Add fallback values to stdtime2integer functions.

section-user-throttling.vcl

#vcl 4.0;

# comment the following imports if imported elsewhere
import cookie;
import header;
import std;
import var;

sub vcl_synth {
    if (resp.status == 837) {
        set resp.status = 204;
        return (deliver);
    }
    if (resp.status == 838) {
        set resp.status = 403;
        return (deliver);
    }
}

sub vcl_recv {
    if (req.method == "PUT" && req.url ~ "^/\.well-known/section-io/visitor-count/") {
        if (req.http.Section-Visitor-Count-Secret != req.http.Section-Visitors-Expected-Secret) {
            return (synth(838, "Forbidden"));
        }

        if (req.url ~ "^/\.well-known/section-io/visitor-count/set\?value=[0-9]+$") {
            var.global_set(req.http.Host + "-visitor-count", regsuball(req.url, "[^0-9]", ""));
            return (synth(837, "No Content"));
        } else if (req.url ~ "^/\.well-known/section-io/visitor-count/threshold-reached\?value=[0-9]+$") {
            set req.http.x-now-unix-string = std.time2integer(now, 0);
            var.global_set(
                req.http.Host + "-visitor-count-threshold-" + regsuball(req.url, "[^0-9]", "") + "-reached",
                req.http.x-now-unix-string
            );
            unset req.http.x-now-unix-string;
            return (synth(837, "No Content"));
        }
    }

    if (req.http.Section-ResourceProxy) {
	    set req.http.Section-Visitors = "";
	} else {
	    set req.http.Section-Visitors = var.global_get(req.http.Host + "-visitor-count");
	}
    cookie.parse(req.http.Cookie);

    if (!cookie.get("sqshowmaintenance." + req.http.Section-Visitors-Version)) {
        # no cookie yet, make a decision
        if (req.http.Section-Visitors != "") {
            if (std.integer(req.http.Section-Visitors, 0) > std.integer(req.http.Section-Visitors-Threshold, 0)) {
                std.log("overflow:count-block");
                set req.http.X-SQ-ShowMaintenance = "true-count";
                return (synth(800, "Maintenance Page"));
            } else {
                std.log("overflow:count-allow");
                set req.http.X-SQ-ShowMaintenance = "false";
                # increment count if the site has recently reached the threshold
                if (
                    std.time2integer(now, 0) < 300 +
                    std.integer(
                        var.global_get(req.http.Host + "-visitor-count-threshold-" + req.http.Section-Visitors-Threshold + "-reached"),
                        0
                    )
                ) {
                    set req.http.x-new-visitor-count = 1 + std.integer(var.global_get(req.http.Host + "-visitor-count"), 0);
                    var.global_set(
                        req.http.Host + "-visitor-count",
                        req.http.x-new-visitor-count
                    );
                    unset req.http.x-new-visitor-count;
                }
            }
        } else {
            set req.http.x-random-100 = std.random(1, 100);
            set req.http.x-random-100 = regsub(req.http.x-random-100, "\..*$", ""); # remove fraction
            if (std.integer(req.http.x-random-100, 1) <= std.integer(req.http.Section-Visitors-Fallback-Block-Percentage, 0)) {
                # fallback to percentage when visitor count data is unavailable ...
                std.log("overflow:percentage-block");
                set req.http.X-SQ-ShowMaintenance = "true";
                return (synth(800, "Maintenance Page"));
            } else {
                std.log("overflow:percentage-allow");
                set req.http.X-SQ-ShowMaintenance = "false";
            }
            unset req.http.x-random-100;
        }
    } else {
        # read the cookie, if true, show maintenance page, if false allow through
        if (cookie.get("sqshowmaintenance." + req.http.Section-Visitors-Version) == "true") {
            std.log("overflow:cookie-block");
            return (synth(800, "Maintenance Page"));
        } else {
            std.log("overflow:cookie-allow");
        }
    }
}

sub vcl_deliver {
    set resp.http.Section-Visitors = req.http.Section-Visitors;
    # Set the maintenance page cookie
    std.log("overflow:deliver-block");
    if (req.http.X-SQ-ShowMaintenance) {
        if (req.http.X-SQ-ShowMaintenance == "true-count") {
            # visitors blocked due to exceeding the count threshold, get a shorter block cookie expiration
            # so that they can be re-evaluated against the latest count sooner.
            std.log("overflow:add-cookie-overflow-true");
            header.append(
                resp.http.Set-Cookie,
                "sqshowmaintenance." +
                    req.http.Section-Visitors-Version +
                    "=true;Path=/; Expires=" +
                    cookie.format_rfc1123(now, 3m) +
                    ";"
            );
        } else {
            header.append(
                resp.http.Set-Cookie,
                "sqshowmaintenance." +
                    req.http.Section-Visitors-Version +
                    "=" +
                    req.http.X-SQ-ShowMaintenance +
                    ";Path=/; Expires=" +
                    cookie.format_rfc1123(now, 1h) +
                    ";"
            );
        }
    }
}