example: add smtp-multi.c

An example application source code sending SMTP mail with the multi
interface. It is based on the code Alona Rossen provided, which in turn
is based on existing example/test code, and I converted it even more
into a decent example with a fair multi API use, put the info required
to edit at the top and I added some comments.

1 files changed, 196 insertions, 0 deletions

diff --git a/docs/examples/smtp-multi.c b/docs/examples/smtp-multi.c
new file mode 100644
index 000000000..0a7aeebf9
--- /dev/null
+++ b/docs/examples/smtp-multi.c
@@ -0,0 +1,196 @@
+/*****************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ *
+ * 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 "user@example.com"
+#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 RECEPIENT "receipient@example.com"
+#define MAILFROM "<realuser@example.com>"
+
+#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, RECEPIENT);
+   /* more addresses can be added here
+      rcpt_list = curl_slist_append(rcpt_list, "others@example.com");
+   */
+
+   curl_easy_setopt(curl, CURLOPT_URL, "smtp://" SMTPSERVER SMTPPORT);
+   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, CURLUSESSL_ALL);
+   curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER,0);
+   curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0);
+   curl_easy_setopt(curl, CURLOPT_READDATA, &pooh);
+   curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);
+   curl_easy_setopt(curl, CURLOPT_SSLVERSION, 0);
+   curl_easy_setopt(curl, CURLOPT_SSL_SESSIONID_CACHE, 0);
+   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, do something else */
+      break;
+    default:
+      /* one or more of curl's file descriptors say there's data to read
+         or write */
+      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;
+}
+
+