ac8a49c114
* Reduce complexity of SignatureCollector.Accept * Add stylecheck linter, and lint accordingly * Rephrase some comments * godot - Top level comments should end with a dot. * nestif - Reduce nested complexity of code * Review changes Co-authored-by: Aron Wussler <aron@wussler.it>
116 lines
2.8 KiB
Go
116 lines
2.8 KiB
Go
package crypto
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import (
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"bytes"
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"io"
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"io/ioutil"
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"mime"
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"net/textproto"
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gomime "github.com/ProtonMail/go-mime"
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"golang.org/x/crypto/openpgp"
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"golang.org/x/crypto/openpgp/packet"
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)
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// SignatureCollector structure.
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type SignatureCollector struct {
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config *packet.Config
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keyring openpgp.KeyRing
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target gomime.VisitAcceptor
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signature string
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verified error
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}
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func newSignatureCollector(
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targetAcceptor gomime.VisitAcceptor, keyring openpgp.KeyRing, config *packet.Config,
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) *SignatureCollector {
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return &SignatureCollector{
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target: targetAcceptor,
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config: config,
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keyring: keyring,
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}
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}
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// Accept collects the signature.
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func (sc *SignatureCollector) Accept(
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part io.Reader, header textproto.MIMEHeader,
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hasPlainSibling, isFirst, isLast bool,
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) (err error) {
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parentMediaType, params, _ := mime.ParseMediaType(header.Get("Content-Type"))
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if parentMediaType != "multipart/signed" {
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return sc.target.Accept(part, header, hasPlainSibling, isFirst, isLast)
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}
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newPart, rawBody := gomime.GetRawMimePart(part, "--"+params["boundary"])
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multiparts, multipartHeaders, err := gomime.GetMultipartParts(newPart, params)
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if err != nil {
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return
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}
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hasPlainChild := false
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for _, header := range multipartHeaders {
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mediaType, _, _ := mime.ParseMediaType(header.Get("Content-Type"))
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hasPlainChild = (mediaType == "text/plain")
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}
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if len(multiparts) != 2 {
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sc.verified = newSignatureNotSigned()
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// Invalid multipart/signed format just pass along
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if _, err = ioutil.ReadAll(rawBody); err != nil {
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return err
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}
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for i, p := range multiparts {
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if err = sc.target.Accept(p, multipartHeaders[i], hasPlainChild, true, true); err != nil {
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return
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}
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}
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return
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}
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// actual multipart/signed format
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err = sc.target.Accept(multiparts[0], multipartHeaders[0], hasPlainChild, true, true)
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if err != nil {
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return err
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}
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partData, err := ioutil.ReadAll(multiparts[1])
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if err != nil {
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return err
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}
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decodedPart := gomime.DecodeContentEncoding(
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bytes.NewReader(partData),
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multipartHeaders[1].Get("Content-Transfer-Encoding"))
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buffer, err := ioutil.ReadAll(decodedPart)
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if err != nil {
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return err
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}
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mediaType, _, _ := mime.ParseMediaType(header.Get("Content-Type"))
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buffer, err = gomime.DecodeCharset(buffer, mediaType, params)
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if err != nil {
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return err
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}
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sc.signature = string(buffer)
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str, _ := ioutil.ReadAll(rawBody)
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rawBody = bytes.NewReader(str)
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if sc.keyring != nil {
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_, err = openpgp.CheckArmoredDetachedSignature(sc.keyring, rawBody, bytes.NewReader(buffer), sc.config)
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if err != nil {
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sc.verified = newSignatureFailed()
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} else {
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sc.verified = nil
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}
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} else {
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sc.verified = newSignatureNoVerifier()
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}
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return err
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}
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// GetSignature collected by Accept.
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func (sc SignatureCollector) GetSignature() string {
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return sc.signature
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}
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