GH-696: Add bytestring_to_float BIF

src/net_util.h

@@ -261,6 +261,15 @@ inline double htond(double d)
 	return d;
 	}
 
+inline float ntohf(float f)
+	{
+	return f;
+	}
+inline float htonf(float f)
+	{
+	return f;
+	}
+
 #ifndef HAVE_BYTEORDER_64
 inline uint64_t ntohll(uint64_t i)
 	{
@@ -299,6 +308,27 @@ inline double htond(double d)
 	return ntohd(d);
 	}
 
+inline float ntohf(float f)
+	{
+	assert(sizeof(f) == 4);
+
+	float tmp;
+	char* src = (char*)&f;
+	char* dst = (char*)&tmp;
+
+	dst[0] = src[3];
+	dst[1] = src[2];
+	dst[2] = src[1];
+	dst[3] = src[0];
+
+	return tmp;
+	}
+
+inline float htonf(float f)
+	{
+	return ntohf(f);
+	}
+
 #ifndef HAVE_BYTEORDER_64
 inline uint64_t ntohll(uint64_t i)
 	{

src/zeek.bif

@@ -2831,13 +2831,16 @@ function to_port%(s: string%): port
     return zeek::val_mgr->Port(port, TRANSPORT_UNKNOWN);
 	%}
 
-## Converts a string of bytes (in network byte order) to a :zeek:type:`double`.
+## Converts a string of bytes representing a double value (in network byte order)
+## to a :zeek:type:`double`. This is similar to :zeek:id:`bytestring_to_float`
+## but works on 8-byte strings.
 ##
 ## s: A string of bytes containing the binary representation of a double value.
 ##
 ## Returns: The double value contained in *s*, or 0 if the conversion
 ##          failed.
 ##
+## .. zeek:see:: bytestring_to_float
 function bytestring_to_double%(s: string%): double
 	%{
 	if ( s->Len() != sizeof(double) )
@@ -2852,6 +2855,29 @@ function bytestring_to_double%(s: string%): double
 	return zeek::make_intrusive<zeek::DoubleVal>(ntohd(d));
 	%}
 
+## Converts a string of bytes representing a float value (in network byte order)
+## to a :zeek:type:`double`. This is similar to :zeek:id:`bytestring_to_double`
+## but works on 4-byte strings.
+##
+## s: A string of bytes containing the binary representation of a float value.
+##
+## Returns: The float value contained in *s*, or 0 if the conversion
+##          failed.
+##
+## .. zeek:see:: bytestring_to_double
+function bytestring_to_float%(s: string%): double
+	%{
+	if ( s->Len() != sizeof(float) )
+		{
+		zeek::emit_builtin_error("bad conversion to float");
+		return zeek::make_intrusive<zeek::DoubleVal>(0.0);
+		}
+
+	float f;
+	memcpy(&f, s->Bytes(), sizeof(float));
+	return zeek::make_intrusive<zeek::DoubleVal>(ntohf(f));
+	%}
+
 ## Converts a string of bytes to a :zeek:type:`count`.
 ##
 ## s: A string of bytes containing the binary representation of the value.

testing/btest/Baseline/bifs.bytestring_to_double/out

@@ -8,3 +8,4 @@ inf
 -inf
 nan
 4.94e-324
+0.0

testing/btest/Baseline/bifs.bytestring_to_float/out

@@ -0,0 +1,11 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+3.139244209995776e+15
+-3.139244209995776e+15
+4.000000e-38
+0.000000e+00
+-0.000000e+00
+inf
+-inf
+nan
+1.40e-45
+0.0

testing/btest/bifs/bytestring_to_double.zeek

@@ -23,4 +23,7 @@ event zeek_init()
 	print bytestring_to_double(s7);
 	print bytestring_to_double(s8);
 	print fmt("%.2e", bytestring_to_double(s9));
+
+	# Error case, passing an incorrectly-sized string. This returns zero.
+	print bytestring_to_double("\x00\x00\x00\x00\x00\x00\x00");
 	}

testing/btest/bifs/bytestring_to_float.zeek

@@ -0,0 +1,29 @@
+#
+# @TEST-EXEC: zeek -b %INPUT >out
+# @TEST-EXEC: btest-diff out
+
+event zeek_init()
+	{
+	local s1 = "\x59\x32\x72\x04"; # 3.14e15
+	local s2 = "\xd9\x32\x72\x04"; #-3.14e15
+	local s3 = "\x01\x59\xc7\xdd"; # 4e-38
+	local s4 = "\x00\x00\x00\x00"; # 0.0
+	local s5 = "\x80\x00\x00\x00"; #-0.0
+	local s6 = "\x7f\x80\x00\x00"; # Inf
+	local s7 = "\xff\x80\x00\x00"; #-Inf
+	local s8 = "\x7f\xc0\x00\x00"; # NaN
+	local s9 = "\x00\x00\x00\x01"; # subnormal
+
+	print bytestring_to_float(s1);
+	print bytestring_to_float(s2);
+	print fmt("%e", bytestring_to_float(s3));
+	print fmt("%e", bytestring_to_float(s4));
+	print fmt("%e", bytestring_to_float(s5));
+	print bytestring_to_float(s6);
+	print bytestring_to_float(s7);
+	print bytestring_to_float(s8);
+	print fmt("%.2e", bytestring_to_float(s9));
+
+	# Error case, passing an incorrectly-sized string. This returns zero.
+	print bytestring_to_float("\x00\x00\x00");
+	}