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fields.go
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fields.go
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package httpsign
import (
"fmt"
"github.com/dunglas/httpsfv"
"strings"
)
// Fields is a list of fields to be signed or verified. To initialize, use Headers or for more complex
// cases, NewFields followed by a chain of Add... methods.
//
// Several component types may be marked as optional. When signing a message, an optional component (e.g., header)
// is signed if it exists in the message to be signed, otherwise it is not included in the signature input.
// Upon verification, a field marked optional must be included in the signed components if it appears at all.
// This allows for intuitive handling of application components (headers, query parameters) whose presence in
// the message depends on application logic. Please do NOT use this functionality for headers that may legitimately be
// added by a proxy, such as X-Forwarded-For.
type Fields struct {
f []field
}
// The SFV representation of a field is name;flagName="flagValue"
// Note that this is a subset of SFV, we only support string-valued params, and only one param
// per field for now.
type field httpsfv.Item
func (f field) String() string {
i := httpsfv.Item(f)
s, err := httpsfv.Marshal(i)
if err == nil {
return s
}
return fmt.Sprintf("malformed field: %v", err)
}
func (f field) Equal(f2 field) bool {
n1, err1 := f.name()
n2, err2 := f2.name()
if err1 == nil && err2 == nil && n1 == n2 {
for _, p := range f.Params.Names() {
v1, _ := f.Params.Get(p)
v2, ok := f2.Params.Get(p)
if !ok || v1 != v2 {
return false
}
}
for _, p := range f2.Params.Names() {
v1, _ := f2.Params.Get(p)
v2, ok := f.Params.Get(p)
if !ok || v1 != v2 {
return false
}
}
return true
}
return false
}
// Headers is a simple way to generate a Fields list, where only simple header names and derived headers
// are needed.
func Headers(hs ...string) Fields {
fs := NewFields()
return *fs.AddHeaders(hs...)
}
// AddHeaders adds a list of simple or derived header names.
func (fs *Fields) AddHeaders(hs ...string) *Fields {
for _, h := range hs {
fs.f = append(fs.f, *fromHeaderName(h))
}
return fs
}
// NewFields returns an empty list of fields.
func NewFields() *Fields {
fs := Fields{}
return &fs
}
func (f field) name() (string, error) {
i := httpsfv.Item(f)
n, ok := i.Value.(string)
if !ok {
return "", fmt.Errorf("field has a non-string value")
}
return n, nil
}
func fromHeaderName(hdr string) *field {
h := strings.ToLower(hdr)
f := field(httpsfv.NewItem(h))
return &f
}
func (f field) headerName() (bool, string) {
_, ok1 := f.Params.Get("name")
_, ok2 := f.Params.Get("key")
if !ok1 && !ok2 {
s, ok := f.Value.(string)
if ok {
return true, s
} else {
return false, ""
}
}
return false, ""
}
// AddHeader appends a bare header name, e.g. "cache-control".
func (fs *Fields) AddHeader(hdr string) *Fields {
return fs.AddHeaderExt(hdr, false, false, false, false)
}
// AddHeaderExt appends a bare header name, e.g. "cache-control". See type documentation
// for details on optional parameters. The component can be marked as coming from an associated request.
func (fs *Fields) AddHeaderExt(hdr string, optional bool, binarySequence bool, associatedRequest bool, trailer bool) *Fields {
f := fromHeaderName(hdr)
f.markField(optional, associatedRequest, trailer)
if binarySequence {
f.markBinarySequence()
}
fs.f = append(fs.f, *f)
return fs
}
// AddHeaderOptional appends a bare header name, e.g. "cache-control". However, the header is not required to exist
// in the message. This is a convenience function and AddHeaderExt is more general.
func (fs *Fields) AddHeaderOptional(hdr string) *Fields {
return fs.AddHeaderExt(hdr, true, false, false, false)
}
func fromQueryParam(qp string) *field {
i := httpsfv.NewItem("@query-param")
i.Params.Add("name", QueryEscapeForSignature(qp))
f := field(i)
return &f
}
func (f field) queryParam() (bool, string) {
name, err := f.name()
if err == nil && name == "@query-param" {
v, ok := httpsfv.Item(f).Params.Get("name")
if ok {
s, ok := v.(string)
if ok {
return true, s
} else {
return false, ""
}
}
}
return false, ""
}
// AddQueryParam indicates a request for a specific query parameter to be signed.
func (fs *Fields) AddQueryParam(qp string) *Fields {
return fs.AddQueryParamExt(qp, false, false, false)
}
// AddQueryParamExt indicates a request for a specific query parameter to be signed. See type documentation
// for details on optional parameters. The component can be marked as coming from an associated request.
func (fs *Fields) AddQueryParamExt(qp string, optional, associatedRequest, trailer bool) *Fields {
f := fromQueryParam(qp)
f.markField(optional, associatedRequest, trailer)
fs.f = append(fs.f, *f)
return fs
}
func fromDictHeader(hdr, key string) *field {
h := strings.ToLower(hdr)
i := httpsfv.NewItem(h)
i.Params.Add("key", key)
f := field(i)
return &f
}
func (f field) dictHeader() (ok bool, hdr, key string) {
v, ok := f.Params.Get("key")
if ok {
s1, ok1 := f.Value.(string)
s2, ok2 := v.(string)
if ok1 && ok2 {
return true, s1, s2
} else {
return false, "", ""
}
}
return false, "", ""
}
// AddDictHeader indicates that out of a header structured as a dictionary, a specific key value is signed/verified.
func (fs *Fields) AddDictHeader(hdr, key string) *Fields {
return fs.AddDictHeaderExt(hdr, key, false, false, false)
}
// AddDictHeaderExt indicates that out of a header structured as a dictionary, a specific key value is signed/verified.
// See type documentation
// for details on optional parameters. The component can be marked as coming from an associated request.
func (fs *Fields) AddDictHeaderExt(hdr, key string, optional, associatedRequest, trailer bool) *Fields {
f := fromDictHeader(hdr, key)
f.markField(optional, associatedRequest, trailer)
fs.f = append(fs.f, *f)
return fs
}
func fromStructuredField(hdr string) *field {
h := strings.ToLower(hdr)
i := httpsfv.NewItem(h)
i.Params.Add("sf", true)
f := field(i)
return &f
}
func (f field) structuredField() bool {
v, ok := f.Params.Get("sf")
return ok && v.(bool)
}
func (f field) binarySequence() bool {
v, ok := f.Params.Get("bs")
return ok && v.(bool)
}
func (f field) trailer() bool {
v, ok := f.Params.Get("tr")
return ok && v.(bool)
}
func (f field) optional() bool {
v, ok := f.Params.Get("optional")
return ok && v.(bool)
}
func (f field) associatedRequest() bool {
v, ok := f.Params.Get("req")
return ok && v.(bool)
}
// AddStructuredField indicates that a header should be interpreted as a structured field, per RFC 8941.
func (fs *Fields) AddStructuredField(hdr string) *Fields {
return fs.AddStructuredFieldExt(hdr, false, false, false)
}
// AddStructuredFieldExt indicates that a header should be interpreted as a structured field, per RFC 8941.
// See type documentation
// for details on optional parameters. The component can be marked as coming from an associated request.
func (fs *Fields) AddStructuredFieldExt(hdr string, optional, associatedRequest, trailer bool) *Fields {
f := fromStructuredField(hdr)
f.markField(optional, associatedRequest, trailer)
fs.f = append(fs.f, *f)
return fs
}
func (f field) toItem() httpsfv.Item {
return httpsfv.Item(f)
}
func (f field) asSignatureBase() (string, error) {
s, err := httpsfv.Marshal(f.toItem())
return s, err
}
func (f field) markField(optional bool, associatedRequest bool, trailer bool) {
if optional {
f.markOptional()
}
if associatedRequest {
f.markAssociatedRequest()
}
if trailer {
f.markTrailer()
}
}
func (f field) markFlag(name string) {
if f.Params == nil {
f.Params = httpsfv.NewParams()
}
f.Params.Add(name, true)
}
func (f field) markOptional() {
f.markFlag("optional")
}
func (f field) markBinarySequence() {
f.markFlag("bs")
}
func (f field) markAssociatedRequest() {
f.markFlag("req")
}
func (f field) markTrailer() {
f.markFlag("tr")
}
func (f field) unmarkOptional() {
if f.Params == nil {
f.Params = httpsfv.NewParams()
}
f.Params.Del("optional")
}
// Not a full deep copy, but good enough for mutating params
func (f field) copy() field {
ff := field{
Value: f.Value,
}
if f.Params == nil {
ff.Params = nil
} else {
ff.Params = httpsfv.NewParams()
for _, n := range f.Params.Names() {
v, _ := f.Params.Get(n)
ff.Params.Add(n, v)
}
}
return ff
}
func (fs *Fields) asSignatureInput(p *httpsfv.Params) (string, error) {
il := httpsfv.InnerList{
Items: []httpsfv.Item{},
Params: httpsfv.NewParams(),
}
for _, f := range fs.f {
il.Items = append(il.Items, f.toItem())
}
il.Params = p
s, err := httpsfv.Marshal(il)
return s, err
}
// contains verifies that all required fields are in the given list of fields (yes, this is O(n^2)).
func (fs *Fields) contains(requiredFields *Fields) bool {
outer:
for _, f1 := range requiredFields.f {
for _, f2 := range fs.f {
if f1.Equal(f2) {
continue outer
}
}
return false
}
return true
}
// TODO: should only compare the header name, Equal() would fail if there are params
func (fs *Fields) hasHeader(name string) bool {
h := *fromHeaderName(name)
for _, f := range fs.f {
if f.Equal(h) {
return true
}
}
return false
}
func (fs *Fields) hasTrailerFields(forAssocRequest bool) bool {
for _, f := range fs.f {
_, tr := f.Params.Get("tr")
_, req := f.Params.Get("req")
if tr && (req && forAssocRequest) {
return true
}
if tr && (!req && !forAssocRequest) {
return true
}
}
return false
}