v2: Implement Network Handling (HTTP Metadata, Conditional Requests, Request Config)

[mmcdole]

Overview

Implement comprehensive network handling for ParseURL including HTTP response metadata, conditional requests, and request configuration using the RequestOptions sub-struct from #244.

Tasks

Request Configuration

• Use RequestOptions from ParseOptions for HTTP configuration:
  • Apply custom Client if provided
  • Set Timeout on HTTP client
  • Set UserAgent header
  • Apply AuthConfig for basic auth

Conditional Requests

• Implement conditional request support:
  • Send If-None-Match header when IfNoneMatch is set in RequestOptions
  • Send If-Modified-Since header when IfModifiedSince is set
  • Return ErrNotModified for 304 responses
  • Handle 304 responses gracefully

Response Metadata

• Add ResponseMetadata struct to gofeed.Feed:

  type ResponseMetadata struct {
      StatusCode int
      ETag string
      LastModified time.Time
      CacheControl struct {
          MaxAge *time.Duration
          MustRevalidate bool
          NoCache bool
          NoStore bool
      }
      RetryAfter *time.Time
      Expires *time.Time
  }

• Parse and populate HTTP headers:

  • ETag response header
  • Last-Modified header (parse HTTP date)
  • Cache-Control directives (max-age, must-revalidate, no-cache, no-store)
  • Retry-After header (both HTTP-date and delay-seconds formats)
  • Expires header

Testing & Documentation

• Add comprehensive tests for all network functionality
• Document usage patterns for:
  • Conditional requests to reduce bandwidth
  • Cache control interpretation
  • Retry-After handling for rate limiting

Benefits

• Enable proper HTTP caching strategies
• Support conditional requests to reduce unnecessary fetches
• Provide scheduling hints from HTTP headers
• Better HTTP client configuration support

Related Issues

• Add support for Etag, Last-Modified, If-None-Match and If-Modified-Since http headers on request and response #111 (HTTP ETag, Last-Modified, conditional requests)
• Add support proxy setting for parserURL #165 (Proxy/custom HTTP client support)
• Please consider exposing skipHours (in shared model) #228 (Scheduling hints)
• v2: Implement ParseOptions and Update Parser API #244 (ParseOptions implementation)

Parent Issue

• RFC: gofeed v2 – Proposed Changes #241 (RFC: gofeed v2)