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Package httputil

import "net/http/httputil"
Overview
Index
Examples

Overview ▾

Package httputil provides HTTP utility functions, complementing the more common ones in the net/http package.

Index ▾

Package files

dump.go httputil.go persist.go reverseproxy.go

Variables

var (
    ErrPersistEOF = &http.ProtocolError{ErrorString: "persistent connection closed"}
    ErrClosed     = &http.ProtocolError{ErrorString: "connection closed by user"}
    ErrPipeline   = &http.ProtocolError{ErrorString: "pipeline error"}
)
var ErrLineTooLong = internal.ErrLineTooLong

ErrLineTooLong is returned when reading malformed chunked data with lines that are too long.

func DumpRequest

func DumpRequest(req *http.Request, body bool) (dump []byte, err error)

DumpRequest returns the given request in its HTTP/1.x wire representation. It should only be used by servers to debug client requests. The returned representation is an approximation only; some details of the initial request are lost while parsing it into an http.Request. In particular, the order and case of header field names are lost. The order of values in multi-valued headers is kept intact. HTTP/2 requests are dumped in HTTP/1.x form, not in their original binary representations.

If body is true, DumpRequest also returns the body. To do so, it consumes req.Body and then replaces it with a new io.ReadCloser that yields the same bytes. If DumpRequest returns an error, the state of req is undefined.

The documentation for http.Request.Write details which fields of req are included in the dump.

▾ Example

Code:

ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    dump, err := httputil.DumpRequest(r, true)
    if err != nil {
        http.Error(w, fmt.Sprint(err), http.StatusInternalServerError)
        return
    }

    fmt.Fprintf(w, "%q", dump)
}))
defer ts.Close()

const body = "Go is a general-purpose language designed with systems programming in mind."
req, err := http.NewRequest("POST", ts.URL, strings.NewReader(body))
if err != nil {
    log.Fatal(err)
}
req.Host = "www.example.org"
resp, err := http.DefaultClient.Do(req)
if err != nil {
    log.Fatal(err)
}
defer resp.Body.Close()

b, err := ioutil.ReadAll(resp.Body)
if err != nil {
    log.Fatal(err)
}

fmt.Printf("%s", b)

Output:

"POST / HTTP/1.1\r\nHost: www.example.org\r\nAccept-Encoding: gzip\r\nUser-Agent: Go-http-client/1.1\r\n\r\nGo is a general-purpose language designed with systems programming in mind."

func DumpRequestOut

func DumpRequestOut(req *http.Request, body bool) ([]byte, error)

DumpRequestOut is like DumpRequest but for outgoing client requests. It includes any headers that the standard http.Transport adds, such as User-Agent.

▾ Example

Code:

const body = "Go is a general-purpose language designed with systems programming in mind."
req, err := http.NewRequest("PUT", "http://www.example.org", strings.NewReader(body))
if err != nil {
    log.Fatal(err)
}

dump, err := httputil.DumpRequestOut(req, true)
if err != nil {
    log.Fatal(err)
}

fmt.Printf("%q", dump)

Output:

"PUT / HTTP/1.1\r\nHost: www.example.org\r\nUser-Agent: Go-http-client/1.1\r\nContent-Length: 75\r\nAccept-Encoding: gzip\r\n\r\nGo is a general-purpose language designed with systems programming in mind."

func DumpResponse

func DumpResponse(resp *http.Response, body bool) (dump []byte, err error)

DumpResponse is like DumpRequest but dumps a response.

▾ Example

Code:

const body = "Go is a general-purpose language designed with systems programming in mind."
ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Date", "Wed, 19 Jul 1972 19:00:00 GMT")
    fmt.Fprintln(w, body)
}))
defer ts.Close()

resp, err := http.Get(ts.URL)
if err != nil {
    log.Fatal(err)
}
defer resp.Body.Close()

dump, err := httputil.DumpResponse(resp, true)
if err != nil {
    log.Fatal(err)
}

fmt.Printf("%q", dump)

Output:

"HTTP/1.1 200 OK\r\nContent-Length: 76\r\nContent-Type: text/plain; charset=utf-8\r\nDate: Wed, 19 Jul 1972 19:00:00 GMT\r\n\r\nGo is a general-purpose language designed with systems programming in mind.\n"

func NewChunkedReader

func NewChunkedReader(r io.Reader) io.Reader

NewChunkedReader returns a new chunkedReader that translates the data read from r out of HTTP "chunked" format before returning it. The chunkedReader returns io.EOF when the final 0-length chunk is read.

NewChunkedReader is not needed by normal applications. The http package automatically decodes chunking when reading response bodies.

func NewChunkedWriter

func NewChunkedWriter(w io.Writer) io.WriteCloser

NewChunkedWriter returns a new chunkedWriter that translates writes into HTTP "chunked" format before writing them to w. Closing the returned chunkedWriter sends the final 0-length chunk that marks the end of the stream.

NewChunkedWriter is not needed by normal applications. The http package adds chunking automatically if handlers don't set a Content-Length header. Using NewChunkedWriter inside a handler would result in double chunking or chunking with a Content-Length length, both of which are wrong.

type BufferPool

type BufferPool interface {
    Get() []byte
    Put([]byte)
}

A BufferPool is an interface for getting and returning temporary byte slices for use by io.CopyBuffer.

type ClientConn

type ClientConn struct {
    // contains filtered or unexported fields
}

A ClientConn sends request and receives headers over an underlying connection, while respecting the HTTP keepalive logic. ClientConn supports hijacking the connection calling Hijack to regain control of the underlying net.Conn and deal with it as desired.

ClientConn is low-level and old. Applications should instead use Client or Transport in the net/http package.

func NewClientConn

func NewClientConn(c net.Conn, r *bufio.Reader) *ClientConn

NewClientConn returns a new ClientConn reading and writing c. If r is not nil, it is the buffer to use when reading c.

ClientConn is low-level and old. Applications should use Client or Transport in the net/http package.

func NewProxyClientConn

func NewProxyClientConn(c net.Conn, r *bufio.Reader) *ClientConn

NewProxyClientConn works like NewClientConn but writes Requests using Request's WriteProxy method.

New code should not use NewProxyClientConn. See Client or Transport in the net/http package instead.

func (*ClientConn) Close

func (cc *ClientConn) Close() error

Close calls Hijack and then also closes the underlying connection

func (*ClientConn) Do

func (cc *ClientConn) Do(req *http.Request) (resp *http.Response, err error)

Do is convenience method that writes a request and reads a response.

func (*ClientConn) Hijack

func (cc *ClientConn) Hijack() (c net.Conn, r *bufio.Reader)

Hijack detaches the ClientConn and returns the underlying connection as well as the read-side bufio which may have some left over data. Hijack may be called before the user or Read have signaled the end of the keep-alive logic. The user should not call Hijack while Read or Write is in progress.

func (*ClientConn) Pending

func (cc *ClientConn) Pending() int

Pending returns the number of unanswered requests that have been sent on the connection.

func (*ClientConn) Read

func (cc *ClientConn) Read(req *http.Request) (resp *http.Response, err error)

Read reads the next response from the wire. A valid response might be returned together with an ErrPersistEOF, which means that the remote requested that this be the last request serviced. Read can be called concurrently with Write, but not with another Read.

func (*ClientConn) Write

func (cc *ClientConn) Write(req *http.Request) (err error)

Write writes a request. An ErrPersistEOF error is returned if the connection has been closed in an HTTP keepalive sense. If req.Close equals true, the keepalive connection is logically closed after this request and the opposing server is informed. An ErrUnexpectedEOF indicates the remote closed the underlying TCP connection, which is usually considered as graceful close.

type ReverseProxy

type ReverseProxy struct {
    // Director must be a function which modifies
    // the request into a new request to be sent
    // using Transport. Its response is then copied
    // back to the original client unmodified.
    Director func(*http.Request)

    // The transport used to perform proxy requests.
    // If nil, http.DefaultTransport is used.
    Transport http.RoundTripper

    // FlushInterval specifies the flush interval
    // to flush to the client while copying the
    // response body.
    // If zero, no periodic flushing is done.
    FlushInterval time.Duration

    // ErrorLog specifies an optional logger for errors
    // that occur when attempting to proxy the request.
    // If nil, logging goes to os.Stderr via the log package's
    // standard logger.
    ErrorLog *log.Logger

    // BufferPool optionally specifies a buffer pool to
    // get byte slices for use by io.CopyBuffer when
    // copying HTTP response bodies.
    BufferPool BufferPool
}

ReverseProxy is an HTTP Handler that takes an incoming request and sends it to another server, proxying the response back to the client.

▾ Example

Code:

backendServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintln(w, "this call was relayed by the reverse proxy")
}))
defer backendServer.Close()

rpURL, err := url.Parse(backendServer.URL)
if err != nil {
    log.Fatal(err)
}
frontendProxy := httptest.NewServer(httputil.NewSingleHostReverseProxy(rpURL))
defer frontendProxy.Close()

resp, err := http.Get(frontendProxy.URL)
if err != nil {
    log.Fatal(err)
}

b, err := ioutil.ReadAll(resp.Body)
if err != nil {
    log.Fatal(err)
}

fmt.Printf("%s", b)

Output:

this call was relayed by the reverse proxy

func NewSingleHostReverseProxy

func NewSingleHostReverseProxy(target *url.URL) *ReverseProxy

NewSingleHostReverseProxy returns a new ReverseProxy that routes URLs to the scheme, host, and base path provided in target. If the target's path is "/base" and the incoming request was for "/dir", the target request will be for /base/dir. NewSingleHostReverseProxy does not rewrite the Host header. To rewrite Host headers, use ReverseProxy directly with a custom Director policy.

func (*ReverseProxy) ServeHTTP

func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request)

type ServerConn

type ServerConn struct {
    // contains filtered or unexported fields
}

A ServerConn reads requests and sends responses over an underlying connection, until the HTTP keepalive logic commands an end. ServerConn also allows hijacking the underlying connection by calling Hijack to regain control over the connection. ServerConn supports pipe-lining, i.e. requests can be read out of sync (but in the same order) while the respective responses are sent.

ServerConn is low-level and old. Applications should instead use Server in the net/http package.

func NewServerConn

func NewServerConn(c net.Conn, r *bufio.Reader) *ServerConn

NewServerConn returns a new ServerConn reading and writing c. If r is not nil, it is the buffer to use when reading c.

ServerConn is low-level and old. Applications should instead use Server in the net/http package.

func (*ServerConn) Close

func (sc *ServerConn) Close() error

Close calls Hijack and then also closes the underlying connection

func (*ServerConn) Hijack

func (sc *ServerConn) Hijack() (c net.Conn, r *bufio.Reader)

Hijack detaches the ServerConn and returns the underlying connection as well as the read-side bufio which may have some left over data. Hijack may be called before Read has signaled the end of the keep-alive logic. The user should not call Hijack while Read or Write is in progress.

func (*ServerConn) Pending

func (sc *ServerConn) Pending() int

Pending returns the number of unanswered requests that have been received on the connection.

func (*ServerConn) Read

func (sc *ServerConn) Read() (req *http.Request, err error)

Read returns the next request on the wire. An ErrPersistEOF is returned if it is gracefully determined that there are no more requests (e.g. after the first request on an HTTP/1.0 connection, or after a Connection:close on a HTTP/1.1 connection).

func (*ServerConn) Write

func (sc *ServerConn) Write(req *http.Request, resp *http.Response) error

Write writes resp in response to req. To close the connection gracefully, set the Response.Close field to true. Write should be considered operational until it returns an error, regardless of any errors returned on the Read side.