fix: possible memory corruption bug when parsing X509 serial numbers

git-svn-id: https://svn.code.sf.net/p/openv2g/code/trunk@118 d9f2db14-54d0-4bde-b00c-16405c910529

src/codec/DecoderChannel.c

@@ -1,32 +1,32 @@
-/*
- * Copyright (C) 2007-2018 Siemens AG
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published
- * by the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-/*******************************************************************
- *
- * @author Daniel.Peintner.EXT@siemens.com
- * @version 2017-03-02 
- * @contact Richard.Kuntschke@siemens.com
- *
- * <p>Code generated by EXIdizer</p>
- * <p>Schema: V2G_CI_MsgDef.xsd</p>
- *
- *
- ********************************************************************/
-
+/*
+ * Copyright (C) 2007-2022 Siemens AG
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*******************************************************************
+ *
+ * @author Daniel.Peintner.EXT@siemens.com
+ * @version 2022-03-08 
+ * @contact Richard.Kuntschke@siemens.com
+ *
+ * <p>Code generated by EXIdizer</p>
+ * <p>Schema: V2G_CI_MsgDef.xsd</p>
+ *
+ *
+ ********************************************************************/
+
 
 
 #include "DecoderChannel.h"
@@ -261,182 +261,320 @@ int decodeUnsignedInteger64(bitstream_t* stream, uint64_t* uint64) {
 
 	return errn;
 }
-
-
-void _reverseArray(uint8_t *array, int number) {
-    int x, t;
-    number--;
-
-    for(x = 0; x < number; x ++, number --) {
-        t = array[x];
-        array[x] = array[number];
-        array[number] = t;
-    }
-}
-
-/**
- * Decode an arbitrary precision non negative integer using a sequence of
- * octets. The most significant bit of the last octet is set to zero to
- * indicate sequence termination. Only seven bits per octet are used to
- * store the integer's value.
- */
-int decodeUnsignedIntegerBig(bitstream_t* stream, size_t size, uint8_t* data, size_t* len) {
-	int errn = 0;
-	uint8_t b = 0;
-	unsigned int mShift1 = 0;
-	unsigned int mShift2 = 0;
-	unsigned int mShift3 = 0;
-	unsigned int mShift4 = 0;
-	unsigned int nBytesRead = 0;
-	unsigned int nBitsAvailable = 0;
-	uint64_t uint64_1 = 0;
-	uint64_t uint64_2 = 0;
-	uint64_t uint64_3 = 0;
-	uint64_t uint64_4 = 0;
-
-	*len = 0;
-
-	do {
-		errn = decode(stream, &b);
-		nBytesRead++;
-		nBitsAvailable += 7;
-
-		if(nBytesRead <= 8) {
-			uint64_1 += ((uint64_t) (b & 127)) << mShift1;
-			mShift1 += 7;
-		} else if(nBytesRead <= 16) {
-			uint64_2 += ((uint64_t) (b & 127)) << mShift2;
-			mShift2 += 7;
-		} else if(nBytesRead <= 24) {
-			uint64_3 += ((uint64_t) (b & 127)) << mShift3;
-			mShift3 += 7;
-		} else if(nBytesRead <= 32) {
-			uint64_4 += ((uint64_t) (b & 127)) << mShift4;
-			mShift4 += 7;
-		} else {
-			return -1; // too large
-		}
-	} while (errn == 0 && (b >> 7) == 1);
-
-	// shift actual data into array
-	if(uint64_4 != 0) {
-		// 7 octets for uint64_1
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 1
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 2
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 3
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 4
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 5
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 6
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 7
-
-		// 7 octets for uint64_2
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 1
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 2
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 3
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 4
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 5
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 6
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 7
-
-		// 7 octets for uint64_3
-		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); // 1
-		uint64_3 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); // 2
-		uint64_3 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); // 3
-		uint64_3 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); // 4
-		uint64_3 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); // 5
-		uint64_3 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); // 6
-		uint64_3 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); // 7
-
-		// remaining octets of uint64_4
-		while (uint64_4 != 0 && errn == 0) {
-			data[(*len)++] = uint64_4 & 0xFF;
-			uint64_4 >>= 8;
-		}
-	} else if(uint64_3 != 0) {
-		// 7 octets for uint64_1
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 1
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 2
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 3
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 4
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 5
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 6
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 7
-
-		// 7 octets for uint64_2
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 1
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 2
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 3
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 4
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 5
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 6
-		uint64_2 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); // 7
-
-		// remaining octets of uint64_3
-		while (uint64_3 != 0 && errn == 0) {
-			data[(*len)++] = uint64_3 & 0xFF;
-			uint64_3 >>= 8;
-		}
-
-	} else if(uint64_2 != 0) {
-		// 7 octets for uint64_1
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 1
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 2
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 3
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 4
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 5
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 6
-		uint64_1 >>= 8;
-		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); // 7
-		// remaining octets of uint64_2
-		while (uint64_2 != 0 && errn == 0) {
-			data[(*len)++] = uint64_2 & 0xFF;
-			uint64_2 >>= 8;
-		}
-	} else if(uint64_1 != 0) {
-		while (uint64_1 != 0 && errn == 0) {
-			data[(*len)++] = uint64_1 & 0xFF;
-			uint64_1 >>= 8;
-		}
-	}
-
-	_reverseArray(data, *len);
-
-	return errn;
+
+
+void _reverseArray(uint8_t *array, int number) {
+    int x, t;
+    number--;
+
+    for(x = 0; x < number; x ++, number --) {
+        t = array[x];
+        array[x] = array[number];
+        array[number] = t;
+    }
+}
+
+/**
+ * Decode an arbitrary precision non negative integer using a sequence of
+ * octets. The most significant bit of the last octet is set to zero to
+ * indicate sequence termination. Only seven bits per octet are used to
+ * store the integer's value.
+ */
+int decodeUnsignedIntegerBig(bitstream_t* stream, size_t size, uint8_t* data, size_t* len) {
+	int errn = 0;
+	uint8_t b = 0;
+	unsigned int mShift1 = 0;
+	unsigned int mShift2 = 0;
+	unsigned int mShift3 = 0;
+	unsigned int mShift4 = 0;
+	unsigned int nBytesRead = 0;
+	unsigned int nBitsAvailable = 0;
+	uint64_t uint64_1 = 0;
+	uint64_t uint64_2 = 0;
+	uint64_t uint64_3 = 0;
+	uint64_t uint64_4 = 0;
+
+	*len = 0;
+
+	do {
+		errn = decode(stream, &b);
+		nBytesRead++;
+		nBitsAvailable += 7;
+
+		if(nBytesRead <= 8) {
+			uint64_1 += ((uint64_t) (b & 127)) << mShift1;
+			mShift1 += 7;
+		} else if(nBytesRead <= 16) {
+			uint64_2 += ((uint64_t) (b & 127)) << mShift2;
+			mShift2 += 7;
+		} else if(nBytesRead <= 24) {
+			uint64_3 += ((uint64_t) (b & 127)) << mShift3;
+			mShift3 += 7;
+		} else if(nBytesRead <= 32) {
+			uint64_4 += ((uint64_t) (b & 127)) << mShift4;
+			mShift4 += 7;
+		} else {
+			return -1; /* too large */
+		}
+	} while (errn == 0 && (b >> 7) == 1);
+
+	/* shift actual data into array */
+	if(uint64_4 != 0) {
+		/* 7 octets for uint64_1 */
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 1 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 2 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 3 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 4 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 5 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 6 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 7 */
+
+		/* 7 octets for uint64_2 */
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 1 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 2 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 3 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 4 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 5 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 6 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 7 */
+
+		/* 7 octets for uint64_3 */
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); /* 1 */
+		uint64_3 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); /* 2 */
+		uint64_3 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); /* 3 */
+		uint64_3 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); /* 4 */
+		uint64_3 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); /* 5 */
+		uint64_3 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); /* 6 */
+		uint64_3 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_3 & 0xFF); /* 7 */
+
+		/* remaining octets of uint64_4 */
+		while (uint64_4 != 0 && errn == 0) {
+			if(*len >= size) {
+				return EXI_ERROR_OUT_OF_BOUNDS;
+			}
+			data[(*len)++] = uint64_4 & 0xFF;
+			uint64_4 >>= 8;
+		}
+	} else if(uint64_3 != 0) {
+		/* 7 octets for uint64_1 */
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 1 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 2 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 3 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 4 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 5 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 6 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 7 */
+
+		/* 7 octets for uint64_2 */
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 1 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 2 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 3 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 4 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 5 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 6 */
+		uint64_2 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_2 & 0xFF); /* 7 */
+
+		/* remaining octets of uint64_3 */
+		while (uint64_3 != 0 && errn == 0) {
+			if(*len >= size) {
+				return EXI_ERROR_OUT_OF_BOUNDS;
+			}
+			data[(*len)++] = uint64_3 & 0xFF;
+			uint64_3 >>= 8;
+		}
+
+	} else if(uint64_2 != 0) {
+		/* 7 octets for uint64_1 */
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 1 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 2 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 3 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 4 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 5 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 6 */
+		uint64_1 >>= 8;
+		if(*len >= size) {
+			return EXI_ERROR_OUT_OF_BOUNDS;
+		}
+		data[(*len)++] = (uint8_t)(uint64_1 & 0xFF); /* 7 */
+		/* remaining octets of uint64_2 */
+		while (uint64_2 != 0 && errn == 0) {
+			if(*len >= size) {
+				return EXI_ERROR_OUT_OF_BOUNDS;
+			}
+			data[(*len)++] = uint64_2 & 0xFF;
+			uint64_2 >>= 8;
+		}
+	} else if(uint64_1 != 0) {
+		while (uint64_1 != 0 && errn == 0) {
+			if(*len >= size) {
+				return EXI_ERROR_OUT_OF_BOUNDS;
+			}
+			data[(*len)++] = uint64_1 & 0xFF;
+			uint64_1 >>= 8;
+		}
+	}
+
+	_reverseArray(data, *len);
+
+	return errn;
 }
 
 int decodeInteger(bitstream_t* stream, exi_integer_t* iv) {
@@ -529,28 +667,28 @@ int decodeInteger64(bitstream_t* stream, int64_t* int64) {
 	}
 
 	return errn;
-}
-
-/**
- * Decode an arbitrary precision integer using a sign bit followed by a
- * sequence of octets. The most significant bit of the last octet is set to
- * zero to indicate sequence termination. Only seven bits per octet are used
- * to store the integer's value.
- */
-int decodeIntegerBig(bitstream_t* stream, int* negative, size_t size, uint8_t* data, size_t* len) {
-	int errn = decodeBoolean(stream, negative);
-
-	if (errn == 0) {
-		if (*negative) {
-			/* For negative values, the Unsigned Integer holds the
-			 * magnitude of the value minus 1 */
-		} else {
-			/* positive */
-		}
-		errn = decodeUnsignedIntegerBig(stream, size, data, len);
-	}
-
-	return errn;
+}
+
+/**
+ * Decode an arbitrary precision integer using a sign bit followed by a
+ * sequence of octets. The most significant bit of the last octet is set to
+ * zero to indicate sequence termination. Only seven bits per octet are used
+ * to store the integer's value.
+ */
+int decodeIntegerBig(bitstream_t* stream, int* negative, size_t size, uint8_t* data, size_t* len) {
+	int errn = decodeBoolean(stream, negative);
+
+	if (errn == 0) {
+		if (*negative) {
+			/* For negative values, the Unsigned Integer holds the
+			 * magnitude of the value minus 1 */
+		} else {
+			/* positive */
+		}
+		errn = decodeUnsignedIntegerBig(stream, size, data, len);
+	}
+
+	return errn;
 }
 
 /**
@@ -637,16 +775,16 @@ int decodeString(bitstream_t* stream, exi_string_t* s) {
  */
 int decodeCharacters(bitstream_t* stream, size_t len, exi_string_character_t* chars, size_t charsSize) {
 	unsigned int i;
-	int errn = 0;
-
-	unsigned int extraChar = 0;
-#if STRING_REPRESENTATION == STRING_REPRESENTATION_ASCII
-	extraChar = 1; /* null terminator */
-#endif /* STRING_REPRESENTATION_ASCII */
-
-	if ( (len + extraChar) > charsSize) {
-		errn = EXI_ERROR_OUT_OF_STRING_BUFFER;
-		return errn;
+	int errn = 0;
+
+	unsigned int extraChar = 0;
+#if STRING_REPRESENTATION == STRING_REPRESENTATION_ASCII
+	extraChar = 1; /* null terminator */
+#endif /* STRING_REPRESENTATION_ASCII */
+
+	if ( (len + extraChar) > charsSize) {
+		errn = EXI_ERROR_OUT_OF_STRING_BUFFER;
+		return errn;
 	}
 
 #if STRING_REPRESENTATION == STRING_REPRESENTATION_ASCII
@@ -679,15 +817,15 @@ int decodeRCSCharacters(bitstream_t* stream, size_t len, exi_string_character_t*
 	unsigned int i;
 	int errn = 0;
 	uint32_t uint32;
-	unsigned int extraChar = 0;
-#if STRING_REPRESENTATION == STRING_REPRESENTATION_ASCII
-	uint8_t b;
-	extraChar = 1; /* null terminator */
-#endif /* STRING_REPRESENTATION_ASCII */
-
-	if ( (len + extraChar) > charsSize) {
-		errn = EXI_ERROR_OUT_OF_STRING_BUFFER;
-		return errn;
+	unsigned int extraChar = 0;
+#if STRING_REPRESENTATION == STRING_REPRESENTATION_ASCII
+	uint8_t b;
+	extraChar = 1; /* null terminator */
+#endif /* STRING_REPRESENTATION_ASCII */
+
+	if ( (len + extraChar) > charsSize) {
+		errn = EXI_ERROR_OUT_OF_STRING_BUFFER;
+		return errn;
 	}