c++ - libcurl SMTP 读取函数返回有趣的值段错误 C++

Question

我正在尝试使用 libcurl SMTP，并且在此示例中一切正常: http://curl.haxx.se/libcurl/c/smtp-mail.html

#include <stdio.h>
#include <string.h>
#include <curl/curl.h>

/* This is a simple example showing how to send mail using libcurl's SMTP
 * capabilities. For an exmaple of using the multi interface please see
 * smtp-multi.c.
 *
 * Note that this example requires libcurl 7.20.0 or above.
 */ 

#define FROM    "<sender@example.org>"
#define TO      "<addressee@example.net>"
#define CC      "<info@example.org>"

static const char *payload_text[] = {
  "Date: Mon, 29 Nov 2010 21:54:29 +1100\r\n",
  "To: " TO "\r\n",
  "From: " FROM "(Example User)\r\n",
  "Cc: " CC "(Another example User)\r\n",
  "Message-ID: <dcd7cb36-11db-487a-9f3a-e652a9458efd@rfcpedant.example.org>\r\n",
  "Subject: SMTP example message\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",
  NULL
};

struct upload_status {
  int lines_read;
};

static size_t payload_source(void *ptr, size_t size, size_t nmemb, void *userp)
{
  struct upload_status *upload_ctx = (struct upload_status *)userp;
  const char *data;

  if((size == 0) || (nmemb == 0) || ((size*nmemb) < 1)) {
    return 0;
  }

  data = payload_text[upload_ctx->lines_read];

  if(data) {
    size_t len = strlen(data);
    memcpy(ptr, data, len);
    upload_ctx->lines_read++;

    return len;
  }

  return 0;
}

int main(void)
{
  CURL *curl;
  CURLcode res = CURLE_OK;
  struct curl_slist *recipients = NULL;
  struct upload_status upload_ctx;

  upload_ctx.lines_read = 0;

  curl = curl_easy_init();
  if(curl) {
    /* This is the URL for your mailserver */ 
    curl_easy_setopt(curl, CURLOPT_URL, "smtp://mail.example.com");

    /* Note that this option isn't strictly required, omitting it will result in
     * libcurl sending the MAIL FROM command with empty sender data. All
     * autoresponses should have an empty reverse-path, and should be directed
     * to the address in the reverse-path which triggered them. Otherwise, they
     * could cause an endless loop. See RFC 5321 Section 4.5.5 for more details.
     */ 
    curl_easy_setopt(curl, CURLOPT_MAIL_FROM, FROM);

    /* Add two recipients, in this particular case they correspond to the
     * To: and Cc: addressees in the header, but they could be any kind of
     * recipient. */ 
    recipients = curl_slist_append(recipients, TO);
    recipients = curl_slist_append(recipients, CC);
    curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);

    /* We're using a callback function to specify the payload (the headers and
     * body of the message). You could just use the CURLOPT_READDATA option to
     * specify a FILE pointer to read from. */ 
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_source);
    curl_easy_setopt(curl, CURLOPT_READDATA, &upload_ctx);
    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);

    /* Send the message */ 
    res = curl_easy_perform(curl);

    /* Check for errors */ 
    if(res != CURLE_OK)
      fprintf(stderr, "curl_easy_perform() failed: %s\n",
              curl_easy_strerror(res));

    /* Free the list of recipients */ 
    curl_slist_free_all(recipients);

    /* curl won't send the QUIT command until you call cleanup, so you should be
     * able to re-use this connection for additional messages (setting
     * CURLOPT_MAIL_FROM and CURLOPT_MAIL_RCPT as required, and calling
     * curl_easy_perform() again. It may not be a good idea to keep the
     * connection open for a very long time though (more than a few minutes may
     * result in the server timing out the connection), and you do want to clean
     * up in the end.
     */ 
    curl_easy_cleanup(curl);
  }

  return (int)res;
}

但是如果我大幅增加有效负载函数，则会收到错误:

读取函数返回有趣的值段错误

我该如何解决这个问题？

Answer 1

The following code is to send a plain text message
rather than a email message.  but the basic ideas are the same.

did you set the curl write function option to point to a callback function?  

curl_easy_setopt(curlHandle, CURLOPT_WRITEFUNCTION, &CurlWriteFunction);

//////////////////
where the CurlWriteFunction()  would look similar to the following:
//////////////////

size_t CurlWriteFunction(void *ptr, size_t size, size_t nmemb, void *stream)
{
    memset(CurlMsgStr, 0, MAX_MSG_STR);
    phpCurlError = FALSE;

    if(((char *)ptr)[0] == '1' || ((char *)ptr)[1] == '1')
    {
        phpCurlError = FALSE;
        sprintf(CurlMsgStr,"Record sent to URL OK...[%c%c]\n",
        ((char *)ptr)[0],((char *)ptr)[1]);
    }
    else if(((char *)ptr)[0] == '0' || ((char *)ptr)[1] == '0')
    {
        phpCurlError = TRUE;
        sprintf(CurlMsgStr,"Record sent to URL FAILED...[%c%c]\n",
        ((char *)ptr)[0],((char *)ptr)[1]);
    }
    else
    {
        phpCurlError = TRUE;
        sprintf(CurlMsgStr,"UNKNOWN URL RETURN VALUE...[%c%c]\n",
        ((char *)ptr)[0],((char *)ptr)[1]);
    }

    return (nmemb);
} // CurlWriteFunction()

////////////////////
Then send the curl message with something like this:
////////////////////

void sendViaCurl(char *str)
{
#if 0 // eliminate heap thrashing of 8k malloc/free
    char* postData = NULL;
#else
    static  char* postData = NULL;
#endif

    CURLcode curlErr;
    long  curlRespCode = 0;
    char recNameStr[MAX_STRING_LENGTH];



    if(curlHandle)
    {
        // Specify the POST data
        if(postData == NULL) // then first time through
        {
            postData = malloc(MAX_RESPONSE_LENGTH * 2);
        }

        memset(postData,0,MAX_RESPONSE_LENGTH * 2);
        sprintf(postData, "%s", str);


        curl_easy_setopt(curlHandle, CURLOPT_POSTFIELDS, postData);


        // Execute the POST, response goes to STDOUT
        curlErr = curl_easy_perform(curlHandle);

        // Report any CURL errors
        if(curlErr)
        {
            log_error("CURL ERROR -- %s\n", curl_easy_strerror(curlErr));
        }


        // Get info on the POST data transfer to URL
        curl_easy_getinfo(curlHandle, CURLINFO_RESPONSE_CODE, &curlRespCode);
        // log_error( "CURL RESPONSE CODE -- %ld\n", curlRespCode);

        if(phpCurlError)
        {
            log_error( " %s rec rejected by DB -- %s\n", recNameStr, str);
            curlRecRejected = TRUE;
        }
        else
        {
            log_error( "%s [%s] rec accepted by DB...\n",recNameStr, str);
            curlRecRejected = FALSE;
        }
    }
    else
    {
        log_error( "NOT ABLE TO GET CURL HANDLE...RECORD NOT SENT\n");
        curlRecRejected = TRUE;
    }

#if 0 // eliminate thrashing of heap with 8k malloc/free
    if(postData)
    {
        free(postData);
        postData = NULL;
    }
#endif



    return;

} // sendViaCurl()