From 3558d8841d2aa23c8717e3249480c138232b1a72 Mon Sep 17 00:00:00 2001
From: Matthias Ringwald <matthias@ringwald.ch>
Date: Tue, 19 Sep 2017 17:11:13 +0200
Subject: [PATCH] sdp_util: add de_get_len_safe, use uint32_t for length
 functions

---
 src/classic/sdp_util.c | 16 ++++++++++++++--
 src/classic/sdp_util.h |  9 +++++++--
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/src/classic/sdp_util.c b/src/classic/sdp_util.c
index 9be72813b..2a7dce94b 100644
--- a/src/classic/sdp_util.c
+++ b/src/classic/sdp_util.c
@@ -78,7 +78,7 @@ de_type_t de_get_element_type(const uint8_t *header){
     return (de_type_t) (header[0] >> 3);
 }
 
-int de_get_header_size(const uint8_t * header){
+uint32_t de_get_header_size(const uint8_t * header){
     de_size_t de_size = de_get_size_type(header);
     if (de_size <= DE_SIZE_128) {
         return 1;
@@ -86,7 +86,7 @@ int de_get_header_size(const uint8_t * header){
     return 1 + (1 << (de_size-DE_SIZE_VAR_8));
 }
 
-int de_get_data_size(const uint8_t * header){
+uint32_t de_get_data_size(const uint8_t * header){
     uint32_t result = 0;
     de_type_t de_type = de_get_element_type(header);
     de_size_t de_size = de_get_size_type(header);
@@ -116,6 +116,18 @@ int de_get_len(const uint8_t *header){
     return de_get_header_size(header) + de_get_data_size(header); 
 }
 
+// returns data element length if data element fits in size
+uint32_t de_get_len_safe(const uint8_t * header, uint32_t size){
+    if (1           > size) return 0;
+    uint32_t header_size = de_get_header_size(header);
+    if (header_size > size) return 0;
+    uint32_t data_size   = de_get_data_size(header);
+    if (data_size   > size) return 0;
+    uint32_t de_len      = header_size + data_size;
+    if (de_len      > size) return 0;
+    return de_len;
+}
+
 // @returns OK, if UINT16 value was read
 int de_element_get_uint16(const uint8_t * element, uint16_t * value){
     if (de_get_size_type(element) != DE_SIZE_16) return 0;
diff --git a/src/classic/sdp_util.h b/src/classic/sdp_util.h
index 2e6d5e884..d0f74d8a6 100644
--- a/src/classic/sdp_util.h
+++ b/src/classic/sdp_util.h
@@ -76,11 +76,13 @@ typedef enum {
 // MARK: DateElement
 void      de_dump_data_element(const uint8_t * record);
 int       de_get_len(const uint8_t * header);
+
+
 de_size_t de_get_size_type(const uint8_t * header);
 de_type_t de_get_element_type(const uint8_t * header);
-int       de_get_header_size(const uint8_t * header);
+uint32_t  de_get_header_size(const uint8_t * header);
 int       de_element_get_uint16(const uint8_t * element, uint16_t * value);
-int       de_get_data_size(const uint8_t * header);
+uint32_t  de_get_data_size(const uint8_t * header);
 uint32_t  de_get_uuid32(const uint8_t * element);
 int       de_get_normalized_uuid(uint8_t *uuid128, const uint8_t *element);
 
@@ -93,6 +95,9 @@ void      de_add_data( uint8_t *seq, de_type_t type, uint16_t size, uint8_t *dat
 
 void      de_add_uuid128(uint8_t * seq, uint8_t * uuid);
 
+// returns data element  len if date element is smaller than size
+uint32_t de_get_len_safe(const uint8_t * header, uint32_t size);
+
 // MARK: DES iterator
 typedef struct {
     uint8_t * element;