{"record":{"id":"0de1313f8358cc02","repo":"sipeed/picoclaw","slug":"invalid-padding-size-d","errorCode":null,"errorMessage":"invalid padding size %d","messagePattern":"invalid padding size (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"pkg/channels/wecom/media.go","lineNumber":127,"sourceCode":"\t\treturn nil, fmt.Errorf(\"ciphertext length %d is not a multiple of block size\", len(ciphertext))\n\t}\n\tblock, err := aes.NewCipher(key)\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"create cipher: %w\", err)\n\t}\n\tplaintext := make([]byte, len(ciphertext))\n\tiv := key[:aes.BlockSize]\n\tcipher.NewCBCDecrypter(block, iv).CryptBlocks(plaintext, ciphertext)\n\treturn pkcs7Unpad(plaintext)\n}\n\nfunc pkcs7Unpad(data []byte) ([]byte, error) {\n\tif len(data) == 0 {\n\t\treturn nil, fmt.Errorf(\"empty plaintext\")\n\t}\n\tpadding := int(data[len(data)-1])\n\tif padding == 0 || padding > 32 || padding > len(data) {\n\t\treturn nil, fmt.Errorf(\"invalid padding size %d\", padding)\n\t}\n\tfor i := 0; i < padding; i++ {\n\t\tif data[len(data)-1-i] != byte(padding) {\n\t\t\treturn nil, fmt.Errorf(\"invalid padding byte\")\n\t\t}\n\t}\n\treturn data[:len(data)-padding], nil\n}\n\nfunc inferMediaExt(contentType, fallback string) string {\n\tcontentType = normalizeWeComContentType(contentType)\n\tswitch contentType {\n\tcase \"image/jpeg\", \"image/jpg\":\n\t\treturn \".jpg\"\n\tcase \"image/png\":\n\t\treturn \".png\"\n\tcase \"image/gif\":\n\t\treturn \".gif\"","sourceCodeStart":109,"sourceCodeEnd":145,"githubUrl":"https://github.com/sipeed/picoclaw/blob/49183d7e8daed0dba89ddbb6fcb60089401d9680/pkg/channels/wecom/media.go#L109-L145","documentation":"Error \"invalid padding size %d\" thrown in sipeed/picoclaw.","triggerScenarios":"Thrown at pkg/channels/wecom/media.go:127 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"49183d7e8daed0dba89ddbb6fcb60089401d9680","analyzedAt":"2026-08-15T21:55:41.315Z","schemaVersion":2},"datasetVersion":"2026-08-16T03:17:38.424Z"}