then
       now=$(date +%s)
       age=$((now - lastsync))
-    (( age > 86400 )) && age="stale"
+      if (( age > 86400 )); then
+        age="stale"
+      fi
+    fi
   fi
 
-  echo "$speed ${ttfb:-0} $age"
+  echo "$speed $ttfb $age"
 }
 
 # Rank ids by probe speed, excluding dead (speed 0) and stale mirrors