Swift和C混合Socket編程實現簡單的ping命令

這個是用Mac下的Network Utility工具實現ping命令,用Wireshark抓取的ICMP數據包:發送ICMP數據包內容接受ICMP數據包內容一.icmp結構要真正瞭解ping命令實現原理，就要瞭解ping命令所使用到的TCP/IP協議。ICMP(Internet Control Me...

這個是用Mac下的Network Utility工具實現ping命令,用Wireshark抓取的ICMP數據包:

發送ICMP數據包內容

接受ICMP數據包內容

一.icmp結構

要真正瞭解ping命令實現原理，就要瞭解ping命令所使用到的TCP/IP協議。
ICMP(Internet
 Control 
Message,網際控制報文協議)是為網關和目標主機而提供的一種差錯控制機制，使它們在遇到差錯時能把錯誤報告給報文源發方。ICMP協議是IP層的
一個協議，但是由於差錯報告在發送給報文源發方時可能也要經過若幹子網，因此牽涉到路由選擇等問題，所以ICMP報文需通過IP協議來發送。

ICMP數據報的數據發送前需要兩級封裝：首先添加ICMP報頭形成ICMP報文，再添加IP報頭形成IP數據報

各種ICMP報文的前32bits都是三個長度固定的欄位：type類型欄位(8位)、code代碼欄位(8位)、checksum校驗和欄位(16位)

8bits類型和8bits代碼欄位：一起決定了ICMP報文的類型。常見的有：
　　
　　類型8、代碼0：回射請求。
　　
　　類型0、代碼0：回射應答。
　　
　　類型11、代碼0：超時。
　　
　　16bits校驗和欄位：包括數據在內的整個ICMP數據包的校驗和，其計算方法和IP頭部校驗和的計算方法是一樣的。

對於ICMP回射請求和應答報文來說，接下來是16bits標識符欄位：用於標識本ICMP進程。
　　
最後是16bits序列號欄位：用於判斷回射應答數據報。

ICMP報文包含在IP數據報中，屬於IP的一個用戶，IP頭部就在ICMP報文的前面

一個ICMP報文包括IP頭部（20位元組）、ICMP頭部（8位元組）和ICMP報文數據部分

ICMP數據包結構

ICMP報文格式,在Mac(Unix)下結構包含在ip_icmp.h中:

引入頭文件#include //icmp數據包結構

struct icmp {
    u_char    icmp_type;        /* type of message, see below */
    u_char    icmp_code;        /* type sub code */
    u_short    icmp_cksum;        /* ones complement cksum of struct */
    union {
        u_char ih_pptr;            /* ICMP_PARAMPROB */
        struct in_addr ih_gwaddr;    /* ICMP_REDIRECT */
        struct ih_idseq {
            n_short    icd_id;
            n_short    icd_seq;
        } ih_idseq;
        int ih_void;

        /* ICMP_UNREACH_NEEDFRAG -- Path MTU Discovery (RFC1191) */
        struct ih_pmtu {
            n_short ipm_void;
            n_short ipm_nextmtu;
        } ih_pmtu;

        struct ih_rtradv {
            u_char irt_num_addrs;
            u_char irt_wpa;
            u_int16_t irt_lifetime;
        } ih_rtradv;
    } icmp_hun;
#define    icmp_pptr    icmp_hun.ih_pptr
#define    icmp_gwaddr    icmp_hun.ih_gwaddr
#define    icmp_id        icmp_hun.ih_idseq.icd_id
#define    icmp_seq    icmp_hun.ih_idseq.icd_seq
#define    icmp_void    icmp_hun.ih_void
#define    icmp_pmvoid    icmp_hun.ih_pmtu.ipm_void
#define    icmp_nextmtu    icmp_hun.ih_pmtu.ipm_nextmtu
#define    icmp_num_addrs    icmp_hun.ih_rtradv.irt_num_addrs
#define    icmp_wpa    icmp_hun.ih_rtradv.irt_wpa
#define    icmp_lifetime    icmp_hun.ih_rtradv.irt_lifetime
    union {
        struct id_ts {
            n_time its_otime;
            n_time its_rtime;
            n_time its_ttime;
        } id_ts;
        struct id_ip  {
            struct ip idi_ip;
            /* options and then 64 bits of data */
        } id_ip;
        struct icmp_ra_addr id_radv;
        u_int32_t id_mask;
        char    id_data[1];
    } icmp_dun;
#define    icmp_otime    icmp_dun.id_ts.its_otime
#define    icmp_rtime    icmp_dun.id_ts.its_rtime
#define    icmp_ttime    icmp_dun.id_ts.its_ttime
#define    icmp_ip        icmp_dun.id_ip.idi_ip
#define    icmp_radv    icmp_dun.id_radv
#define    icmp_mask    icmp_dun.id_mask
#define    icmp_data    icmp_dun.id_data
};

IP報頭格式如下圖：


/////////////////////////////////////////////////////////////////////////////////////////////////////////////

IP報文格式,在Mac(Unix)下結構包含在ip.h中:

引入頭文件#include //ip數據包結構

struct ip {
#ifdef _IP_VHL
    u_char    ip_vhl;            /* version << 4 | header length >> 2 */
#else
#if BYTE_ORDER == LITTLE_ENDIAN
    u_int    ip_hl:4,        /* header length */
        ip_v:4;            /* version */
#endif
#if BYTE_ORDER == BIG_ENDIAN
    u_int    ip_v:4,            /* version */
        ip_hl:4;        /* header length */
#endif
#endif /* not _IP_VHL */
    u_char    ip_tos;            /* type of service */
    u_short    ip_len;            /* total length */
    u_short    ip_id;            /* identification */
    u_short    ip_off;            /* fragment offset field */
#define    IP_RF 0x8000            /* reserved fragment flag */
#define    IP_DF 0x4000            /* dont fragment flag */
#define    IP_MF 0x2000            /* more fragments flag */
#define    IP_OFFMASK 0x1fff        /* mask for fragmenting bits */
    u_char    ip_ttl;            /* time to live */
    u_char    ip_p;            /* protocol */
    u_short    ip_sum;            /* checksum */
    struct    in_addr ip_src,ip_dst;    /* source and dest address */
};

二.具體實現代碼

//xSocketPing.c


#include "xSocketPing.h"

//statistics
void statistics(char* back){
    double percent = ((double)sendPacketNumber - (double)recvPacketNumber) / (double)sendPacketNumber * 100;
    sprintf(back, "---%s ping statistics---\n%d packets trasmitted, %d packet received, %0.1f%% packet loss",inet_ntoa(dstAddr.sin_addr),sendPacketNumber,recvPacketNumber,percent);
}
//check sum
unsigned short checkSum(unsigned short *buffer, int size){
    unsigned long checkSum = 0;
    while (size > 1) {
        checkSum += *buffer++;
        size -= sizeof(unsigned short);//unsigned short is 2 bytes = 16 bits
    }
    //if size is odd number
    if (size == 1){
        checkSum += *(unsigned short *)buffer;
    }
    checkSum = (checkSum >> 16) + (checkSum & 0xFFFF);
    checkSum += (checkSum >> 16);
    return ~checkSum;
}

//calculate time difference
double timeSubtract(struct timeval *recvTimeStamp, struct timeval *sendTimeStamp){
    //calculate seconds
    long timevalSec = recvTimeStamp->tv_sec - sendTimeStamp->tv_sec;
    //calculate microsends
    long timevalUsec = recvTimeStamp->tv_usec - sendTimeStamp->tv_usec;
    
    //if microsends less then zero
    if (timevalUsec < 0) {
        timevalSec -= 1;
        timevalUsec = - timevalUsec;
    }
    return (timevalSec * 1000.0 + timevalUsec) / 1000.0;
}

//fill icmp packet and return size of packet
int fillPacket(int packetSequence){
    int packetSize = 0;
    struct icmp *icmpHeader = (struct icmp *)sendBuffer;
    
    icmpHeader->icmp_type = ICMP_ECHO;
    icmpHeader->icmp_code = 0;
    icmpHeader->icmp_cksum = 0;
    icmpHeader->icmp_id = pid;
    icmpHeader->icmp_seq = packetSequence;
    packetSize = dataSize + 8;
    tvSend = (struct timeval *)icmpHeader->icmp_data;
    gettimeofday(tvSend, NULL);//get current of time
    icmpHeader->icmp_cksum = checkSum((unsigned short *)icmpHeader, packetSize);
    return packetSize;
}

//send icmp packet to dstAddr
int sendPacket(int packetSequence){
    int packSize = 0;
    packSize = fillPacket(packetSequence);
    if ((sendto(socketfd, sendBuffer, packSize, 0, (struct sockaddr *)&dstAddr, sizeof(dstAddr))) < 0) {
        printf("Send icmp packet Error\n");
        sendPacketNumber--;
        recvPacketNumber--;
        return -1;
    }
    return 0;
}

//setting ip address
void settingIP(){
    //initialize
    bzero(&dstAddr,sizeof(dstAddr));
    dstAddr.sin_family = AF_INET;
    dstAddr.sin_addr.s_addr = inet_addr(ipAddr);
}

//get current process id
void getPid(){
    pid = getpid();
}

//create socket
int createSocket(){
    //原始套接字SOCK_RAW需要使用root許可權,所以改用SOCK_DGRAM
    if ((socketfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP)) < 0) {
        printf("Create Socket Error\n");
        return -1;
    }
    return 0;
}

//setting socket
void settingSocket(int timeout){
    int size = 50 * 1024;
    //setting timeout seconds or you can set it by microseconds
    struct timeval timeOut;
    timeOut.tv_sec = timeout;
    //擴大套接字接收緩衝區到50K這樣做主要為了減小接收緩衝區溢出的可能性,若無意中ping一個廣播地址或多播地址,將會引來大量應答
    setsockopt(socketfd, SOL_SOCKET, SO_RCVBUF, &size, sizeof(size));
    setsockopt(socketfd, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeOut, sizeof(timeOut));
}

//destory socket
void destorySocket(){
    close(socketfd);
}

//unpacket
void unPacket(char* packetBuffer,char* back, long size){
    struct ip *ipHeader = NULL;
    struct icmp *icmpHeader = NULL;
    
    double rtt;//往返時間
    int ipHeaderLength;//ip header length
    
    ipHeader = (struct ip *)packetBuffer;
    ipHeaderLength = ipHeader->ip_hl<<2;//求ip報頭長度,即ip報頭的長度標誌乘4
    icmpHeader = (struct icmp *)(packetBuffer + ipHeaderLength);//越過IP頭，point to ICMP header
    size -= ipHeaderLength;
    if (size < 8){
        back = "Unpacket Error:packet size minmum 8 bytes\n";
    }
    
    if ((icmpHeader->icmp_type == ICMP_ECHOREPLY) && (icmpHeader->icmp_id == pid)) {
        tvSend = (struct timeval *)icmpHeader->icmp_data;
        gettimeofday(&tvRecv, NULL);
        //以毫秒為單位計算rtt
        rtt = timeSubtract(&tvRecv, tvSend);
        sprintf(back,"%ld bytes from %s: icmp_seq=%u ttl=%d time=%.1f ms\n",size,inet_ntoa(recvAddr.sin_addr),icmpHeader->icmp_seq,ipHeader->ip_ttl,rtt);
    }else{
        back = "Unpacket Error\n";
    }
}

//receive packet
void receivePacket(char* back){
    //claculate packet size
    int packetSize = sizeof(recvAddr);
    long size;
    if ((size = recvfrom(socketfd, recvBuffer, sizeof(recvBuffer), 0, (struct sockaddr *)&recvAddr, (socklen_t *)&packetSize)) < 0) {
        sprintf(back,"Receive timeout\n");
        recvPacketNumber--;
    }else{
        gettimeofday(&tvRecv, NULL);
        //char temp[100] = {0};
        unPacket(recvBuffer, back, size);
        //printf("%s\n",temp);
    }
}

void ping(char *ipAddress, int number, int timeout){
    int packetnumber = 0;
    ipAddr = ipAddress;
    sendPacketNumber = number;
    recvPacketNumber = number;
    
    settingIP();
    getPid();
    if (createSocket() != -1){
        settingSocket(timeout);
        printf("PING %s: %d bytes of data.\n",ipAddress,dataSize);
        while(packetnumber < number){
            if (sendPacket(packetnumber) != -1){
                char back[100] = {0};
                receivePacket(back);
                printf("%s",back);
            }
            sleep(1);
            packetnumber++;
        }
        char back[100] = {0};
        statistics(back);
        printf("%s\n",back);
        destorySocket();
    }
}

//xSocketPing.h

#ifndef xSocketPing_h
#define xSocketPing_h

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>//基本系統數據類型
#include <sys/socket.h>
#include <netinet/in.h>
//get current of time
#include <sys/time.h>
#include <arpa/inet.h>//inet_ntoa將一個IP轉換成一個互聯網標準點分格式的字元串
#include <unistd.h>//close(int)
#include <netdb.h>//定義了與網路有關的結構、變數類型、巨集、函數等
//ip packet structure
#include <netinet/ip.h>
//icmp packet structure
#include <netinet/ip_icmp.h>

//time to live
int ttl = 64;
//icmp data size ,icmp header 8bytes,data size 56bytes,the maximum of packet size 64bytes
int dataSize = 56;
//packet number
int sendPacketNumber;
int recvPacketNumber;
//ip address
char * ipAddr;

//send packet of time
struct timeval *tvSend;
//receive packet of time
struct timeval tvRecv;

//Socket address, internet style.
//the destination address
struct sockaddr_in dstAddr;
//the receive address
struct sockaddr_in recvAddr;

//send icmp buffer
char sendBuffer[1024] = {0};
//receive icmp replay buffer
char recvBuffer[1024] = {0};

//the current process of id
int pid;
//socket
int socketfd = 0;


void statistics(char* back);
unsigned short checkSum(unsigned short *buffer, int size);
double timeSubtract(struct timeval *recvTimeStamp, struct timeval *sendTimeStamp);
int fillPacket(int packetSequence);
int sendPacket(int packetSequence);
void settingIP();
void getPid();
int createSocket();
void settingSocket(int timeout);
void destorySocket();
void unPacket(char* packetBuffer,char* back, long size);
void receivePacket(char* back);
void ping(char *ipAddress, int number, int timeout);


#endif /* xSocketPing_h */

//xSocketPing.swift

import Foundation

public class xSocketPing{
    
    private var ipAddress:String
    //default packet number 3 or you can setting it by yourself
    private var packetNumber:Int = 3
    private var timeout:Int = 1
    //refresh UI
    weak var delegate:refreshTextDelegate?

    init(ipAddress:String, delegate:refreshTextDelegate){
        self.ipAddress = ipAddress
        self.delegate = delegate
    }
    convenience init(ipAddress:String, packetNumber:Int, delegate:refreshTextDelegate){
        self.init(ipAddress: ipAddress,delegate: delegate)
        self.packetNumber = packetNumber
    }
    convenience init(ipAddress:String, packetNumber:Int, timeout:Int, delegate:refreshTextDelegate){
        self.init(ipAddress: ipAddress,packetNumber: packetNumber,delegate: delegate)
        self.timeout = timeout
    }
    
    public func xPing(){
        let tempIpAddress:UnsafeMutablePointer = UnsafeMutablePointer<Int8>((ipAddress as NSString).UTF8String)
        ipAddr = tempIpAddress
        sendPacketNumber = Int32(packetNumber)
        recvPacketNumber = Int32(packetNumber)
        
        settingIP()
        getPid()
        if createSocket() != -1 {
            settingSocket(Int32(timeout))
            let message:String = "PING \(ipAddress): 56 bytes of data.\n"
            refresh(message, speed: 0.0)
            //將String轉換為UnsafeMutablePointer<CChar>,相當於char tempmessage[100]
            let tempmessage:UnsafeMutablePointer = UnsafeMutablePointer<CChar>.alloc(100)
            var packetsequence:Int = 0
            var speed:Float = 0.0
            
            while packetsequence < packetNumber {
                if sendPacket(Int32(packetsequence)) != -1 {
                    receivePacket(tempmessage)
                    //Calculate percentage
                    speed = (Float(packetNumber) - (Float(packetNumber) - Float(packetsequence))) / Float(packetNumber)
                    //將UnsafeMutablePointer<CChar>轉換為String
                    refresh(String.fromCString(tempmessage)!, speed: speed)
                }
                sleep(1);
                packetsequence++
            }
            statistics(tempmessage)
            refresh(String.fromCString(tempmessage)!, speed: 1)
            destorySocket()
        }
    }
    
    func refresh(text:String, speed:Float){
        delegate?.refresh(text, speed: speed)
    }
    deinit{
        print("xSocketPing destory")
    }
}

//ViewController.swift

import UIKit

protocol refreshTextDelegate:NSObjectProtocol{
    func refresh(text:String, speed:Float)
}

class ViewController: UIViewController,refreshTextDelegate {

    @IBOutlet weak var xprogress: UIProgressView!
    @IBOutlet weak var xip: UITextField!
    @IBOutlet weak var xnumber: UITextField!
    @IBOutlet weak var xtext: UITextView!
    
    var number:Int = 3
    var ip:String = "192.168.1.1"
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        xtext.text = ""
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    @IBAction func xNumberChange(sender: UIStepper) {
        xnumber.text = "\(Int(sender.value))"
        self.number = Int(sender.value)
    }
    
    @IBAction func beginPing(sender: UIButton) {
        sender.enabled = false
        xip.enabled = false
        xnumber.enabled = false
        
        xprogress.progress = 0
        xtext.text = ""
        
        let ip = xip.text
        if ip == ""{
            let alert = UIAlertView(title: "Error", message: "No IP Address", delegate: self, cancelButtonTitle: "OK")
            alert.show()
        }else{
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
                let ping:xSocketPing = xSocketPing(ipAddress: "\(ip!)", packetNumber: self.number, delegate: self)
                ping.xPing()
            })
        }
        xnumber.enabled = true
        xip.enabled = true
        sender.enabled = true
    }
    
    
    func refresh(text:String, speed:Float) {
        dispatch_async(dispatch_get_main_queue(), {
            //更新進度條
            self.xprogress.progress = speed
            //更新UITextView,追加內容並滾動到最下麵
            self.xtext.text.appendContentsOf(text)
            self.xtext.scrollRangeToVisible(NSMakeRange(self.xtext.text.characters.count, 0))
        })
    }
    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
        self.view.endEditing(true)
    }
}

運行結果圖:

運行環境OS X10.10.5,Xcode7.0,Swift2.1,iOS9.0模擬器
真機測試的時候有可能找不到#include ,猜測是蘋果不給在機子上使用icmp數據包,如果只是在自己機子上測試,可以將模擬器的ip_icmp.h文件複製到真機環境,再進行編譯運行.

部分出現的疑惑或者問題,可以看我之前的新浪博客
Wireshark找不到網卡

Swift和C語言交互-String和UnsafeMutablePointer轉換

 Swift和c的類型轉換

 Swift與c的交互

GitHub項目地址:Swift和C混合Socket編程實現簡單的ping命令
本程式還有很多不足之處,後續會持續更新,並更新GitHub項目,需要改進的,請在博客上留言
抓包的圖片是不更新的,所以會和運行結果圖不一樣.

更新於2016-1-13
修複bug,優化部分顯示,更好,更安全的處理指針類型.
更新於2016-1-12
新增功能:優化顯示,將返回的結果顯示到模擬器中.發送數據包在額外的線程中進行,不會阻塞主線程.由於程式使用的是Swift和C語言混合編程,用到了指針,交互的時候容易crash.後續會繼續修複bug.
更新2016-1-7
新增功能:優化顯示,將返回結果集中到主函數中,方便調用,修複部分bug,添加超時處理,防止程式一直處於阻塞狀態.,