Implement client library

Signed-off-by: Knut Ahlers <knut@ahlers.me>

pkg/client/client.go

@@ -0,0 +1,199 @@
+// Package client implements a client library for OTS supporting the
+// OTSMeta content format for file upload support
+package client
+
+import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"crypto/sha512"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/Luzifer/go-openssl/v4"
+)
+
+// HTTPClient defines the client to use for create and fetch requests
+// and can be overwritten to provide authentication
+var HTTPClient = http.DefaultClient
+
+// KeyDerivationFunc defines the key derivation algorithm used in OTS
+// to derive the key / iv from the password for encryption. You only
+// should change this if you are running an OTS instance with modified
+// parameters.
+//
+// The corresponding settings are found in `/src/crypto.js` in the OTS
+// source code.
+var KeyDerivationFunc = openssl.NewPBKDF2Generator(sha512.New, 300000)
+
+// PasswordLength defines the length of the generated encryption password
+var PasswordLength = 20
+
+// RequestTimeout defines how long the request to the OTS instance for
+// create and fetch may take
+var RequestTimeout = 5 * time.Second
+
+// UserAgent defines the user-agent to send when interacting with an
+// OTS instance. When using this library please set this to something
+// the operator of the instance can determine your client from and
+// provide an URL to useful information about your tool.
+var UserAgent = "ots-client/1.x +https://github.com/Luzifer/ots"
+
+// Create serializes the secret and creates a new secret on the
+// instance given by its URL.
+//
+// The given URL should point to the frontend of the instance. Do not
+// include the API paths, they are added automatically. For the
+// expireIn parameter zero value can be used to use server-default.
+//
+// So for OTS.fyi you'd use `New("https://ots.fyi/")`
+func Create(instanceURL string, secret Secret, expireIn time.Duration) (string, time.Time, error) {
+	u, err := url.Parse(instanceURL)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("parsing instance URL: %w", err)
+	}
+
+	pass, err := genPass()
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("generating password: %w", err)
+	}
+
+	data, err := secret.serialize(pass)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("serializing data: %w", err)
+	}
+
+	body := new(bytes.Buffer)
+	if err = json.NewEncoder(body).Encode(struct {
+		Secret string `json:"secret"`
+	}{Secret: string(data)}); err != nil {
+		return "", time.Time{}, fmt.Errorf("encoding request payload: %w", err)
+	}
+
+	createURL := u.JoinPath(strings.Join([]string{".", "api", "create"}, "/"))
+	ctx, cancel := context.WithTimeout(context.Background(), RequestTimeout)
+	defer cancel()
+
+	if expireIn > time.Second {
+		createURL.RawQuery = url.Values{
+			"expire": []string{strconv.Itoa(int(expireIn / time.Second))},
+		}.Encode()
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, createURL.String(), body)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("creating request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", UserAgent)
+
+	resp, err := HTTPClient.Do(req)
+	if err != nil {
+		return "", time.Time{}, fmt.Errorf("executing request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusCreated {
+		respBody, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return "", time.Time{}, fmt.Errorf("unexpected HTTP status %d", resp.StatusCode)
+		}
+		return "", time.Time{}, fmt.Errorf("unexpected HTTP status %d (%s)", resp.StatusCode, respBody)
+	}
+
+	var payload struct {
+		ExpiresAt time.Time `json:"expires_at"`
+		SecretID  string    `json:"secret_id"`
+		Success   bool      `json:"success"`
+	}
+
+	if err = json.NewDecoder(resp.Body).Decode(&payload); err != nil {
+		return "", time.Time{}, fmt.Errorf("decoding response: %w", err)
+	}
+
+	u.Fragment = strings.Join([]string{payload.SecretID, pass}, "|")
+
+	return u.String(), payload.ExpiresAt, nil
+}
+
+// Fetch retrieves a secret by its given URL. The URL given must
+// include the fragment (part after the `#`) with the secret ID and
+// the encryption passphrase.
+//
+// The object returned will always be an OTSMeta object even in case
+// the secret is a plain secret without attachments.
+func Fetch(secretURL string) (s Secret, err error) {
+	u, err := url.Parse(secretURL)
+	if err != nil {
+		return s, fmt.Errorf("parsing secret URL: %w", err)
+	}
+
+	fragment, err := url.QueryUnescape(u.Fragment)
+	if err != nil {
+		return s, fmt.Errorf("unescaping fragment: %w", err)
+	}
+	fragmentParts := strings.SplitN(fragment, "|", 2) //nolint:gomnd
+
+	fetchURL := u.JoinPath(strings.Join([]string{".", "api", "get", fragmentParts[0]}, "/")).String()
+	ctx, cancel := context.WithTimeout(context.Background(), RequestTimeout)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, fetchURL, nil)
+	if err != nil {
+		return s, fmt.Errorf("creating request: %w", err)
+	}
+	req.Header.Set("User-Agent", UserAgent)
+
+	resp, err := HTTPClient.Do(req)
+	if err != nil {
+		return s, fmt.Errorf("executing request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return s, fmt.Errorf("unexpected HTTP status %d", resp.StatusCode)
+	}
+
+	var payload struct {
+		Secret string `json:"secret"`
+	}
+
+	if err = json.NewDecoder(resp.Body).Decode(&payload); err != nil {
+		return s, fmt.Errorf("decoding response body: %w", err)
+	}
+
+	if err = s.read([]byte(payload.Secret), fragmentParts[1]); err != nil {
+		return s, fmt.Errorf("decoding secret: %w", err)
+	}
+
+	return s, nil
+}
+
+func genPass() (string, error) {
+	var (
+		charSet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+		pass    = make([]byte, PasswordLength)
+
+		n   int
+		err error
+	)
+
+	for n < PasswordLength {
+		n, err = rand.Read(pass)
+		if err != nil {
+			return "", fmt.Errorf("reading random data: %w", err)
+		}
+	}
+
+	for i := 0; i < PasswordLength; i++ {
+		pass[i] = charSet[int(pass[i])%len(charSet)]
+	}
+
+	return string(pass), nil
+}

pkg/client/client_test.go

@@ -0,0 +1,38 @@
+package client
+
+import (
+	"regexp"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGeneratePassword(t *testing.T) {
+	pass, err := genPass()
+	require.NoError(t, err)
+
+	assert.Len(t, pass, PasswordLength)
+	assert.Regexp(t, regexp.MustCompile(`^[0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ]+$`), pass)
+}
+
+func TestIntegration(t *testing.T) {
+	s := Secret{
+		Secret: "I'm a secret!",
+		Attachments: []SecretAttachment{{
+			Name:    "secret.txt",
+			Type:    "text/plain",
+			Content: []byte("I'm a very secret file.\n"),
+		}},
+	}
+
+	secretURL, _, err := Create("https://ots.fyi/", s, time.Minute)
+	require.NoError(t, err)
+	assert.Regexp(t, regexp.MustCompile(`^https://ots.fyi/#[0-9a-f-]+%7C[0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ]+$`), secretURL)
+
+	apiSecret, err := Fetch(secretURL)
+	require.NoError(t, err)
+
+	assert.Equal(t, s, apiSecret)
+}

pkg/client/go.mod

@@ -0,0 +1,15 @@
+module github.com/Luzifer/ots/pkg/client
+
+go 1.21.1
+
+require (
+	github.com/Luzifer/go-openssl/v4 v4.2.1
+	github.com/stretchr/testify v1.8.4
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	golang.org/x/crypto v0.12.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

pkg/client/go.sum

@@ -0,0 +1,14 @@
+github.com/Luzifer/go-openssl/v4 v4.2.1 h1:0+/gaQ5TcBhGmVqGrfyA21eujlbbaNwj0VlOA3nh4ts=
+github.com/Luzifer/go-openssl/v4 v4.2.1/go.mod h1:CZZZWY0buCtkxrkqDPQYigC4Kn55UuO97TEoV+hwz2s=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+golang.org/x/crypto v0.12.0 h1:tFM/ta59kqch6LlvYnPa0yx5a83cL2nHflFhYKvv9Yk=
+golang.org/x/crypto v0.12.0/go.mod h1:NF0Gs7EO5K4qLn+Ylc+fih8BSTeIjAP05siRnAh98yw=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

pkg/client/otsMeta.go

@@ -0,0 +1,92 @@
+package client
+
+import (
+	"bytes"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+
+	"github.com/Luzifer/go-openssl/v4"
+)
+
+var metaMarker = []byte("OTSMeta")
+
+type (
+	// Secret represents a secret parsed from / prepared for
+	// serialization to the OTS API
+	Secret struct {
+		Secret      string             `json:"secret"`
+		Attachments []SecretAttachment `json:"attachments,omitempty"`
+	}
+
+	// SecretAttachment represents a file attached to a Secret. The Data
+	// property must be the plain content (binary / text / ...) of the
+	// file to attach. The base64 en-/decoding is done transparently.
+	// The Name is the name of the file shown to the user (so ideally
+	// should be the file-name on the source system). The Type should
+	// contain the mime time of the file or an empty string.
+	SecretAttachment struct {
+		Name    string `json:"name"`
+		Type    string `json:"type"`
+		Data    string `json:"data"`
+		Content []byte `json:"-"`
+	}
+)
+
+func (o *Secret) read(data []byte, passphrase string) (err error) {
+	if passphrase != "" {
+		if data, err = openssl.New().DecryptBytes(passphrase, data, KeyDerivationFunc); err != nil {
+			return fmt.Errorf("decrypting data: %w", err)
+		}
+	}
+
+	if !bytes.HasPrefix(data, []byte(metaMarker)) {
+		// We have a simple secret, makes less effort for us
+		o.Secret = string(data)
+		return nil
+	}
+
+	if err = json.Unmarshal(data[len(metaMarker):], o); err != nil {
+		return fmt.Errorf("decoding JSON payload: %w", err)
+	}
+
+	for i := range o.Attachments {
+		o.Attachments[i].Content, err = base64.StdEncoding.DecodeString(o.Attachments[i].Data)
+		if err != nil {
+			return fmt.Errorf("decoding attachment %d: %w", i, err)
+		}
+	}
+
+	return nil
+}
+
+func (o Secret) serialize(passphrase string) ([]byte, error) {
+	var data []byte
+
+	if len(o.Attachments) == 0 {
+		// No attachments? No problem, we create a classic simple secret
+		data = []byte(o.Secret)
+	} else {
+		for i := range o.Attachments {
+			o.Attachments[i].Data = base64.StdEncoding.EncodeToString(o.Attachments[i].Content)
+		}
+
+		j, err := json.Marshal(o)
+		if err != nil {
+			return nil, fmt.Errorf("encoding JSON payload: %w", err)
+		}
+
+		data = append(metaMarker, j...)
+	}
+
+	if passphrase == "" {
+		// No encryption requested
+		return data, nil
+	}
+
+	out, err := openssl.New().EncryptBytes(passphrase, data, KeyDerivationFunc)
+	if err != nil {
+		return nil, fmt.Errorf("encrypting data: %w", err)
+	}
+	return out, nil
+}