lib-mail: Add qp encoder

src/lib-mail/Makefile.am

@@ -13,6 +13,7 @@ libmail_la_SOURCES = \
 	istream-header-filter.c \
 	istream-nonuls.c \
 	istream-qp-decoder.c \
+	istream-qp-encoder.c \
 	mail-html2text.c \
 	mail-user-hash.c \
 	mbox-from.c \
@@ -34,6 +35,7 @@ libmail_la_SOURCES = \
 	message-snippet.c \
 	ostream-dot.c \
 	qp-decoder.c \
+	qp-encoder.c \
 	quoted-printable.c \
 	rfc2231-parser.c \
 	rfc822-parser.c
@@ -71,6 +73,7 @@ headers = \
 	message-snippet.h \
 	ostream-dot.h \
 	qp-decoder.h \
+	qp-encoder.h \
 	quoted-printable.h \
 	rfc2231-parser.h \
 	rfc822-parser.h
@@ -84,6 +87,7 @@ test_programs = \
 	test-istream-binary-converter \
 	test-istream-header-filter \
 	test-istream-qp-decoder \
+	test-istream-qp-encoder \
 	test-mail-html2text \
 	test-mbox-from \
 	test-message-address \
@@ -100,6 +104,7 @@ test_programs = \
 	test-message-snippet \
 	test-ostream-dot \
 	test-qp-decoder \
+	test-qp-encoder \
 	test-quoted-printable \
 	test-rfc2231-parser \
 	test-rfc822-parser
@@ -121,6 +126,10 @@ test_istream_qp_decoder_SOURCES = test-istream-qp-decoder.c
 test_istream_qp_decoder_LDADD = $(test_libs)
 test_istream_qp_decoder_DEPENDENCIES = $(test_deps)
 
+test_istream_qp_encoder_SOURCES = test-istream-qp-encoder.c
+test_istream_qp_encoder_LDADD = $(test_libs)
+test_istream_qp_encoder_DEPENDENCIES = $(test_deps)
+
 test_istream_binary_converter_SOURCES = test-istream-binary-converter.c
 test_istream_binary_converter_LDADD = $(test_libs)
 test_istream_binary_converter_DEPENDENCIES = $(test_deps)
@@ -197,6 +206,10 @@ test_qp_decoder_SOURCES = test-qp-decoder.c
 test_qp_decoder_LDADD = $(test_libs)
 test_qp_decoder_DEPENDENCIES = $(test_deps)
 
+test_qp_encoder_SOURCES = test-qp-encoder.c
+test_qp_encoder_LDADD = $(test_libs)
+test_qp_encoder_DEPENDENCIES = $(test_deps)
+
 test_quoted_printable_SOURCES = test-quoted-printable.c
 test_quoted_printable_LDADD = $(test_libs)
 test_quoted_printable_DEPENDENCIES = $(test_deps)

src/lib-mail/istream-qp-encoder.c

@@ -0,0 +1,128 @@
+/* Copyright (c) 2017 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "buffer.h"
+#include "hex-binary.h"
+#include "qp-encoder.h"
+#include "istream-private.h"
+#include "istream-qp.h"
+
+struct qp_encoder_istream {
+	struct istream_private istream;
+	buffer_t *buf;
+	struct qp_encoder *qp;
+};
+
+static void i_stream_qp_encoder_close(struct iostream_private *stream,
+				      bool close_parent)
+{
+	struct qp_encoder_istream *bstream =
+		(struct qp_encoder_istream *)stream;
+
+	if (bstream->qp != NULL)
+		qp_encoder_deinit(&bstream->qp);
+	if (bstream->buf != NULL)
+		buffer_free(&bstream->buf);
+	if (close_parent)
+		i_stream_close(bstream->istream.parent);
+}
+
+static ssize_t i_stream_qp_encoder_read(struct istream_private *stream)
+{
+	struct qp_encoder_istream *bstream =
+		(struct qp_encoder_istream *)stream;
+	const unsigned char *data;
+	size_t size;
+	int ret;
+
+	for(;;) {
+		if (stream->skip > 0) {
+			i_assert(stream->skip <= bstream->buf->used);
+			buffer_delete(bstream->buf, 0, stream->skip);
+			stream->pos -= stream->skip;
+			stream->skip = 0;
+		}
+
+		stream->buffer = bstream->buf->data;
+		i_assert(stream->pos <= bstream->buf->used);
+
+		if (stream->pos >= bstream->istream.max_buffer_size) {
+			/* stream buffer still at maximum */
+			return -2;
+		}
+
+		/* if something is already interpolated, return as much of it as
+		   we can */
+		if (bstream->buf->used > 0) {
+			size_t new_pos, bytes;
+
+			/* only return up to max_buffer_size bytes, even when buffer
+			   actually has more, as not to confuse the caller */
+			if (bstream->buf->used <= bstream->istream.max_buffer_size) {
+				new_pos = bstream->buf->used;
+				if (stream->parent->eof)
+					stream->istream.eof = TRUE;
+			} else {
+				new_pos = bstream->istream.max_buffer_size;
+			}
+
+			bytes = new_pos - stream->pos;
+			stream->pos = new_pos;
+			return (ssize_t)bytes;
+		}
+
+		/* need to read more input */
+		ret = i_stream_read_more(stream->parent, &data, &size);
+		if (ret == 0)
+			return ret;
+		if (size == 0 && ret == -1) {
+			stream->istream.stream_errno =
+				stream->parent->stream_errno;
+			stream->istream.eof = stream->parent->eof;
+			return ret;
+		}
+		qp_encoder_more(bstream->qp, data, size);
+		i_stream_skip(stream->parent, size);
+	}
+}
+
+static void
+i_stream_qp_encoder_seek(struct istream_private *stream,
+			     uoff_t v_offset, bool mark)
+{
+	struct qp_encoder_istream *bstream =
+		(struct qp_encoder_istream *)stream;
+
+	if (v_offset < stream->istream.v_offset) {
+		/* seeking backwards - go back to beginning and seek
+		   forward from there. */
+		stream->parent_expected_offset = stream->parent_start_offset;
+		stream->skip = stream->pos = 0;
+		stream->istream.v_offset = 0;
+		i_stream_seek(stream->parent, 0);
+		qp_encoder_finish(bstream->qp);
+		buffer_set_used_size(bstream->buf, 0);
+	}
+	i_stream_default_seek_nonseekable(stream, v_offset, mark);
+}
+
+struct istream *i_stream_create_qp_encoder(struct istream *input,
+					   enum qp_encoder_flag flags)
+{
+	struct qp_encoder_istream *bstream;
+
+	bstream = i_new(struct qp_encoder_istream, 1);
+	bstream->istream.max_buffer_size = input->real_stream->max_buffer_size;
+	bstream->buf = buffer_create_dynamic(default_pool, 128);
+	bstream->qp = qp_encoder_init(bstream->buf, ISTREAM_QP_ENCODER_MAX_LINE_LENGTH, flags);
+
+	bstream->istream.iostream.close = i_stream_qp_encoder_close;
+	bstream->istream.read = i_stream_qp_encoder_read;
+	bstream->istream.seek = i_stream_qp_encoder_seek;
+
+	bstream->istream.istream.readable_fd = FALSE;
+	bstream->istream.istream.blocking = input->blocking;
+	bstream->istream.istream.seekable = input->seekable;
+	return i_stream_create(&bstream->istream, input,
+			       i_stream_get_fd(input));
+}

src/lib-mail/istream-qp.h

@@ -1,6 +1,12 @@
 #ifndef ISTREAM_QP_H
 #define ISTREAM_QP_H
 
+#include "qp-encoder.h"
+
+#define ISTREAM_QP_ENCODER_MAX_LINE_LENGTH 75
+
 struct istream *i_stream_create_qp_decoder(struct istream *input);
+struct istream *i_stream_create_qp_encoder(struct istream *input,
+					   enum qp_encoder_flag flags);
 
 #endif

src/lib-mail/qp-encoder.c

@@ -0,0 +1,140 @@
+/* Copyright (c) 2017 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "str.h"
+#include "istream.h"
+#include "istream-private.h"
+#include "qp-encoder.h"
+#include <ctype.h>
+
+struct qp_encoder {
+	const char *linebreak;
+	string_t *dest;
+	size_t line_len;
+	size_t max_len;
+	enum qp_encoder_flag flags;
+	bool add_header_preamble:1;
+	bool cr_last:1;
+};
+
+struct qp_encoder *
+qp_encoder_init(string_t *dest, unsigned int max_len, enum qp_encoder_flag flags)
+{
+	i_assert(max_len > 0);
+
+	if ((flags & QP_ENCODER_FLAG_HEADER_FORMAT) != 0 &&
+	    (flags & QP_ENCODER_FLAG_BINARY_DATA) != 0)
+		i_panic("qp encoder cannot do header format with binary data");
+
+	struct qp_encoder *qp = i_new(struct qp_encoder, 1);
+	qp->flags = flags;
+	qp->dest = dest;
+	qp->max_len = max_len;
+
+	if ((flags & QP_ENCODER_FLAG_HEADER_FORMAT) != 0) {
+		qp->linebreak = "?=\r\n =?utf-8?Q?";
+		qp->add_header_preamble = TRUE;
+	} else {
+		qp->linebreak = "=\r\n";
+	}
+	return qp;
+}
+
+void qp_encoder_deinit(struct qp_encoder **qp)
+{
+	i_free(*qp);
+}
+
+static inline void
+qp_encode_or_break(struct qp_encoder *qp, unsigned char c)
+{
+	bool encode = FALSE;
+
+	if ((qp->flags & QP_ENCODER_FLAG_HEADER_FORMAT) != 0) {
+		if (c == ' ')
+			c = '_';
+		else if (c != '\t' &&
+			 (c == '?' || c == '_' || c == '=' || c < 33 || c > 126))
+			encode = TRUE;
+	} else if (c != ' ' && c != '\t' &&
+		   (c == '=' || c < 33 || c > 126)) {
+		encode = TRUE;
+	}
+
+	/* Include terminating = as well */
+	if ((c == ' ' || c == '\t') && qp->line_len + 4 >= qp->max_len) {
+		const char *ptr = strchr(qp->linebreak, '\n');
+		str_printfa(qp->dest, "=%02X%s", c, qp->linebreak);
+		if (ptr != NULL)
+			qp->line_len = strlen(ptr+1);
+		else
+			qp->line_len = 0;
+		return;
+	}
+
+	/* Include terminating = as well */
+	if (qp->line_len + (encode?4:2) >= qp->max_len) {
+		str_append(qp->dest, qp->linebreak);
+		qp->line_len = 0;
+	}
+
+	if (encode) {
+		str_printfa(qp->dest, "=%02X", c);
+		qp->line_len += 3;
+	} else {
+		str_append_c(qp->dest, c);
+		qp->line_len += 1;
+	}
+}
+
+void qp_encoder_more(struct qp_encoder *qp, const void *_src, size_t src_size)
+{
+	const unsigned char *src = _src;
+	i_assert(_src != NULL || src_size == 0);
+	if (src_size == 0)
+		return;
+	if (qp->add_header_preamble) {
+		size_t used = qp->dest->used;
+		qp->add_header_preamble = FALSE;
+		str_append(qp->dest, "=?utf-8?Q?");
+		qp->line_len = qp->dest->used - used;
+	}
+	for(unsigned int i = 0; i < src_size; i++) {
+		unsigned char c = src[i];
+		/* if input is not binary data and we encounter newline
+		   convert it as crlf, or if the last byte was CR, preserve
+		   CRLF */
+		if (c == '\n' &&
+		    ((qp->flags & (QP_ENCODER_FLAG_BINARY_DATA|QP_ENCODER_FLAG_HEADER_FORMAT)) == 0 ||
+		      qp->cr_last)) {
+			str_append_c(qp->dest, '\r');
+			str_append_c(qp->dest, '\n');
+			/* reset line length here */
+			qp->line_len = 0;
+			qp->cr_last = FALSE;
+			continue;
+		} else if (qp->cr_last) {
+			qp_encode_or_break(qp, '\r');
+			qp->cr_last = FALSE;
+		}
+		if (c == '\r') {
+			qp->cr_last = TRUE;
+		} else {
+			qp_encode_or_break(qp, c);
+		}
+	}
+}
+
+void qp_encoder_finish(struct qp_encoder *qp)
+{
+	if (qp->cr_last)
+		qp_encode_or_break(qp, '\r');
+
+	if ((qp->flags & QP_ENCODER_FLAG_HEADER_FORMAT) != 0 &&
+	    !qp->add_header_preamble)
+		str_append(qp->dest, "?=");
+	if ((qp->flags & QP_ENCODER_FLAG_HEADER_FORMAT) != 0)
+		qp->add_header_preamble = TRUE;
+	qp->line_len = 0;
+	qp->cr_last = FALSE;
+}

src/lib-mail/qp-encoder.h

@@ -0,0 +1,25 @@
+#ifndef QP_ENCODER_H
+#define QP_ENCODER_H 1
+
+enum qp_encoder_flag {
+	/* encode spaces as underscores, encode crlfs, adds =?utf-8?q?..?= encapsulation */
+	QP_ENCODER_FLAG_HEADER_FORMAT = 0x1,
+	/* treat input as true binary, no lf => crlf conversion, only CRLF is preserved */
+	QP_ENCODER_FLAG_BINARY_DATA   = 0x2,
+};
+
+/* Initialize quoted-printable encoder. Write all the encoded output to dest. */
+struct qp_encoder *qp_encoder_init(string_t *dest, unsigned int max_length,
+				   enum qp_encoder_flag flags);
+void qp_encoder_deinit(struct qp_encoder **qp);
+
+/* Translate more (binary) data into quoted printable.
+   If QP_ENCODER_FLAG_BINARY_DATA is not set, text is assumed to be in
+   UTF-8 (but not enforced). No other character sets are supported. */
+void qp_encoder_more(struct qp_encoder *qp, const void *src, size_t src_size);
+/* Finish encoding any pending input.
+   This function also resets the entire encoder state, so the same encoder can
+   be used to encode more data if wanted. */
+void qp_encoder_finish(struct qp_encoder *qp);
+
+#endif