On 5/1/06, Fabrice Bellard <[EMAIL PROTECTED]> wrote:
Why not changing the definition itself to uint16_t and verifying each
occurence of ip_off and ip_len ?
Indeed, why not. This is the solution adopted by Apple's OpenDarwin
(another BSD derivative). The attached patch changes the signed
definitions to unsigned.
I tried to verify by inspecting each occurrence of ip_off and ip_len;
in cases where the values are implicitly converted, the unsigned short
is converted to a signed int, which should be OK assuming 32-bit ints.
Does qemu support any platforms with 16-bit ints?
I also ran some tests (on i386 Linux) to ensure that slirp still works
as expected, and also handles packets > 32KB. Of course, more testing
on other platforms would be welcome.
--Ed
diff -BurN qemu.orig/slirp/ip.h qemu/slirp/ip.h
--- qemu.orig/slirp/ip.h 2004-04-22 00:10:47.000000000 +0000
+++ qemu/slirp/ip.h 2006-05-02 02:07:34.000000000 +0000
@@ -75,10 +75,6 @@
/*
* Structure of an internet header, naked of options.
- *
- * We declare ip_len and ip_off to be short, rather than u_short
- * pragmatically since otherwise unsigned comparisons can result
- * against negative integers quite easily, and fail in subtle ways.
*/
struct ip {
#ifdef WORDS_BIGENDIAN
@@ -89,9 +85,9 @@
ip_v:4; /* version */
#endif
u_int8_t ip_tos; /* type of service */
- int16_t ip_len; /* total length */
+ u_int16_t ip_len; /* total length */
u_int16_t ip_id; /* identification */
- int16_t ip_off; /* fragment offset field */
+ u_int16_t ip_off; /* fragment offset field */
#define IP_DF 0x4000 /* don't fragment flag */
#define IP_MF 0x2000 /* more fragments flag */
#define IP_OFFMASK 0x1fff /* mask for fragmenting bits */
@@ -212,7 +208,7 @@
caddr32_t ih_next, ih_prev; /* for protocol sequence q's */
u_int8_t ih_x1; /* (unused) */
u_int8_t ih_pr; /* protocol */
- int16_t ih_len; /* protocol length */
+ u_int16_t ih_len; /* protocol length */
struct in_addr ih_src; /* source internet address */
struct in_addr ih_dst; /* destination internet address */
};
@@ -253,9 +249,9 @@
u_int8_t ipf_mff; /* XXX overlays ip_tos: use low bit
* to avoid destroying tos (PPPDTRuu);
* copied from (ip_off&IP_MF) */
- int16_t ip_len;
+ u_int16_t ip_len;
u_int16_t ip_id;
- int16_t ip_off;
+ u_int16_t ip_off;
u_int8_t ip_ttl;
u_int8_t ip_p;
u_int16_t ip_sum;
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