package openresty
import (
"fmt"
"strconv"
"strings"
)
const (
// OriginErrorPageSupportPath is the SupportFile path for the origin error HTML template.
OriginErrorPageSupportPath = "error_pages/origin_error.html.tmpl"
// OriginErrorPageInternalLocation is the internal nginx location that serves the error body.
OriginErrorPageInternalLocation = "/__openflare_origin_error"
defaultOriginErrorPageStatusTag = "500-599"
)
// DefaultOriginErrorPageHTML is the built-in default (aligned with frontend minimalist).
// Placeholders {{status}} and {{host}} are substituted at request time by Lua.
const DefaultOriginErrorPageHTML = `
{{status}} | OpenFlare
{{status}}
The upstream server is unreachable. Please try again later or contact the site administrator if the problem persists.
{{host}}
`
// EffectiveOriginErrorPageHTML returns custom HTML when set, otherwise the built-in default.
func EffectiveOriginErrorPageHTML(cfg ConfigSnapshot) string {
if strings.TrimSpace(cfg.OriginErrorPageHTML) == "" {
return DefaultOriginErrorPageHTML
}
return cfg.OriginErrorPageHTML
}
func effectiveOriginErrorPageStatusTags(cfg ConfigSnapshot) []string {
if len(cfg.OriginErrorPageStatusCodes) == 0 {
return []string{defaultOriginErrorPageStatusTag}
}
return cfg.OriginErrorPageStatusCodes
}
func originErrorPageSupportFile(cfg ConfigSnapshot) SupportFile {
return SupportFile{
Path: OriginErrorPageSupportPath,
Content: EffectiveOriginErrorPageHTML(cfg),
}
}
func renderOriginErrorPageIntercept(cfg ConfigSnapshot) string {
if !cfg.OriginErrorPageEnabled {
return ""
}
if _, err := ExpandStatusCodeTags(effectiveOriginErrorPageStatusTags(cfg)); err != nil {
return ""
}
return " proxy_intercept_errors on;\n"
}
// renderOriginErrorPageServerBits emits server-level error_page + internal location.
// Returns empty string when disabled, expand fails, or no codes remain.
func renderOriginErrorPageServerBits(cfg ConfigSnapshot) string {
if !cfg.OriginErrorPageEnabled {
return ""
}
codes, err := ExpandStatusCodeTags(effectiveOriginErrorPageStatusTags(cfg))
if err != nil || len(codes) == 0 {
return ""
}
parts := make([]string, len(codes))
for i, code := range codes {
parts[i] = strconv.Itoa(code)
}
var builder strings.Builder
fmt.Fprintf(&builder, " error_page %s = %s;\n", strings.Join(parts, " "), OriginErrorPageInternalLocation)
builder.WriteString(renderOriginErrorPageInternalLocation())
return builder.String()
}
func renderOriginErrorPageInternalLocation() string {
return fmt.Sprintf(` location = %s {
internal;
default_type text/html;
charset utf-8;
content_by_lua_block {
local f = io.open("%s", "r")
if not f then
ngx.status = ngx.status
ngx.say("Error ", ngx.status)
return
end
local body = f:read("*a")
f:close()
local status = tostring(ngx.status)
local host = ngx.var.host or ""
body = body:gsub("{{status}}", status, 1)
body = body:gsub("{{host}}", host, 1)
body = body:gsub("{{status}}", status)
body = body:gsub("{{host}}", host)
ngx.header["Content-Type"] = "text/html; charset=utf-8"
ngx.say(body)
}
}
`, OriginErrorPageInternalLocation, ErrorPageTmplPlaceholder)
}