test: Unify (most) SMTP client calls

To send mails, today some tests use msmtp and others our internal smtpc.py.

This works, but msmtp slows down the tests significantly, and smtpc.py
is also not particularly fast, and also has some limitations.

This patch introduces a new SMTP client tool written in Go, and makes
almost all the tests use it.

Some tests still remain on msmtp, mainly for client-check compatibility.
It's likely that this will be moved in later patches to a separate
special-purpose test.

With this patch, integration tests take ~20% less time than before.

test/t-10-hooks/config/chasquid.conf

@@ -1,5 +1,6 @@
 smtp_address: ":1025"
 submission_address: ":1587"
+submission_over_tls_address: ":1465"
 monitoring_address: ":1099"
 
 mail_delivery_agent_bin: "test-mda"

test/t-10-hooks/msmtprc

@@ -1,15 +0,0 @@
-account default
-
-host testserver
-port 1587
-
-tls on
-tls_trust_file config/certs/testserver/fullchain.pem
-
-from user@testserver
-
-auth on
-user user@testserver
-password secretpassword
-
-logfile .logs/msmtp

test/t-10-hooks/run.sh

@@ -18,7 +18,7 @@ wait_until_ready 1025
 
 cp config/hooks/post-data.good config/hooks/post-data
 
-run_msmtp someone@testserver < content
+smtpc someone@testserver < content
 
 wait_for_file .mail/someone@testserver
 
@@ -51,20 +51,20 @@ check "SPF_PASS=0"
 
 # Check that failures in the script result in failing delivery.
 # Transient failure.
-if run_msmtp blockme@testserver < content 2>/dev/null; then
+if smtpc blockme@testserver < content >.logs/smtpc.log 2>&1; then
 	fail "ERROR: hook did not block email as expected"
 fi
-if ! tail -n 1 .logs/msmtp | grep -q "smtpstatus=451"; then
-	tail -n 1 .logs/msmtp
+if ! grep -q "451 ¡No pasarán!" .logs/smtpc.log; then
+	cat .logs/smtpc.log
 	fail "ERROR: transient hook error not returned correctly"
 fi
 
 # Permanent failure.
-if run_msmtp permanent@testserver < content 2>/dev/null; then
+if smtpc permanent@testserver < content >.logs/smtpc.log 2>&1; then
 	fail "ERROR: hook did not block email as expected"
 fi
-if ! tail -n 1 .logs/msmtp | grep -q "smtpstatus=554"; then
-	tail -n 1 .logs/msmtp
+if ! grep -q "554 Nos hacemos la permanente" .logs/smtpc.log; then
+	cat .logs/smtpc.log
 	fail "ERROR: permanent hook error not returned correctly"
 fi
 
@@ -72,7 +72,7 @@ fi
 for i in config/hooks/post-data.bad*; do
 	cp "$i" config/hooks/post-data
 
-	run_msmtp someone@testserver < content
+	smtpc someone@testserver < content
 	wait_for_file .mail/someone@testserver
 	mail_diff content .mail/someone@testserver
 done

test/t-10-hooks/smtpc.conf

@@ -0,0 +1,4 @@
+addr localhost:1465
+server_cert config/certs/testserver/fullchain.pem
+user user@testserver
+password secretpassword