Socket

• Socket是應(yīng)用層與TCP/IP協(xié)議族通信的中間軟件抽象層，它是一組接口谱姓。

  
  
• 網(wǎng)絡(luò)中進(jìn)程之間如何通信
  • 網(wǎng)絡(luò)中進(jìn)程之間如何通信？首要解決的問題是如何唯一標(biāo)識(shí)一個(gè)進(jìn)程后控，否則通信無從談起匿级！在本地可以通過進(jìn)程PID來唯一標(biāo)識(shí)一個(gè)進(jìn)程，但是在網(wǎng)絡(luò)中這是行不通的媳板。其實(shí)TCP/IP協(xié)議族已經(jīng)幫我們解決了這個(gè)問題桑腮，網(wǎng)絡(luò)層的“ip地址”可以唯一標(biāo)識(shí)網(wǎng)絡(luò)中的主機(jī)，而傳輸層的“協(xié)議+端口”可以唯一標(biāo)識(shí)主機(jī)中的應(yīng)用程序（進(jìn)程）蛉幸。這樣利用三元組（ip地址破讨，協(xié)議，端口）就可以標(biāo)識(shí)網(wǎng)絡(luò)的進(jìn)程了奕纫，網(wǎng)絡(luò)中的進(jìn)程通信就可以利用這個(gè)標(biāo)志與其它進(jìn)程進(jìn)行交互提陶。
  • 使用TCP/IP協(xié)議的應(yīng)用程序通常采用應(yīng)用編程接口：UNIX BSD的套接字（socket）和UNIX System V的TLI（已經(jīng)被淘汰），來實(shí)現(xiàn)網(wǎng)絡(luò)進(jìn)程之間的通信匹层。就目前而言隙笆，幾乎所有的應(yīng)用程序都是采用socket，而現(xiàn)在又是網(wǎng)絡(luò)時(shí)代又固，網(wǎng)絡(luò)中進(jìn)程通信是無處不在仲器，這就是我為什么說“一切皆socket”。
• socket起源于Unix仰冠，而Unix/Linux基本哲學(xué)之一就是“一切皆文件”乏冀，都可以用“打開open –> 讀寫write/read –> 關(guān)閉close”模式來操作。我的理解就是Socket就是該模式的一個(gè)實(shí)現(xiàn)洋只，socket即是一種特殊的文件辆沦，一些socket函數(shù)就是對其進(jìn)行的操作（讀/寫IO昼捍、打開、關(guān)閉）
  關(guān)于如下問題可參考這里

網(wǎng)絡(luò)中進(jìn)程之間如何通信肢扯？
socket的基本操作
    socket()函數(shù)
    bind()函數(shù)
    listen()妒茬、connect()函數(shù)
    accept()函數(shù)
    read()、write()函數(shù)等
    close()函數(shù)

iOS網(wǎng)絡(luò)編程層次模型

• Cocoa層：NSURL蔚晨，Bonjour乍钻，Game Kit，WebKit
• Core Foundation層：基于 C 的 CFNetwork 和 CFNetServices
• OS層：基于 C 的 BSD socket

Cocoa層：是最上層的基于 Objective-C 的 API铭腕，比如 URL訪問银择，NSStream，Bonjour累舷，GameKit等浩考，這是大多數(shù)情況下我們常用的 API。Cocoa 層是基于 Core Foundation 實(shí)現(xiàn)的被盈。

Core Foundation層：因?yàn)橹苯邮褂?socket 需要更多的編程工作析孽，所以蘋果對 OS 層的 socket 進(jìn)行簡單的封裝以簡化編程任務(wù)。該層提供了 CFNetwork 和 CFNetServices只怎，其中 CFNetwork 又是基于 CFStream 和 CFSocket袜瞬。

OS層：最底層的 BSD socket 提供了對網(wǎng)絡(luò)編程最大程度的控制，但是編程工作也是最多的身堡。因此吞滞，蘋果建議我們使用 Core Foundation 及以上層的 API 進(jìn)行編程。

C/S架構(gòu)程序設(shè)計(jì)基本框架

常用的Socket類型
有兩種：流式Socket（SOCK_STREAM）和數(shù)據(jù)報(bào)式Socket（SOCK_DGRAM）盾沫。流式是一種面向連接的Socket，針對于面向連接的TCP服務(wù)應(yīng)用殿漠；數(shù)據(jù)報(bào)式Socket是一種無連接的Socket赴精，對應(yīng)于無連接的UDP服務(wù)應(yīng)用。

• TCP C/S架構(gòu)程序設(shè)計(jì)基本框架
  
• UDP C/S架構(gòu)程序設(shè)計(jì)基本框架
  

SocketDemo

主要使用：NSStream绞幌、CFStream蕾哟、CFSocket

效果圖

客戶端 + 服務(wù)端.png

客戶端主要代碼、完整代碼下載地址

#include <CoreFoundation/CoreFoundation.h>
#include <sys/socket.h>
#include <netinet/in.h>
static ViewController *selfClass =nil;

@interface ViewController ()<NSStreamDelegate>
{
    NSInteger flag;
}

@property (nonatomic, strong) NSInputStream *inputStream;
@property (nonatomic, strong) NSOutputStream *outputStream;
@property (nonatomic, assign) NSInteger kPort;

@property (weak, nonatomic) IBOutlet UITextField *port;

@property (weak, nonatomic) IBOutlet UITextField *serviceIP;

@property (weak, nonatomic) IBOutlet UILabel *message;

@property (weak, nonatomic) IBOutlet UITextField *putText;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    selfClass = self;
    // Do any additional setup after loading the view, typically from a nib.
}

- (IBAction)connectService:(id)sender {
    flag = 0;
    [self initNetworkCommunication];
}
- (IBAction)reviveMsg:(id)sender {
    flag = 1;
    [self initNetworkCommunication];
}
- (void)initNetworkCommunication {
    CFReadStreamRef readStream;
    CFWriteStreamRef writeStream;
    CFStreamCreatePairWithSocketToHost(NULL, (__bridge CFStringRef)self.serviceIP.text, (int)[self.port.text intValue], &readStream, &writeStream);
    _inputStream = (__bridge_transfer NSInputStream *)readStream;
    _outputStream = (__bridge_transfer NSOutputStream *)writeStream;
    
    [_inputStream setDelegate:self];
    [_outputStream setDelegate:self];
    
    [_inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [_outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    
    [_inputStream open];
    [_outputStream open];
    
}

- (void)close {
    [_outputStream close];
    [_outputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [_outputStream setDelegate:nil];
    [_inputStream close];
    [_inputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [_inputStream setDelegate:nil];
}

- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode
{
    NSString *event;
    switch (eventCode) {
        case NSStreamEventNone:
            event = @"NSStreamEventNone";
            NSLog(@"%@",event);
            break;
        case NSStreamEventOpenCompleted:
            event = @"NSStreamEventOpenCompleted";
            NSLog(@"%@",event);
            break;
        case NSStreamEventHasBytesAvailable:
            event = @"NSStreamEventHasBytesAvailable";
            NSLog(@"%@",event);
            if (flag == 1 && aStream == _inputStream) {
                NSMutableData *input = [[NSMutableData alloc] init];
                uint8_t buffer[1024];
                NSInteger len;
                while ([_inputStream hasBytesAvailable]) {
                    len = [_inputStream read:buffer maxLength:sizeof(buffer)];
                    if (len > 0) {
                        [input appendBytes:buffer length:len];
                    }
                }
                NSString *result = [[NSString alloc] initWithData:input encoding:NSUTF8StringEncoding];
                NSLog(@"%@",result);
                _message.text = result;
            }
        case NSStreamEventHasSpaceAvailable:
            event = @"NSStreamEventHasSpaceAvailable";
            NSLog(@"%@",event);
            if (flag ==0 && aStream == _outputStream) {
                //輸出
                NSString * putText = selfClass.putText.text;
                UInt8 buff[1024];
                memcpy(buff, [putText UTF8String],[putText lengthOfBytesUsingEncoding:NSUTF8StringEncoding] + 1);
                [_outputStream write:buff maxLength: strlen((const char*)buff)+1];
                //必須關(guān)閉輸出流否則莲蜘，服務(wù)器端一直讀取不會(huì)停止谭确，
                [_outputStream close];
            }
            break;
        case NSStreamEventErrorOccurred:
            event = @"NSStreamEventErrorOccurred";
            NSLog(@"%@",event);
            [self close];
            break;
        case NSStreamEventEndEncountered:
            event = @"NSStreamEventEndEncountered";
            NSLog(@"%@",event);
            NSLog(@"Error:%ld:%@",[[aStream streamError] code], [[aStream streamError] localizedDescription]);
            break;
        default:
            [self close];
            event = @"Unknown";
            break;
    }
}

服務(wù)端主要代碼、完整代碼下載地址

#import "ViewController.h"
#import <CoreFoundation/CoreFoundation.h>
#include <sys/socket.h>
#include <netinet/in.h>

static ViewController *selfClass =nil;
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UITextField *portText;
@property (nonatomic, assign) NSInteger kPORT;
@property (weak, nonatomic) IBOutlet UITextField *putText;
@property (weak, nonatomic) IBOutlet UILabel *readText;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    selfClass = self;
    // Do any additional setup after loading the view, typically from a nib.
}

- (IBAction)startService:(id)sender {
    //設(shè)置服務(wù)端端口號(hào)
    self.kPORT = [self.portText.text integerValue];
    
    CFSocketRef service;
    /*CFSocketContext 參數(shù)cgindex version 版本號(hào)票渠，必須為0逐哈；
     *void *info; 一個(gè)指向任意程序定義數(shù)據(jù)的指針，可以在CFScocket對象剛創(chuàng)建的時(shí)候與之關(guān)聯(lián)问顷，被傳遞給所有在上下文中回調(diào),可為NULL昂秃；
     *CFAllocatorRetainCallBack retain; info指針中的retain回調(diào)禀梳，可以為NULL
     *CFAllocatorReleaseCallBack release; info指針中的release的回調(diào)，可以為NULL
     *CFAllocatorCopyDescriptionCallBack copyDescription; info指針中的回調(diào)描述肠骆，可以為NULL
     */
    CFSocketContext CTX = {0,NULL,NULL,NULL,NULL};
    //CFSockerRef
    //內(nèi)存分配類型算途，一般為默認(rèn)的Allocator->kCFAllocatorDefault,
    //協(xié)議族,一般為Ipv4:PF_INET,(Ipv6,PF_INET6),
    //套接字類型，TCP用流式—>SOCK_STREAM蚀腿，UDP用報(bào)文式->SOCK_DGRAM,
    //套接字協(xié)議嘴瓤，如果之前用的是流式套接字類型：IPROTO_TCP，如果是報(bào)文式：IPPROTO_UDP,
    //回調(diào)事件觸發(fā)類型 *1,
    //觸發(fā)時(shí)候調(diào)用的方法 *2,
    //用戶定義的數(shù)據(jù)指針莉钙，用于對CFSocket對象的額外定義或者申明廓脆，可以為NULL
    service = CFSocketCreate(NULL, PF_INET, SOCK_STREAM, IPPROTO_TCP, kCFSocketAcceptCallBack, (CFSocketCallBack)AcceptCallBack, &CTX);
    if (service == NULL) {
        return;
    }
    //設(shè)置是否重新綁定標(biāo)志
    int yes = 1;
    /* 設(shè)置socket屬性 SOL_SOCKET是設(shè)置tcp SO_REUSEADDR是重新綁定，yes 是否重新綁定*/
    setsockopt(CFSocketGetNative(service), SOL_SOCKET, SO_REUSEADDR, (void *)&yes, sizeof(yes));
    
    //設(shè)置端口和地址
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));       //memset函數(shù)對指定的地址進(jìn)行內(nèi)存拷貝
    addr.sin_len = sizeof(addr);
    addr.sin_family = AF_INET;            //AF_INET是設(shè)置 IPv4
    addr.sin_port = htons(self.kPORT);    //htons函數(shù) 無符號(hào)短整型數(shù)轉(zhuǎn)換成“網(wǎng)絡(luò)字節(jié)序”
    addr.sin_addr.s_addr = htonl(INADDR_ANY);  //INADDR_ANY有內(nèi)核分配胆胰，htonl函數(shù) 無符號(hào)長整型數(shù)轉(zhuǎn)換成“網(wǎng)絡(luò)字節(jié)序”
    
    /* 從指定字節(jié)緩沖區(qū)復(fù)制狞贱，一個(gè)不可變的CFData對象*/
    CFDataRef address = CFDataCreate(kCFAllocatorDefault, (UInt8 *)&addr, sizeof(addr));
    
    /* 設(shè)置Socket*/
    if (CFSocketSetAddress(service, (CFDataRef)address) != kCFSocketSuccess) {
        fprintf(stderr, "Socket綁定失敗\n");
        CFRelease(service);
        return ;
    }
    /* 創(chuàng)建一個(gè)Run Loop Socket源 */
    CFRunLoopSourceRef sourceRef = CFSocketCreateRunLoopSource(kCFAllocatorDefault, service, 0);
    /* Socket源添加到Run Loop中 */
    CFRunLoopAddSource(CFRunLoopGetCurrent(), sourceRef, kCFRunLoopCommonModes);
    CFRelease(sourceRef);
    
    printf("Socket listening on port %zd\n", self.kPORT);
    /* 運(yùn)行Loop */
    CFRunLoopRun();
    
    
}

//接受客戶端請求后回調(diào)函數(shù)
void AcceptCallBack(
                    CFSocketRef socket,
                    CFSocketCallBackType type,
                    CFDataRef address,
                    const void *data,
                    void *info)
{
    CFReadStreamRef readStream = NULL;
    CFWriteStreamRef writeStream = NULL;
    
    //data參數(shù)的含義是，如果是kCFSocketAcceptCallBack類型蜀涨，data是CFSocketNativeHandle類型的指針
    CFSocketNativeHandle sock = *(CFSocketNativeHandle *) data;
    
    //創(chuàng)建讀寫socket流
    CFStreamCreatePairWithSocket(kCFAllocatorDefault, sock, &readStream, &writeStream);
    
    if (!readStream || !writeStream) {
        close(sock);
        fprintf(stderr, "CFStreamCreatePairWithSocket() 失敗\n");
        return;
    }
    
    CFStreamClientContext streamCtxt = {0,NULL,NULL,NULL,NULL};
    //注冊兩種回調(diào)函數(shù)
    CFReadStreamSetClient(readStream, kCFStreamEventHasBytesAvailable, ReadStreamClientCallBack, &streamCtxt);
    CFWriteStreamSetClient(writeStream, kCFStreamEventCanAcceptBytes, WriteStreamClientCallBack, &streamCtxt);
    
    //加入到循環(huán)當(dāng)中
    CFReadStreamScheduleWithRunLoop(readStream, CFRunLoopGetCurrent(),kCFRunLoopCommonModes);
    CFWriteStreamScheduleWithRunLoop(writeStream, CFRunLoopGetCurrent(),kCFRunLoopCommonModes);
    
    CFReadStreamOpen(readStream);
    CFWriteStreamOpen(writeStream);
}

//讀取操作瞎嬉，讀取客戶端發(fā)送的數(shù)據(jù)
static UInt8 buff[255];
void ReadStreamClientCallBack (CFReadStreamRef stream,CFStreamEventType eventType, void* clientCallBackInfo ) {
    
    CFReadStreamRef inputStream = stream;
    
    if (NULL != inputStream) {
        CFReadStreamRead(inputStream, buff, 255);
        
        printf("接收到的數(shù)據(jù) :%s\n", buff);
        selfClass.readText.text = [NSString stringWithCString:(char*)buff encoding:NSUTF8StringEncoding];
        CFReadStreamClose(inputStream);
        //從循環(huán)中移除
        CFReadStreamUnscheduleFromRunLoop(inputStream, CFRunLoopGetCurrent(),kCFRunLoopCommonModes);
        inputStream = NULL;
    }
    
}

/* 寫入流操作 客戶端在讀取數(shù)據(jù)時(shí)候調(diào)用 */
void WriteStreamClientCallBack(CFWriteStreamRef stream, CFStreamEventType eventType, void* clientCallBackInfo)
{
    CFWriteStreamRef    outputStream = stream;
    //輸出
    NSString * putText = selfClass.putText.text;
    UInt8 buff[1024];
    memcpy(buff, [putText UTF8String],[putText lengthOfBytesUsingEncoding:NSUTF8StringEncoding] + 1);
    
    if(NULL != outputStream)
    {
        CFWriteStreamWrite(outputStream, buff, strlen((const char*)buff)+1);
        //關(guān)閉輸出流
        CFWriteStreamClose(outputStream);
        //從循環(huán)中移除
        CFWriteStreamUnscheduleFromRunLoop(outputStream, CFRunLoopGetCurrent(),kCFRunLoopCommonModes);
        outputStream = NULL;
    }
}

寫在最后

• 參考
  Linux Socket編程（不限Linux）
• 第三方庫
  CocoaAsyncSocket

客戶端完整代碼下載地址
服務(wù)端完整代碼下載地址