将字符串添加到文件缓冲区，用于 cURL smtp 发送电子邮件的消息正文

Question

我正在尝试修改有效的 cURL 电子邮件发送示例以添加邮件正文。 我不确定为什么我发现的所有带有附件的 curl 电子邮件示例都没有消息正文。

我需要发送带有 PDF 文件附件的短文本电子邮件。

这是我迄今为止尝试过的，未注释行，它编译并运行，但无法发送。我了解邮件正文应与主题分开一个“\r\n”（空白行），但这不是正确的方法。

//Create structure of email to be sent
    fileBuf = new char[ADD_SIZE + no_of_rows][CHARS];  //ADD_SIZE for TO,FROM,SUBJECT,CONTENT-TYPE,CONTENT-TRANSFER-
                                                       //ENCODING,CONETNT-DISPOSITION and \r\n
    strcpy(fileBuf[len++],"To: " TO "\r\n");
    buffer_size += strlen(fileBuf[len-1]);
    strcpy(fileBuf[len++],"From: " FROM "\r\n");
    buffer_size += strlen(fileBuf[len-1]);
    strcpy(fileBuf[len++],"Subject: SMTP TLS example message\r\n");
    buffer_size += strlen(fileBuf[len-1]);

    //strcpy(fileBuf[len++],"\r\n");
    //buffer_size += strlen(fileBuf[len-1]);
    //strcpy(fileBuf[len++],"Message goes here, hopefully...\r\n");
    //buffer_size += strlen(fileBuf[len-1]);

    strcpy(fileBuf[len++],"Content-Type: application/x-msdownload; name=\"" FILENAME "\"\r\n");
    buffer_size += strlen(fileBuf[len-1]);
    strcpy(fileBuf[len++],"Content-Transfer-Encoding: base64\r\n");
    buffer_size += strlen(fileBuf[len-1]);
    strcpy(fileBuf[len++],"Content-Disposition: attachment; filename=\"" FILENAME "\"\r\n");
    buffer_size += strlen(fileBuf[len-1]);
    strcpy(fileBuf[len++],"\r\n");
    buffer_size += strlen(fileBuf[len-1]);

完整的项目代码是here 参见解决方案7。

任何关于如何实现这一点的建议将不胜感激。

[edit] 使用非常简单的 cURL 进行测试，生成 0 字节附件：

#define FILENAME  "Rpt05162017.pdf"
static const char *payload_text[] = {
  "To: " TO "\r\n",
  "From: " FROM "(Example User)\r\n",
  //"Cc: " CC "(Another example User)\r\n",
  "Subject: SMTPS Example\r\n",
  "Date: 17-May-2017\r\n",
  "User-Agent: My eMail Client\r\n",
  "MIME-Version: 1.0\r\n",
  "Content-Type: multipart/mixed;\r\n",
   " boundary=\"------------030203080101020302070708\"\r\n",
  "\r\nThis is a multi-part message in MIME format.\r\n",
  "--------------030203080101020302070708\r\n",
  "Content-Type: text/plain; charset=utf-8; format=flowed\r\n",
  "Content-Transfer-Encoding: 7bit\r\n",
  "\r\n", // empty line to divide headers from body, see RFC5322
  "The body of the message starts here.\r\n",
  "\r\n",
  "It could be a lot of lines, could be MIME encoded, whatever.\r\n",
  "Check RFC5322.\r\n\r\n",
  "--------------030203080101020302070708\r\n",
  "Content-Type: application/x-msdownload; name=\"" FILENAME "\"\r\n",
  "Content-Transfer-Encoding: base64\r\n",
  "Content-Disposition: attachment; filename=\"" FILENAME "\"\r\n",
  "\r\n--------------030203080101020302070708--",
  NULL
};

Answer 1

不清楚你是如何发送所有这些东西的。您创建了二维字符串数组，并将 strcpy 放入每个标题中。它们都有填充字节，会损坏您的消息。

可以尝试简化吗？

std:string header =
"To: " TO "\r\n"
"From: " FROM "\r\n"
"Subject: SMTP TLS example message\r\n"
"Content-Type: application/x-msdownload; name=\"" FILENAME "\"\r\n"
"Content-Transfer-Encoding: base64\r\n"
"Content-Disposition: attachment; filename=\"" FILENAME "\"\r\n"
"\r\n";

然后只需发送您的消息header，然后发送您的消息的body。

---

使用您更新的payload_text，您收到 0 大小的附件并不奇怪，因为您发送的是空文件。发送 payload_text 后，您必须发送文件正文，然后在正文之后附加多部分结束后缀：

"\r\n--------------030203080101020302070708--"