feat: add secure remote channel media

src/shared/channel-contracts.ts

@@ -7,7 +7,11 @@ export const CHANNEL_LIMITS = {
   maximumTextLength: 32_000,
   maximumResultLength: 16_000,
   maximumErrorLength: 1_000,
-  maximumStatusLength: 64
+  maximumStatusLength: 64,
+  maximumAttachmentCount: 4,
+  maximumAttachmentBytes: 12 * 1024 * 1024,
+  maximumAttachmentNameLength: 240,
+  maximumAttachmentMimeTypeLength: 128
 } as const
 
 const channelIdentifierSchema = z
@@ -19,6 +23,81 @@ const channelIdentifierSchema = z
 export const channelWorkModeSchema = z.enum(['ask', 'plan'])
 export type ChannelWorkMode = z.infer<typeof channelWorkModeSchema>
 
+const attachmentBase64Schema = z
+  .string()
+  .max(
+    Math.ceil(CHANNEL_LIMITS.maximumAttachmentBytes / 3) * 4 + 4
+  )
+  .regex(/^(?:[a-z0-9+/]{4})*(?:[a-z0-9+/]{2}==|[a-z0-9+/]{3}=)?$/iu)
+
+export function decodedBase64Size(value: string): number {
+  const padding = value.endsWith('==') ? 2 : value.endsWith('=') ? 1 : 0
+  return (value.length / 4) * 3 - padding
+}
+
+export const channelMediaAttachmentSchema = z
+  .object({
+    name: z
+      .string()
+      .trim()
+      .min(1)
+      .max(CHANNEL_LIMITS.maximumAttachmentNameLength),
+    mimeType: z
+      .string()
+      .trim()
+      .min(1)
+      .max(CHANNEL_LIMITS.maximumAttachmentMimeTypeLength)
+      .regex(/^[a-z0-9][a-z0-9!#$&^_.+-]*\/[a-z0-9][a-z0-9!#$&^_.+-]*$/iu),
+    size: z
+      .number()
+      .int()
+      .positive()
+      .max(CHANNEL_LIMITS.maximumAttachmentBytes),
+    kind: z.enum(['image', 'file']),
+    dataBase64: attachmentBase64Schema
+  })
+  .strict()
+  .superRefine((attachment, context) => {
+    const decodedSize = decodedBase64Size(attachment.dataBase64)
+    if (decodedSize !== attachment.size) {
+      context.addIssue({
+        code: 'custom',
+        path: ['dataBase64'],
+        message: '附件大小与内容不匹配'
+      })
+    }
+    if (
+      attachment.kind === 'image' &&
+      !attachment.mimeType.startsWith('image/')
+    ) {
+      context.addIssue({
+        code: 'custom',
+        path: ['mimeType'],
+        message: '图片附件类型无效'
+      })
+    }
+  })
+
+export type ChannelMediaAttachment = z.infer<
+  typeof channelMediaAttachmentSchema
+>
+
+export const channelAttachmentsSchema = z
+  .array(channelMediaAttachmentSchema)
+  .max(CHANNEL_LIMITS.maximumAttachmentCount)
+  .superRefine((attachments, context) => {
+    const total = attachments.reduce(
+      (sum, attachment) => sum + attachment.size,
+      0
+    )
+    if (total > CHANNEL_LIMITS.maximumAttachmentBytes) {
+      context.addIssue({
+        code: 'custom',
+        message: '附件总大小超过限制'
+      })
+    }
+  })
+
 export const channelInboundTextSchema = z
   .object({
     channel: z
@@ -35,15 +114,35 @@ export const channelInboundTextSchema = z
     conversationId: channelIdentifierSchema,
     conversationType: z.enum(['direct', 'group']),
     text: z
+      .string()
+      .trim()
+      .max(CHANNEL_LIMITS.maximumTextLength)
+      .default(''),
+    attachments: channelAttachmentsSchema.optional(),
+    attachmentError: z
       .string()
       .trim()
       .min(1)
-      .max(CHANNEL_LIMITS.maximumTextLength),
+      .max(CHANNEL_LIMITS.maximumErrorLength)
+      .optional(),
     mentioned: z.boolean().default(false),
     workMode: channelWorkModeSchema.default('ask'),
     receivedAt: z.number().int().nonnegative().optional()
   })
   .strict()
+  .superRefine((message, context) => {
+    if (
+      message.text.length === 0 &&
+      !message.attachments?.length &&
+      !message.attachmentError
+    ) {
+      context.addIssue({
+        code: 'custom',
+        path: ['text'],
+        message: '消息内容不能为空'
+      })
+    }
+  })
 
 export type ChannelInboundText = z.infer<
   typeof channelInboundTextSchema
@@ -57,7 +156,8 @@ export const channelExecutorResultSchema = z
       .min(1)
       .max(CHANNEL_LIMITS.maximumStatusLength),
     output: z.string().optional(),
-    error: z.string().optional()
+    error: z.string().optional(),
+    attachments: channelAttachmentsSchema.optional()
   })
   .strict()
 
@@ -91,7 +191,8 @@ export const channelResultMessageSchema = z
     error: z
       .string()
       .max(CHANNEL_LIMITS.maximumErrorLength)
-      .optional()
+      .optional(),
+    attachments: channelAttachmentsSchema.optional()
   })
   .strict()