src/lib/http/request.go - go - Git at Google

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // HTTP Request reading and parsing.

 // The http package implements parsing of HTTP requests and URLs
 // and provides an extensible HTTP server.
 //
 // In the future it should also implement parsing of HTTP replies
 // and provide methods to fetch URLs via HTTP.
 package http

 import (
 	"bufio";
 	"http";
 	"io";
 	"os";
 	"strings"
 )

 const (
 	maxLineLength = 1024;	// assumed < bufio.DefaultBufSize
 	maxValueLength = 1024;
 	maxHeaderLines = 1024;
 )

 // HTTP request parsing errors.
 var (
 	LineTooLong = os.NewError("http header line too long");
 	ValueTooLong = os.NewError("http header value too long");
 	HeaderTooLong = os.NewError("http header too long");
 	BadHeader = os.NewError("malformed http header");
 	BadRequest = os.NewError("invalid http request");
 	BadHTTPVersion = os.NewError("unsupported http version");
 )

 // A Request represents a parsed HTTP request header.
 type Request struct {
 	Method string;		// GET, PUT,etc.
 	RawUrl string;		// The raw URL given in the request.
 	Url *URL;		// URL after GET, PUT etc.
 	Proto string;	// "HTTP/1.0"
 	ProtoMajor int;	// 1
 	ProtoMinor int;	// 0

 	// A header mapping request lines to their values.
 	// If the header says
 	//
 	//	Accept-Language: en-us
 	//	accept-encoding: gzip, deflate
 	//	Connection: keep-alive
 	//
 	// then
 	//
 	//	Header = map[string]string{
 	//		"Accept-Encoding": "en-us",
 	//		"Accept-Language": "gzip, deflate",
 	//		"Connection": "keep-alive"
 	//	}
 	//
 	// HTTP defines that header names are case-insensitive.
 	// The request parser implements this by canonicalizing the
 	// name, making the first character and any characters
 	// following a hyphen uppercase and the rest lowercase.
 	Header map[string] string;

 	// Whether to close the connection after replying to this request.
 	Close bool;

 	// The host on which the URL is sought.
 	// Per RFC 2616, this is either the value of the Host: header
 	// or the host name given in the URL itself.
 	Host string;

 	// 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 structure field is that the compiler
 	// can diagnose programs that use the alternate
 	// (correct English) spelling req.Referrer but cannot
 	// diagnose programs that use Header["Referrer"].
 	Referer string;

 	// The User-Agent: header string, if sent in the request.
 	UserAgent string;
 }

 // ProtoAtLeast returns whether the HTTP protocol used
 // in the request is at least major.minor.
 func (r *Request) ProtoAtLeast(major, minor int) bool {
 	return r.ProtoMajor > major ||
 		r.ProtoMajor == major && r.ProtoMinor >= minor
 }

 // Read a line of bytes (up to \n) from b.
 // Give up if the line exceeds maxLineLength.
 // The returned bytes are a pointer into storage in
 // the bufio, so they are only valid until the next bufio read.
 func readLineBytes(b *bufio.BufRead) (p []byte, err *os.Error) {
 	if p, err = b.ReadLineSlice('\n'); err != nil {
 		return nil, err
 	}
 	if len(p) >= maxLineLength {
 		return nil, LineTooLong
 	}

 	// Chop off trailing white space.
 	var i int;
 	for i = len(p); i > 0; i-- {
 		if c := p[i-1]; c != ' ' && c != '\r' && c != '\t' && c != '\n' {
 			break
 		}
 	}
 	return p[0:i], nil
 }

 // readLineBytes, but convert the bytes into a string.
 func readLine(b *bufio.BufRead) (s string, err *os.Error) {
 	p, e := readLineBytes(b);
 	if e != nil {
 		return "", e
 	}
 	return string(p), nil
 }

 // Read a key/value pair from b.
 // A key/value has the form Key: Value\r\n
 // and the Value can continue on multiple lines if each continuation line
 // starts with a space.
 func readKeyValue(b *bufio.BufRead) (key, value string, err *os.Error) {
 	line, e := readLineBytes(b);
 	if e != nil {
 		return "", "", e
 	}
 	if len(line) == 0 {
 		return "", "", nil
 	}

 	// Scan first line for colon.
 	for i := 0; i < len(line); i++ {
 		switch line[i] {
 		case ' ':
 			// Key field has space - no good.
 			return "", "", BadHeader;
 		case ':':
 			key = string(line[0:i]);
 			// Skip initial space before value.
 			for i++; i < len(line); i++ {
 				if line[i] != ' ' {
 					break
 				}
 			}
 			value = string(line[i:len(line)]);

 			// Look for extension lines, which must begin with space.
 			for {
 				var c byte;

 				if c, e = b.ReadByte(); e != nil {
 					return "", "", e
 				}
 				if c != ' ' {
 					// Not leading space; stop.
 					b.UnreadByte();
 					break
 				}

 				// Eat leading space.
 				for c == ' ' {
 					if c, e = b.ReadByte(); e != nil {
 						return "", "", e
 					}
 				}
 				b.UnreadByte();

 				// Read the rest of the line and add to value.
 				if line, e = readLineBytes(b); e != nil {
 					return "", "", e
 				}
 				value += " " + string(line);

 				if len(value) >= maxValueLength {
 					return "", "", ValueTooLong
 				}
 			}
 			return key, value, nil
 		}
 	}

 	// Line ended before space or colon.
 	return "", "", BadHeader;
 }

 // Convert decimal at s[i:len(s)] to integer,
 // returning value, string position where the digits stopped,
 // and whether there was a valid number (digits, not too big).
 func atoi(s string, i int) (n, i1 int, ok bool) {
 	const Big = 1000000;
 	if i >= len(s) || s[i] < '0' || s[i] > '9' {
 		return 0, 0, false
 	}
 	n = 0;
 	for ; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
 		n = n*10 + int(s[i]-'0');
 		if n > Big {
 			return 0, 0, false
 		}
 	}
 	return n, i, true
 }

 // Parse HTTP version: "HTTP/1.2" -> (1, 2, true).
 func parseHTTPVersion(vers string) (int, int, bool) {
 	if vers[0:5] != "HTTP/" {
 		return 0, 0, false
 	}
 	major, i, ok := atoi(vers, 5);
 	if !ok || i >= len(vers) || vers[i] != '.' {
 		return 0, 0, false
 	}
 	var minor int;
 	minor, i, ok = atoi(vers, i+1);
 	if !ok || i != len(vers) {
 		return 0, 0, false
 	}
 	return major, minor, true
 }

 var cmap = make(map[string]string)

 // CanonicalHeaderKey returns the canonical format of the
 // HTTP 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".
 func CanonicalHeaderKey(s string) string {
 	if t, ok := cmap[s]; ok {
 		return t;
 	}

 	// canonicalize: first letter upper case
 	// and upper case after each dash.
 	// (Host, User-Agent, If-Modified-Since).
 	// HTTP headers are ASCII only, so no Unicode issues.
 	a := io.StringBytes(s);
 	upper := true;
 	for i,v := range a {
 		if upper && 'a' <= v && v <= 'z' {
 			a[i] = v + 'A' - 'a';
 		}
 		if !upper && 'A' <= v && v <= 'Z' {
 			a[i] = v + 'a' - 'A';
 		}
 		upper = false;
 		if v == '-' {
 			upper = true;
 		}
 	}
 	t := string(a);
 	cmap[s] = t;
 	return t;
 }

 // ReadRequest reads and parses a request from b.
 func ReadRequest(b *bufio.BufRead) (req *Request, err *os.Error) {
 	req = new(Request);

 	// First line: GET /index.html HTTP/1.0
 	var s string;
 	if s, err = readLine(b); err != nil {
 		return nil, err
 	}

 	var f []string;
 	if f = strings.Split(s, " "); len(f) != 3 {
 		return nil, BadRequest
 	}
 	req.Method, req.RawUrl, req.Proto = f[0], f[1], f[2];
 	var ok bool;
 	if req.ProtoMajor, req.ProtoMinor, ok = parseHTTPVersion(req.Proto); !ok {
 		return nil, BadHTTPVersion
 	}

 	if req.Url, err = ParseURL(req.RawUrl); err != nil {
 		return nil, err
 	}

 	// Subsequent lines: Key: value.
 	nheader := 0;
 	req.Header = make(map[string] string);
 	for {
 		var key, value string;
 		if key, value, err = readKeyValue(b); err != nil {
 			return nil, err
 		}
 		if key == "" {
 			break
 		}
 		if nheader++; nheader >= maxHeaderLines {
 			return nil, HeaderTooLong
 		}

 		key = CanonicalHeaderKey(key);

 		// RFC 2616 says that if you send the same header key
 		// multiple times, it has to be semantically equivalent
 		// to concatenating the values separated by commas.
 		oldvalue, present := req.Header[key];
 		if present {
 			req.Header[key] = oldvalue+","+value
 		} else {
 			req.Header[key] = value
 		}
 	}

 	// RFC2616: Must treat
 	//	GET /index.html HTTP/1.1
 	//	Host: www.google.com
 	// and
 	//	GET http://www.google.com/index.html HTTP/1.1
 	//	Host: doesntmatter
 	// the same.  In the second case, any Host line is ignored.
 	if v, present := req.Header["Host"]; present && req.Url.Host == "" {
 		req.Host = v
 	}

 	// RFC2616: Should treat
 	//	Pragma: no-cache
 	// like
 	//	Cache-Control: no-cache
 	if v, present := req.Header["Pragma"]; present && v == "no-cache" {
 		if cc, presentcc := req.Header["Cache-Control"]; !presentcc {
 			req.Header["Cache-Control"] = "no-cache"
 		}
 	}

 	// Determine whether to hang up after sending the reply.
 	if req.ProtoMajor < 1 || (req.ProtoMajor == 1 && req.ProtoMinor < 1) {
 		req.Close = true
 	} else if v, present := req.Header["Connection"]; present {
 		// TODO: Should split on commas, toss surrounding white space,
 		// and check each field.
 		if v == "close" {
 			req.Close = true
 		}
 	}

 	// Pull out useful fields as a convenience to clients.
 	if v, present := req.Header["Referer"]; present {
 		req.Referer = v
 	}
 	if v, present := req.Header["User-Agent"]; present {
 		req.UserAgent = v
 	}

 	// TODO: Parse specific header values:
 	//	Accept
 	//	Accept-Encoding
 	//	Accept-Language
 	//	Authorization
 	//	Cache-Control
 	//	Connection
 	//	Date
 	//	Expect
 	//	From
 	//	If-Match
 	//	If-Modified-Since
 	//	If-None-Match
 	//	If-Range
 	//	If-Unmodified-Since
 	//	Max-Forwards
 	//	Proxy-Authorization
 	//	Referer [sic]
 	//	TE (transfer-codings)
 	//	Trailer
 	//	Transfer-Encoding
 	//	Upgrade
 	//	User-Agent
 	//	Via
 	//	Warning

 	return req, nil;
 }
	// Copyright 2009 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// HTTP Request reading and parsing.

	// The http package implements parsing of HTTP requests and URLs
	// and provides an extensible HTTP server.
	//
	// In the future it should also implement parsing of HTTP replies
	// and provide methods to fetch URLs via HTTP.
	package http

	import (
	"bufio";
	"http";
	"io";
	"os";
	"strings"
	)

	const (
	maxLineLength = 1024; // assumed < bufio.DefaultBufSize
	maxValueLength = 1024;
	maxHeaderLines = 1024;
	)

	// HTTP request parsing errors.
	var (
	LineTooLong = os.NewError("http header line too long");
	ValueTooLong = os.NewError("http header value too long");
	HeaderTooLong = os.NewError("http header too long");
	BadHeader = os.NewError("malformed http header");
	BadRequest = os.NewError("invalid http request");
	BadHTTPVersion = os.NewError("unsupported http version");
	)

	// A Request represents a parsed HTTP request header.
	type Request struct {
	Method string; // GET, PUT,etc.
	RawUrl string; // The raw URL given in the request.
	Url *URL; // URL after GET, PUT etc.
	Proto string; // "HTTP/1.0"
	ProtoMajor int; // 1
	ProtoMinor int; // 0

	// A header mapping request lines to their values.
	// If the header says
	//
	// Accept-Language: en-us
	// accept-encoding: gzip, deflate
	// Connection: keep-alive
	//
	// then
	//
	// Header = map[string]string{
	// "Accept-Encoding": "en-us",
	// "Accept-Language": "gzip, deflate",
	// "Connection": "keep-alive"
	// }
	//
	// HTTP defines that header names are case-insensitive.
	// The request parser implements this by canonicalizing the
	// name, making the first character and any characters
	// following a hyphen uppercase and the rest lowercase.
	Header map[string] string;

	// Whether to close the connection after replying to this request.
	Close bool;

	// The host on which the URL is sought.
	// Per RFC 2616, this is either the value of the Host: header
	// or the host name given in the URL itself.
	Host string;

	// 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 structure field is that the compiler
	// can diagnose programs that use the alternate
	// (correct English) spelling req.Referrer but cannot
	// diagnose programs that use Header["Referrer"].
	Referer string;

	// The User-Agent: header string, if sent in the request.
	UserAgent string;
	}

	// ProtoAtLeast returns whether the HTTP protocol used
	// in the request is at least major.minor.
	func (r *Request) ProtoAtLeast(major, minor int) bool {
	return r.ProtoMajor > major \|\|
	r.ProtoMajor == major && r.ProtoMinor >= minor
	}

	// Read a line of bytes (up to \n) from b.
	// Give up if the line exceeds maxLineLength.
	// The returned bytes are a pointer into storage in
	// the bufio, so they are only valid until the next bufio read.
	func readLineBytes(b bufio.BufRead) (p []byte, err os.Error) {
	if p, err = b.ReadLineSlice('\n'); err != nil {
	return nil, err
	}
	if len(p) >= maxLineLength {
	return nil, LineTooLong
	}

	// Chop off trailing white space.
	var i int;
	for i = len(p); i > 0; i-- {
	if c := p[i-1]; c != ' ' && c != '\r' && c != '\t' && c != '\n' {
	break
	}
	}
	return p[0:i], nil
	}

	// readLineBytes, but convert the bytes into a string.
	func readLine(b bufio.BufRead) (s string, err os.Error) {
	p, e := readLineBytes(b);
	if e != nil {
	return "", e
	}
	return string(p), nil
	}

	// Read a key/value pair from b.
	// A key/value has the form Key: Value\r\n
	// and the Value can continue on multiple lines if each continuation line
	// starts with a space.
	func readKeyValue(b bufio.BufRead) (key, value string, err os.Error) {
	line, e := readLineBytes(b);
	if e != nil {
	return "", "", e
	}
	if len(line) == 0 {
	return "", "", nil
	}

	// Scan first line for colon.
	for i := 0; i < len(line); i++ {
	switch line[i] {
	case ' ':
	// Key field has space - no good.
	return "", "", BadHeader;
	case ':':
	key = string(line[0:i]);
	// Skip initial space before value.
	for i++; i < len(line); i++ {
	if line[i] != ' ' {
	break
	}
	}
	value = string(line[i:len(line)]);

	// Look for extension lines, which must begin with space.
	for {
	var c byte;

	if c, e = b.ReadByte(); e != nil {
	return "", "", e
	}
	if c != ' ' {
	// Not leading space; stop.
	b.UnreadByte();
	break
	}

	// Eat leading space.
	for c == ' ' {
	if c, e = b.ReadByte(); e != nil {
	return "", "", e
	}
	}
	b.UnreadByte();

	// Read the rest of the line and add to value.
	if line, e = readLineBytes(b); e != nil {
	return "", "", e
	}
	value += " " + string(line);

	if len(value) >= maxValueLength {
	return "", "", ValueTooLong
	}
	}
	return key, value, nil
	}
	}

	// Line ended before space or colon.
	return "", "", BadHeader;
	}

	// Convert decimal at s[i:len(s)] to integer,
	// returning value, string position where the digits stopped,
	// and whether there was a valid number (digits, not too big).
	func atoi(s string, i int) (n, i1 int, ok bool) {
	const Big = 1000000;
	if i >= len(s) \|\| s[i] < '0' \|\| s[i] > '9' {
	return 0, 0, false
	}
	n = 0;
	for ; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
	n = n*10 + int(s[i]-'0');
	if n > Big {
	return 0, 0, false
	}
	}
	return n, i, true
	}

	// Parse HTTP version: "HTTP/1.2" -> (1, 2, true).
	func parseHTTPVersion(vers string) (int, int, bool) {
	if vers[0:5] != "HTTP/" {
	return 0, 0, false
	}
	major, i, ok := atoi(vers, 5);
	if !ok \|\| i >= len(vers) \|\| vers[i] != '.' {
	return 0, 0, false
	}
	var minor int;
	minor, i, ok = atoi(vers, i+1);
	if !ok \|\| i != len(vers) {
	return 0, 0, false
	}
	return major, minor, true
	}

	var cmap = make(map[string]string)

	// CanonicalHeaderKey returns the canonical format of the
	// HTTP 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".
	func CanonicalHeaderKey(s string) string {
	if t, ok := cmap[s]; ok {
	return t;
	}

	// canonicalize: first letter upper case
	// and upper case after each dash.
	// (Host, User-Agent, If-Modified-Since).
	// HTTP headers are ASCII only, so no Unicode issues.
	a := io.StringBytes(s);
	upper := true;
	for i,v := range a {
	if upper && 'a' <= v && v <= 'z' {
	a[i] = v + 'A' - 'a';
	}
	if !upper && 'A' <= v && v <= 'Z' {
	a[i] = v + 'a' - 'A';
	}
	upper = false;
	if v == '-' {
	upper = true;
	}
	}
	t := string(a);
	cmap[s] = t;
	return t;
	}

	// ReadRequest reads and parses a request from b.
	func ReadRequest(b bufio.BufRead) (req Request, err *os.Error) {
	req = new(Request);

	// First line: GET /index.html HTTP/1.0
	var s string;
	if s, err = readLine(b); err != nil {
	return nil, err
	}

	var f []string;
	if f = strings.Split(s, " "); len(f) != 3 {
	return nil, BadRequest
	}
	req.Method, req.RawUrl, req.Proto = f[0], f[1], f[2];
	var ok bool;
	if req.ProtoMajor, req.ProtoMinor, ok = parseHTTPVersion(req.Proto); !ok {
	return nil, BadHTTPVersion
	}

	if req.Url, err = ParseURL(req.RawUrl); err != nil {
	return nil, err
	}

	// Subsequent lines: Key: value.
	nheader := 0;
	req.Header = make(map[string] string);
	for {
	var key, value string;
	if key, value, err = readKeyValue(b); err != nil {
	return nil, err
	}
	if key == "" {
	break
	}
	if nheader++; nheader >= maxHeaderLines {
	return nil, HeaderTooLong
	}

	key = CanonicalHeaderKey(key);

	// RFC 2616 says that if you send the same header key
	// multiple times, it has to be semantically equivalent
	// to concatenating the values separated by commas.
	oldvalue, present := req.Header[key];
	if present {
	req.Header[key] = oldvalue+","+value
	} else {
	req.Header[key] = value
	}
	}

	// RFC2616: Must treat
	// GET /index.html HTTP/1.1
	// Host: www.google.com
	// and
	// GET http://www.google.com/index.html HTTP/1.1
	// Host: doesntmatter
	// the same. In the second case, any Host line is ignored.
	if v, present := req.Header["Host"]; present && req.Url.Host == "" {
	req.Host = v
	}

	// RFC2616: Should treat
	// Pragma: no-cache
	// like
	// Cache-Control: no-cache
	if v, present := req.Header["Pragma"]; present && v == "no-cache" {
	if cc, presentcc := req.Header["Cache-Control"]; !presentcc {
	req.Header["Cache-Control"] = "no-cache"
	}
	}

	// Determine whether to hang up after sending the reply.
	if req.ProtoMajor < 1 \|\| (req.ProtoMajor == 1 && req.ProtoMinor < 1) {
	req.Close = true
	} else if v, present := req.Header["Connection"]; present {
	// TODO: Should split on commas, toss surrounding white space,
	// and check each field.
	if v == "close" {
	req.Close = true
	}
	}

	// Pull out useful fields as a convenience to clients.
	if v, present := req.Header["Referer"]; present {
	req.Referer = v
	}
	if v, present := req.Header["User-Agent"]; present {
	req.UserAgent = v
	}

	// TODO: Parse specific header values:
	// Accept
	// Accept-Encoding
	// Accept-Language
	// Authorization
	// Cache-Control
	// Connection
	// Date
	// Expect
	// From
	// If-Match
	// If-Modified-Since
	// If-None-Match
	// If-Range
	// If-Unmodified-Since
	// Max-Forwards
	// Proxy-Authorization
	// Referer [sic]
	// TE (transfer-codings)
	// Trailer
	// Transfer-Encoding
	// Upgrade
	// User-Agent
	// Via
	// Warning

	return req, nil;
	}