har

package
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 Go to latest Published: Aug 31, 2026 License: Apache-2.0 Imports: 17 Imported by: 0

Documentation

Overview

Package har exports captured flows as HAR 1.2 documents and imports HAR documents produced by pano, browsers (Chrome, Firefox) and other proxies.

Export streams entries one at a time so a large capture never has to be held in memory twice. Bodies are looked up on demand through a BodyFunc, which must return decoded bytes (Content-Encoding removed); text bodies are inlined as UTF-8, everything else is base64. An optional Redactor masks secrets in header values and text bodies before they reach the writer.

Each exported entry carries a "_pano" extension object (HAR permits underscore-prefixed custom fields) holding the flow id, kind, session, error, tags, rule hits and truncation flags. Import restores those fields when present and falls back to sensible defaults for HARs produced elsewhere.

The Log, Entry and related types mirror the HAR 1.2 schema and are exported so callers can inspect or build documents directly.

Index

Constants

View Source 
const DefaultMaxBodyBytes = 1 << 20

DefaultMaxBodyBytes is the per-body inline cap used when ExportOptions.MaxBodyBytes is zero.

View Source 
const Version = "1.2"

Version is the HAR format version this package writes.

Variables

View Source 
var ErrNotHAR = errors.New("har: document has no log object")

ErrNotHAR is returned when the input parses as JSON but has no "log" object.

Functions

func Export 

func Export(w io.Writer, flows []*flow.Flow, opts ExportOptions) (int, error)

Export writes a HAR 1.2 document for flows, in the given order, to w and returns the number of entries written. Nil flows are skipped. The document is streamed entry by entry, so memory use is bounded by the largest single entry rather than the whole capture.

Types

type BodyFunc 

type BodyFunc func(hash string) (b []byte, ok bool)

BodyFunc fetches a body's decoded bytes (Content-Encoding removed) by hash. It returns ok=false when the body is unavailable.

type Cache 

type Cache struct {
	BeforeRequest *CacheState `json:"beforeRequest,omitempty"`
	AfterRequest  *CacheState `json:"afterRequest,omitempty"`
	Comment       string      `json:"comment,omitempty"`
}

Cache describes cache usage; pano always writes an empty object.

type CacheState 

type CacheState struct {
	Expires    string `json:"expires,omitempty"`
	LastAccess string `json:"lastAccess"`
	ETag       string `json:"eTag"`
	HitCount   int64  `json:"hitCount"`
	Comment    string `json:"comment,omitempty"`
}

CacheState is a cache entry snapshot.

type Content 

type Content struct {
	Size        int64  `json:"size"`
	Compression *int64 `json:"compression,omitempty"`
	MimeType    string `json:"mimeType"`
	Text        string `json:"text,omitempty"`
	Encoding    string `json:"encoding,omitempty"`
	Comment     string `json:"comment,omitempty"`
}

Content is a response body. Size is the decoded length; Encoding is "base64" when Text is base64 rather than literal text. 

type Cookie struct {
	Name     string `json:"name"`
	Value    string `json:"value"`
	Path     string `json:"path,omitempty"`
	Domain   string `json:"domain,omitempty"`
	Expires  string `json:"expires,omitempty"`
	HTTPOnly bool   `json:"httpOnly,omitempty"`
	Secure   bool   `json:"secure,omitempty"`
	Comment  string `json:"comment,omitempty"`
}

Cookie is a parsed request or response cookie.

type Creator 

type Creator struct {
	Name    string `json:"name"`
	Version string `json:"version"`
	Comment string `json:"comment,omitempty"`
}

Creator identifies the application that produced the log.

type Document 

type Document struct {
	Log *Log `json:"log"`
}

Document is a HAR file: a single "log" object.

type Entry 

type Entry struct {
	Pageref         string   `json:"pageref,omitempty"`
	StartedDateTime string   `json:"startedDateTime"`
	Time            float64  `json:"time"`
	Request         Request  `json:"request"`
	Response        Response `json:"response"`
	Cache           Cache    `json:"cache"`
	Timings         Timings  `json:"timings"`
	ServerIPAddress string   `json:"serverIPAddress"`
	Connection      string   `json:"connection,omitempty"`
	Comment         string   `json:"comment,omitempty"`
	// Pano is the "_pano" extension carrying flow metadata that has no HAR
	// equivalent. It is nil on documents written by other tools.
	Pano *PanoExt `json:"_pano,omitempty"`
}

Entry is one exchange.

type ExportOptions 

type ExportOptions struct {
	// Creator and Version populate log.creator.
	Creator, Version string
	// Body resolves body hashes to decoded bytes. When nil no bodies are
	// inlined and each body carries an explanatory comment.
	Body BodyFunc
	// Redact, when non-nil, masks header values and text bodies.
	Redact *Redactor
	// MaxBodyBytes caps the size of a single inlined body. Zero selects
	// [DefaultMaxBodyBytes]; a negative value omits all bodies. Larger bodies
	// are left out and the content/postData comment explains why.
	MaxBodyBytes int
}

ExportOptions controls Export.

type Imported 

type Imported struct {
	Flow     *flow.Flow
	ReqBody  []byte
	RespBody []byte
}

Imported is one flow parsed from a HAR document. Bodies are returned separately as decoded bytes so the caller can store them and fill in the BodyRef hashes; Flow.ID is 0 and is assigned by the caller.

func Import 

func Import(r io.Reader) ([]Imported, error)

Import parses a HAR document into flows. It tolerates missing or mistyped fields, both literal and base64 bodies, and browser-specific extensions (Chrome's _initiator, _priority, _resourceType and friends are ignored). Bodies are returned decoded; the caller stores them and assigns IDs.

Timing is reconstructed from startedDateTime, time and the timings phases, so TTFB and totals survive a round trip. Header maps keep their Content-Encoding header even though the returned bytes are decoded; the BodyRef.Encoding field is left empty to reflect what the caller stores.

type Log 

type Log struct {
	Version string   `json:"version"`
	Creator Creator  `json:"creator"`
	Browser *Creator `json:"browser,omitempty"`
	Pages   []Page   `json:"pages,omitempty"`
	Entries []Entry  `json:"entries"`
	Comment string   `json:"comment,omitempty"`
}

Log is the HAR 1.2 log object.

type NVP 

type NVP struct {
	Name    string `json:"name"`
	Value   string `json:"value"`
	Comment string `json:"comment,omitempty"`
}

NVP is a name/value pair used for headers and query parameters.

type Page 

type Page struct {
	StartedDateTime string      `json:"startedDateTime"`
	ID              string      `json:"id"`
	Title           string      `json:"title"`
	PageTimings     PageTimings `json:"pageTimings"`
	Comment         string      `json:"comment,omitempty"`
}

Page is a browser page; pano never writes pages but tolerates them on import.

type PageTimings 

type PageTimings struct {
	OnContentLoad float64 `json:"onContentLoad,omitempty"`
	OnLoad        float64 `json:"onLoad,omitempty"`
	Comment       string  `json:"comment,omitempty"`
}

PageTimings holds page load milestones in milliseconds.

type PanoExt 

type PanoExt struct {
	ID            flow.ID        `json:"id"`
	Short         string         `json:"short"`
	Kind          flow.Kind      `json:"kind"`
	State         flow.State     `json:"state,omitempty"`
	Session       string         `json:"session,omitempty"`
	Error         string         `json:"error,omitempty"`
	Tags          []string       `json:"tags,omitempty"`
	Rules         []flow.RuleHit `json:"rules,omitempty"`
	ReqTruncated  bool           `json:"reqTruncated,omitempty"`
	RespTruncated bool           `json:"respTruncated,omitempty"`
	Replay        bool           `json:"replay,omitempty"`
	ReplayOf      flow.ID        `json:"replayOf,omitempty"`
}

PanoExt is the per-entry "_pano" extension object.

type Param 

type Param struct {
	Name        string `json:"name"`
	Value       string `json:"value,omitempty"`
	FileName    string `json:"fileName,omitempty"`
	ContentType string `json:"contentType,omitempty"`
	Comment     string `json:"comment,omitempty"`
}

Param is one posted form parameter.

type PostData 

type PostData struct {
	MimeType string  `json:"mimeType"`
	Params   []Param `json:"params,omitempty"`
	Text     string  `json:"text,omitempty"`
	Encoding string  `json:"encoding,omitempty"`
	Comment  string  `json:"comment,omitempty"`
}

PostData is a request body. Encoding is a pano extension (HAR 1.2 has no base64 flag for request bodies): it is "base64" when Text is not UTF-8 text.

type Redactor 

type Redactor struct {
	// Headers returns a redacted copy of h. It must not modify h.
	Headers func(http.Header) http.Header
	// Text returns a redacted copy of a text body.
	Text func(string) string
}

Redactor masks secrets in header values and text bodies. Either function may be nil; a nil *Redactor disables redaction entirely.

type Request 

type Request struct {
	Method      string    `json:"method"`
	URL         string    `json:"url"`
	HTTPVersion string    `json:"httpVersion"`
	Cookies     []Cookie  `json:"cookies"`
	Headers     []NVP     `json:"headers"`
	QueryString []NVP     `json:"queryString"`
	PostData    *PostData `json:"postData,omitempty"`
	HeadersSize int64     `json:"headersSize"`
	BodySize    int64     `json:"bodySize"`
	Comment     string    `json:"comment,omitempty"`
}

Request is the request half of an entry.

type Response 

type Response struct {
	Status      int      `json:"status"`
	StatusText  string   `json:"statusText"`
	HTTPVersion string   `json:"httpVersion"`
	Cookies     []Cookie `json:"cookies"`
	Headers     []NVP    `json:"headers"`
	Content     Content  `json:"content"`
	RedirectURL string   `json:"redirectURL"`
	HeadersSize int64    `json:"headersSize"`
	BodySize    int64    `json:"bodySize"`
	Comment     string   `json:"comment,omitempty"`
	// Error is Chrome's "_error" extension (e.g. "net::ERR_CONNECTION_RESET").
	// pano never writes it but uses it on import when no "_pano" is present.
	Error string `json:"_error,omitempty"`
}

Response is the response half of an entry.

type Timings 

type Timings struct {
	Blocked float64 `json:"blocked"`
	DNS     float64 `json:"dns"`
	Connect float64 `json:"connect"`
	Send    float64 `json:"send"`
	Wait    float64 `json:"wait"`
	Receive float64 `json:"receive"`
	SSL     float64 `json:"ssl"`
	Comment string  `json:"comment,omitempty"`
}

Timings breaks the entry down by phase, in milliseconds. -1 marks a phase that does not apply or was not measured.

Source Files

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