http

package
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 Go to latest Published: Sep 26, 2023 License: MIT Imports: 14 Imported by: 0

Documentation

Overview

Package http provides HTTP client and server implementations.

Get, Head, Post, and PostForm make HTTP (or HTTPS) requests: 

resp, err := http.Get("http://example.com/")
...
resp, err := http.Post("http://example.com/upload", "image/jpeg", &buf)
...
resp, err := http.PostForm("http://example.com/form",
	url.Values{"key": {"Value"}, "id": {"123"}})

The client must close the response body when finished with it: 

resp, err := http.Get("http://example.com/")
if err != nil {
	// handle error
}
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
// ...

For control over HTTP client headers, redirect policy, and other settings, create a Client: 

client := &http.Client{
	CheckRedirect: redirectPolicyFunc,
}

resp, err := client.Get("http://example.com")
// ...

req, err := http.NewRequest("GET", "http://example.com", nil)
// ...
req.Header.Add("If-None-Match", `W/"wyzzy"`)
resp, err := client.Do(req)
// ...

For control over proxies, TLS configuration, keep-alives, compression, and other settings, create a Transport: 

tr := &http.Transport{
	MaxIdleConns:       10,
	IdleConnTimeout:    30 * time.Second,
	DisableCompression: true,
}
client := &http.Client{Transport: tr}
resp, err := client.Get("https://example.com")

Clients and Transports are safe for concurrent use by multiple goroutines and for efficiency should only be created once and re-used.

ListenAndServe starts an HTTP server with a given address and handler. The handler is usually nil, which means to use DefaultServeMux. Handle and HandleFunc add handlers to DefaultServeMux: 

http.Handle("/foo", fooHandler)

http.HandleFunc("/bar", func(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path))
})

log.Fatal(http.ListenAndServe(":8080", nil))

More control over the server's behavior is available by creating a custom Server: 

s := &http.Server{
	Addr:           ":8080",
	Handler:        myHandler,
	ReadTimeout:    10 * time.Second,
	WriteTimeout:   10 * time.Second,
	MaxHeaderBytes: 1 << 20,
}
log.Fatal(s.ListenAndServe())

Starting with Go 1.6, the http package has transparent support for the HTTP/2 protocol when using HTTPS. Programs that must disable HTTP/2 can do so by setting Transport.TLSNextProto (for clients) or Server.TLSNextProto (for servers) to a non-nil, empty map. Alternatively, the following GODEBUG environment variables are currently supported: 

GODEBUG=http2client=0  # disable HTTP/2 client support
GODEBUG=http2server=0  # disable HTTP/2 server support
GODEBUG=http2debug=1   # enable verbose HTTP/2 debug logs
GODEBUG=http2debug=2   # ... even more verbose, with frame dumps

The GODEBUG variables are not covered by Go's API compatibility promise. Please report any issues before disabling HTTP/2 support: https://golang.org/s/http2bug

The http package's Transport and Server both automatically enable HTTP/2 support for simple configurations. To enable HTTP/2 for more complex configurations, to use lower-level HTTP/2 features, or to use a newer version of Go's http2 package, import "golang.org/x/net/http2" directly and use its ConfigureTransport and/or ConfigureServer functions. Manually configuring HTTP/2 via the golang.org/x/net/http2 package takes precedence over the net/http package's built-in HTTP/2 support.

Index

Examples

Constants

View Source 
const (
	MethodGet     = "GET"
	MethodHead    = "HEAD"
	MethodPost    = "POST"
	MethodPut     = "PUT"
	MethodPatch   = "PATCH"
	MethodDelete  = "DELETE"
	MethodConnect = "CONNECT"
	MethodOptions = "OPTIONS"
	MethodTrace   = "TRACE"
)

Common HTTP methods.

Unless otherwise noted, these are defined in RFC 7231 section 4.3.

View Source 
const (
	StatusContinue           = 100
	StatusSwitchingProtocols = 101
	StatusProcessing         = 102

	StatusOK                   = 200
	StatusCreated              = 201
	StatusAccepted             = 202
	StatusNonAuthoritativeInfo = 203
	StatusNoContent            = 204
	StatusResetContent         = 205
	StatusPartialContent       = 206
	StatusMultiStatus          = 207
	StatusAlreadyReported      = 208
	StatusIMUsed               = 226

	StatusMultipleChoices  = 300
	StatusMovedPermanently = 301
	StatusFound            = 302
	StatusSeeOther         = 303
	StatusNotModified      = 304
	StatusUseProxy         = 305

	StatusTemporaryRedirect = 307
	StatusPermanentRedirect = 308

	StatusBadRequest                   = 400
	StatusUnauthorized                 = 401
	StatusPaymentRequired              = 402
	StatusForbidden                    = 403
	StatusNotFound                     = 404
	StatusMethodNotAllowed             = 405
	StatusNotAcceptable                = 406
	StatusProxyAuthRequired            = 407
	StatusRequestTimeout               = 408
	StatusConflict                     = 409
	StatusGone                         = 410
	StatusLengthRequired               = 411
	StatusPreconditionFailed           = 412
	StatusRequestEntityTooLarge        = 413
	StatusRequestURITooLong            = 414
	StatusUnsupportedMediaType         = 415
	StatusRequestedRangeNotSatisfiable = 416
	StatusExpectationFailed            = 417
	StatusTeapot                       = 418
	StatusMisdirectedRequest           = 421
	StatusUnprocessableEntity          = 422
	StatusLocked                       = 423
	StatusFailedDependency             = 424
	StatusUpgradeRequired              = 426
	StatusPreconditionRequired         = 428
	StatusTooManyRequests              = 429
	StatusRequestHeaderFieldsTooLarge  = 431
	StatusUnavailableForLegalReasons   = 451

	StatusInternalServerError           = 500
	StatusNotImplemented                = 501
	StatusBadGateway                    = 502
	StatusServiceUnavailable            = 503
	StatusGatewayTimeout                = 504
	StatusHTTPVersionNotSupported       = 505
	StatusVariantAlsoNegotiates         = 506
	StatusInsufficientStorage           = 507
	StatusLoopDetected                  = 508
	StatusNotExtended                   = 510
	StatusNetworkAuthenticationRequired = 511
)

HTTP status codes as registered with IANA. See: https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml

View Source 
const DefaultMaxHeaderBytes = 1 << 20

DefaultMaxHeaderBytes is the maximum permitted size of the headers in an HTTP request. This can be overridden by setting Server.MaxHeaderBytes.

View Source 
const DefaultMaxIdleConnsPerHost = 2

DefaultMaxIdleConnsPerHost is the default value of Transport's MaxIdleConnsPerHost.

View Source 
const TimeFormat = "Mon, 02 Jan 2006 15:04:05 GMT"

TimeFormat is the time format to use when generating times in HTTP headers. It is like time.RFC1123 but hard-codes GMT as the time zone. The time being formatted must be in UTC for Format to generate the correct format.

For parsing this time format, see ParseTime.

View Source 
const TrailerPrefix = "Trailer:"

TrailerPrefix is a magic prefix for ResponseWriter.Header map keys that, if present, signals that the map entry is actually for the response trailers, and not the response headers. The prefix is stripped after the ServeHTTP call finishes and the values are sent in the trailers.

This mechanism is intended only for trailers that are not known prior to the headers being written. If the set of trailers is fixed or known before the header is written, the normal Go trailers mechanism is preferred: 

https://golang.org/pkg/net/http/#ResponseWriter
https://golang.org/pkg/net/http/#example_ResponseWriter_trailers

Variables

View Source 
var (
	// ErrNotSupported is returned by the Push method of Pusher
	// implementations to indicate that HTTP/2 Push support is not
	// available.
	ErrNotSupported = &ProtocolError{"feature not supported"}

	// ErrUnexpectedTrailer is returned by the Transport when a server
	// replies with a Trailer header, but without a chunked reply.
	ErrUnexpectedTrailer = &ProtocolError{"trailer header without chunked transfer encoding"}

	// ErrMissingBoundary is returned by Request.MultipartReader when the
	// request's Content-Type does not include a "boundary" parameter.
	ErrMissingBoundary = &ProtocolError{"no multipart boundary param in Content-Type"}

	// ErrNotMultipart is returned by Request.MultipartReader when the
	// request's Content-Type is not multipart/form-data.
	ErrNotMultipart = &ProtocolError{"request Content-Type isn't multipart/form-data"}

	// Deprecated: ErrHeaderTooLong is no longer returned by
	// anything in the net/http package. Callers should not
	// compare errors against this variable.
	ErrHeaderTooLong = &ProtocolError{"header too long"}

	// Deprecated: ErrShortBody is no longer returned by
	// anything in the net/http package. Callers should not
	// compare errors against this variable.
	ErrShortBody = &ProtocolError{"entity body too short"}

	// Deprecated: ErrMissingContentLength is no longer returned by
	// anything in the net/http package. Callers should not
	// compare errors against this variable.
	ErrMissingContentLength = &ProtocolError{"missing ContentLength in HEAD response"}
)
View Source 
var (
	// ErrBodyNotAllowed is returned by ResponseWriter.Write calls
	// when the HTTP method or response code does not permit a
	// body.
	ErrBodyNotAllowed = errors.New("http: request method or response status code does not allow body")

	// ErrHijacked is returned by ResponseWriter.Write calls when
	// the underlying connection has been hijacked using the
	// Hijacker interface. A zero-byte write on a hijacked
	// connection will return ErrHijacked without any other side
	// effects.
	ErrHijacked = errors.New("http: connection has been hijacked")

	// ErrContentLength is returned by ResponseWriter.Write calls
	// when a Handler set a Content-Length response header with a
	// declared size and then attempted to write more bytes than
	// declared.
	ErrContentLength = errors.New("http: wrote more than the declared Content-Length")

	// Deprecated: ErrWriteAfterFlush is no longer returned by
	// anything in the net/http package. Callers should not
	// compare errors against this variable.
	ErrWriteAfterFlush = errors.New("unused")
)

Errors used by the HTTP server.

View Source 
var (
	// ServerContextKey is a context key. It can be used in HTTP
	// handlers with context.WithValue to access the server that
	// started the handler. The associated value will be of
	// type *Server.
	ServerContextKey = &contextKey{"http-server"}

	// LocalAddrContextKey is a context key. It can be used in
	// HTTP handlers with context.WithValue to access the local
	// address the connection arrived on.
	// The associated value will be of type net.Addr.
	LocalAddrContextKey = &contextKey{"local-addr"}
)
View Source 
var DefaultClient = &Client{}

DefaultClient is the default Client and is used by Get, Head, and Post.

View Source 
var DefaultServeMux = &defaultServeMux

DefaultServeMux is the default ServeMux used by Serve.

View Source 
var ErrAbortHandler = errors.New("net/http: abort Handler")

ErrAbortHandler is a sentinel panic value to abort a handler. While any panic from ServeHTTP aborts the response to the client, panicking with ErrAbortHandler also suppresses logging of a stack trace to the server's error log.

View Source 
var ErrBodyReadAfterClose = errors.New("http: invalid Read on closed Body")

ErrBodyReadAfterClose is returned when reading a Request or Response Body after the body has been closed. This typically happens when the body is read after an HTTP Handler calls WriteHeader or Write on its ResponseWriter.

View Source 
var ErrHandlerTimeout = errors.New("http: Handler timeout")

ErrHandlerTimeout is returned on ResponseWriter Write calls in handlers which have timed out.

View Source 
var ErrLineTooLong = internal.ErrLineTooLong

ErrLineTooLong is returned when reading request or response bodies with malformed chunked encoding.

View Source 
var ErrMissingFile = errors.New("http: no such file")

ErrMissingFile is returned by FormFile when the provided file field name is either not present in the request or not a file field.

View Source 
var ErrNoCookie = errors.New("http: named cookie not present")

ErrNoCookie is returned by Request's Cookie method when a cookie is not found.

View Source 
var ErrNoLocation = errors.New("http: no Location header in response")

ErrNoLocation is returned by Response's Location method when no Location header is present.

View Source 
var ErrServerClosed = errors.New("http: Server closed")

ErrServerClosed is returned by the Server's Serve, ServeTLS, ListenAndServe, and ListenAndServeTLS methods after a call to Shutdown or Close.

View Source 
var ErrSkipAltProtocol = errors.New("net/http: skip alternate protocol")

ErrSkipAltProtocol is a sentinel error value defined by Transport.RegisterProtocol.

View Source 
var ErrUseLastResponse = errors.New("net/http: use last response")

ErrUseLastResponse can be returned by Client.CheckRedirect hooks to control how redirects are processed. If returned, the next request is not sent and the most recent response is returned with its body unclosed.

View Source 
var NoBody = noBody{}

NoBody is an io.ReadCloser with no bytes. Read always returns EOF and Close always returns nil. It can be used in an outgoing client request to explicitly signal that a request has zero bytes. An alternative, however, is to simply set Request.Body to nil.

Functions

func CanonicalHeaderKey 

func CanonicalHeaderKey(s string) string

CanonicalHeaderKey returns the canonical format of the header key s. The canonicalization converts the first letter and any letter following a hyphen to upper case; the rest are converted to lowercase. For example, the canonical key for "accept-encoding" is "Accept-Encoding". If s contains a space or invalid header field bytes, it is returned without modifications.

func DetectContentType 

func DetectContentType(data []byte) string

DetectContentType implements the algorithm described at https://mimesniff.spec.whatwg.org/ to determine the Content-Type of the given data. It considers at most the first 512 bytes of data. DetectContentType always returns a valid MIME type: if it cannot determine a more specific one, it returns "application/octet-stream".

func Error 

func Error(w ResponseWriter, error string, code int)

Error replies to the request with the specified error message and HTTP code. It does not otherwise end the request; the caller should ensure no further writes are done to w. The error message should be plain text.

func Handle 

func Handle(pattern string, handler Handler)

Handle registers the handler for the given pattern in the DefaultServeMux. The documentation for ServeMux explains how patterns are matched.

func HandleFunc 

func HandleFunc(pattern string, handler func(ResponseWriter, *Request))

HandleFunc registers the handler function for the given pattern in the DefaultServeMux. The documentation for ServeMux explains how patterns are matched.

func ListenAndServe 

func ListenAndServe(addr string, handler Handler) error

ListenAndServe listens on the TCP network address addr and then calls Serve with handler to handle requests on incoming connections. Accepted connections are configured to enable TCP keep-alives.

The handler is typically nil, in which case the DefaultServeMux is used.

ListenAndServe always returns a non-nil error.

Example 
package main

import (
	"io"
	"log"
	"net/http"
)

func main() {
	// Hello world, the web server

	helloHandler := func(w http.ResponseWriter, req *http.Request) {
		io.WriteString(w, "Hello, world!\n")
	}

	http.HandleFunc("/hello", helloHandler)
	log.Fatal(http.ListenAndServe(":8080", nil))
}

Output:

func ListenAndServeTLS 

func ListenAndServeTLS(addr, certFile, keyFile string, handler Handler) error

ListenAndServeTLS acts identically to ListenAndServe, except that it expects HTTPS connections. Additionally, files containing a certificate and matching private key for the server must be provided. If the certificate is signed by a certificate authority, the certFile should be the concatenation of the server's certificate, any intermediates, and the CA's certificate.

Example 
package main

import (
	"io"
	"log"
	"net/http"
)

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
		io.WriteString(w, "Hello, TLS!\n")
	})

	// One can use generate_cert.go in crypto/tls to generate cert.pem and key.pem.
	log.Printf("About to listen on 8443. Go to https://127.0.0.1:8443/")
	err := http.ListenAndServeTLS(":8443", "cert.pem", "key.pem", nil)
	log.Fatal(err)
}

Output:

func MaxBytesReader 

func MaxBytesReader(w ResponseWriter, r io.ReadCloser, n int64) io.ReadCloser

MaxBytesReader is similar to io.LimitReader but is intended for limiting the size of incoming request bodies. In contrast to io.LimitReader, MaxBytesReader's result is a ReadCloser, returns a non-EOF error for a Read beyond the limit, and closes the underlying reader when its Close method is called.

MaxBytesReader prevents clients from accidentally or maliciously sending a large request and wasting server resources.

func NotFound 

func NotFound(w ResponseWriter, r *Request)

NotFound replies to the request with an HTTP 404 not found error.

func ParseHTTPVersion 

func ParseHTTPVersion(vers string) (major, minor int, ok bool)

ParseHTTPVersion parses a HTTP version string. "HTTP/1.0" returns (1, 0, true).

func ParseTime added in v1.1.0 

func ParseTime(text string) (t time.Time, err error)

ParseTime parses a time header (such as the Date: header), trying each of the three formats allowed by HTTP/1.1: TimeFormat, time.RFC850, and time.ANSIC.

func ProxyFromEnvironment 

func ProxyFromEnvironment(req *Request) (*url.URL, error)

ProxyFromEnvironment returns the URL of the proxy to use for a given request, as indicated by the environment variables HTTP_PROXY, HTTPS_PROXY and NO_PROXY (or the lowercase versions thereof). HTTPS_PROXY takes precedence over HTTP_PROXY for https requests.

The environment values may be either a complete URL or a "host[:port]", in which case the "http" scheme is assumed. An error is returned if the value is a different form.

A nil URL and nil error are returned if no proxy is defined in the environment, or a proxy should not be used for the given request, as defined by NO_PROXY.

As a special case, if req.URL.Host is "localhost" (with or without a port number), then a nil URL and nil error will be returned.

func ProxyURL 

func ProxyURL(fixedURL *url.URL) func(*Request) (*url.URL, error)

ProxyURL returns a proxy function (for use in a Transport) that always returns the same URL.

func Redirect 

func Redirect(w ResponseWriter, r *Request, url string, code int)

Redirect replies to the request with a redirect to url, which may be a path relative to the request path.

The provided code should be in the 3xx range and is usually StatusMovedPermanently, StatusFound or StatusSeeOther.

If the Content-Type header has not been set, Redirect sets it to "text/html; charset=utf-8" and writes a small HTML body. Setting the Content-Type header to any value, including nil, disables that behavior.

func Serve 

func Serve(l net.Listener, handler Handler) error

Serve accepts incoming HTTP connections on the listener l, creating a new service goroutine for each. The service goroutines read requests and then call handler to reply to them.

The handler is typically nil, in which case the DefaultServeMux is used.

HTTP/2 support is only enabled if the Listener returns *tls.Conn connections and they were configured with "h2" in the TLS Config.NextProtos.

Serve always returns a non-nil error.

func ServeContent 

func ServeContent(w ResponseWriter, req *Request, name string, modtime time.Time, content io.ReadSeeker)

ServeContent replies to the request using the content in the provided ReadSeeker. The main benefit of ServeContent over io.Copy is that it handles Range requests properly, sets the MIME type, and handles If-Match, If-Unmodified-Since, If-None-Match, If-Modified-Since, and If-Range requests.

If the response's Content-Type header is not set, ServeContent first tries to deduce the type from name's file extension and, if that fails, falls back to reading the first block of the content and passing it to DetectContentType. The name is otherwise unused; in particular it can be empty and is never sent in the response.

If modtime is not the zero time or Unix epoch, ServeContent includes it in a Last-Modified header in the response. If the request includes an If-Modified-Since header, ServeContent uses modtime to decide whether the content needs to be sent at all.

The content's Seek method must work: ServeContent uses a seek to the end of the content to determine its size.

If the caller has set w's ETag header formatted per RFC 7232, section 2.3, ServeContent uses it to handle requests using If-Match, If-None-Match, or If-Range.

Note that *os.File implements the io.ReadSeeker interface.

func ServeFile 

func ServeFile(w ResponseWriter, r *Request, name string)

ServeFile replies to the request with the contents of the named file or directory.

If the provided file or directory name is a relative path, it is interpreted relative to the current directory and may ascend to parent directories. If the provided name is constructed from user input, it should be sanitized before calling ServeFile.

As a precaution, ServeFile will reject requests where r.URL.Path contains a ".." path element; this protects against callers who might unsafely use filepath.Join on r.URL.Path without sanitizing it and then use that filepath.Join result as the name argument.

As another special case, ServeFile redirects any request where r.URL.Path ends in "/index.html" to the same path, without the final "index.html". To avoid such redirects either modify the path or use ServeContent.

Outside of those two special cases, ServeFile does not use r.URL.Path for selecting the file or directory to serve; only the file or directory provided in the name argument is used.

func ServeTLS added in v1.9.0 

func ServeTLS(l net.Listener, handler Handler, certFile, keyFile string) error

ServeTLS accepts incoming HTTPS connections on the listener l, creating a new service goroutine for each. The service goroutines read requests and then call handler to reply to them.

The handler is typically nil, in which case the DefaultServeMux is used.

Additionally, files containing a certificate and matching private key for the server must be provided. If the certificate is signed by a certificate authority, the certFile should be the concatenation of the server's certificate, any intermediates, and the CA's certificate.

ServeTLS always returns a non-nil error.

func SetCookie 

func SetCookie(w ResponseWriter, cookie *Cookie)

SetCookie adds a Set-Cookie header to the provided ResponseWriter's headers. The provided cookie must have a valid Name. Invalid cookies may be silently dropped.

func StatusText 

func StatusText(code int) string

StatusText returns a text for the HTTP status code. It returns the empty string if the code is unknown.

Types

type Client 

type Client struct {
	Transport RoundTripper

	CheckRedirect func(req *Request, via []*Request) error

	Jar CookieJar

	Timeout time.Duration
}

A Client is an HTTP client. Its zero value (DefaultClient) is a usable client that uses DefaultTransport.

The Client's Transport typically has internal state (cached TCP connections), so Clients should be reused instead of created as needed. Clients are safe for concurrent use by multiple goroutines.

A Client is higher-level than a RoundTripper (such as Transport) and additionally handles HTTP details such as cookies and redirects.

When following redirects, the Client will forward all headers set on the initial Request except:

• when forwarding sensitive headers like "Authorization", "WWW-Authenticate", and "Cookie" to untrusted targets. These headers will be ignored when following a redirect to a domain that is not a subdomain match or exact match of the initial domain. For example, a redirect from "foo.com" to either "foo.com" or "sub.foo.com" will forward the sensitive headers, but a redirect to "bar.com" will not.

• when forwarding the "Cookie" header with a non-nil cookie Jar. Since each redirect may mutate the state of the cookie jar, a redirect may possibly alter a cookie set in the initial request. When forwarding the "Cookie" header, any mutated cookies will be omitted, with the expectation that the Jar will insert those mutated cookies with the updated values (assuming the origin matches). If Jar is nil, the initial cookies are forwarded without change.

func (*Client) Do 

func (c *Client) Do(req *Request) (*Response, error)

Do sends an HTTP request and returns an HTTP response, following policy (such as redirects, cookies, auth) as configured on the client.

An error is returned if caused by client policy (such as CheckRedirect), or failure to speak HTTP (such as a network connectivity problem). A non-2xx status code doesn't cause an error.

If the returned error is nil, the Response will contain a non-nil Body which the user is expected to close. If the Body is not closed, the Client's underlying RoundTripper (typically Transport) may not be able to re-use a persistent TCP connection to the server for a subsequent "keep-alive" request.

The request Body, if non-nil, will be closed by the underlying Transport, even on errors.

On error, any Response can be ignored. A non-nil Response with a non-nil error only occurs when CheckRedirect fails, and even then the returned Response.Body is already closed.

Generally Get, Post, or PostForm will be used instead of Do.

If the server replies with a redirect, the Client first uses the CheckRedirect function to determine whether the redirect should be followed. If permitted, a 301, 302, or 303 redirect causes subsequent requests to use HTTP method GET (or HEAD if the original request was HEAD), with no body. A 307 or 308 redirect preserves the original HTTP method and body, provided that the Request.GetBody function is defined. The NewRequest function automatically sets GetBody for common standard library body types.

Any returned error will be of type *url.Error. The url.Error value's Timeout method will report true if request timed out or was canceled.

func (*Client) Get 

func (c *Client) Get(url string) (resp *Response, err error)

Get issues a GET to the specified URL. If the response is one of the following redirect codes, Get follows the redirect after calling the Client's CheckRedirect function: 

301 (Moved Permanently)
302 (Found)
303 (See Other)
307 (Temporary Redirect)
308 (Permanent Redirect)

An error is returned if the Client's CheckRedirect function fails or if there was an HTTP protocol error. A non-2xx response doesn't cause an error. Any returned error will be of type *url.Error. The url.Error value's Timeout method will report true if request timed out or was canceled.

When err is nil, resp always contains a non-nil resp.Body. Caller should close resp.Body when done reading from it.

To make a request with custom headers, use NewRequest and Client.Do.

func (*Client) Head 

func (c *Client) Head(url string) (resp *Response, err error)

Head issues a HEAD to the specified URL. If the response is one of the following redirect codes, Head follows the redirect after calling the Client's CheckRedirect function: 

301 (Moved Permanently)
302 (Found)
303 (See Other)
307 (Temporary Redirect)
308 (Permanent Redirect)

func (*Client) Post 

func (c *Client) Post(url, contentType string, body io.Reader) (resp *Response, err error)

Post issues a POST to the specified URL.

Caller should close resp.Body when done reading from it.

If the provided body is an io.Closer, it is closed after the request.

To set custom headers, use NewRequest and Client.Do.

See the Client.Do method documentation for details on how redirects are handled.

func (*Client) PostForm 

func (c *Client) PostForm(url string, data url.Values) (resp *Response, err error)

PostForm issues a POST to the specified URL, with data's keys and values URL-encoded as the request body.

The Content-Type header is set to application/x-www-form-urlencoded. To set other headers, use NewRequest and Client.Do.

When err is nil, resp always contains a non-nil resp.Body. Caller should close resp.Body when done reading from it.

See the Client.Do method documentation for details on how redirects are handled.

type CloseNotifier deprecated added in v1.1.0 

type CloseNotifier interface {
	CloseNotify() <-chan bool
}

The CloseNotifier interface is implemented by ResponseWriters which allow detecting when the underlying connection has gone away.

This mechanism can be used to cancel long operations on the server if the client has disconnected before the response is ready.

Deprecated: the CloseNotifier interface predates Go's context package. New code should use Request.Context instead.

type ConnState added in v1.3.0 

type ConnState int

A ConnState represents the state of a client connection to a server. It's used by the optional Server.ConnState hook. 

const (
	// StateNew represents a new connection that is expected to
	// send a request immediately. Connections begin at this
	// state and then transition to either StateActive or
	// StateClosed.
	StateNew ConnState = iota

	// StateActive represents a connection that has read 1 or more
	// bytes of a request. The Server.ConnState hook for
	// StateActive fires before the request has entered a handler
	// and doesn't fire again until the request has been
	// handled. After the request is handled, the state
	// transitions to StateClosed, StateHijacked, or StateIdle.
	// For HTTP/2, StateActive fires on the transition from zero
	// to one active request, and only transitions away once all
	// active requests are complete. That means that ConnState
	// cannot be used to do per-request work; ConnState only notes
	// the overall state of the connection.
	StateActive

	// StateIdle represents a connection that has finished
	// handling a request and is in the keep-alive state, waiting
	// for a new request. Connections transition from StateIdle
	// to either StateActive or StateClosed.
	StateIdle

	// StateHijacked represents a hijacked connection.
	// This is a terminal state. It does not transition to StateClosed.
	StateHijacked

	// StateClosed represents a closed connection.
	// This is a terminal state. Hijacked connections do not
	// transition to StateClosed.
	StateClosed
)

func (ConnState) String added in v1.3.0 

func (c ConnState) String() string
type Cookie struct {
	Name  string
	Value string

	Path       string
	Domain     string
	Expires    time.Time
	RawExpires string

	MaxAge   int
	Secure   bool
	HttpOnly bool
	SameSite SameSite
	Raw      string
	Unparsed []string
}

A Cookie represents an HTTP cookie as sent in the Set-Cookie header of an HTTP response or the Cookie header of an HTTP request.

See https://tools.ietf.org/html/rfc6265 for details.

func (*Cookie) String 

func (c *Cookie) String() string

String returns the serialization of the cookie for use in a Cookie header (if only Name and Value are set) or a Set-Cookie response header (if other fields are set). If c is nil or c.Name is invalid, the empty string is returned.

type CookieJar 

type CookieJar interface {
	SetCookies(u *url.URL, cookies []*Cookie)

	Cookies(u *url.URL) []*Cookie
}

A CookieJar manages storage and use of cookies in HTTP requests.

Implementations of CookieJar must be safe for concurrent use by multiple goroutines.

The net/http/cookiejar package provides a CookieJar implementation.

type Dir 

type Dir string

A Dir implements FileSystem using the native file system restricted to a specific directory tree.

While the FileSystem.Open method takes '/'-separated paths, a Dir's string value is a filename on the native file system, not a URL, so it is separated by filepath.Separator, which isn't necessarily '/'.

Note that Dir will allow access to files and directories starting with a period, which could expose sensitive directories like a .git directory or sensitive files like .htpasswd. To exclude files with a leading period, remove the files/directories from the server or create a custom FileSystem implementation.

An empty Dir is treated as ".".

func (Dir) Open 

func (d Dir) Open(name string) (File, error)

type File 

type File interface {
	io.Closer
	io.Reader
	io.Seeker
	Readdir(count int) ([]os.FileInfo, error)
	Stat() (os.FileInfo, error)
}

A File is returned by a FileSystem's Open method and can be served by the FileServer implementation.

The methods should behave the same as those on an *os.File.

type FileSystem 

type FileSystem interface {
	Open(name string) (File, error)
}

A FileSystem implements access to a collection of named files. The elements in a file path are separated by slash ('/', U+002F) characters, regardless of host operating system convention.

type Flusher 

type Flusher interface {
	Flush()
}

The Flusher interface is implemented by ResponseWriters that allow an HTTP handler to flush buffered data to the client.

The default HTTP/1.x and HTTP/2 ResponseWriter implementations support Flusher, but ResponseWriter wrappers may not. Handlers should always test for this ability at runtime.

Note that even for ResponseWriters that support Flush, if the client is connected through an HTTP proxy, the buffered data may not reach the client until the response completes.

type Handler 

type Handler interface {
	ServeHTTP(ResponseWriter, *Request)
}

A Handler responds to an HTTP request.

ServeHTTP should write reply headers and data to the ResponseWriter and then return. Returning signals that the request is finished; it is not valid to use the ResponseWriter or read from the Request.Body after or concurrently with the completion of the ServeHTTP call.

Depending on the HTTP client software, HTTP protocol version, and any intermediaries between the client and the Go server, it may not be possible to read from the Request.Body after writing to the ResponseWriter. Cautious handlers should read the Request.Body first, and then reply.

Except for reading the body, handlers should not modify the provided Request.

If ServeHTTP panics, the server (the caller of ServeHTTP) assumes that the effect of the panic was isolated to the active request. It recovers the panic, logs a stack trace to the server error log, and either closes the network connection or sends an HTTP/2 RST_STREAM, depending on the HTTP protocol. To abort a handler so the client sees an interrupted response but the server doesn't log an error, panic with the value ErrAbortHandler.

func FileServer 

func FileServer(root FileSystem) Handler

FileServer returns a handler that serves HTTP requests with the contents of the file system rooted at root.

To use the operating system's file system implementation, use http.Dir: 

http.Handle("/", http.FileServer(http.Dir("/tmp")))

As a special case, the returned file server redirects any request ending in "/index.html" to the same path, without the final "index.html".

Example 
package main

import (
	"log"
	"net/http"
)

func main() {
	// Simple static webserver:
	log.Fatal(http.ListenAndServe(":8080", http.FileServer(http.Dir("/usr/share/doc"))))
}

Output:
Example (StripPrefix) 
package main

import (
	"net/http"
)

func main() {
	// To serve a directory on disk (/tmp) under an alternate URL
	// path (/tmpfiles/), use StripPrefix to modify the request
	// URL's path before the FileServer sees it:
	http.Handle("/tmpfiles/", http.StripPrefix("/tmpfiles/", http.FileServer(http.Dir("/tmp"))))
}

Output:

func NotFoundHandler 

func NotFoundHandler() Handler

NotFoundHandler returns a simple request handler that replies to each request with a “404 page not found” reply.

func RedirectHandler 

func RedirectHandler(url string, code int) Handler

RedirectHandler returns a request handler that redirects each request it receives to the given url using the given status code.

The provided code should be in the 3xx range and is usually StatusMovedPermanently, StatusFound or StatusSeeOther.

func StripPrefix 

func StripPrefix(prefix string, h Handler) Handler

StripPrefix returns a handler that serves HTTP requests by removing the given prefix from the request URL's Path and invoking the handler h. StripPrefix handles a request for a path that doesn't begin with prefix by replying with an HTTP 404 not found error.

Example 
package main

import (
	"net/http"
)

func main() {
	// To serve a directory on disk (/tmp) under an alternate URL
	// path (/tmpfiles/), use StripPrefix to modify the request
	// URL's path before the FileServer sees it:
	http.Handle("/tmpfiles/", http.StripPrefix("/tmpfiles/", http.FileServer(http.Dir("/tmp"))))
}

Output:

func TimeoutHandler 

func TimeoutHandler(h Handler, dt time.Duration, msg string) Handler

TimeoutHandler returns a Handler that runs h with the given time limit.

The new Handler calls h.ServeHTTP to handle each request, but if a call runs for longer than its time limit, the handler responds with a 503 Service Unavailable error and the given message in its body. (If msg is empty, a suitable default message will be sent.) After such a timeout, writes by h to its ResponseWriter will return ErrHandlerTimeout.

TimeoutHandler buffers all Handler writes to memory and does not support the Hijacker or Flusher interfaces.

type HandlerFunc 

type HandlerFunc func(ResponseWriter, *Request)

The HandlerFunc type is an adapter to allow the use of ordinary functions as HTTP handlers. If f is a function with the appropriate signature, HandlerFunc(f) is a Handler that calls f.

func (HandlerFunc) ServeHTTP 

func (f HandlerFunc) ServeHTTP(w ResponseWriter, r *Request)

ServeHTTP calls f(w, r). 

type Header map[string][]string

A Header represents the key-value pairs in an HTTP header.

func (Header) Add 

func (h Header) Add(key, value string)

Add adds the key, value pair to the header. It appends to any existing values associated with key.

func (Header) Del 

func (h Header) Del(key string)

Del deletes the values associated with key.

func (Header) Get 

func (h Header) Get(key string) string

Get gets the first value associated with the given key. It is case insensitive; textproto.CanonicalMIMEHeaderKey is used to canonicalize the provided key. If there are no values associated with the key, Get returns "". To access multiple values of a key, or to use non-canonical keys, access the map directly.

func (Header) Set 

func (h Header) Set(key, value string)

Set sets the header entries associated with key to the single element value. It replaces any existing values associated with key.

func (Header) Write 

func (h Header) Write(w io.Writer) error

Write writes a header in wire format.

func (Header) WriteSubset 

func (h Header) WriteSubset(w io.Writer, exclude map[string]bool) error

WriteSubset writes a header in wire format. If exclude is not nil, keys where exclude[key] == true are not written.

type Hijacker 

type Hijacker interface {
	Hijack() (net.Conn, *bufio.ReadWriter, error)
}

The Hijacker interface is implemented by ResponseWriters that allow an HTTP handler to take over the connection.

The default ResponseWriter for HTTP/1.x connections supports Hijacker, but HTTP/2 connections intentionally do not. ResponseWriter wrappers may also not support Hijacker. Handlers should always test for this ability at runtime.

Example 
package main

import (
	"fmt"
	"log"
	"net/http"
)

func main() {
	http.HandleFunc("/hijack", func(w http.ResponseWriter, r *http.Request) {
		hj, ok := w.(http.Hijacker)
		if !ok {
			http.Error(w, "webserver doesn't support hijacking", http.StatusInternalServerError)
			return
		}
		conn, bufrw, err := hj.Hijack()
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		// Don't forget to close the connection:
		defer conn.Close()
		bufrw.WriteString("Now we're speaking raw TCP. Say hi: ")
		bufrw.Flush()
		s, err := bufrw.ReadString('\n')
		if err != nil {
			log.Printf("error reading string: %v", err)
			return
		}
		fmt.Fprintf(bufrw, "You said: %q\nBye.\n", s)
		bufrw.Flush()
	})
}

Output:

type ProtocolError deprecated 

type ProtocolError struct {
	ErrorString string
}

ProtocolError represents an HTTP protocol error.

Deprecated: Not all errors in the http package related to protocol errors are of type ProtocolError.

func (*ProtocolError) Error 

func (pe *ProtocolError) Error() string

type PushOptions added in v1.8.0 

type PushOptions struct {
	Method string

	Header Header
}

PushOptions describes options for Pusher.Push.

type Pusher added in v1.8.0 

type Pusher interface {
	Push(target string, opts *PushOptions) error
}

Pusher is the interface implemented by ResponseWriters that support HTTP/2 server push. For more background, see https://tools.ietf.org/html/rfc7540#section-8.2.

type Request 

type Request struct {
	Method string

	URL *url.URL

	Proto      string
	ProtoMajor int
	ProtoMinor int

	Header Header

	Body io.ReadCloser

	GetBody func() (io.ReadCloser, error)

	ContentLength int64

	TransferEncoding []string

	Close bool

	Host string

	Form url.Values

	PostForm url.Values

	MultipartForm *multipart.Form

	Trailer Header

	RemoteAddr string

	RequestURI string

	TLS *tls.ConnectionState

	Cancel <-chan struct{}

	Response *Response
	// contains filtered or unexported fields
}

A Request represents an HTTP request received by a server or to be sent by a client.

The field semantics differ slightly between client and server usage. In addition to the notes on the fields below, see the documentation for Request.Write and RoundTripper.

func NewRequest 

func NewRequest(method, url string, body io.Reader) (*Request, error)

NewRequest returns a new Request given a method, URL, and optional body.

If the provided body is also an io.Closer, the returned Request.Body is set to body and will be closed by the Client methods Do, Post, and PostForm, and Transport.RoundTrip.

NewRequest returns a Request suitable for use with Client.Do or Transport.RoundTrip. To create a request for use with testing a Server Handler, either use the NewRequest function in the net/http/httptest package, use ReadRequest, or manually update the Request fields. See the Request type's documentation for the difference between inbound and outbound request fields.

If body is of type *bytes.Buffer, *bytes.Reader, or *strings.Reader, the returned request's ContentLength is set to its exact value (instead of -1), GetBody is populated (so 307 and 308 redirects can replay the body), and Body is set to NoBody if the ContentLength is 0.

func ReadRequest 

func ReadRequest(b *bufio.Reader) (*Request, error)

ReadRequest reads and parses an incoming request from b.

ReadRequest is a low-level function and should only be used for specialized applications; most code should use the Server to read requests and handle them via the Handler interface. ReadRequest only supports HTTP/1.x requests. For HTTP/2, use golang.org/x/net/http2.

func (*Request) AddCookie 

func (r *Request) AddCookie(c *Cookie)

AddCookie adds a cookie to the request. Per RFC 6265 section 5.4, AddCookie does not attach more than one Cookie header field. That means all cookies, if any, are written into the same line, separated by semicolon.

func (*Request) BasicAuth added in v1.4.0 

func (r *Request) BasicAuth() (username, password string, ok bool)

BasicAuth returns the username and password provided in the request's Authorization header, if the request uses HTTP Basic Authentication. See RFC 2617, Section 2.

func (*Request) Context added in v1.7.0 

func (r *Request) Context() context.Context

Context returns the request's context. To change the context, use WithContext.

The returned context is always non-nil; it defaults to the background context.

For outgoing client requests, the context controls cancelation.

For incoming server requests, the context is canceled when the client's connection closes, the request is canceled (with HTTP/2), or when the ServeHTTP method returns.

func (*Request) Cookie 

func (r *Request) Cookie(name string) (*Cookie, error)

Cookie returns the named cookie provided in the request or ErrNoCookie if not found. If multiple cookies match the given name, only one cookie will be returned.

func (*Request) Cookies 

func (r *Request) Cookies() []*Cookie

Cookies parses and returns the HTTP cookies sent with the request.

func (*Request) FormFile 

func (r *Request) FormFile(key string) (multipart.File, *multipart.FileHeader, error)

FormFile returns the first file for the provided form key. FormFile calls ParseMultipartForm and ParseForm if necessary.

func (*Request) FormValue 

func (r *Request) FormValue(key string) string

FormValue returns the first value for the named component of the query. POST and PUT body parameters take precedence over URL query string values. FormValue calls ParseMultipartForm and ParseForm if necessary and ignores any errors returned by these functions. If key is not present, FormValue returns the empty string. To access multiple values of the same key, call ParseForm and then inspect Request.Form directly.

func (*Request) MultipartReader 

func (r *Request) MultipartReader() (*multipart.Reader, error)

MultipartReader returns a MIME multipart reader if this is a multipart/form-data or a multipart/mixed POST request, else returns nil and an error. Use this function instead of ParseMultipartForm to process the request body as a stream.

func (*Request) ParseForm 

func (r *Request) ParseForm() error

ParseForm populates r.Form and r.PostForm.

For all requests, ParseForm parses the raw query from the URL and updates r.Form.

For POST, PUT, and PATCH requests, it also parses the request body as a form and puts the results into both r.PostForm and r.Form. Request body parameters take precedence over URL query string values in r.Form.

For other HTTP methods, or when the Content-Type is not application/x-www-form-urlencoded, the request Body is not read, and r.PostForm is initialized to a non-nil, empty value.

If the request Body's size has not already been limited by MaxBytesReader, the size is capped at 10MB.

ParseMultipartForm calls ParseForm automatically. ParseForm is idempotent.

func (*Request) ParseMultipartForm 

func (r *Request) ParseMultipartForm(maxMemory int64) error

ParseMultipartForm parses a request body as multipart/form-data. The whole request body is parsed and up to a total of maxMemory bytes of its file parts are stored in memory, with the remainder stored on disk in temporary files. ParseMultipartForm calls ParseForm if necessary. After one call to ParseMultipartForm, subsequent calls have no effect.

func (*Request) PostFormValue added in v1.1.0 

func (r *Request) PostFormValue(key string) string

PostFormValue returns the first value for the named component of the POST, PATCH, or PUT request body. URL query parameters are ignored. PostFormValue calls ParseMultipartForm and ParseForm if necessary and ignores any errors returned by these functions. If key is not present, PostFormValue returns the empty string.

func (*Request) ProtoAtLeast 

func (r *Request) ProtoAtLeast(major, minor int) bool

ProtoAtLeast reports whether the HTTP protocol used in the request is at least major.minor.

func (*Request) Referer 

func (r *Request) Referer() string

Referer returns the referring URL, if sent in the request.

Referer is misspelled as in the request itself, a mistake from the earliest days of HTTP. This value can also be fetched from the Header map as Header["Referer"]; the benefit of making it available as a method is that the compiler can diagnose programs that use the alternate (correct English) spelling req.Referrer() but cannot diagnose programs that use Header["Referrer"].

func (*Request) SetBasicAuth 

func (r *Request) SetBasicAuth(username, password string)

SetBasicAuth sets the request's Authorization header to use HTTP Basic Authentication with the provided username and password.

With HTTP Basic Authentication the provided username and password are not encrypted.

func (*Request) UserAgent 

func (r *Request) UserAgent() string

UserAgent returns the client's User-Agent, if sent in the request.

func (*Request) WithContext added in v1.7.0 

func (r *Request) WithContext(ctx context.Context) *Request

WithContext returns a shallow copy of r with its context changed to ctx. The provided ctx must be non-nil.

For outgoing client request, the context controls the entire lifetime of a request and its response: obtaining a connection, sending the request, and reading the response headers and body.

func (*Request) Write 

func (r *Request) Write(w io.Writer) error

Write writes an HTTP/1.1 request, which is the header and body, in wire format. This method consults the following fields of the request: 

Host
URL
Method (defaults to "GET")
Header
ContentLength
TransferEncoding
Body

If Body is present, Content-Length is <= 0 and TransferEncoding hasn't been set to "identity", Write adds "Transfer-Encoding: chunked" to the header. Body is closed after it is sent.

func (*Request) WriteProxy 

func (r *Request) WriteProxy(w io.Writer) error

WriteProxy is like Write but writes the request in the form expected by an HTTP proxy. In particular, WriteProxy writes the initial Request-URI line of the request with an absolute URI, per section 5.3 of RFC 7230, including the scheme and host. In either case, WriteProxy also writes a Host header, using either r.Host or r.URL.Host.

type Response 

type Response struct {
	Status     string
	StatusCode int
	Proto      string
	ProtoMajor int
	ProtoMinor int

	Header Header

	Body io.ReadCloser

	ContentLength int64

	TransferEncoding []string

	Close bool

	Uncompressed bool

	Trailer Header

	Request *Request

	TLS *tls.ConnectionState
}

Response represents the response from an HTTP request.

The Client and Transport return Responses from servers once the response headers have been received. The response body is streamed on demand as the Body field is read.

func Get 

func Get(url string) (resp *Response, err error)

Get issues a GET to the specified URL. If the response is one of the following redirect codes, Get follows the redirect, up to a maximum of 10 redirects: 

301 (Moved Permanently)
302 (Found)
303 (See Other)
307 (Temporary Redirect)
308 (Permanent Redirect)

An error is returned if there were too many redirects or if there was an HTTP protocol error. A non-2xx response doesn't cause an error. Any returned error will be of type *url.Error. The url.Error value's Timeout method will report true if request timed out or was canceled.

When err is nil, resp always contains a non-nil resp.Body. Caller should close resp.Body when done reading from it.

Get is a wrapper around DefaultClient.Get.

To make a request with custom headers, use NewRequest and DefaultClient.Do.

Example 
package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
)

func main() {
	res, err := http.Get("http://www.google.com/robots.txt")
	if err != nil {
		log.Fatal(err)
	}
	robots, err := ioutil.ReadAll(res.Body)
	res.Body.Close()
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%s", robots)
}

Output:


func Head(url string) (resp *Response, err error)

Head issues a HEAD to the specified URL. If the response is one of the following redirect codes, Head follows the redirect, up to a maximum of 10 redirects: 

301 (Moved Permanently)
302 (Found)
303 (See Other)
307 (Temporary Redirect)
308 (Permanent Redirect)

Head is a wrapper around DefaultClient.Head

func Post 

func Post(url, contentType string, body io.Reader) (resp *Response, err error)

Post issues a POST to the specified URL.

Caller should close resp.Body when done reading from it.

If the provided body is an io.Closer, it is closed after the request.

Post is a wrapper around DefaultClient.Post.

To set custom headers, use NewRequest and DefaultClient.Do.

See the Client.Do method documentation for details on how redirects are handled.

func PostForm 

func PostForm(url string, data url.Values) (resp *Response, err error)

PostForm issues a POST to the specified URL, with data's keys and values URL-encoded as the request body.

The Content-Type header is set to application/x-www-form-urlencoded. To set other headers, use NewRequest and DefaultClient.Do.

When err is nil, resp always contains a non-nil resp.Body. Caller should close resp.Body when done reading from it.

PostForm is a wrapper around DefaultClient.PostForm.

See the Client.Do method documentation for details on how redirects are handled.

func ReadResponse 

func ReadResponse(r *bufio.Reader, req *Request) (*Response, error)

ReadResponse reads and returns an HTTP response from r. The req parameter optionally specifies the Request that corresponds to this Response. If nil, a GET request is assumed. Clients must call resp.Body.Close when finished reading resp.Body. After that call, clients can inspect resp.Trailer to find key/value pairs included in the response trailer.

func (*Response) Cookies 

func (r *Response) Cookies() []*Cookie

Cookies parses and returns the cookies set in the Set-Cookie headers.

func (*Response) Location 

func (r *Response) Location() (*url.URL, error)

Location returns the URL of the response's "Location" header, if present. Relative redirects are resolved relative to the Response's Request. ErrNoLocation is returned if no Location header is present.

func (*Response) ProtoAtLeast 

func (r *Response) ProtoAtLeast(major, minor int) bool

ProtoAtLeast reports whether the HTTP protocol used in the response is at least major.minor.

func (*Response) Write 

func (r *Response) Write(w io.Writer) error

Write writes r to w in the HTTP/1.x server response format, including the status line, headers, body, and optional trailer.

This method consults the following fields of the response r: 

StatusCode
ProtoMajor
ProtoMinor
Request.Method
TransferEncoding
Trailer
Body
ContentLength
Header, values for non-canonical keys will have unpredictable behavior

The Response Body is closed after it is sent.

type ResponseWriter 

type ResponseWriter interface {
	Header() Header

	Write([]byte) (int, error)

	WriteHeader(statusCode int)
}

A ResponseWriter interface is used by an HTTP handler to construct an HTTP response.

A ResponseWriter may not be used after the Handler.ServeHTTP method has returned.

Example (Trailers)

HTTP Trailers are a set of key/value pairs like headers that come after the HTTP response, instead of before. 

package main

import (
	"io"
	"net/http"
)

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/sendstrailers", func(w http.ResponseWriter, req *http.Request) {
		// Before any call to WriteHeader or Write, declare
		// the trailers you will set during the HTTP
		// response. These three headers are actually sent in
		// the trailer.
		w.Header().Set("Trailer", "AtEnd1, AtEnd2")
		w.Header().Add("Trailer", "AtEnd3")

		w.Header().Set("Content-Type", "text/plain; charset=utf-8") // normal header
		w.WriteHeader(http.StatusOK)

		w.Header().Set("AtEnd1", "value 1")
		io.WriteString(w, "This HTTP response has both headers before this text and trailers at the end.\n")
		w.Header().Set("AtEnd2", "value 2")
		w.Header().Set("AtEnd3", "value 3") // These will appear as trailers.
	})
}

Output:

type RoundTripper 

type RoundTripper interface {
	RoundTrip(*Request) (*Response, error)
}

RoundTripper is an interface representing the ability to execute a single HTTP transaction, obtaining the Response for a given Request.

A RoundTripper must be safe for concurrent use by multiple goroutines. 

var DefaultTransport RoundTripper = &Transport{
	Proxy: ProxyFromEnvironment,
	DialContext: (&net.Dialer{
		Timeout:   30 * time.Second,
		KeepAlive: 30 * time.Second,
		DualStack: true,
	}).DialContext,
	MaxIdleConns:          100,
	IdleConnTimeout:       90 * time.Second,
	TLSHandshakeTimeout:   10 * time.Second,
	ExpectContinueTimeout: 1 * time.Second,
}

DefaultTransport is the default implementation of Transport and is used by DefaultClient. It establishes network connections as needed and caches them for reuse by subsequent calls. It uses HTTP proxies as directed by the $HTTP_PROXY and $NO_PROXY (or $http_proxy and $no_proxy) environment variables.

func NewFileTransport 

func NewFileTransport(fs FileSystem) RoundTripper

NewFileTransport returns a new RoundTripper, serving the provided FileSystem. The returned RoundTripper ignores the URL host in its incoming requests, as well as most other properties of the request.

The typical use case for NewFileTransport is to register the "file" protocol with a Transport, as in: 

t := &http.Transport{}
t.RegisterProtocol("file", http.NewFileTransport(http.Dir("/")))
c := &http.Client{Transport: t}
res, err := c.Get("file:///etc/passwd")
...

type SameSite added in v1.11.0 

type SameSite int

SameSite allows a server define a cookie attribute making it impossible to the browser send this cookie along with cross-site requests. The main goal is mitigate the risk of cross-origin information leakage, and provides some protection against cross-site request forgery attacks.

See https://tools.ietf.org/html/draft-ietf-httpbis-cookie-same-site-00 for details. 

const (
	SameSiteDefaultMode SameSite = iota + 1
	SameSiteLaxMode
	SameSiteStrictMode
)

type ServeMux 

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

ServeMux is an HTTP request multiplexer. It matches the URL of each incoming request against a list of registered patterns and calls the handler for the pattern that most closely matches the URL.

Patterns name fixed, rooted paths, like "/favicon.ico", or rooted subtrees, like "/images/" (note the trailing slash). Longer patterns take precedence over shorter ones, so that if there are handlers registered for both "/images/" and "/images/thumbnails/", the latter handler will be called for paths beginning "/images/thumbnails/" and the former will receive requests for any other paths in the "/images/" subtree.

Note that since a pattern ending in a slash names a rooted subtree, the pattern "/" matches all paths not matched by other registered patterns, not just the URL with Path == "/".

If a subtree has been registered and a request is received naming the subtree root without its trailing slash, ServeMux redirects that request to the subtree root (adding the trailing slash). This behavior can be overridden with a separate registration for the path without the trailing slash. For example, registering "/images/" causes ServeMux to redirect a request for "/images" to "/images/", unless "/images" has been registered separately.

Patterns may optionally begin with a host name, restricting matches to URLs on that host only. Host-specific patterns take precedence over general patterns, so that a handler might register for the two patterns "/codesearch" and "codesearch.google.com/" without also taking over requests for "http://www.google.com/".

ServeMux also takes care of sanitizing the URL request path and the Host header, stripping the port number and redirecting any request containing . or .. elements or repeated slashes to an equivalent, cleaner URL.

func NewServeMux 

func NewServeMux() *ServeMux

NewServeMux allocates and returns a new ServeMux.

func (*ServeMux) Handle 

func (mux *ServeMux) Handle(pattern string, handler Handler)

Handle registers the handler for the given pattern. If a handler already exists for pattern, Handle panics.

Example 
mux := http.NewServeMux()
mux.Handle("/api/", apiHandler{})
mux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
	// The "/" pattern matches everything, so we need to check
	// that we're at the root here.
	if req.URL.Path != "/" {
		http.NotFound(w, req)
		return
	}
	fmt.Fprintf(w, "Welcome to the home page!")
})

Output:

func (*ServeMux) HandleFunc 

func (mux *ServeMux) HandleFunc(pattern string, handler func(ResponseWriter, *Request))

HandleFunc registers the handler function for the given pattern.

func (*ServeMux) Handler added in v1.1.0 

func (mux *ServeMux) Handler(r *Request) (h Handler, pattern string)

Handler returns the handler to use for the given request, consulting r.Method, r.Host, and r.URL.Path. It always returns a non-nil handler. If the path is not in its canonical form, the handler will be an internally-generated handler that redirects to the canonical path. If the host contains a port, it is ignored when matching handlers.

The path and host are used unchanged for CONNECT requests.

Handler also returns the registered pattern that matches the request or, in the case of internally-generated redirects, the pattern that will match after following the redirect.

If there is no registered handler that applies to the request, Handler returns a “page not found” handler and an empty pattern.

func (*ServeMux) ServeHTTP 

func (mux *ServeMux) ServeHTTP(w ResponseWriter, r *Request)

ServeHTTP dispatches the request to the handler whose pattern most closely matches the request URL.

type Server 

type Server struct {
	Addr    string
	Handler Handler

	TLSConfig *tls.Config

	ReadTimeout time.Duration

	ReadHeaderTimeout time.Duration

	WriteTimeout time.Duration

	IdleTimeout time.Duration

	MaxHeaderBytes int

	TLSNextProto map[string]func(*Server, *tls.Conn, Handler)

	ConnState func(net.Conn, ConnState)

	ErrorLog *log.Logger
	// contains filtered or unexported fields
}

A Server defines parameters for running an HTTP server. The zero value for Server is a valid configuration.

func (*Server) Close added in v1.8.0 

func (srv *Server) Close() error

Close immediately closes all active net.Listeners and any connections in state StateNew, StateActive, or StateIdle. For a graceful shutdown, use Shutdown.

Close does not attempt to close (and does not even know about) any hijacked connections, such as WebSockets.

Close returns any error returned from closing the Server's underlying Listener(s).

func (*Server) ListenAndServe 

func (srv *Server) ListenAndServe() error

ListenAndServe listens on the TCP network address srv.Addr and then calls Serve to handle requests on incoming connections. Accepted connections are configured to enable TCP keep-alives.

If srv.Addr is blank, ":http" is used.

ListenAndServe always returns a non-nil error. After Shutdown or Close, the returned error is ErrServerClosed.

func (*Server) ListenAndServeTLS 

func (srv *Server) ListenAndServeTLS(certFile, keyFile string) error

ListenAndServeTLS listens on the TCP network address srv.Addr and then calls ServeTLS to handle requests on incoming TLS connections. Accepted connections are configured to enable TCP keep-alives.

Filenames containing a certificate and matching private key for the server must be provided if neither the Server's TLSConfig.Certificates nor TLSConfig.GetCertificate are populated. If the certificate is signed by a certificate authority, the certFile should be the concatenation of the server's certificate, any intermediates, and the CA's certificate.

If srv.Addr is blank, ":https" is used.

ListenAndServeTLS always returns a non-nil error. After Shutdown or Close, the returned error is ErrServerClosed.

func (*Server) RegisterOnShutdown added in v1.9.0 

func (srv *Server) RegisterOnShutdown(f func())

RegisterOnShutdown registers a function to call on Shutdown. This can be used to gracefully shutdown connections that have undergone NPN/ALPN protocol upgrade or that have been hijacked. This function should start protocol-specific graceful shutdown, but should not wait for shutdown to complete.

func (*Server) Serve 

func (srv *Server) Serve(l net.Listener) error

Serve accepts incoming connections on the Listener l, creating a new service goroutine for each. The service goroutines read requests and then call srv.Handler to reply to them.

HTTP/2 support is only enabled if the Listener returns *tls.Conn connections and they were configured with "h2" in the TLS Config.NextProtos.

Serve always returns a non-nil error and closes l. After Shutdown or Close, the returned error is ErrServerClosed.

func (*Server) ServeTLS added in v1.9.0 

func (srv *Server) ServeTLS(l net.Listener, certFile, keyFile string) error

ServeTLS accepts incoming connections on the Listener l, creating a new service goroutine for each. The service goroutines perform TLS setup and then read requests, calling srv.Handler to reply to them.

Files containing a certificate and matching private key for the server must be provided if neither the Server's TLSConfig.Certificates nor TLSConfig.GetCertificate are populated. If the certificate is signed by a certificate authority, the certFile should be the concatenation of the server's certificate, any intermediates, and the CA's certificate.

ServeTLS always returns a non-nil error. After Shutdown or Close, the returned error is ErrServerClosed.

func (*Server) SetKeepAlivesEnabled added in v1.3.0 

func (srv *Server) SetKeepAlivesEnabled(v bool)

SetKeepAlivesEnabled controls whether HTTP keep-alives are enabled. By default, keep-alives are always enabled. Only very resource-constrained environments or servers in the process of shutting down should disable them.

func (*Server) Shutdown added in v1.8.0 

func (srv *Server) Shutdown(ctx context.Context) error

Shutdown gracefully shuts down the server without interrupting any active connections. Shutdown works by first closing all open listeners, then closing all idle connections, and then waiting indefinitely for connections to return to idle and then shut down. If the provided context expires before the shutdown is complete, Shutdown returns the context's error, otherwise it returns any error returned from closing the Server's underlying Listener(s).

When Shutdown is called, Serve, ListenAndServe, and ListenAndServeTLS immediately return ErrServerClosed. Make sure the program doesn't exit and waits instead for Shutdown to return.

Shutdown does not attempt to close nor wait for hijacked connections such as WebSockets. The caller of Shutdown should separately notify such long-lived connections of shutdown and wait for them to close, if desired. See RegisterOnShutdown for a way to register shutdown notification functions.

Once Shutdown has been called on a server, it may not be reused; future calls to methods such as Serve will return ErrServerClosed.

Example 
package main

import (
	"context"
	"log"
	"net/http"
	"os"
	"os/signal"
)

func main() {
	var srv http.Server

	idleConnsClosed := make(chan struct{})
	go func() {
		sigint := make(chan os.Signal, 1)
		signal.Notify(sigint, os.Interrupt)
		<-sigint

		// We received an interrupt signal, shut down.
		if err := srv.Shutdown(context.Background()); err != nil {
			// Error from closing listeners, or context timeout:
			log.Printf("HTTP server Shutdown: %v", err)
		}
		close(idleConnsClosed)
	}()

	if err := srv.ListenAndServe(); err != http.ErrServerClosed {
		// Error starting or closing listener:
		log.Printf("HTTP server ListenAndServe: %v", err)
	}

	<-idleConnsClosed
}

Output:

type Transport 

type Transport struct {
	Proxy func(*Request) (*url.URL, error)

	DialContext func(ctx context.Context, network, addr string) (net.Conn, error)

	Dial func(network, addr string) (net.Conn, error)

	DialTLS func(network, addr string) (net.Conn, error)

	TLSClientConfig *tls.Config

	TLSHandshakeTimeout time.Duration

	DisableKeepAlives bool

	DisableCompression bool

	MaxIdleConns int

	MaxIdleConnsPerHost int

	MaxConnsPerHost int

	IdleConnTimeout time.Duration

	ResponseHeaderTimeout time.Duration

	ExpectContinueTimeout time.Duration

	TLSNextProto map[string]func(authority string, c *tls.Conn) RoundTripper

	ProxyConnectHeader Header

	MaxResponseHeaderBytes int64
	// contains filtered or unexported fields
}

Transport is an implementation of RoundTripper that supports HTTP, HTTPS, and HTTP proxies (for either HTTP or HTTPS with CONNECT).

By default, Transport caches connections for future re-use. This may leave many open connections when accessing many hosts. This behavior can be managed using Transport's CloseIdleConnections method and the MaxIdleConnsPerHost and DisableKeepAlives fields.

Transports should be reused instead of created as needed. Transports are safe for concurrent use by multiple goroutines.

A Transport is a low-level primitive for making HTTP and HTTPS requests. For high-level functionality, such as cookies and redirects, see Client.

Transport uses HTTP/1.1 for HTTP URLs and either HTTP/1.1 or HTTP/2 for HTTPS URLs, depending on whether the server supports HTTP/2, and how the Transport is configured. The DefaultTransport supports HTTP/2. To explicitly enable HTTP/2 on a transport, use golang.org/x/net/http2 and call ConfigureTransport. See the package docs for more about HTTP/2.

The Transport will send CONNECT requests to a proxy for its own use when processing HTTPS requests, but Transport should generally not be used to send a CONNECT request. That is, the Request passed to the RoundTrip method should not have a Method of "CONNECT", as Go's HTTP/1.x implementation does not support full-duplex request bodies being written while the response body is streamed. Go's HTTP/2 implementation does support full duplex, but many CONNECT proxies speak HTTP/1.x.

Responses with status codes in the 1xx range are either handled automatically (100 expect-continue) or ignored. The one exception is HTTP status code 101 (Switching Protocols), which is considered a terminal status and returned by RoundTrip. To see the ignored 1xx responses, use the httptrace trace package's ClientTrace.Got1xxResponse.

func (*Transport) CancelRequest deprecated added in v1.1.0 

func (t *Transport) CancelRequest(req *Request)

CancelRequest cancels an in-flight request by closing its connection. CancelRequest should only be called after RoundTrip has returned.

Deprecated: Use Request.WithContext to create a request with a cancelable context instead. CancelRequest cannot cancel HTTP/2 requests.

func (*Transport) CloseIdleConnections 

func (t *Transport) CloseIdleConnections()

CloseIdleConnections closes any connections which were previously connected from previous requests but are now sitting idle in a "keep-alive" state. It does not interrupt any connections currently in use.

func (*Transport) RegisterProtocol 

func (t *Transport) RegisterProtocol(scheme string, rt RoundTripper)

RegisterProtocol registers a new protocol with scheme. The Transport will pass requests using the given scheme to rt. It is rt's responsibility to simulate HTTP request semantics.

RegisterProtocol can be used by other packages to provide implementations of protocol schemes like "ftp" or "file".

If rt.RoundTrip returns ErrSkipAltProtocol, the Transport will handle the RoundTrip itself for that one request, as if the protocol were not registered.

func (*Transport) RoundTrip 

func (t *Transport) RoundTrip(req *Request) (*Response, error)

RoundTrip implements the RoundTripper interface.

For higher-level HTTP client support (such as handling of cookies and redirects), see Get, Post, and the Client type.

Like the RoundTripper interface, the error types returned by RoundTrip are unspecified.

Source Files

View all Source files

Directories

Path Synopsis
Package cgi implements CGI (Common Gateway Interface) as specified in RFC 3875.
 Package cgi implements CGI (Common Gateway Interface) as specified in RFC 3875.
Package cookiejar implements an in-memory RFC 6265-compliant http.CookieJar.
 Package cookiejar implements an in-memory RFC 6265-compliant http.CookieJar.
Package fcgi implements the FastCGI protocol.
 Package fcgi implements the FastCGI protocol.
Package httptest provides utilities for HTTP testing.
 Package httptest provides utilities for HTTP testing.
Package httptrace provides mechanisms to trace the events within HTTP client requests.
 Package httptrace provides mechanisms to trace the events within HTTP client requests.
Package httputil provides HTTP utility functions, complementing the more common ones in the net/http package.
 Package httputil provides HTTP utility functions, complementing the more common ones in the net/http package.
Package pprof serves via its HTTP server runtime profiling data in the format expected by the pprof visualization tool.
 Package pprof serves via its HTTP server runtime profiling data in the format expected by the pprof visualization tool.

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