private string GenerateBody()
{
if (string.IsNullOrEmpty(this.Body))
{
throw new InvalidOperationException("message.Body is empty");
}
//编码完成
var body = Convert.ToBase64String(this.encoding.GetBytes(this.Body));
var sb = new StringBuilder();
//begin
sb.Append("--");
sb.Append(this.boundary);
sb.Append(MailCommon.NewLine); //分隔完成
if (this.IsBodyHtml == true)
{
sb.Append("Content-Type: text/html; charset=" + this.encoding.HeaderName);
}
else
{
sb.Append("Content-Type: text/plain; charset=" + this.encoding.HeaderName);
}
sb.Append(MailCommon.NewLine);
sb.Append("Content-Transfer-Encoding: base64");
sb.Append(MailCommon.NewLine);
sb.Append(MailCommon.NewLine);
sb.Append(MailCommon.Line76Break(body));
sb.Append(MailCommon.NewLine);
sb.Append(MailCommon.NewLine);
//end
// "--" + this.Boundary + "--" + MailCommon.NewLine;
sb.Append("--");
sb.Append(this.Boundary);
sb.Append("--");
sb.Append(MailCommon.NewLine);
return(sb.ToString());
}
/// <summary>
/// DKIM message
/// </summary>
/// <param name="message"></param>
/// <returns></returns>
public string Sign(MailMessage message)
{
//http://dkimcore.org/specification.html#1
//DKIM-Signature: v=1;a=rsa-sha256;bh=BODYHASH;c=relaxed;d=TOKEN;h=HEADERS;s=SELECTOR;b=SIGNATURE
//http://www.dkim.org/specs/rfc4871-dkimbase.html#dkim-sig-hdr
/*
* DKIM-Signature: v=1; a=rsa-sha256; c=simple/relaxed; d=domain.com;
* h=From:To:Subject:Date; q=dns/txt; s=newsletter17100; t=1510020630;
* bh=+5tUEqyyuolGsLc9usglUSkelpZtxEkEWKaGC21PSEM=;
* b=
*/
var dsLength = "DKIM-Signature: ".Length;
var build = new StringBuilder(128);
build.Append("DKIM-Signature:");
build.Append(" v=1;");
//
string algorithm = this.algorithm == DKIMAlgorithm.RSASha1 ? "rsa-sha1" : "rsa-sha256";
build.Append(" a=").Append(algorithm).Append(';');
//c=header type / bodey type;
string htype = this.headerType == DKIMType.Simple ? "simple" : "relaxed";
string bType = this.bodyType == DKIMType.Simple ? "simple" : "relaxed";
//build.Append(" c=simple/relaxed;");
build.Append(" c=").Append(htype).Append('/').Append(bType).Append(';').Append(MailCommon.NewLine);
//create time
long unixtime = Adf.UnixTimestampHelper.ToInt64Timestamp();
build.Append("\tt=").Append(unixtime).Append(';');
build.Append(" q=dns/txt;").Append(MailCommon.NewLine);
// domain
build.Append("\td=").Append(domain).Append(';');
// DNS selector
build.Append(" s=").Append(selector).Append(';').Append(MailCommon.NewLine);
//headers
build.Append("\th=").Append(string.Join(":", this.signHeaders)).Append(';').Append(MailCommon.NewLine);
//body hash
var body = "";
if (this.bodyType == DKIMType.Relaxed)
{
body = this.RelaxedBodyCanonicalization(message.GetBody());
}
else
{
body = this.SimpleBodyCanonicalization(message.GetBody());
}
var bodyBytes = message.Encoding.GetBytes(body);
var bodySigned = this.Hash(bodyBytes);
var bodyHash = Convert.ToBase64String(bodySigned);
build.Append("\tbh=").Append(bodyHash).Append(';').Append(MailCommon.NewLine);
//b
build.Append("\tb=");
//build string
/*
* DKIM-Signature: v=1; a=rsa-sha256; c=simple/relaxed; d=caping.co.id;
* s=newsletter17800; q=dns/txt; t=1510023325; h=From:To:Subject:Date;
* h=yklAmb1CNh0SAfmrk97PlZTEHrGKV94Ps6R7KDwLLoo=;
* b=
*/
//set current DKIM-Signature
var dkimHead = build.ToString(dsLength, build.Length - dsLength);
message.OutputHeaders["DKIM-Signature"] = dkimHead;
var headers = "";
if (this.headerType == DKIMType.Relaxed)
{
headers = this.RelaxedHeaderCanonicalization(message.OutputHeaders);
}
else
{
headers = this.SimpleHeaderCanonicalization(message.OutputHeaders);
}
var headerBytes = message.Encoding.GetBytes(headers);
var headerSigned = this.Sign(headerBytes);
// assumes signature ends with "b="
var b = Convert.ToBase64String(headerSigned);
b = MailCommon.Line76Break("b=" + b, "\t");
//remove last b
build.Length -= "\tb=".Length;
//append b
build.Append(b);
//update DKIM-Signature
dkimHead = build.ToString(dsLength, build.Length - dsLength);
message.OutputHeaders["DKIM-Signature"] = dkimHead;
var signed = build.ToString();
return(signed);
}