如何使用libcurl和c语言通过电子邮件发送附件？

我正在使用curl库发送电子邮件。 我能够成功地发送电子邮件。在接收端，我能正确地看到物体、主体和身体。 现在我需要的是在电子邮件附件。 我是这样做的：

他们建议使用RFC5322。但在这一点上，我找不到像依恋这样的东西。 对吗？也欢迎使用libcurl+C语言的任何其他方式

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我想那个叫豪尔赫的人在2012年10月13日也问过同样的问题。但是答案不在那里。

我认为你是对的，但是你为什么附加了一个空文件？我想你需要在最后的附体公寓里放些东西

例如：

--XXXXboundary text 
Content-Type: text/plain;
Content-Disposition: attachment;
        filename="test.txt"

this is the attachment text ---- this is attachment content

--XXXXboundary text--

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也许你应该看看libquickmail（）。

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它完成了附加文件所需的所有功能，并使用libcurl进行SMTP传输（甚至在libquickmailllight中不使用libcurl）。

最简单的方法是使用base64编码之类的东西进行编码，它将二进制数据转换为可以通过电子邮件发送的ASCII字符。base64编码文件并插入字符串，如下所示。用正确的材料替换瓶盖中的所有东西

--XXXXboundary text
Content-Type: application/FILETYPE; name="FILENAME"
Content-Disposition: attachment; filename="FILENAME"
Content-Transfer-Encoding: base64
STRINGFROMBASE64ENCODING

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base64上有一个线程：

可以按如下方式执行

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: Mon, 29 Nov 2010 21:54:29 +1100\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: text/plain; charset=utf-8; format=flowed\r\n",
  "  name=\"send.c\"\r\n",
  "Content-Type: text/plain; charset=utf-8; format=flowed\r\n",
  "Content-Disposition: attachment;\r\n",
  "  filename=\"abc.txt\"\r\n",
  "\r\n",
  "bla bla file content is here\r\n",
  "--------------030203080101020302070708--\r\n",
  NULL
};

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电子邮件的标准分隔行是

“\r\n”

@pmg，请您解释一下。@Malay:您在RFC中指出：“一行是一系列字符，由回车符和换行符两个字符分隔”；我想我必须给出文件所在的路径，它将从那里获取文件。根据您的建议，它正在打印电子邮件中的“这是附件文本”。我请求关闭此帖子。谢谢。我会检查自己能做些什么。如果我能做到这一点，我会发布答案。

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: Mon, 29 Nov 2010 21:54:29 +1100\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: text/plain; charset=utf-8; format=flowed\r\n",
  "  name=\"send.c\"\r\n",
  "Content-Type: text/plain; charset=utf-8; format=flowed\r\n",
  "Content-Disposition: attachment;\r\n",
  "  filename=\"abc.txt\"\r\n",
  "\r\n",
  "bla bla file content is here\r\n",
  "--------------030203080101020302070708--\r\n",
  NULL
};