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/* Copyright (c) 2017-2018 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>
enum qp_encoder_last_char {
QP_ENCODER_LAST_ANY = 0,
QP_ENCODER_LAST_CR,
QP_ENCODER_LAST_WHITE_SPACE,
};
struct qp_encoder {
const char *linebreak;
string_t *dest;
size_t line_len;
size_t max_len;
enum qp_encoder_flag flags;
enum qp_encoder_last_char last_char;
bool add_header_preamble: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->last_char == QP_ENCODER_LAST_CR)) {
str_append_c(qp->dest, '\r');
str_append_c(qp->dest, '\n');
/* reset line length here */
qp->line_len = 0;
qp->last_char = QP_ENCODER_LAST_ANY;
continue;
} else if (qp->last_char == QP_ENCODER_LAST_CR) {
qp_encode_or_break(qp, '\r');
qp->last_char = QP_ENCODER_LAST_ANY;
}
if (c == ' ' || c == '\t')
qp->last_char = QP_ENCODER_LAST_WHITE_SPACE;
else if (c == '\r')
qp->last_char = QP_ENCODER_LAST_CR;
else
qp->last_char = QP_ENCODER_LAST_ANY;
if (c != '\r')
qp_encode_or_break(qp, c);
}
}
void qp_encoder_finish(struct qp_encoder *qp)
{
switch (qp->last_char) {
case QP_ENCODER_LAST_CR:
/* Last char was CR which was not yet encoded */
qp_encode_or_break(qp, '\r');
break;
case QP_ENCODER_LAST_WHITE_SPACE:
/* Last char was a white space, it must be followed by
* a printable char. */
str_append_c(qp->dest, '=');
break;
default:
break;
}
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->last_char = QP_ENCODER_LAST_ANY;
}
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