szymonwieloch / rust-rawsock Goto Github PK

I'm using wpcap as backend. My program uses multithreading to send packets, but it panics when the rate is fast.

thread '<unnamed>' panicked at 'assertion failed: `(left == right)`
  left: `-1`,
 right: `0`', .....\rawsock-0.3.0\src\wpcap\interface.rs:85:13

Maybe instead of panic here, return a Result::Err(). This is helpful for error handling

It seems that we prefer npcap. But when WinPcap and npcap coexist, rawsock actually loads WinPcap.

Since Npcap\wpcap.dll searchs Packet.dll instead of Npcap\Packet.dll(could be seen using procmon), and Npcap\wpcap.dll wouldn't load correctly with wrong Packet.dll.

And because what we need is wpcap.dll, I think all Packet.dll could be removed from default paths.

Solution:

I think it should be an issue about dlopen.

According to the document (npcap-sdk-1.03/docs/npcap-devguide.html#npcap-feature-native in npcap-sdk-1.03.zip), we need to call SetDllDirectory to make wpcap.dll loading right dll.

You need to do the following one step:

Before calling LoadLibrary to load wpcap.dll, call SetDllDirectory to add C:\Windows\System32\Npcap\ to DLL search path.

Command: cargo run --example dynamic

Opening packet capturing library
Library opened, version is  pcap libpcap version 1.8.1 -- Apple version 79.200.4
Opening the en0 interface
Interface opened, data link: ethernet
Sending 5 packets:
Sending ICMP ping packet no 0
Sending ICMP ping packet no 1
Sending ICMP ping packet no 2
Sending ICMP ping packet no 3
Sending ICMP ping packet no 4
Receiving 5 packets:
[1]    20518 segmentation fault  cargo run --example dynamic

I think uncomment this two line should work.

pcap.h

struct pcap_pkthdr {
	struct timeval ts;	/* time stamp */
	bpf_u_int32 caplen;	/* length of portion present */
	bpf_u_int32 len;	/* length this packet (off wire) */
#ifdef __APPLE__
	char comment[256];
#endif
};

tv_usec is 64bit unsigned integer.

But on macOS, tv_usec is 32bit unsigned integer with 32bit padding:

/usr/include/sys/_types/_timeval.h

#ifndef _STRUCT_TIMEVAL
#define _STRUCT_TIMEVAL		struct timeval

#include <machine/types.h> /* __darwin_time_t */
#include <sys/_types.h> /* __darwin_suseconds_t */

_STRUCT_TIMEVAL
{
	__darwin_time_t	        tv_sec;	        /* seconds */
	__darwin_suseconds_t    tv_usec;        /* and microseconds */
};
#endif /* _STRUCT_TIMEVAL */

/usr/include/sys/_types.h

typedef __int32_t	__darwin_suseconds_t;	/* [???] microseconds */

And using ida to see how the struct looks like:

00000000 timeval         struc ; (sizeof=0x10, align=0x8, copyof_63)
00000000                                         ; XREF: _uv__fs_futime/r
00000000                                         ; _uv__fs_utime/r ...
00000000 tv_sec          dq ?                    ; XREF: _uv_getrusage:loc_1001258B9/r
00000000                                         ; _uv_getrusage+56/r ...
00000008 tv_usec         dd ?                    ; XREF: _uv_getrusage+47/r
00000008                                         ; _uv_getrusage+65/r ...
0000000C                 db ? ; undefined
0000000D                 db ? ; undefined
0000000E                 db ? ; undefined
0000000F                 db ? ; undefined
00000010 timeval         ends

With this declaration, rawsock works fine on my machine.

///Equivalent of C struct timeval_t
#[repr(C)]
#[derive(Copy, Clone, Debug)]
pub struct TimeVal {
    pub tv_sec: c_long,         /* seconds */
    pub tv_usec: c_uint        /* and microseconds */
}

the tag name should be v0.2.1

https://github.com/szymonwieloch/rust-rawsock/tree/v02.1

Hey,

I was going to look into making this work with PF_RING ZC if it doesn't already...
Is that something you've considered / looked at?

Very new to both Rust and userspace networking but currently building a low-latency network application and loving this library already!

Cheers

switch-lan-play@b64f79b

btw I also want trait Interface and Library impls Send and Sync for multi-thread. Because I need to break loop from other thread.