email: add small function to send multi-part emails using sendmail

Signed-off-by: Hannes Laimer <h.laimer@proxmox.com>

proxmox/src/tools/email.rs

@@ -0,0 +1,152 @@
+//! Email related utilities.
+
+use std::process::{Command, Stdio};
+use anyhow::{bail, Error};
+use std::io::Write;
+use chrono::{DateTime, Local};
+use crate::tools::time::time;
+
+
+/// Sends multi-part mail with text and/or html to a list of recipients
+///
+/// ``sendmail`` is used for sending the mail.
+pub fn sendmail(mailto: Vec<&str>,
+                subject: &str,
+                text: Option<&str>,
+                html: Option<&str>,
+                mailfrom: Option<&str>,
+                author: Option<&str>) -> Result<(), Error> {
+    let mail_regex = regex::Regex::new(r"^[a-zA-Z\.0-9-]+@[a-zA-Z\.0-9-]+$").unwrap();
+
+    if mailto.is_empty() {
+        bail!("At least one recipient has to be specified!")
+    }
+
+    for recipient in &mailto {
+        if !mail_regex.is_match(recipient) {
+            bail!("'{}' is not a valid email address", recipient)
+        }
+    }
+
+    let mailfrom = mailfrom.unwrap_or("root");
+    if !mailfrom.eq("root") && !mail_regex.is_match(mailfrom) {
+        bail!("'{}' is not a valid email address", mailfrom)
+    }
+
+    let recipients = mailto.join(",");
+    let author = author.unwrap_or("Proxmox Backup Server");
+
+    let now: DateTime<Local> = Local::now();
+
+    let mut sendmail_process = match Command::new("/usr/sbin/sendmail")
+        .arg("-B")
+        .arg("8BITMIME")
+        .arg("-f")
+        .arg(mailfrom)
+        .arg("--")
+        .arg(&recipients)
+        .stdin(Stdio::piped())
+        .spawn() {
+        Err(err) => bail!("could not spawn sendmail process: {}", err),
+        Ok(process) => process
+    };
+    let mut is_multipart = false;
+    if let (Some(_), Some(_)) = (text, html) {
+        is_multipart = true;
+    }
+
+    let mut body = String::new();
+    let boundary = format!("----_=_NextPart_001_{}", time()?);
+    if is_multipart {
+        body.push_str("Content-Type: multipart/alternative;\n");
+        body.push_str(&format!("\tboundary=\"{}\"\n", boundary));
+        body.push_str("MIME-Version: 1.0\n");
+    } else if !subject.is_ascii() {
+        body.push_str("MIME-Version: 1.0\n");
+    }
+    if !subject.is_ascii() {
+        body.push_str(&format!("Subject: =?utf-8?B?{}?=\n", base64::encode(subject)));
+    } else {
+        body.push_str(&format!("Subject: {}\n", subject));
+    }
+    body.push_str(&format!("From: {} <{}>\n", author, mailfrom));
+    body.push_str(&format!("To: {}\n", &recipients));
+    body.push_str(&format!("Date: {}\n", now.to_rfc2822()));
+    if is_multipart {
+        body.push('\n');
+        body.push_str("This is a multi-part message in MIME format.\n");
+        body.push_str(&format!("\n--{}\n", boundary));
+    }
+    if let Some(text) = text {
+        body.push_str("Content-Type: text/plain;\n");
+        body.push_str("\tcharset=\"UTF-8\"\n");
+        body.push_str("Content-Transfer-Encoding: 8bit\n");
+        body.push('\n');
+        body.push_str(text);
+        if is_multipart {
+            body.push_str(&format!("\n--{}\n", boundary));
+        }
+    }
+    if let Some(html) = html {
+        body.push_str("Content-Type: text/html;\n");
+        body.push_str("\tcharset=\"UTF-8\"\n");
+        body.push_str("Content-Transfer-Encoding: 8bit\n");
+        body.push('\n');
+        body.push_str(html);
+        if is_multipart {
+            body.push_str(&format!("\n--{}--", boundary));
+        }
+    }
+
+    if let Err(err) = sendmail_process.stdin.take().unwrap().write_all(body.as_bytes()) {
+        bail!("couldn't write to sendmail stdin: {}", err)
+    };
+
+    // wait() closes stdin of the child
+    if let Err(err) = sendmail_process.wait() {
+        bail!("sendmail did not exit successfully: {}", err)
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod test {
+    use crate::tools::email::sendmail;
+
+    #[test]
+    fn test1() {
+        let result = sendmail(
+            vec!["somenotvalidemail!", "somealmostvalid email"],
+            "Subject1",
+            Some("TEXT"),
+            Some("<b>HTML</b>"),
+            Some("bim@bam.bum"),
+            Some("test1"));
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test2() {
+        let result = sendmail(
+            vec![],
+            "Subject2",
+            None,
+            Some("<b>HTML</b>"),
+            None,
+            Some("test1"));
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test3() {
+        let result = sendmail(
+            vec!["a@b.c"],
+            "Subject3",
+            None,
+            Some("<b>HTML</b>"),
+            Some("notv@lid.com!"),
+            Some("test1"));
+        assert!(result.is_err());
+    }
+}

proxmox/src/tools/mod.rs

@@ -10,6 +10,7 @@ pub mod borrow;
 pub mod byte_buffer;
 pub mod common_regex;
 pub mod constnamemap;
+pub mod email;
 pub mod fd;
 pub mod fs;
 pub mod io;