{"record":{"id":"a34becb9921d6018","repo":"shadow1ng/fscan","slug":"domain-length-invalid","errorCode":null,"errorMessage":"domain_length_invalid","messagePattern":"domain_length_invalid","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"plugins/local/socks5proxy.go","lineNumber":228,"sourceCode":"\tvar targetHost string\n\tvar targetPort int\n\n\tswitch addrType {\n\tcase 0x01: // IPv4\n\t\taddr := make([]byte, 6)\n\t\tif _, err := io.ReadFull(clientConn, addr); err != nil {\n\t\t\treturn nil, 0, fmt.Errorf(\"%s\", i18n.GetText(\"ipv4_address_invalid\"))\n\t\t}\n\t\ttargetHost = fmt.Sprintf(\"%d.%d.%d.%d\", addr[0], addr[1], addr[2], addr[3])\n\t\ttargetPort = int(addr[4])<<8 + int(addr[5])\n\tcase 0x03: // 域名\n\t\tlenBuf := make([]byte, 1)\n\t\tif _, err := io.ReadFull(clientConn, lenBuf); err != nil {\n\t\t\treturn nil, 0, fmt.Errorf(\"%s\", i18n.GetText(\"domain_format_invalid\"))\n\t\t}\n\t\tdomainLen := int(lenBuf[0])\n\t\tif domainLen == 0 {\n\t\t\treturn nil, 0, fmt.Errorf(\"%s\", i18n.GetText(\"domain_length_invalid\"))\n\t\t}\n\t\taddr := make([]byte, domainLen+2)\n\t\tif _, err := io.ReadFull(clientConn, addr); err != nil {\n\t\t\treturn nil, 0, fmt.Errorf(\"%s\", i18n.GetText(\"domain_length_invalid\"))\n\t\t}\n\t\ttargetHost = string(addr[:domainLen])\n\t\ttargetPort = int(addr[domainLen])<<8 + int(addr[domainLen+1])\n\tcase 0x04: // IPv6\n\t\taddr := make([]byte, 18)\n\t\tif _, err := io.ReadFull(clientConn, addr); err != nil {\n\t\t\treturn nil, 0, fmt.Errorf(\"%s\", i18n.GetText(\"ipv6_address_invalid\"))\n\t\t}\n\t\t// IPv6地址解析（简化实现）\n\t\ttargetHost = net.IP(addr[:16]).String()\n\t\ttargetPort = int(addr[16])<<8 + int(addr[17])\n\tdefault:\n\t\t// 发送不支持的地址类型响应\n\t\tresponse := []byte{0x05, 0x08, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}","sourceCodeStart":210,"sourceCodeEnd":246,"githubUrl":"https://github.com/shadow1ng/fscan/blob/95cc12e753bf43de7004e5aef42a9ffba3934303/plugins/local/socks5proxy.go#L210-L246","documentation":"Guard in the domain branch of the SOCKS5 address parser: either the declared domain length is zero, or io.ReadFull failed while reading the domainLen+2 payload (domain bytes plus 2-byte port). Both cases mean the domain section is empty or truncated and the target address cannot be reconstructed.","triggerScenarios":"Thrown at plugins/local/socks5proxy.go:228 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Reject zero-length domain prefixes early on the client side","Ensure the full domain+port payload is written in one request","Distinguish the length==0 case from the read-error case with separate messages for easier diagnosis"],"exampleFix":null,"handlingStrategy":"validation","validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"95cc12e753bf43de7004e5aef42a9ffba3934303","analyzedAt":"2026-09-06T17:07:30.094Z","contentChangedAt":"2026-09-06T17:07:30.094Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}