diff options
Diffstat (limited to 'vendor/github.com/aws/aws-sdk-go/aws/signer/v4/v4.go')
| -rw-r--r-- | vendor/github.com/aws/aws-sdk-go/aws/signer/v4/v4.go | 761 |
1 files changed, 761 insertions, 0 deletions
diff --git a/vendor/github.com/aws/aws-sdk-go/aws/signer/v4/v4.go b/vendor/github.com/aws/aws-sdk-go/aws/signer/v4/v4.go new file mode 100644 index 00000000..434ac872 --- /dev/null +++ b/vendor/github.com/aws/aws-sdk-go/aws/signer/v4/v4.go @@ -0,0 +1,761 @@ +// Package v4 implements signing for AWS V4 signer +// +// Provides request signing for request that need to be signed with +// AWS V4 Signatures. +// +// Standalone Signer +// +// Generally using the signer outside of the SDK should not require any additional +// logic when using Go v1.5 or higher. The signer does this by taking advantage +// of the URL.EscapedPath method. If your request URI requires additional escaping +// you many need to use the URL.Opaque to define what the raw URI should be sent +// to the service as. +// +// The signer will first check the URL.Opaque field, and use its value if set. +// The signer does require the URL.Opaque field to be set in the form of: +// +// "//<hostname>/<path>" +// +// // e.g. +// "//example.com/some/path" +// +// The leading "//" and hostname are required or the URL.Opaque escaping will +// not work correctly. +// +// If URL.Opaque is not set the signer will fallback to the URL.EscapedPath() +// method and using the returned value. If you're using Go v1.4 you must set +// URL.Opaque if the URI path needs escaping. If URL.Opaque is not set with +// Go v1.5 the signer will fallback to URL.Path. +// +// AWS v4 signature validation requires that the canonical string's URI path +// element must be the URI escaped form of the HTTP request's path. +// http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html +// +// The Go HTTP client will perform escaping automatically on the request. Some +// of these escaping may cause signature validation errors because the HTTP +// request differs from the URI path or query that the signature was generated. +// https://golang.org/pkg/net/url/#URL.EscapedPath +// +// Because of this, it is recommended that when using the signer outside of the +// SDK that explicitly escaping the request prior to being signed is preferable, +// and will help prevent signature validation errors. This can be done by setting +// the URL.Opaque or URL.RawPath. The SDK will use URL.Opaque first and then +// call URL.EscapedPath() if Opaque is not set. +// +// If signing a request intended for HTTP2 server, and you're using Go 1.6.2 +// through 1.7.4 you should use the URL.RawPath as the pre-escaped form of the +// request URL. https://github.com/golang/go/issues/16847 points to a bug in +// Go pre 1.8 that failes to make HTTP2 requests using absolute URL in the HTTP +// message. URL.Opaque generally will force Go to make requests with absolute URL. +// URL.RawPath does not do this, but RawPath must be a valid escaping of Path +// or url.EscapedPath will ignore the RawPath escaping. +// +// Test `TestStandaloneSign` provides a complete example of using the signer +// outside of the SDK and pre-escaping the URI path. +package v4 + +import ( + "bytes" + "crypto/hmac" + "crypto/sha256" + "encoding/hex" + "fmt" + "io" + "io/ioutil" + "net/http" + "net/url" + "sort" + "strconv" + "strings" + "time" + + "github.com/aws/aws-sdk-go/aws" + "github.com/aws/aws-sdk-go/aws/credentials" + "github.com/aws/aws-sdk-go/aws/request" + "github.com/aws/aws-sdk-go/private/protocol/rest" +) + +const ( + authHeaderPrefix = "AWS4-HMAC-SHA256" + timeFormat = "20060102T150405Z" + shortTimeFormat = "20060102" + + // emptyStringSHA256 is a SHA256 of an empty string + emptyStringSHA256 = `e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855` +) + +var ignoredHeaders = rules{ + blacklist{ + mapRule{ + "Authorization": struct{}{}, + "User-Agent": struct{}{}, + "X-Amzn-Trace-Id": struct{}{}, + }, + }, +} + +// requiredSignedHeaders is a whitelist for build canonical headers. +var requiredSignedHeaders = rules{ + whitelist{ + mapRule{ + "Cache-Control": struct{}{}, + "Content-Disposition": struct{}{}, + "Content-Encoding": struct{}{}, + "Content-Language": struct{}{}, + "Content-Md5": struct{}{}, + "Content-Type": struct{}{}, + "Expires": struct{}{}, + "If-Match": struct{}{}, + "If-Modified-Since": struct{}{}, + "If-None-Match": struct{}{}, + "If-Unmodified-Since": struct{}{}, + "Range": struct{}{}, + "X-Amz-Acl": struct{}{}, + "X-Amz-Copy-Source": struct{}{}, + "X-Amz-Copy-Source-If-Match": struct{}{}, + "X-Amz-Copy-Source-If-Modified-Since": struct{}{}, + "X-Amz-Copy-Source-If-None-Match": struct{}{}, + "X-Amz-Copy-Source-If-Unmodified-Since": struct{}{}, + "X-Amz-Copy-Source-Range": struct{}{}, + "X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": struct{}{}, + "X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": struct{}{}, + "X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": struct{}{}, + "X-Amz-Grant-Full-control": struct{}{}, + "X-Amz-Grant-Read": struct{}{}, + "X-Amz-Grant-Read-Acp": struct{}{}, + "X-Amz-Grant-Write": struct{}{}, + "X-Amz-Grant-Write-Acp": struct{}{}, + "X-Amz-Metadata-Directive": struct{}{}, + "X-Amz-Mfa": struct{}{}, + "X-Amz-Request-Payer": struct{}{}, + "X-Amz-Server-Side-Encryption": struct{}{}, + "X-Amz-Server-Side-Encryption-Aws-Kms-Key-Id": struct{}{}, + "X-Amz-Server-Side-Encryption-Customer-Algorithm": struct{}{}, + "X-Amz-Server-Side-Encryption-Customer-Key": struct{}{}, + "X-Amz-Server-Side-Encryption-Customer-Key-Md5": struct{}{}, + "X-Amz-Storage-Class": struct{}{}, + "X-Amz-Website-Redirect-Location": struct{}{}, + }, + }, + patterns{"X-Amz-Meta-"}, +} + +// allowedHoisting is a whitelist for build query headers. The boolean value +// represents whether or not it is a pattern. +var allowedQueryHoisting = inclusiveRules{ + blacklist{requiredSignedHeaders}, + patterns{"X-Amz-"}, +} + +// Signer applies AWS v4 signing to given request. Use this to sign requests +// that need to be signed with AWS V4 Signatures. +type Signer struct { + // The authentication credentials the request will be signed against. + // This value must be set to sign requests. + Credentials *credentials.Credentials + + // Sets the log level the signer should use when reporting information to + // the logger. If the logger is nil nothing will be logged. See + // aws.LogLevelType for more information on available logging levels + // + // By default nothing will be logged. + Debug aws.LogLevelType + + // The logger loging information will be written to. If there the logger + // is nil, nothing will be logged. + Logger aws.Logger + + // Disables the Signer's moving HTTP header key/value pairs from the HTTP + // request header to the request's query string. This is most commonly used + // with pre-signed requests preventing headers from being added to the + // request's query string. + DisableHeaderHoisting bool + + // Disables the automatic escaping of the URI path of the request for the + // siganture's canonical string's path. For services that do not need additional + // escaping then use this to disable the signer escaping the path. + // + // S3 is an example of a service that does not need additional escaping. + // + // http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html + DisableURIPathEscaping bool + + // Disales the automatical setting of the HTTP request's Body field with the + // io.ReadSeeker passed in to the signer. This is useful if you're using a + // custom wrapper around the body for the io.ReadSeeker and want to preserve + // the Body value on the Request.Body. + // + // This does run the risk of signing a request with a body that will not be + // sent in the request. Need to ensure that the underlying data of the Body + // values are the same. + DisableRequestBodyOverwrite bool + + // currentTimeFn returns the time value which represents the current time. + // This value should only be used for testing. If it is nil the default + // time.Now will be used. + currentTimeFn func() time.Time + + // UnsignedPayload will prevent signing of the payload. This will only + // work for services that have support for this. + UnsignedPayload bool +} + +// NewSigner returns a Signer pointer configured with the credentials and optional +// option values provided. If not options are provided the Signer will use its +// default configuration. +func NewSigner(credentials *credentials.Credentials, options ...func(*Signer)) *Signer { + v4 := &Signer{ + Credentials: credentials, + } + + for _, option := range options { + option(v4) + } + + return v4 +} + +type signingCtx struct { + ServiceName string + Region string + Request *http.Request + Body io.ReadSeeker + Query url.Values + Time time.Time + ExpireTime time.Duration + SignedHeaderVals http.Header + + DisableURIPathEscaping bool + + credValues credentials.Value + isPresign bool + formattedTime string + formattedShortTime string + unsignedPayload bool + + bodyDigest string + signedHeaders string + canonicalHeaders string + canonicalString string + credentialString string + stringToSign string + signature string + authorization string +} + +// Sign signs AWS v4 requests with the provided body, service name, region the +// request is made to, and time the request is signed at. The signTime allows +// you to specify that a request is signed for the future, and cannot be +// used until then. +// +// Returns a list of HTTP headers that were included in the signature or an +// error if signing the request failed. Generally for signed requests this value +// is not needed as the full request context will be captured by the http.Request +// value. It is included for reference though. +// +// Sign will set the request's Body to be the `body` parameter passed in. If +// the body is not already an io.ReadCloser, it will be wrapped within one. If +// a `nil` body parameter passed to Sign, the request's Body field will be +// also set to nil. Its important to note that this functionality will not +// change the request's ContentLength of the request. +// +// Sign differs from Presign in that it will sign the request using HTTP +// header values. This type of signing is intended for http.Request values that +// will not be shared, or are shared in a way the header values on the request +// will not be lost. +// +// The requests body is an io.ReadSeeker so the SHA256 of the body can be +// generated. To bypass the signer computing the hash you can set the +// "X-Amz-Content-Sha256" header with a precomputed value. The signer will +// only compute the hash if the request header value is empty. +func (v4 Signer) Sign(r *http.Request, body io.ReadSeeker, service, region string, signTime time.Time) (http.Header, error) { + return v4.signWithBody(r, body, service, region, 0, signTime) +} + +// Presign signs AWS v4 requests with the provided body, service name, region +// the request is made to, and time the request is signed at. The signTime +// allows you to specify that a request is signed for the future, and cannot +// be used until then. +// +// Returns a list of HTTP headers that were included in the signature or an +// error if signing the request failed. For presigned requests these headers +// and their values must be included on the HTTP request when it is made. This +// is helpful to know what header values need to be shared with the party the +// presigned request will be distributed to. +// +// Presign differs from Sign in that it will sign the request using query string +// instead of header values. This allows you to share the Presigned Request's +// URL with third parties, or distribute it throughout your system with minimal +// dependencies. +// +// Presign also takes an exp value which is the duration the +// signed request will be valid after the signing time. This is allows you to +// set when the request will expire. +// +// The requests body is an io.ReadSeeker so the SHA256 of the body can be +// generated. To bypass the signer computing the hash you can set the +// "X-Amz-Content-Sha256" header with a precomputed value. The signer will +// only compute the hash if the request header value is empty. +// +// Presigning a S3 request will not compute the body's SHA256 hash by default. +// This is done due to the general use case for S3 presigned URLs is to share +// PUT/GET capabilities. If you would like to include the body's SHA256 in the +// presigned request's signature you can set the "X-Amz-Content-Sha256" +// HTTP header and that will be included in the request's signature. +func (v4 Signer) Presign(r *http.Request, body io.ReadSeeker, service, region string, exp time.Duration, signTime time.Time) (http.Header, error) { + return v4.signWithBody(r, body, service, region, exp, signTime) +} + +func (v4 Signer) signWithBody(r *http.Request, body io.ReadSeeker, service, region string, exp time.Duration, signTime time.Time) (http.Header, error) { + currentTimeFn := v4.currentTimeFn + if currentTimeFn == nil { + currentTimeFn = time.Now + } + + ctx := &signingCtx{ + Request: r, + Body: body, + Query: r.URL.Query(), + Time: signTime, + ExpireTime: exp, + isPresign: exp != 0, + ServiceName: service, + Region: region, + DisableURIPathEscaping: v4.DisableURIPathEscaping, + unsignedPayload: v4.UnsignedPayload, + } + + for key := range ctx.Query { + sort.Strings(ctx.Query[key]) + } + + if ctx.isRequestSigned() { + ctx.Time = currentTimeFn() + ctx.handlePresignRemoval() + } + + var err error + ctx.credValues, err = v4.Credentials.Get() + if err != nil { + return http.Header{}, err + } + + ctx.assignAmzQueryValues() + ctx.build(v4.DisableHeaderHoisting) + + // If the request is not presigned the body should be attached to it. This + // prevents the confusion of wanting to send a signed request without + // the body the request was signed for attached. + if !(v4.DisableRequestBodyOverwrite || ctx.isPresign) { + var reader io.ReadCloser + if body != nil { + var ok bool + if reader, ok = body.(io.ReadCloser); !ok { + reader = ioutil.NopCloser(body) + } + } + r.Body = reader + } + + if v4.Debug.Matches(aws.LogDebugWithSigning) { + v4.logSigningInfo(ctx) + } + + return ctx.SignedHeaderVals, nil +} + +func (ctx *signingCtx) handlePresignRemoval() { + if !ctx.isPresign { + return + } + + // The credentials have expired for this request. The current signing + // is invalid, and needs to be request because the request will fail. + ctx.removePresign() + + // Update the request's query string to ensure the values stays in + // sync in the case retrieving the new credentials fails. + ctx.Request.URL.RawQuery = ctx.Query.Encode() +} + +func (ctx *signingCtx) assignAmzQueryValues() { + if ctx.isPresign { + ctx.Query.Set("X-Amz-Algorithm", authHeaderPrefix) + if ctx.credValues.SessionToken != "" { + ctx.Query.Set("X-Amz-Security-Token", ctx.credValues.SessionToken) + } else { + ctx.Query.Del("X-Amz-Security-Token") + } + + return + } + + if ctx.credValues.SessionToken != "" { + ctx.Request.Header.Set("X-Amz-Security-Token", ctx.credValues.SessionToken) + } +} + +// SignRequestHandler is a named request handler the SDK will use to sign +// service client request with using the V4 signature. +var SignRequestHandler = request.NamedHandler{ + Name: "v4.SignRequestHandler", Fn: SignSDKRequest, +} + +// SignSDKRequest signs an AWS request with the V4 signature. This +// request handler is bested used only with the SDK's built in service client's +// API operation requests. +// +// This function should not be used on its on its own, but in conjunction with +// an AWS service client's API operation call. To sign a standalone request +// not created by a service client's API operation method use the "Sign" or +// "Presign" functions of the "Signer" type. +// +// If the credentials of the request's config are set to +// credentials.AnonymousCredentials the request will not be signed. +func SignSDKRequest(req *request.Request) { + signSDKRequestWithCurrTime(req, time.Now) +} + +// BuildNamedHandler will build a generic handler for signing. +func BuildNamedHandler(name string, opts ...func(*Signer)) request.NamedHandler { + return request.NamedHandler{ + Name: name, + Fn: func(req *request.Request) { + signSDKRequestWithCurrTime(req, time.Now, opts...) + }, + } +} + +func signSDKRequestWithCurrTime(req *request.Request, curTimeFn func() time.Time, opts ...func(*Signer)) { + // If the request does not need to be signed ignore the signing of the + // request if the AnonymousCredentials object is used. + if req.Config.Credentials == credentials.AnonymousCredentials { + return + } + + region := req.ClientInfo.SigningRegion + if region == "" { + region = aws.StringValue(req.Config.Region) + } + + name := req.ClientInfo.SigningName + if name == "" { + name = req.ClientInfo.ServiceName + } + + v4 := NewSigner(req.Config.Credentials, func(v4 *Signer) { + v4.Debug = req.Config.LogLevel.Value() + v4.Logger = req.Config.Logger + v4.DisableHeaderHoisting = req.NotHoist + v4.currentTimeFn = curTimeFn + if name == "s3" { + // S3 service should not have any escaping applied + v4.DisableURIPathEscaping = true + } + // Prevents setting the HTTPRequest's Body. Since the Body could be + // wrapped in a custom io.Closer that we do not want to be stompped + // on top of by the signer. + v4.DisableRequestBodyOverwrite = true + }) + + for _, opt := range opts { + opt(v4) + } + + signingTime := req.Time + if !req.LastSignedAt.IsZero() { + signingTime = req.LastSignedAt + } + + signedHeaders, err := v4.signWithBody(req.HTTPRequest, req.GetBody(), + name, region, req.ExpireTime, signingTime, + ) + if err != nil { + req.Error = err + req.SignedHeaderVals = nil + return + } + + req.SignedHeaderVals = signedHeaders + req.LastSignedAt = curTimeFn() +} + +const logSignInfoMsg = `DEBUG: Request Signature: +---[ CANONICAL STRING ]----------------------------- +%s +---[ STRING TO SIGN ]-------------------------------- +%s%s +-----------------------------------------------------` +const logSignedURLMsg = ` +---[ SIGNED URL ]------------------------------------ +%s` + +func (v4 *Signer) logSigningInfo(ctx *signingCtx) { + signedURLMsg := "" + if ctx.isPresign { + signedURLMsg = fmt.Sprintf(logSignedURLMsg, ctx.Request.URL.String()) + } + msg := fmt.Sprintf(logSignInfoMsg, ctx.canonicalString, ctx.stringToSign, signedURLMsg) + v4.Logger.Log(msg) +} + +func (ctx *signingCtx) build(disableHeaderHoisting bool) { + ctx.buildTime() // no depends + ctx.buildCredentialString() // no depends + + unsignedHeaders := ctx.Request.Header + if ctx.isPresign { + if !disableHeaderHoisting { + urlValues := url.Values{} + urlValues, unsignedHeaders = buildQuery(allowedQueryHoisting, unsignedHeaders) // no depends + for k := range urlValues { + ctx.Query[k] = urlValues[k] + } + } + } + + ctx.buildBodyDigest() + ctx.buildCanonicalHeaders(ignoredHeaders, unsignedHeaders) + ctx.buildCanonicalString() // depends on canon headers / signed headers + ctx.buildStringToSign() // depends on canon string + ctx.buildSignature() // depends on string to sign + + if ctx.isPresign { + ctx.Request.URL.RawQuery += "&X-Amz-Signature=" + ctx.signature + } else { + parts := []string{ + authHeaderPrefix + " Credential=" + ctx.credValues.AccessKeyID + "/" + ctx.credentialString, + "SignedHeaders=" + ctx.signedHeaders, + "Signature=" + ctx.signature, + } + ctx.Request.Header.Set("Authorization", strings.Join(parts, ", ")) + } +} + +func (ctx *signingCtx) buildTime() { + ctx.formattedTime = ctx.Time.UTC().Format(timeFormat) + ctx.formattedShortTime = ctx.Time.UTC().Format(shortTimeFormat) + + if ctx.isPresign { + duration := int64(ctx.ExpireTime / time.Second) + ctx.Query.Set("X-Amz-Date", ctx.formattedTime) + ctx.Query.Set("X-Amz-Expires", strconv.FormatInt(duration, 10)) + } else { + ctx.Request.Header.Set("X-Amz-Date", ctx.formattedTime) + } +} + +func (ctx *signingCtx) buildCredentialString() { + ctx.credentialString = strings.Join([]string{ + ctx.formattedShortTime, + ctx.Region, + ctx.ServiceName, + "aws4_request", + }, "/") + + if ctx.isPresign { + ctx.Query.Set("X-Amz-Credential", ctx.credValues.AccessKeyID+"/"+ctx.credentialString) + } +} + +func buildQuery(r rule, header http.Header) (url.Values, http.Header) { + query := url.Values{} + unsignedHeaders := http.Header{} + for k, h := range header { + if r.IsValid(k) { + query[k] = h + } else { + unsignedHeaders[k] = h + } + } + + return query, unsignedHeaders +} +func (ctx *signingCtx) buildCanonicalHeaders(r rule, header http.Header) { + var headers []string + headers = append(headers, "host") + for k, v := range header { + canonicalKey := http.CanonicalHeaderKey(k) + if !r.IsValid(canonicalKey) { + continue // ignored header + } + if ctx.SignedHeaderVals == nil { + ctx.SignedHeaderVals = make(http.Header) + } + + lowerCaseKey := strings.ToLower(k) + if _, ok := ctx.SignedHeaderVals[lowerCaseKey]; ok { + // include additional values + ctx.SignedHeaderVals[lowerCaseKey] = append(ctx.SignedHeaderVals[lowerCaseKey], v...) + continue + } + + headers = append(headers, lowerCaseKey) + ctx.SignedHeaderVals[lowerCaseKey] = v + } + sort.Strings(headers) + + ctx.signedHeaders = strings.Join(headers, ";") + + if ctx.isPresign { + ctx.Query.Set("X-Amz-SignedHeaders", ctx.signedHeaders) + } + + headerValues := make([]string, len(headers)) + for i, k := range headers { + if k == "host" { + headerValues[i] = "host:" + ctx.Request.URL.Host + } else { + headerValues[i] = k + ":" + + strings.Join(ctx.SignedHeaderVals[k], ",") + } + } + + ctx.canonicalHeaders = strings.Join(stripExcessSpaces(headerValues), "\n") +} + +func (ctx *signingCtx) buildCanonicalString() { + ctx.Request.URL.RawQuery = strings.Replace(ctx.Query.Encode(), "+", "%20", -1) + + uri := getURIPath(ctx.Request.URL) + + if !ctx.DisableURIPathEscaping { + uri = rest.EscapePath(uri, false) + } + + ctx.canonicalString = strings.Join([]string{ + ctx.Request.Method, + uri, + ctx.Request.URL.RawQuery, + ctx.canonicalHeaders + "\n", + ctx.signedHeaders, + ctx.bodyDigest, + }, "\n") +} + +func (ctx *signingCtx) buildStringToSign() { + ctx.stringToSign = strings.Join([]string{ + authHeaderPrefix, + ctx.formattedTime, + ctx.credentialString, + hex.EncodeToString(makeSha256([]byte(ctx.canonicalString))), + }, "\n") +} + +func (ctx *signingCtx) buildSignature() { + secret := ctx.credValues.SecretAccessKey + date := makeHmac([]byte("AWS4"+secret), []byte(ctx.formattedShortTime)) + region := makeHmac(date, []byte(ctx.Region)) + service := makeHmac(region, []byte(ctx.ServiceName)) + credentials := makeHmac(service, []byte("aws4_request")) + signature := makeHmac(credentials, []byte(ctx.stringToSign)) + ctx.signature = hex.EncodeToString(signature) +} + +func (ctx *signingCtx) buildBodyDigest() { + hash := ctx.Request.Header.Get("X-Amz-Content-Sha256") + if hash == "" { + if ctx.unsignedPayload || (ctx.isPresign && ctx.ServiceName == "s3") { + hash = "UNSIGNED-PAYLOAD" + } else if ctx.Body == nil { + hash = emptyStringSHA256 + } else { + hash = hex.EncodeToString(makeSha256Reader(ctx.Body)) + } + if ctx.unsignedPayload || ctx.ServiceName == "s3" || ctx.ServiceName == "glacier" { + ctx.Request.Header.Set("X-Amz-Content-Sha256", hash) + } + } + ctx.bodyDigest = hash +} + +// isRequestSigned returns if the request is currently signed or presigned +func (ctx *signingCtx) isRequestSigned() bool { + if ctx.isPresign && ctx.Query.Get("X-Amz-Signature") != "" { + return true + } + if ctx.Request.Header.Get("Authorization") != "" { + return true + } + + return false +} + +// unsign removes signing flags for both signed and presigned requests. +func (ctx *signingCtx) removePresign() { + ctx.Query.Del("X-Amz-Algorithm") + ctx.Query.Del("X-Amz-Signature") + ctx.Query.Del("X-Amz-Security-Token") + ctx.Query.Del("X-Amz-Date") + ctx.Query.Del("X-Amz-Expires") + ctx.Query.Del("X-Amz-Credential") + ctx.Query.Del("X-Amz-SignedHeaders") +} + +func makeHmac(key []byte, data []byte) []byte { + hash := hmac.New(sha256.New, key) + hash.Write(data) + return hash.Sum(nil) +} + +func makeSha256(data []byte) []byte { + hash := sha256.New() + hash.Write(data) + return hash.Sum(nil) +} + +func makeSha256Reader(reader io.ReadSeeker) []byte { + hash := sha256.New() + start, _ := reader.Seek(0, 1) + defer reader.Seek(start, 0) + + io.Copy(hash, reader) + return hash.Sum(nil) +} + +const doubleSpaces = " " + +var doubleSpaceBytes = []byte(doubleSpaces) + +func stripExcessSpaces(headerVals []string) []string { + vals := make([]string, len(headerVals)) + for i, str := range headerVals { + // Trim leading and trailing spaces + trimmed := strings.TrimSpace(str) + + idx := strings.Index(trimmed, doubleSpaces) + var buf []byte + for idx > -1 { + // Multiple adjacent spaces found + if buf == nil { + // first time create the buffer + buf = []byte(trimmed) + } + + stripToIdx := -1 + for j := idx + 1; j < len(buf); j++ { + if buf[j] != ' ' { + buf = append(buf[:idx+1], buf[j:]...) + stripToIdx = j + break + } + } + + if stripToIdx >= 0 { + idx = bytes.Index(buf[stripToIdx:], doubleSpaceBytes) + if idx >= 0 { + idx += stripToIdx + } + } else { + idx = -1 + } + } + + if buf != nil { + vals[i] = string(buf) + } else { + vals[i] = trimmed + } + } + return vals +} |