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linux socket 编程(C语言)
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https://www.cnblogs.com/x_wukong/p/4541010.html
最近看了一些網(wǎng)絡(luò)編程的書籍,一直以來(lái)總感覺(jué)網(wǎng)絡(luò)編程神秘莫測(cè),其實(shí)網(wǎng)絡(luò)編程入門還是很容易學(xué)的,下面這些代碼是我在linux下編寫的,已經(jīng)運(yùn)行過(guò)了,編譯之后就可以運(yùn)行了。有不足之處希望大家多多指出,共同學(xué)習(xí)交流。
???? 套接字是一種進(jìn)程間的通信的方法,不同于以往介紹的進(jìn)程間通信方法的是,它并不局限于同一臺(tái)計(jì)算機(jī)的資源,例如文件系統(tǒng)空間,共享內(nèi)存或者消息隊(duì)列。套接字可以認(rèn)為是對(duì)管道概念的擴(kuò)展——一臺(tái)機(jī)器上的進(jìn)程可以使用套接字與另一臺(tái)機(jī)器上的進(jìn)程通信。因此客戶與服務(wù)器可以分散在網(wǎng)絡(luò)中。同一臺(tái)機(jī)器上的進(jìn)程間也可以用套接字通信。套接字是一種通信機(jī)制,客戶/服務(wù)器系統(tǒng)既可以在本地單機(jī)上運(yùn)行,也可以在網(wǎng)絡(luò)中運(yùn)行。套接字與管道的區(qū)別:它明確區(qū)分客戶與服務(wù)器,可以實(shí)現(xiàn)將多個(gè)客戶連接到一個(gè)服務(wù)器。
?????套接字的工作過(guò)程(服務(wù)器端):首先,服務(wù)器應(yīng)用程序通過(guò)socket系統(tǒng)調(diào)用創(chuàng)建一個(gè)套接字,它是系統(tǒng)分配給該服務(wù)器進(jìn)程的類似文件描述符的資源,不能與其他進(jìn)程共享。其次,服務(wù)器進(jìn)程使用bind系統(tǒng)調(diào)用給套接字命名。本地套接字的名字是linux文件系統(tǒng)的文件名,一般放在/tmp或者/usr/tmp 目錄下。網(wǎng)絡(luò)套接字的名字是與客戶相連接的特定網(wǎng)絡(luò)有關(guān)的服務(wù)標(biāo)識(shí)符。此標(biāo)識(shí)符允許linux將進(jìn)入的針對(duì)特定端口號(hào)的連接轉(zhuǎn)到正確的服務(wù)器進(jìn)程。接下來(lái),服務(wù)器進(jìn)程開(kāi)始等待客戶連接到這個(gè)命名套接字,調(diào)用listen創(chuàng)建一個(gè)等待隊(duì)列以便存放來(lái)自客戶的進(jìn)入連接。最后,服務(wù)器通過(guò)accept系統(tǒng)調(diào)用來(lái)接受客戶的連接。此時(shí),會(huì)產(chǎn)生一個(gè)與原有的命名套接字不同的新套接字,它僅用于與這個(gè)特定的客戶通信,而命名套接字則被保留下來(lái)繼續(xù)處理來(lái)自其他客戶的連接。??
?????套接字的工作過(guò)程(客戶端):調(diào)用socket創(chuàng)建一個(gè)未命名套接字,將服務(wù)器的命名套接字作為一個(gè)地址來(lái)調(diào)用connect與服務(wù)器建立連接。一旦建立了連接,就可以像使用底層文件描述符那樣來(lái)用套接字進(jìn)行雙向的數(shù)據(jù)通信。?
TCP協(xié)議:
服務(wù)器端:tcp_server.c
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[cpp]?view plaincopy #include?<stdio.h>?? #include?<sys/types.h>?? #include?<sys/socket.h>?? #include?<netinet/in.h>?? #include?<arpa/inet.h>?? ?? int?main(int?argc,?char?*argv[])?? {?? ????int?server_sockfd; ????int?client_sockfd; ????int?len;?? ????struct?sockaddr_in?my_addr;??? ????struct?sockaddr_in?remote_addr;? ????int?sin_size;?? ????char?buf[BUFSIZ];?? ????memset(&my_addr,0,sizeof(my_addr));? ????my_addr.sin_family=AF_INET;? ????my_addr.sin_addr.s_addr=INADDR_ANY; ????my_addr.sin_port=htons(8000);? ?????? ???? ????if((server_sockfd=socket(PF_INET,SOCK_STREAM,0))<0)?? ????{???? ????????perror("socket");?? ????????return?1;?? ????}?? ??? ???????? ????if?(bind(server_sockfd,(struct?sockaddr?*)&my_addr,sizeof(struct?sockaddr))<0)?? ????{?? ????????perror("bind");?? ????????return?1;?? ????}?? ?????? ???? ????listen(server_sockfd,5);?? ?????? ????sin_size=sizeof(struct?sockaddr_in);?? ?????? ???? ????if((client_sockfd=accept(server_sockfd,(struct?sockaddr?*)&remote_addr,&sin_size))<0)?? ????{?? ????????perror("accept");?? ????????return?1;?? ????}?? ????printf("accept?client?%s/n",inet_ntoa(remote_addr.sin_addr));?? ????len=send(client_sockfd,"Welcome?to?my?server/n",21,0); ?????? ???? ????while((len=recv(client_sockfd,buf,BUFSIZ,0))>0))?? ????{?? ????????buf[len]='/0';?? ????????printf("%s/n",buf);?? ????????if(send(client_sockfd,buf,len,0)<0)?? ????????{?? ????????????perror("write");?? ????????????return?1;?? ????????}?? ????}?? ????close(client_sockfd);?? ????close(server_sockfd);?? ????????return?0;?? }??
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TCP協(xié)議:
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客戶端:tcp_client.c
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[c-sharp]?view plaincopy
#include?<stdio.h>?? #include?<sys/types.h>?? #include?<sys/socket.h>?? #include?<netinet/in.h>?? #include?<arpa/inet.h>?? ?? int?main(int?argc,?char?*argv[])?? {?? ????int?client_sockfd;?? ????int?len;?? ????struct?sockaddr_in?remote_addr;? ????char?buf[BUFSIZ];?? ????memset(&remote_addr,0,sizeof(remote_addr));? ????remote_addr.sin_family=AF_INET;? ????remote_addr.sin_addr.s_addr=inet_addr("127.0.0.1"); ????remote_addr.sin_port=htons(8000);? ?????? ???? ????if((client_sockfd=socket(PF_INET,SOCK_STREAM,0))<0)?? ????{?? ????????perror("socket");?? ????????return?1;?? ????}?? ?????? ???? ????if(connect(client_sockfd,(struct?sockaddr?*)&remote_addr,sizeof(struct?sockaddr))<0)?? ????{?? ????????perror("connect");?? ????????return?1;?? ????}?? ????printf("connected?to?server/n");?? ????len=recv(client_sockfd,buf,BUFSIZ,0); ?????????buf[len]='/0';?? ????printf("%s",buf);? ?????? ???? ????while(1)?? ????{?? ????????printf("Enter?string?to?send:");?? ????????scanf("%s",buf);?? ????????if(!strcmp(buf,"quit")?? ????????????break;?? ????????len=send(client_sockfd,buf,strlen(buf),0);?? ????????len=recv(client_sockfd,buf,BUFSIZ,0);?? ????????buf[len]='/0';?? ????????printf("received:%s/n",buf);?? ????}?? ????close(client_sockfd); ?????????return?0;?? }??
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UDP協(xié)議:
服務(wù)器端:udp_server.c
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[cpp]?view plaincopy
#include?<stdio.h>?? #include?<sys/types.h>?? #include?<sys/socket.h>?? #include?<netinet/in.h>?? #include?<arpa/inet.h>?? ?? int?main(int?argc,?char?*argv[])?? {?? ????int?server_sockfd;?? ????int?len;?? ????struct?sockaddr_in?my_addr;??? ?????????struct?sockaddr_in?remote_addr;? ????int?sin_size;?? ????char?buf[BUFSIZ];?? ????memset(&my_addr,0,sizeof(my_addr));? ????my_addr.sin_family=AF_INET;? ????my_addr.sin_addr.s_addr=INADDR_ANY; ????my_addr.sin_port=htons(8000);? ?????? ???? ????if((server_sockfd=socket(PF_INET,SOCK_DGRAM,0))<0)?? ????{???? ????????perror("socket");?? ????????return?1;?? ????}?? ??? ???????? ????if?(bind(server_sockfd,(struct?sockaddr?*)&my_addr,sizeof(struct?sockaddr))<0)?? ????{?? ????????perror("bind");?? ????????return?1;?? ????}?? ????sin_size=sizeof(struct?sockaddr_in);?? ????printf("waiting?for?a?packet.../n");?? ?????? ???? ????if((len=recvfrom(server_sockfd,buf,BUFSIZ,0,(struct?sockaddr?*)&remote_addr,&sin_size))<0)?? ????{?? ????????perror("recvfrom");??? ????????return?1;?? ????}?? ????printf("received?packet?from?%s:/n",inet_ntoa(remote_addr.sin_addr));?? ????buf[len]='/0';?? ????printf("contents:?%s/n",buf);?? ????close(server_sockfd);?? ????????return?0;?? }??
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客戶端:udp_client.c
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[cpp]?view plaincopy
#include?<stdio.h>?? #include?<sys/types.h>?? #include?<sys/socket.h>?? #include?<netinet/in.h>?? #include?<arpa/inet.h>?? ?? int?main(int?argc,?char?*argv[])?? {?? ????int?client_sockfd;?? ????int?len;?? ????????struct?sockaddr_in?remote_addr;? ????int?sin_size;?? ????char?buf[BUFSIZ];?? ????memset(&remote_addr,0,sizeof(remote_addr));? ????remote_addr.sin_family=AF_INET;? ????remote_addr.sin_addr.s_addr=inet_addr("127.0.0.1"); ????remote_addr.sin_port=htons(8000);? ?? ????????? ????if((client_sockfd=socket(PF_INET,SOCK_DGRAM,0))<0)?? ????{???? ????????perror("socket");?? ????????return?1;?? ????}?? ????strcpy(buf,"This?is?a?test?message");?? ????printf("sending:?'%s'/n",buf);?? ????sin_size=sizeof(struct?sockaddr_in);?? ?????? ???? ????if((len=sendto(client_sockfd,buf,strlen(buf),0,(struct?sockaddr?*)&remote_addr,sizeof(struct?sockaddr)))<0)?? ????{?? ????????perror("recvfrom");??? ????????return?1;?? ????}?? ????close(client_sockfd);?? ????return?0;?? }??
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socket函數(shù)API.cpp
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htons();//將short類型的值從主機(jī)字節(jié)序轉(zhuǎn)換為網(wǎng)絡(luò)字節(jié)序
inet_addr();//將IP地址字符串轉(zhuǎn)換為long類型的網(wǎng)絡(luò)字節(jié)序
gethostbyname();//獲得與該域名對(duì)應(yīng)的IP地址
inet_ntoa();//將long類型的網(wǎng)絡(luò)字節(jié)序轉(zhuǎn)換成IP地址字符串
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