go-pkgz / email / 32195276346

93%

Build Type

push

github

Committed by web-flow

Commit Message

Wrap base64 attachments, accept empty files, build the message in one buffer (#28)

* Build the message in a single buffer

Previously, buildMessage assembled the headers into a string, the body into
a separate buffer, joined the two into another string, and Send copied that
into a buffer again. With attachments this held several full copies of the
base64-expanded message at once.

After this change, buildMessage writes everything into one buffer and Send
writes it to the smtp writer directly. The produced message is unchanged.

* Wrap base64 encoded attachments at 76 characters

Previously, the base64 encoder wrote each attachment and inline image as a
single unbroken line, so anything over 57 bytes produced a line longer than
the 76 characters RFC 2045 allows. The test image alone made a line of
116396 characters, and strict relays reject such messages.

After this change, the encoded output goes through a line wrapper which
breaks it into 76 character lines separated by CRLF.

The MIME test helper now decodes the content of leaf parts, so attachment
assertions compare the decoded bytes with the file instead of matching the
encoded blob as a substring.

* Accept empty files as attachments

Previously, an existing but zero-byte file failed the whole message with
"failed to read file type: EOF", because the type detection treated EOF as
fatal. After this change, EOF from the type sniffing read is accepted and
the empty file becomes a valid, empty attachment part.

Content type is now detected from the bytes actually read instead of the
512 byte buffer with the trailing null bytes trimmed off, so a file whose
own content ends with null bytes is sniffed correctly too.

* Add a benchmark for building a message with a large attachment

Building a message with a 4mb attachment takes 21.0mb and 84 allocations,
against 23.8mb and 103 allocations before the single buffer change.

Coverage Stats

49 of 55 new or added lines in 1 file covered. (89.09%)

2 existing lines in 1 file now uncovered.

349 of 376 relevant lines covered (92.82%)

233.36 hits per line