86 lines
2.6 KiB
TypeScript
86 lines
2.6 KiB
TypeScript
import sharp from 'sharp'
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export const MAX_BRAND_IMAGE_BYTES = 5 * 1024 * 1024
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export const MAX_BRAND_IMAGE_PIXELS = 4_194_304
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export const MAX_BRAND_IMAGE_DIMENSION = 4096
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export type ValidatedBrandImage = {
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extension: 'png' | 'jpg' | 'webp'
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contentType: 'image/png' | 'image/jpeg' | 'image/webp'
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width: number
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height: number
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}
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export type BrandImageValidationOptions = {
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maxBytes?: number
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maxBytesLabel?: string
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}
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const FORMAT_DETAILS: Record<string, Pick<ValidatedBrandImage, 'extension' | 'contentType'>> = {
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png: { extension: 'png', contentType: 'image/png' },
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jpeg: { extension: 'jpg', contentType: 'image/jpeg' },
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webp: { extension: 'webp', contentType: 'image/webp' },
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}
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/**
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* 品牌图属于高可见度系统配置，不能只看 magic bytes。
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* 这里会真正解码整张图，阻止截断文件、伪造 MIME、动画和解压炸弹进入数据库。
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*/
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export async function validateBrandImage(
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buffer: Buffer,
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declaredContentType?: string | null,
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options: BrandImageValidationOptions = {},
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): Promise<ValidatedBrandImage> {
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const maxBytes = options.maxBytes ?? MAX_BRAND_IMAGE_BYTES
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const maxBytesLabel = options.maxBytesLabel ?? '5MB'
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if (!Number.isSafeInteger(maxBytes) || maxBytes <= 0) {
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throw new TypeError('品牌图片大小上限必须是正的安全整数')
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}
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if (buffer.length <= 0 || buffer.length > maxBytes) {
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throw new Error(`品牌图片必须是 ${maxBytesLabel} 以内的有效文件`)
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}
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const image = sharp(buffer, {
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failOn: 'error',
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limitInputPixels: MAX_BRAND_IMAGE_PIXELS,
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animated: false,
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})
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const metadata = await image.metadata()
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const format = metadata.format ? FORMAT_DETAILS[metadata.format] : undefined
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const width = metadata.width || 0
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const height = metadata.height || 0
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if (!format) {
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throw new Error('品牌图片只支持 PNG、JPEG 或 WebP')
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}
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if (
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width < 1 ||
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height < 1 ||
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width > MAX_BRAND_IMAGE_DIMENSION ||
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height > MAX_BRAND_IMAGE_DIMENSION ||
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width * height > MAX_BRAND_IMAGE_PIXELS
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) {
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throw new Error('品牌图片尺寸无效或像素过大')
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}
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if ((metadata.pages || 1) > 1) {
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throw new Error('品牌图片不支持动画格式')
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}
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const normalizedDeclaredType = String(declaredContentType || '')
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.split(';', 1)[0]
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.trim()
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.toLowerCase()
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if (normalizedDeclaredType && normalizedDeclaredType !== format.contentType) {
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throw new Error('品牌图片内容与声明格式不一致')
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}
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// metadata() 主要读取头信息；raw().toBuffer() 强制完整解码，截断图片会在这里失败。
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await image.clone().raw().toBuffer()
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return {
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...format,
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width,
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height,
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}
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}
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