From 55467ed90c19bc82506433f8f7d274b5bfb8d10f Mon Sep 17 00:00:00 2001
From: Vsevolod Stakhov <vsevolod@highsecure.ru>
Date: Mon, 12 Dec 2016 11:22:50 +0000
Subject: [PATCH] [Feature] Implement quoted printable decoding

---
 src/libutil/str_util.c | 89 +++++++++++++++++++++++++++++++++++++++++-
 src/libutil/str_util.h | 13 +++++-
 2 files changed, 100 insertions(+), 2 deletions(-)

diff --git a/src/libutil/str_util.c b/src/libutil/str_util.c
index c12a9c562..5be41f784 100644
--- a/src/libutil/str_util.c
+++ b/src/libutil/str_util.c
@@ -1671,7 +1671,7 @@ rspamd_encode_hex (const guchar *in, gsize inlen)
 	return out;
 }
 
-gint
+gssize
 rspamd_decode_hex_buf (const gchar *in, gsize inlen,
 		guchar *out, gsize outlen)
 {
@@ -1738,6 +1738,93 @@ rspamd_decode_hex (const gchar *in, gsize inlen)
 	return NULL;
 }
 
+gssize
+rspamd_decode_qp_buf (const gchar *in, gsize inlen,
+		gchar *out, gsize outlen)
+{
+	gchar *o, *end, *pos, c;
+	const gchar *p;
+	guchar ret;
+	gsize remain, processed;
+
+	p = in;
+	o = out;
+	end = out + outlen;
+	remain = inlen;
+
+	while (remain > 0 && o < end) {
+		if (*p == '=') {
+			p ++;
+			remain --;
+
+			if (remain == 0) {
+				if (end - o > 0) {
+					*o++ = *p;
+					break;
+				}
+			}
+decode:
+			/* Decode character after '=' */
+			c = *p++;
+			remain --;
+
+			if      (c >= '0' && c <= '9') { ret = c - '0'; }
+			else if (c >= 'A' && c <= 'F') { ret = c - 'A' + 10; }
+			else if (c >= 'a' && c <= 'f') { ret = c - 'a' + 10; }
+			else if (c == '\r' || c == '\n') {
+				/* Soft line break */
+				while (remain > 0 && (*p == '\r' || *p == '\n')) {
+					remain --;
+					p ++;
+				}
+
+				continue;
+			}
+
+			if (remain > 0) {
+				c = *p++;
+				ret *= 16;
+
+				if      (c >= '0' && c <= '9') ret += c - '0';
+				else if (c >= 'A' && c <= 'F') ret += c - 'A' + 10;
+				else if (c >= 'a' && c <= 'f') ret += c - 'a' + 10;
+
+				if (end - o > 0) {
+					*o++ = (gchar)ret;
+				}
+				else {
+					return (-1);
+				}
+
+				remain --;
+			}
+		}
+		else {
+			if (end - o >= remain) {
+				if ((pos = memccpy (o, p, '=', remain)) == NULL) {
+					/* All copied */
+					o += remain;
+					break;
+				}
+				else {
+					processed = pos - o;
+					remain -= processed;
+					p += processed;
+					o = pos - 1;
+					/* Skip comparison, as we know that we have found match */
+					goto decode;
+				}
+			}
+			else {
+				/* Buffer overflow */
+				return (-1);
+			}
+		}
+	}
+
+	return (o - out);
+}
+
 
 /*
  * GString ucl emitting functions
diff --git a/src/libutil/str_util.h b/src/libutil/str_util.h
index 9b9bbe0c1..37bd9fe82 100644
--- a/src/libutil/str_util.h
+++ b/src/libutil/str_util.h
@@ -180,7 +180,7 @@ gint rspamd_encode_hex_buf (const guchar *in, gsize inlen, gchar *out,
  * @param outlen output buf len
  * @return decoded len if in is valid hex and `outlen` is enough to encode `inlen`
  */
-gint rspamd_decode_hex_buf (const gchar *in, gsize inlen,
+gssize rspamd_decode_hex_buf (const gchar *in, gsize inlen,
 		guchar *out, gsize outlen);
 
 /**
@@ -212,6 +212,17 @@ gchar * rspamd_encode_base64_fold (const guchar *in, gsize inlen, gint str_len,
  */
 gsize rspamd_decode_url (gchar *dst, const gchar *src, gsize size);
 
+/**
+ * Decode quoted-printable encoded buffer, input and output must not overlap
+ * @param in input
+ * @param inlen length of input
+ * @param out output
+ * @param outlen length of output
+ * @return real size of decoded output or (-1) if outlen is not enough
+ */
+gssize rspamd_decode_qp_buf (const gchar *in, gsize inlen,
+		gchar *out, gsize outlen);
+
 #ifndef g_tolower
 #   define g_tolower(x) (((x) >= 'A' && (x) <= 'Z') ? (x) - 'A' + 'a' : (x))
 #endif
-- 
2.39.5