RFC 9112 - HTTP/1.1

Published: June 2022
Status: Standards Track
Authors: R. Fielding (Adobe), M. Nottingham (Fastly), J. Reschke (greenbytes)
Obsoletes: RFC 7230

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Abstract

The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document specifies the HTTP/1.1 message syntax, message parsing, connection management, and related security concerns.

This document obsoletes portions of RFC 7230.

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Table of Contents

• 1. Introduction
  • 1.1 Requirements Notation
  • 1.2 Syntax Notation
• 2. Message
  • 2.1 Message Format
  • 2.2 Message Parsing
  • 2.3 HTTP Version
• 3. Request Line
  • 3.1 Method
  • 3.2 Request Target
  • 3.3 Reconstructing the Target URI
• 4. Status Line
• 5. Field Syntax
  • 5.1 Field Line Parsing
  • 5.2 Obsolete Line Folding
• 6. Message Body
  • 6.1 Transfer-Encoding
  • 6.2 Content-Length
  • 6.3 Message Body Length
• 7. Transfer Codings
  • 7.1 Chunked Transfer Coding
  • 7.2 Transfer Codings for Compression
  • 7.3 Transfer Coding Registry
  • 7.4 Negotiating Transfer Codings
• 8. Handling Incomplete Messages
• 9. Connection Management
  • 9.1 Establishment
  • 9.2 Associating a Response to a Request
  • 9.3 Persistence
  • 9.4 Concurrency
  • 9.5 Failures and Timeouts
  • 9.6 Tear-down
  • 9.7 TLS Connection Initiation
  • 9.8 TLS Connection Closure
• 10. Enclosing Messages as Data
  • 10.1 Media Type message/http
  • 10.2 Media Type application/http
• 11. Security Considerations
  • 11.1 Response Splitting
  • 11.2 Request Smuggling
  • 11.3 Message Integrity
  • 11.4 Message Confidentiality
• 12. IANA Considerations
  • 12.1 Field Name Registration
  • 12.2 Media Type Registration
  • 12.3 Transfer Coding Registration
  • 12.4 ALPN Protocol ID Registration
• 13. References
  • 13.1 Normative References
  • 13.2 Informative References

Appendices

• Appendix A. Collected ABNF
• Appendix B. Differences between HTTP and MIME
  • B.1 MIME-Version
  • B.2 Conversion to Canonical Form
  • B.3 Conversion of Date Formats
  • B.4 Conversion of Content-Encoding
  • B.5 Conversion of Content-Transfer-Encoding
  • B.6 MHTML and Line Length Limitations
• Appendix C. Changes from Previous RFCs
  • C.1 Changes from HTTP/0.9
  • C.2 Changes from HTTP/1.0
  • C.3 Changes from RFC 7230

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Resources

• Official Text: RFC 9112
• Official Page: RFC 9112 DataTracker
• Errata: RFC Editor Errata

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