Pretty: limit the number of recursions, like the Parser

The pretty-dumper code did not have a limit, assuming that the input had
been validated beforehand, so if the nesting was too deep, one would
have got an error before getting to the dumper.

However, it's not inconceivable that someone adds a logger code to a
packet a bit too early. So let's be defensive and apply the limiter here
too.

Signed-off-by: Thiago Macieira <[email protected]>

Author: thiagomacieira

src/cborinternal_p.h

@@ -31,6 +31,10 @@
 #  define CBOR_INTERNAL_API
 #endif
 
+#ifndef CBOR_PARSER_MAX_RECURSIONS
+#  define CBOR_PARSER_MAX_RECURSIONS 1024
+#endif
+
 /*
  * CBOR Major types
  * Encoded in the high 3 bits of the descriptor byte

src/cborparser.c

@@ -38,10 +38,6 @@
 
 #include <string.h>
 
-#ifndef CBOR_PARSER_MAX_RECURSIONS
-#  define CBOR_PARSER_MAX_RECURSIONS 1024
-#endif
-
 /**
  * \defgroup CborParsing Parsing CBOR streams
  * \brief Group of functions used to parse CBOR streams.

src/cborpretty.c

@@ -147,6 +147,11 @@
  * \value CborPrettyDefaultFlags       Default conversion flags.
  */
 
+static void printRecursionLimit(FILE *out)
+{
+    fputs("<nesting too deep, recursion stopped>", out);
+}
+
 static CborError hexDump(FILE *out, const void *ptr, size_t n)
 {
     const uint8_t *buffer = (const uint8_t *)ptr;
@@ -273,16 +278,22 @@ static const char *get_indicator(const CborValue *it, int flags)
     return resolve_indicator(it->ptr, it->parser->end, flags);
 }
 
-static CborError value_to_pretty(FILE *out, CborValue *it, int flags);
-static CborError container_to_pretty(FILE *out, CborValue *it, CborType containerType, int flags)
+static CborError value_to_pretty(FILE *out, CborValue *it, int flags, int recursionsLeft);
+static CborError container_to_pretty(FILE *out, CborValue *it, CborType containerType,
+                                     int flags, int recursionsLeft)
 {
+    if (!recursionsLeft) {
+        printRecursionLimit(out);
+        return CborNoError; /* do allow the dumping to continue */
+    }
+
     const char *comma = "";
     while (!cbor_value_at_end(it)) {
         if (fprintf(out, "%s", comma) < 0)
             return CborErrorIO;
         comma = ", ";
 
-        CborError err = value_to_pretty(out, it, flags);
+        CborError err = value_to_pretty(out, it, flags, recursionsLeft);
         if (err)
             return err;
 
@@ -292,14 +303,14 @@ static CborError container_to_pretty(FILE *out, CborValue *it, CborType containe
         /* map: that was the key, so get the value */
         if (fprintf(out, ": ") < 0)
             return CborErrorIO;
-        err = value_to_pretty(out, it, flags);
+        err = value_to_pretty(out, it, flags, recursionsLeft);
         if (err)
             return err;
     }
     return CborNoError;
 }
 
-static CborError value_to_pretty(FILE *out, CborValue *it, int flags)
+static CborError value_to_pretty(FILE *out, CborValue *it, int flags, int recursionsLeft)
 {
     CborError err;
     CborType type = cbor_value_get_type(it);
@@ -319,7 +330,7 @@ static CborError value_to_pretty(FILE *out, CborValue *it, int flags)
             it->ptr = recursed.ptr;
             return err;       /* parse error */
         }
-        err = container_to_pretty(out, &recursed, type, flags);
+        err = container_to_pretty(out, &recursed, type, flags, recursionsLeft - 1);
         if (err) {
             it->ptr = recursed.ptr;
             return err;       /* parse error */
@@ -424,7 +435,10 @@ static CborError value_to_pretty(FILE *out, CborValue *it, int flags)
         err = cbor_value_advance_fixed(it);
         if (err)
             return err;
-        err = value_to_pretty(out, it, flags);
+        if (recursionsLeft)
+            err = value_to_pretty(out, it, flags, recursionsLeft - 1);
+        else
+            printRecursionLimit(out);
         if (err)
             return err;
         if (fprintf(out, ")") < 0)
@@ -533,7 +547,7 @@ static CborError value_to_pretty(FILE *out, CborValue *it, int flags)
  */
 CborError cbor_value_to_pretty_advance(FILE *out, CborValue *value)
 {
-    return value_to_pretty(out, value, CborPrettyDefaultFlags);
+    return value_to_pretty(out, value, CborPrettyDefaultFlags, CBOR_PARSER_MAX_RECURSIONS);
 }
 
 /**
@@ -552,7 +566,7 @@ CborError cbor_value_to_pretty_advance(FILE *out, CborValue *value)
  */
 CborError cbor_value_to_pretty_advance_flags(FILE *out, CborValue *value, int flags)
 {
-    return value_to_pretty(out, value, flags);
+    return value_to_pretty(out, value, flags, CBOR_PARSER_MAX_RECURSIONS);
 }
 
 /** @} */