Bug 31649
| Summary: | libpcap doesn't work with -pthread | ||
|---|---|---|---|
| Product: | Base System | Reporter: | edwin |
| Component: | bin | Assignee: | freebsd-bugs (Nobody) <bugs> |
| Status: | Closed FIXED | ||
| Severity: | Affects Only Me | ||
| Priority: | Normal | ||
| Version: | 4.4-RELEASE | ||
| Hardware: | Any | ||
| OS: | Any | ||
Some minor further investigations in libpcap showed that the read()
function in /usr/src/contrib/libpcap/pcap-bpf.c:81 looks like it's
blocking until the buffer is fully filled:
if (p->cc == 0) {
+ fprintf(stderr,"pcap_read before read (bufsize: %d bytes)\n",p->bufsize);
cc = read(p->fd, (char *)p->buffer, p->bufsize);
+ fprintf(stderr,"pcap_read after read (read: %d bytes)\n",cc);
if (cc < 0) {
This is the effect on a version without -pthread:
[~/bpf] edwin@friet44>./nw_u
pcap_read entered
pcap_read before read (bufsize: 32768 bytes)
pcap_read after read (read: 244 bytes)
..pcap_read entered
pcap_read before read (bufsize: 32768 bytes)
pcap_read after read (read: 276 bytes)
..pcap_read entered
This is the effect on a version with -pthread:
[~/bpf] edwin@friet44>./nw
pcap_read entered
pcap_read before read bufsize: (32768 bytes)
pcap_read after read (read: 32232 bytes)
...........................................................pcap_read entered
pcap_read before read (bufsize: 32768 bytes)
pcap_read after read (read: 32160 bytes)
.........................................................pcap_read entered
pcap_read before read (bufsize: 32768 bytes)
pcap_read after read (read: 31648 bytes)
I have no idea how to solve this...
Edwin
--
Edwin Groothuis | Personal website: http://www.MavEtJu.org
edwin@mavetju.org | Interested in MUDs? Visit Fatal Dimensions:
------------------+ http://www.FatalDimensions.org/
I've tried the solution as suggested on:
http://archives.neohapsis.com/archives/openbsd/2001-03/0857.html
At least the threading works with it, but the data is still coming
in a burst instead of on a per-packet base like in a normal unthreaded
environment.
Edwin
--
Edwin Groothuis | Personal website: http://www.MavEtJu.org
edwin@mavetju.org | Interested in MUDs? Visit Fatal Dimensions:
------------------+ http://www.FatalDimensions.org/
In essence, this is the same problem as identified in PR 22063. If no one objects, I'll close this in a couple of days. I have submitted a patch to PR 22063 that solves this problem in the kernel code. Guy State Changed From-To: open->closed Fixed in sys/net/bpf.c revision 1.59.2.8 and sys/net/bpfdesc.h revision 1.14.2.2. |
When compiling a program which listens to a network device via the pcap-library with -pthread, it stops working in the pcap_loop() bits. Fix: none known. How-To-Repeat: #include <pcap.h> #include <net/bpf.h> #include <stdlib.h> #include <string.h> #include <signal.h> #include <sys/ioctl.h> pcap_t *pd = NULL; char *dev = "fxp0"; int link_offset; int link_type; int snaplen = 65535, promisc = 1, to = 1000; char pc_err[PCAP_ERRBUF_SIZE]; void networkinit(void) { if ((pd = pcap_open_live(dev, snaplen, promisc, to, pc_err)) == NULL) { perror(pc_err); exit(-1); } } void process(u_char *data1, struct pcap_pkthdr* h, u_char *p) { fprintf(stderr,"."); } void networkrun(void) { while (pcap_loop(pd, 0, (pcap_handler)process, 0)); exit(-2); } int main(void) { networkinit(); networkrun(); } (You might have to tweak the fxp0 in the dev-variable) Compile as "gcc -Wall -o nw nw.c -lpcap". It will print a dot for every IP packet. Compile as "gcc -Wall -o nw nw.c -lpcap -pthread". It will print nothing.