router: cache per-file resolve results, report changed files

router/route-update.sh

@@ -15,6 +15,7 @@ cd "$(dirname "$(realpath "$0")")" || exit
 ROUTES_DIR=routes.d
 ROUTES6_DIR=routes6.d
 STATE_DIR=.state
+HISTORY_SIZE=10
 
 FORCE=
 RESOLVE=
@@ -109,6 +110,41 @@ vlog() { [ -n "$VERBOSE" ] && log "  $*" || true ; }
 md5_lists() { cat "$@" 2>/dev/null | md5sum | awk '{print $1}' ; }
 ensure_state_dir() { mkdir -p "$STATE_DIR/$1" ; }
 
+# Detect domains with DNS balancing (single A record + short TTL)
+# Writes volatile domain list to STATE_DIR/$state/volatile_domains
+# Args: $1=state_dir $2=name $3=label $4...=domain list files
+detect_volatile_domains()
+{
+    local state="$1" name="$2" label="$3"
+    shift 3
+    local volatile_file="$STATE_DIR/$state/volatile_domains"
+    local ttl_threshold=120
+    local domains=$(mktemp)
+    trap "rm -f $domains" RETURN
+
+    # Extract unique domain names from list files
+    for f in "$@" ; do
+        cat_expanded "$f"
+    done | grep -v '^#' | grep -v '^$' | grep '[a-zA-Z]' | sort -u > "$domains"
+
+    [ -s "$domains" ] || { rm -f "$volatile_file" ; return 0 ; }
+
+    > "$volatile_file"
+    while read -r domain ; do
+        local output=$(dig +noall +answer "$domain" A 2>/dev/null | grep "IN[[:space:]]*A[[:space:]]")
+        local count=$(echo "$output" | grep -c .)
+        local ttl=$(echo "$output" | head -1 | awk '{print $2}')
+        if [ "$count" -le 1 ] && [ "${ttl:-9999}" -le "$ttl_threshold" ] ; then
+            echo "$domain	ttl=$ttl records=$count" >> "$volatile_file"
+        fi
+    done < "$domains"
+
+    if [ -s "$volatile_file" ] ; then
+        vlog "[$name]$label volatile domains (TTL≤${ttl_threshold}s, single A): $(wc -l < "$volatile_file")"
+        [ -n "$VERBOSE" ] && sed "s/^/  [$name]$label   /" "$volatile_file" >&2 || true
+    fi
+}
+
 # Look up table number: first from rt_tables by name, then from last IP octet
 # If derived from IP, auto-creates entry in rt_tables
 lookup_table()
@@ -348,36 +384,66 @@ process_routes()
             if [ -n "$RESOLVE" ] ; then
                 log "[$name]$label Re-resolving..."
             else
-                log "[$name]$label Changes detected, resolving..."
+                # Report which files changed (newer than saved hash)
+                local changed_files=""
+                local hash_file="$STATE_DIR/$state/hash"
+                if [ -f "$hash_file" ] ; then
+                    for f in "$gwdir/gateway" "$gwdir/options" $lists ; do
+                        if [ "$f" -nt "$hash_file" ] ; then
+                            changed_files="$changed_files $(basename "$f")"
+                        fi
+                    done
+                fi
+                log "[$name]$label Changes detected${changed_files:+ in:$changed_files}, resolving..."
             fi
 
-            # Split: pure IP files go through cat, domain files through resolve
-            local ip_lists="" domain_lists=""
+            # Resolve each list file individually, cache results per file
+            local resolved_parts_dir="$STATE_DIR/$state/resolved_parts"
+            mkdir -p "$resolved_parts_dir"
             for f in $lists ; do
+                local bname=$(basename "$f")
+                local cached="$resolved_parts_dir/$bname"
+                # Re-resolve only changed files (or all if no cache)
+                if [ -f "$cached" ] && [ -f "$hash_file" ] && ! [ "$f" -nt "$hash_file" ] ; then
+                    vlog "[$name]$label $bname: unchanged, using cache"
+                    continue
+                fi
+                vlog "[$name]$label $bname: resolving..."
                 if grep -v '^#' "$f" | grep -q '[a-zA-Z]' ; then
-                    domain_lists="$domain_lists $f"
+                    # Domain file: resolve
+                    cat_expanded "$f" | grep -v '^#' | grep -v '^$' | $resolve_func | \
+                        grep -v '^#' | grep -v '^$' > "$cached.tmp"
                 else
-                    ip_lists="$ip_lists $f"
-                fi
-            done
-            vlog "[$name]$label ip_lists:$(echo $ip_lists | wc -w) domain_lists:$(echo $domain_lists | wc -w)"
-
-            {
-                for f in $ip_lists ; do
+                    # IP-only file: just filter
                     if [ "$ipcmd" = "ip -6" ] ; then
-                        # IPv6 mode: only pass lines containing ":"
-                        grep -v '^#' "$f" | grep -v '^$' | grep ':'
+                        grep -v '^#' "$f" | grep -v '^$' | grep ':' > "$cached.tmp"
                     else
-                        grep -v '^#' "$f" | grep -v '^$'
+                        grep -v '^#' "$f" | grep -v '^$' > "$cached.tmp"
                     fi
-                done
-                if [ -n "$domain_lists" ] ; then
-                    for f in $domain_lists ; do
-                        cat_expanded "$f"
-                    done | grep -v '^#' | grep -v '^$' | $resolve_func | \
-                        grep -v '^#' | grep -v '^$'
                 fi
-            } | sed 's|/32$||' | sort -u > "$resolved_new"
+                mv "$cached.tmp" "$cached"
+            done
+            cat "$resolved_parts_dir"/* 2>/dev/null | sed 's|/32$||' | sort -u > "$resolved_new"
+
+            # Accumulate resolve history to handle DNS balancing (round-robin)
+            # Keeps last HISTORY_SIZE snapshots; IPs not seen for HISTORY_SIZE runs expire
+            local history_dir="$STATE_DIR/$state/resolve_history"
+            mkdir -p "$history_dir"
+            rm -f "$history_dir/$HISTORY_SIZE"
+            local i=$((HISTORY_SIZE - 1))
+            while [ $i -ge 1 ] ; do
+                [ -f "$history_dir/$i" ] && mv "$history_dir/$i" "$history_dir/$((i + 1))"
+                i=$((i - 1))
+            done
+            cp "$resolved_new" "$history_dir/1"
+            sort -u "$history_dir"/* > "${resolved_new}.merged"
+            mv "${resolved_new}.merged" "$resolved_new"
+            vlog "[$name]$label resolve history: $(ls "$history_dir" | wc -l) snapshots, $(wc -l < "$resolved_new") unique IPs"
+
+            # Detect domains using DNS balancing (only for IPv4, where dig A applies)
+            if [ -n "$domain_lists" ] && [ "$ipcmd" = "ip" ] ; then
+                detect_volatile_domains "$state" "$name" "$label" $domain_lists
+            fi
         fi
 
         # Check if resolved IPs actually changed