doc: add ExampleMessage_Verify

Author: jvatic

message_test.go

@@ -0,0 +1,48 @@
+package httpsign_test
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/yaronf/httpsign"
+)
+
+func ExampleMessage_Verify() {
+	config := httpsign.NewVerifyConfig().SetKeyID("my-shared-secret").SetVerifyCreated(false) // for testing only
+	verifier, _ := httpsign.NewHMACSHA256Verifier(bytes.Repeat([]byte{0x77}, 64), config,
+		httpsign.Headers("@authority", "Date", "@method"))
+	reqStr := `GET /foo HTTP/1.1
+Host: example.org
+Date: Tue, 20 Apr 2021 02:07:55 GMT
+Cache-Control: max-age=60
+Signature-Input: sig77=("@authority" "date" "@method");alg="hmac-sha256";keyid="my-shared-secret"
+Signature:       sig77=:3e9KqLP62NHfHY5OMG4036+U6tvBowZF35ALzTjpsf0=:
+
+`
+	req, _ := http.ReadRequest(bufio.NewReader(strings.NewReader(reqStr)))
+
+	// Using WithRequest
+	msgWithRequest, _ := httpsign.NewMessage(httpsign.NewMessageConfig().WithRequest(req))
+	_, err1 := msgWithRequest.Verify("sig77", *verifier)
+
+	// Using constituent parts
+	msgWithConstituents, _ := httpsign.NewMessage(httpsign.NewMessageConfig().
+		WithMethod(req.Method).
+		WithURL(req.URL).
+		WithHeaders(req.Header).
+		WithTrailers(req.Trailer).
+		WithBody(&req.Body).
+		WithAuthority(req.Host).
+		WithScheme(req.URL.Scheme))
+
+	_, err2 := msgWithConstituents.Verify("sig77", *verifier)
+
+	fmt.Printf("WithRequest: %t\n", err1 == nil)
+	fmt.Printf("Constituents: %t", err2 == nil)
+	// Output:
+	// WithRequest: true
+	// Constituents: true
+}