public-ip-tracker/tracker/ip/ip.go
Melora Hugues 568aaa9f8c
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Add publig IP getter
Ref #3

This commit uses a GET query to ifconfig.me in order to get the current
public IP. It also modifies the initialization message to send the
current public IP to the Telegram channel instead of a simple message.
2023-01-25 21:06:00 +01:00

52 lines
1.2 KiB
Go

package ip
import (
"bytes"
"context"
"fmt"
"io"
"net"
"net/http"
)
const ifconfigURL = "https://ifconfig.me"
const httpMaxRead = 100
// TODO: use a struct, but a baseHTTPClient inside it to perform unit tests
type Getter interface {
GetCurrentPublicIP(ctx context.Context) (net.IP, error)
}
type concreteIPGetter struct {
}
func (c *concreteIPGetter) GetCurrentPublicIP(ctx context.Context) (net.IP, error) {
req, err := http.NewRequestWithContext(ctx, http.MethodGet, ifconfigURL, nil)
if err != nil {
return nil, fmt.Errorf("failed to prepare public IP request: %w", err)
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
return nil, fmt.Errorf("failed to get current IP from ifconfig: %w", err)
}
if resp.ContentLength > httpMaxRead {
return nil, fmt.Errorf("response too big: %d/%d", resp.ContentLength, httpMaxRead)
}
buf := bytes.NewBuffer([]byte{})
if _, err := io.CopyN(buf, resp.Body, resp.ContentLength); err != nil {
return nil, fmt.Errorf("error parsing body: %w", err)
}
content := string(buf.Bytes())
res := net.ParseIP(content)
if res == nil {
return nil, fmt.Errorf("got an invalid public IP %q", content)
}
return res, nil
}
func New() *concreteIPGetter {
return &concreteIPGetter{}
}