Use jschwinger233/elibpcap to compile and inject libpcap

[jschwinger233]

The https://github.com/jschwinger233/elibpcap has been adopted by several popular projects such as https://github.com/gojue/ecapture, let's use it to simplify the codebase.

Historically, elibpcap was derived from pwru/internal/libpcap/ following #198. The two share nearly identical code and logic, so there should be no compatibility issues in transitioning pwru to use elibpcap.

Signed-off-by: gray [email protected]

[chenhengqi]

Failed to compile locally, the path should be ./libpcap.

[jschwinger233]

What command did you run locally? make release and make are both okay on my local ubuntu.

[chenhengqi]

I don't know why this is supposed to work locally. The CI build with docker which set workdir to /pwru so there is no problem.

[rgo3]

I agree that this shouldn't be an absolute path, otherwise e.g. make pwru will fail on hosts where /pwru/libpcap/ does not exist. We could also consider using -L$(CURDIR)/libpcap.

[brb]

If I run make, I get the following error:

CGO_CFLAGS="-I/pwru/libpcap" CGO_LDFLAGS="-L/pwru/libpcap -lpcap -static" CC=cc GOARCH=amd64 CGO_ENABLED=1 go build  \
        -ldflags "-w -s \
        -X 'github.com/cilium/pwru/internal/pwru.Version=v1.0.10-pre-69-g3c948a7'"
# github.com/jschwinger233/elibpcap
vendor/github.com/jschwinger233/elibpcap/compile.go:15:10: fatal error: pcap.h: No such file or directory
   15 | #include <pcap.h>
      |          ^~~~~~~~
compilation terminated.
make: *** [Makefile:24: pwru] Error 1

The issue goes away if I apply the following diff:

diff --git a/vendor/github.com/jschwinger233/elibpcap/compile_static.go b/vendor/github.com/jschwinger233/elibpcap/compile_static.go
index 928555f..366d101 100644
--- a/vendor/github.com/jschwinger233/elibpcap/compile_static.go
+++ b/vendor/github.com/jschwinger233/elibpcap/compile_static.go
@@ -1,12 +1,12 @@
+//go:build static || !dynamic
 // +build static !dynamic

 package elibpcap

-
 /*
-#cgo LDFLAGS: -L/usr/local/lib -lpcap -static
+#cgo CFLAGS: -I${SRCDIR}/../../../../libpcap
+#cgo LDFLAGS: -L${SRCDIR}/../../../../libpcap -lpcap -static
 #include <stdlib.h>
 #include <pcap.h>
 */
 import "C"

@jschwinger233 One solution would be to ship the libcap in the jschwinger233/elibpcap?

[brb]

One solution would be to ship the libcap in the jschwinger233/elibpcap?

@jschwinger233 👋 Would you accept such a contribution?

[jschwinger233]

Thank you for suggestion! I believe shipping libpcap in elibpcap is the correct direction. I am learning from https://github.com/mattn/go-sqlite3 to see how to do it properly, then I'll upgrade the pr. 🙏