94 lines
3.4 KiB
Rust
94 lines
3.4 KiB
Rust
use std::{env, process, time::Duration};
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use lettre::SmtpTransport;
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fn main() {
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tracing_subscriber::fmt::init();
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let smtp_host = match env::args().nth(1) {
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Some(smtp_host) => smtp_host,
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None => {
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println!("Please provide the SMTP host as the first argument to this command");
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process::exit(1);
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}
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};
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// TLS wrapped connection
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{
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tracing::info!(
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"Trying to establish a TLS wrapped connection to {}",
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smtp_host
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);
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let transport = SmtpTransport::relay(&smtp_host)
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.expect("build SmtpTransport::relay")
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.timeout(Some(Duration::from_secs(10)))
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.build();
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match transport.test_connection() {
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Ok(true) => {
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tracing::info!("Successfully connected to {} via a TLS wrapped connection (SmtpTransport::relay). This is the fastest option available for connecting to an SMTP server", smtp_host);
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}
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Ok(false) => {
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tracing::error!("Couldn't connect to {} via a TLS wrapped connection. No more information is available", smtp_host);
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}
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Err(err) => {
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tracing::error!(err = %err, "Couldn't connect to {} via a TLS wrapped connection", smtp_host);
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}
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}
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}
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println!();
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// Plaintext connection which MUST then successfully upgrade to TLS via STARTTLS
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{
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tracing::info!("Trying to establish a plaintext connection to {} and then upgrading it via the SMTP STARTTLS extension", smtp_host);
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let transport = SmtpTransport::starttls_relay(&smtp_host)
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.expect("build SmtpTransport::starttls_relay")
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.timeout(Some(Duration::from_secs(10)))
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.build();
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match transport.test_connection() {
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Ok(true) => {
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tracing::info!("Successfully connected to {} via a plaintext connection which then got upgraded to TLS via the SMTP STARTTLS extension (SmtpTransport::starttls_relay). This is the second best option after the previous TLS wrapped option", smtp_host);
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}
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Ok(false) => {
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tracing::error!(
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"Couldn't connect to {} via STARTTLS. No more information is available",
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smtp_host
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);
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}
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Err(err) => {
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tracing::error!(err = %err, "Couldn't connect to {} via STARTTLS", smtp_host);
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}
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}
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}
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println!();
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// Plaintext connection (very insecure)
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{
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tracing::info!(
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"Trying to establish a plaintext connection to {}",
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smtp_host
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);
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let transport = SmtpTransport::builder_dangerous(&smtp_host)
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.timeout(Some(Duration::from_secs(10)))
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.build();
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match transport.test_connection() {
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Ok(true) => {
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tracing::info!("Successfully connected to {} via a plaintext connection. This option is very insecure and shouldn't be used on the public internet (SmtpTransport::builder_dangerous)", smtp_host);
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}
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Ok(false) => {
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tracing::error!(
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"Couldn't connect to {} via a plaintext connection. No more information is available",
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smtp_host
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);
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}
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Err(err) => {
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tracing::error!(err = %err, "Couldn't connect to {} via a plaintext connection", smtp_host);
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}
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}
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}
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}
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