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capture.go
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capture.go
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package httpcap
import (
"context"
"fmt"
"github.com/google/gopacket"
"github.com/google/gopacket/layers"
"github.com/google/gopacket/pcap"
"github.com/google/gopacket/reassembly"
"github.com/uole/httpcap/http"
"github.com/uole/httpcap/internal/factory"
tcpFactory "github.com/uole/httpcap/internal/factory/tcp"
"strconv"
"strings"
"time"
)
type Capture struct {
ctx context.Context
iface string
snaplen int
filter *Filter
packChan chan gopacket.Packet
handle *pcap.Handle
handleFunc factory.HandleFunc
}
func (cap *Capture) process(req *http.Request, res *http.Response) {
if !cap.filter.Match(req.Host) {
req.Release()
res.Release()
return
}
if cap.handleFunc != nil {
cap.handleFunc(req, res)
}
}
func (cap *Capture) ioLoop(assembler *reassembly.Assembler) {
ticker := time.NewTicker(time.Minute)
defer func() {
ticker.Stop()
assembler.FlushAll()
}()
for {
select {
case pkg := <-cap.packChan:
if pkg == nil {
return
}
if tcp, ok := pkg.TransportLayer().(*layers.TCP); ok {
assembler.AssembleWithContext(pkg.NetworkLayer().NetworkFlow(), tcp, &AssemblerContext{captureInfo: pkg.Metadata().CaptureInfo})
}
case <-ticker.C:
assembler.FlushCloseOlderThan(time.Now().Add(time.Minute * -3))
case <-cap.ctx.Done():
return
}
}
}
func (cap *Capture) grantRules() []string {
rules := make([]string, 0)
rules = append(rules, "tcp")
if cap.filter.Port > 0 {
rules = append(rules, "port "+strconv.Itoa(cap.filter.Port))
}
if cap.filter.IP != "" {
rules = append(rules, "host "+cap.filter.IP)
}
return rules
}
func (cap *Capture) WithHandle(f factory.HandleFunc) *Capture {
cap.handleFunc = f
return cap
}
func (cap *Capture) Start(ctx context.Context) (err error) {
var (
ifs []pcap.Interface
rules []string
assembler *reassembly.Assembler
)
cap.ctx = ctx
if cap.iface == "" {
if ifs, err = pcap.FindAllDevs(); err != nil {
return
}
for _, i := range ifs {
fmt.Println(i.Name, i.Description, i.Addresses)
}
}
if cap.handle, err = pcap.OpenLive(cap.iface, int32(cap.snaplen), true, pcap.BlockForever); err != nil {
return
}
if cap.filter.BPF != "" {
if err = cap.handle.SetBPFFilter(cap.filter.BPF); err != nil {
return
}
} else {
rules = cap.grantRules()
if len(rules) > 0 {
bpf := strings.Join(rules, " and ")
if err = cap.handle.SetBPFFilter(bpf); err != nil {
return
}
}
}
streamFactory := tcpFactory.New(cap.ctx, cap.process)
streamPool := reassembly.NewStreamPool(streamFactory)
assembler = reassembly.NewAssembler(streamPool)
source := gopacket.NewPacketSource(cap.handle, cap.handle.LinkType())
source.NoCopy = true
cap.packChan = source.Packets()
go cap.ioLoop(assembler)
return
}
func (cap *Capture) Stop() (err error) {
cap.handle.Close()
return
}
func NewCapture(iface string, snaplen int, filter *Filter) *Capture {
return &Capture{
iface: iface,
snaplen: snaplen,
filter: filter,
}
}