Plamen Alexandrov wrote... > Depending on the endian of the system, the macros le64toh(), > be64toh(), htole64(), htobe64(), etc. could not return a 64-bit type. > This can lead to issues ranging from compilation errors to runtime > crashes.
Yepp, ran into crashes.
The same problem exists for the ntoh*/hton* functions in <in.h>. On big-
endian architectures, the input value is passed unchanged; on litte
endian it's capped to the respective size by __bswap_*
Reproducer:
======================================================================
#include <netinet/in.h>
#include <stdio.h>
int main (int argc, char **argv) {
long l1 = 0x12345678;
long l2 = ntohs (l1);
printf ("Got: %08lx\n", l2);
long long ll1 = 0x123456789abcdef;
long long ll2 = ntohl (ll1);
printf ("Got: %016llx\n", ll2);
}
======================================================================
Enable optimizations (-O2 -Wall) when building.
Result on amd64:
| Got: 00007856
| Got: 00000000efcdab89
Result on powerpc and ppc64:
| Got: 12345678
| Got: 0123456789abcdef
... which is out the domain for uint16_t and uint32_t resp.
My suggested fix is to mask the according bits:
@@ -393,10 +393,10 @@
# if __BYTE_ORDER == __BIG_ENDIAN
/* The host byte order is the same as network byte order,
so these functions are all just identity. */
-# define ntohl(x) (x)
-# define ntohs(x) (x)
-# define htonl(x) (x)
-# define htons(x) (x)
+# define ntohl(x) ((x)&0xffffffff)
+# define ntohs(x) ((x)&0xffff)
+# define htonl(x) ((x)&0xffffffff)
+# define htons(x) ((x)&0xffff)
# else
# if __BYTE_ORDER == __LITTLE_ENDIAN
# define ntohl(x) __bswap_32 (x)
This results in a consistent output:
| Got: 00005678
| Got: 0000000089abcdef
The worse part is gcc doesn't even raise warnings from this.
Christoph
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