cURL开源库中的发送邮件示例代码（smtp-multi.c）

/*************************************************************************** *                                  _   _ ____  _ *  Project                     ___| | | |  _ \| | *                             / __| | | | |_) | | *                            | (__| |_| |  _ <| |___ *                             \___|\___/|_| \_\_____| * * Copyright (C) 1998 - 2011, Daniel Stenberg, <[e-mail]>, et al. * * This software is licensed as described in the file COPYING, which * you should have received as part of this distribution. The terms * are also available at http://curl.haxx.se/docs/copyright.html. * * You may opt to use, copy, modify, merge, publish, distribute and/or sell * copies of the Software, and permit persons to whom the Software is * furnished to do so, under the terms of the COPYING file. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * ***************************************************************************//* This is an example application source code sending SMTP mail using the * multi interface. */#include <string.h>#include <curl/curl.h>/* * This is the list of basic details you need to tweak to get things right. */#define USERNAME "[e-mail]"#define PASSWORD "123qwerty"#define SMTPSERVER "smtp.example.com"#define SMTPPORT ":587" /* it is a colon+port string, but you can set it                           to "" to use the default port */#define RECIPIENT "<[e-mail]>"#define MAILFROM "<[e-mail]>"#define MULTI_PERFORM_HANG_TIMEOUT 60 * 1000/* Note that you should include the actual meta data headers here as well if   you want the mail to have a Subject, another From:, show a To: or whatever   you think your mail should feature! */static const char *text[]={  "one\n",  "two\n",  "three\n",  " Hello, this is CURL email SMTP\n",  NULL};struct WriteThis {  int counter;};static size_t read_callback(void *ptr, size_t size, size_t nmemb, void *userp){  struct WriteThis *pooh = (struct WriteThis *)userp;  const char *data;  if(size*nmemb < 1)    return 0;  data = text[pooh->counter];  if(data) {    size_t len = strlen(data);    memcpy(ptr, data, len);    pooh->counter++; /* advance pointer */    return len;  }  return 0;                         /* no more data left to deliver */}static struct timeval tvnow(void){  /*  ** time() returns the value of time in seconds since the Epoch.  */  struct timeval now;  now.tv_sec = (long)time(NULL);  now.tv_usec = 0;  return now;}static long tvdiff(struct timeval newer, struct timeval older){  return (newer.tv_sec-older.tv_sec)*1000+    (newer.tv_usec-older.tv_usec)/1000;}int main(void){   CURL *curl;   CURLM *mcurl;   int still_running = 1;   struct timeval mp_start;   char mp_timedout = 0;   struct WriteThis pooh;   struct curl_slist* rcpt_list = NULL;   pooh.counter = 0;   curl_global_init(CURL_GLOBAL_DEFAULT);   curl = curl_easy_init();   if(!curl)     return 1;   mcurl = curl_multi_init();   if(!mcurl)     return 2;   rcpt_list = curl_slist_append(rcpt_list, RECIPIENT);   /* more addresses can be added here      rcpt_list = curl_slist_append(rcpt_list, "<[e-mail]>");   */   curl_easy_setopt(curl, CURLOPT_URL, "smtp://" SMTPSERVER SMTPPORT); // 此处的要带上smtp端口   curl_easy_setopt(curl, CURLOPT_USERNAME, USERNAME);   curl_easy_setopt(curl, CURLOPT_PASSWORD, PASSWORD);   curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);   curl_easy_setopt(curl, CURLOPT_MAIL_FROM, MAILFROM);   curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, rcpt_list);   curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);   curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);   curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);   curl_easy_setopt(curl, CURLOPT_READDATA, &pooh);   curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);   curl_easy_setopt(curl, CURLOPT_SSLVERSION, 0L);   curl_easy_setopt(curl, CURLOPT_SSL_SESSIONID_CACHE, 0L);   curl_multi_add_handle(mcurl, curl);   mp_timedout = 0;   mp_start = tvnow();  /* we start some action by calling perform right away */  curl_multi_perform(mcurl, &still_running);  while(still_running) {    struct timeval timeout;    int rc; /* select() return code */    fd_set fdread;    fd_set fdwrite;    fd_set fdexcep;    int maxfd = -1;    long curl_timeo = -1;    FD_ZERO(&fdread);    FD_ZERO(&fdwrite);    FD_ZERO(&fdexcep);    /* set a suitable timeout to play around with */    timeout.tv_sec = 1;    timeout.tv_usec = 0;    curl_multi_timeout(mcurl, &curl_timeo);    if(curl_timeo >= 0) {      timeout.tv_sec = curl_timeo / 1000;      if(timeout.tv_sec > 1)        timeout.tv_sec = 1;      else        timeout.tv_usec = (curl_timeo % 1000) * 1000;    }    /* get file descriptors from the transfers */    curl_multi_fdset(mcurl, &fdread, &fdwrite, &fdexcep, &maxfd);    /* In a real-world program you OF COURSE check the return code of the       function calls.  On success, the value of maxfd is guaranteed to be       greater or equal than -1.  We call select(maxfd + 1, ...), specially in       case of (maxfd == -1), we call select(0, ...), which is basically equal       to sleep. */    rc = select(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout);    if (tvdiff(tvnow(), mp_start) > MULTI_PERFORM_HANG_TIMEOUT) {      fprintf(stderr, "ABORTING TEST, since it seems "              "that it would have run forever.\n");      break;    }    switch(rc) {    case -1:      /* select error */      break;    case 0: /* timeout */    default: /* action */      curl_multi_perform(mcurl, &still_running);      break;    }  }  curl_slist_free_all(rcpt_list);  curl_multi_remove_handle(mcurl, curl);  curl_multi_cleanup(mcurl);  curl_easy_cleanup(curl);  curl_global_cleanup();  return 0;}

不过最新版本的7.54.0中的示例代码好像略有不同：

/*************************************************************************** *                                  _   _ ____  _ *  Project                     ___| | | |  _ \| | *                             / __| | | | |_) | | *                            | (__| |_| |  _ <| |___ *                             \___|\___/|_| \_\_____| * * Copyright (C) 1998 - 2016, Daniel Stenberg, <[e-mail]>, et al. * * This software is licensed as described in the file COPYING, which * you should have received as part of this distribution. The terms * are also available at https://curl.haxx.se/docs/copyright.html. * * You may opt to use, copy, modify, merge, publish, distribute and/or sell * copies of the Software, and permit persons to whom the Software is * furnished to do so, under the terms of the COPYING file. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * ***************************************************************************//* <DESC> * SMTP example using the multi interface * </DESC> */#include <string.h>#include <curl/curl.h>/* This is an example showing how to send mail using libcurl's SMTP * capabilities. It builds on the smtp-mail.c example to demonstrate how to use * libcurl's multi interface. * * Note that this example requires libcurl 7.20.0 or above. */#define FROM     "<[e-mail]>"#define TO       "<[e-mail]>"#define CC       "<[e-mail]>"#define MULTI_PERFORM_HANG_TIMEOUT 60 * 1000static 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 multi 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;}static struct timeval tvnow(void){  struct timeval now;  /* time() returns the value of time in seconds since the epoch */  now.tv_sec = (long)time(NULL);  now.tv_usec = 0;  return now;}static long tvdiff(struct timeval newer, struct timeval older){  return (newer.tv_sec - older.tv_sec) * 1000 +    (newer.tv_usec - older.tv_usec) / 1000;}int main(void){  CURL *curl;  CURLM *mcurl;  int still_running = 1;  struct timeval mp_start;  struct curl_slist *recipients = NULL;  struct upload_status upload_ctx;  upload_ctx.lines_read = 0;  curl_global_init(CURL_GLOBAL_DEFAULT);  curl = curl_easy_init();  if(!curl)    return 1;  mcurl = curl_multi_init();  if(!mcurl)    return 2;  /* 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);  /* Tell the multi stack about our easy handle */  curl_multi_add_handle(mcurl, curl);  /* Record the start time which we can use later */  mp_start = tvnow();  /* We start some action by calling perform right away */  curl_multi_perform(mcurl, &still_running);  while(still_running) {    struct timeval timeout;    fd_set fdread;    fd_set fdwrite;    fd_set fdexcep;    int maxfd = -1;    int rc;    CURLMcode mc; /* curl_multi_fdset() return code */    long curl_timeo = -1;    /* Initialise the file descriptors */    FD_ZERO(&fdread);    FD_ZERO(&fdwrite);    FD_ZERO(&fdexcep);    /* Set a suitable timeout to play around with */    timeout.tv_sec = 1;    timeout.tv_usec = 0;    curl_multi_timeout(mcurl, &curl_timeo);    if(curl_timeo >= 0) {      timeout.tv_sec = curl_timeo / 1000;      if(timeout.tv_sec > 1)        timeout.tv_sec = 1;      else        timeout.tv_usec = (curl_timeo % 1000) * 1000;    }    /* get file descriptors from the transfers */    mc = curl_multi_fdset(mcurl, &fdread, &fdwrite, &fdexcep, &maxfd);    if(mc != CURLM_OK) {      fprintf(stderr, "curl_multi_fdset() failed, code %d.\n", mc);      break;    }    /* On success the value of maxfd is guaranteed to be >= -1. We call       select(maxfd + 1, ...); specially in case of (maxfd == -1) there are       no fds ready yet so we call select(0, ...) --or Sleep() on Windows--       to sleep 100ms, which is the minimum suggested value in the       curl_multi_fdset() doc. */    if(maxfd == -1) {#ifdef _WIN32      Sleep(100);      rc = 0;#else      /* Portable sleep for platforms other than Windows. */      struct timeval wait = { 0, 100 * 1000 }; /* 100ms */      rc = select(0, NULL, NULL, NULL, &wait);#endif    }    else {      /* Note that on some platforms 'timeout' may be modified by select().         If you need access to the original value save a copy beforehand. */      rc = select(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout);    }    if(tvdiff(tvnow(), mp_start) > MULTI_PERFORM_HANG_TIMEOUT) {      fprintf(stderr,              "ABORTING: Since it seems that we would have run forever.\n");      break;    }    switch(rc) {    case -1:  /* select error */      break;    case 0:   /* timeout */    default:  /* action */      curl_multi_perform(mcurl, &still_running);      break;    }  }  /* Free the list of recipients */  curl_slist_free_all(recipients);  /* Always cleanup */  curl_multi_remove_handle(mcurl, curl);  curl_multi_cleanup(mcurl);  curl_easy_cleanup(curl);  curl_global_cleanup();  return 0;}