From 5d937a51725609adcfba2c663ca4c1fe65974a55 Mon Sep 17 00:00:00 2001
From: Jan Engelhardt <jengelh@inai.de>
Date: Mon, 17 Sep 2018 17:15:28 +0200
Subject: [PATCH 3/5] vcc.y - fix infinite loop with non-hex digits
References: https://github.com/libical/libical/pull/354

When nonsensical characters are used in a QP character,
an infinite loop would occur in the vcard parser.

"N;ENCODING=QUOTED-PRINTABLE:=c3=g4\n"

References: #353
---
 src/libicalvcal/vcc.c | 38 ++++++++++++++++----------------------
 src/libicalvcal/vcc.y | 38 ++++++++++++++++----------------------
 2 files changed, 32 insertions(+), 44 deletions(-)

diff --git a/src/libicalvcal/vcc.c b/src/libicalvcal/vcc.c
index 29354df4..f723a4e1 100644
--- a/src/libicalvcal/vcc.c
+++ b/src/libicalvcal/vcc.c
@@ -1146,31 +1146,25 @@ static char* lexGetQuotedPrintable()
         cur = lexGetc();
         switch (cur) {
             case '=': {
-                int c = 0;
-                int next[2];
-                int i;
-                for (i = 0; i < 2; i++) {
-                    next[i] = hexdigit_decode(lexGetc());
-                    if (next[i] < 0)
-                        break;
+                int c = 0, d;
+                cur = lexGetc();
+                if (cur == '\n') {
+                    ++mime_lineNum;
+                    break;
                     }
-                if (i == 0) {
-                    /* single '=' follow by LINESEP is continuation sign? */
-                    if (next[0] == '\n') {
-                        ++mime_lineNum;
-                        }
-                    else {
-                        lexPushLookaheadc('=');
-                        goto EndString;
-                        }
+                d = hexdigit_decode(cur);
+                if (d < 0) {
+                    lexAppendc(cur);
+                    break;
                     }
-                else if (i == 1) {
-                    lexPushLookaheadc(next[1]);
-                    lexPushLookaheadc(next[0]);
-                    lexAppendc('=');
-                } else {
-                    lexAppendc(c);
+                c = d << 4;
+                cur = lexGetc();
+                d = hexdigit_decode(cur);
+                if (d < 0) {
+                    lexAppendc(cur);
+                    break;
                     }
+                lexAppendc(c | d);
                 break;
                 } /* '=' */
             case '\n': {
diff --git a/src/libicalvcal/vcc.y b/src/libicalvcal/vcc.y
index a052e9a2..4f52fe35 100644
--- a/src/libicalvcal/vcc.y
+++ b/src/libicalvcal/vcc.y
@@ -967,31 +967,25 @@ static char* lexGetQuotedPrintable()
         cur = lexGetc();
         switch (cur) {
             case '=': {
-                int c = 0;
-                int next[2];
-                int i;
-                for (i = 0; i < 2; i++) {
-                    next[i] = hexdigit_decode(lexGetc());
-                    if (next[i] < 0)
-                        break;
+                int c = 0, d;
+                cur = lexGetc();
+                if (cur == '\n') {
+                    ++mime_lineNum;
+                    break;
                     }
-                if (i == 0) {
-                    /* single '=' follow by LINESEP is continuation sign? */
-                    if (next[0] == '\n') {
-                        ++mime_lineNum;
-                        }
-                    else {
-                        lexPushLookaheadc('=');
-                        goto EndString;
-                        }
+                d = hexdigit_decode(cur);
+                if (d < 0) {
+                    lexAppendc(cur);
+                    break;
                     }
-                else if (i == 1) {
-                    lexPushLookaheadc(next[1]);
-                    lexPushLookaheadc(next[0]);
-                    lexAppendc('=');
-                } else {
-                    lexAppendc(c);
+                c = d << 4;
+                cur = lexGetc();
+                d = hexdigit_decode(cur);
+                if (d < 0) {
+                    lexAppendc(cur);
+                    break;
                     }
+                lexAppendc(c | d);
                 break;
                 } /* '=' */
             case '\n': {
-- 
2.19.1