added network config

2019-11-29 19:53:17 +01:00
parent ce335164ff
commit d7e0591576
6 changed files with 310 additions and 4 deletions
--- a/network.go
+++ b/network.go
@@ -0,0 +1,171 @@
+package alpine_builder
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"regexp"
+	"strings"
+)
+
+// network configuration
+var networkConfig = "/data/etc/network/interfaces"
+var networkInterface = "eth0"
+
+// regular expressions
+var reSectionStart = regexp.MustCompile("^(iface|mapping|auto|allow-|source)")
+var reIface = regexp.MustCompile("^iface (\\w+) inet (\\w+)")
+var reStaticAddress = regexp.MustCompile("^(\\s*)address ([0-9.]+)")
+var reStaticNetmask = regexp.MustCompile("^(\\s*)netmask ([0-9.]+)")
+var reStaticGateway = regexp.MustCompile("^(\\s*)gateway ([0-9.]+)")
+
+// NetworkInfo represents the actual network configuration
+type NetworkInfo struct {
+	IsStatic bool
+	Address  string
+	Netmask  string
+	Gateway  string
+}
+
+// GetNetworkInfo from config file
+func GetNetworkInfo() (*NetworkInfo, error) {
+	// load config file
+	file, err := os.Open(networkConfig)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open network config: %w", err)
+	}
+	defer file.Close()
+
+	var info *NetworkInfo
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+
+		// check for section start
+		if reSectionStart.MatchString(line) {
+			infLine := reIface.FindStringSubmatch(line)
+			if infLine != nil {
+				// interface found
+				if infLine[1] == networkInterface {
+					info = &NetworkInfo{
+						IsStatic: infLine[2] == "static",
+					}
+				}
+			} else {
+				// info set -> stop here
+				if info != nil {
+					break
+				}
+			}
+
+		} else if info != nil {
+			// interface config
+			address := reStaticAddress.FindStringSubmatch(line)
+			if address != nil {
+				info.Address = address[2]
+			}
+			netmask := reStaticNetmask.FindStringSubmatch(line)
+			if netmask != nil {
+				info.Netmask = netmask[2]
+			}
+			gateway := reStaticGateway.FindStringSubmatch(line)
+			if gateway != nil {
+				info.Gateway = gateway[2]
+			}
+		}
+	}
+	if info != nil {
+		return info, nil
+	}
+	return nil, errors.New("invalid network config")
+}
+
+// NetworkEnableDHCP configures the network to use DHCP client
+func NetworkEnableDHCP() error {
+	// load config file
+	file, err := os.Open(networkConfig)
+	if err != nil {
+		return fmt.Errorf("failed to open network config: %w", err)
+	}
+	defer file.Close()
+
+	var buffer bytes.Buffer
+	var infFound bool
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+
+		// check for section start
+		if reSectionStart.MatchString(line) {
+			infLine := reIface.FindStringSubmatch(line)
+			if infLine != nil {
+				// interface found
+				if infLine[1] == networkInterface {
+					infFound = true
+					buffer.WriteString(fmt.Sprintf("iface %s inet dhcp\n", networkInterface))
+					continue
+				}
+			} else {
+				if infFound {
+					infFound = false
+				}
+			}
+			buffer.WriteString(line + "\n")
+
+		} else if !infFound {
+			buffer.WriteString(line + "\n")
+		}
+	}
+
+	// write config file
+	return ioutil.WriteFile(networkConfig, buffer.Bytes(), os.ModePerm)
+}
+
+// NetworkSetStatic IP configuration
+func NetworkSetStatic(address, netmask, gateway string) error {
+	// load config file
+	file, err := os.Open(networkConfig)
+	if err != nil {
+		return fmt.Errorf("failed to open network config: %w", err)
+	}
+	defer file.Close()
+
+	var buffer bytes.Buffer
+	var infFound bool
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+
+		// check for section start
+		if reSectionStart.MatchString(line) {
+			infLine := reIface.FindStringSubmatch(line)
+			if infLine != nil {
+				// interface found
+				if infLine[1] == networkInterface {
+					infFound = true
+					buffer.WriteString(fmt.Sprintf("iface %s inet static\n", networkInterface))
+					buffer.WriteString(fmt.Sprintf("  address %s\n", address))
+					buffer.WriteString(fmt.Sprintf("  netmask %s\n", netmask))
+					buffer.WriteString(fmt.Sprintf("  gateway %s\n", gateway))
+					continue
+				}
+			} else {
+				if infFound {
+					infFound = false
+				}
+			}
+			buffer.WriteString(line + "\n")
+
+		} else if !infFound {
+			buffer.WriteString(line + "\n")
+		}
+	}
+
+	// write config file
+	return ioutil.WriteFile(networkConfig, buffer.Bytes(), os.ModePerm)
+}