linux网络socket编程服务器端（tcp/udp）

//passive.c 对tcp和udp通用

#include
#include
#include
#include
#include
#include

void error(int status, int err,char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
if(err)
fprintf(stderr,":%s(%d)/n",strerror(err),err);
if(status)
exit(status);
}

static void  set_address(const char * hname, const char *sname,
struct sockaddr_in *sap, char *protocol) {
struct servent *sp;
struct hostent *hp;
short port;
bzero(sap, sizeof(*sap));
sap->sin_family = AF_INET;
if(hname != NULL) {
if(!inet_aton(hname, &sap->sin_addr)) {
hp = gethostbyname(hname);
if(hp == NULL)
error(1, 0, "unkown host %s", hname);
sap->sin_addr = *(struct in_addr *)hp->h_addr;
}
}
else
sap->sin_addr.s_addr = htonl(INADDR_ANY);
if (sp = getservbyname(sname, protocol))
sap->sin_port = sp->s_port;
else if ((sap->sin_port = htons((short)atoi(sname))) == 0)
error(1,0,"unkown serivce  %s", sname);
}

int server(char *hname, char *sname, char *protocol) {
struct sockaddr_in local;
int s,type;
const int on = 1;
if(strcmp(protocol,"tcp")==0)
type = SOCK_STREAM;
else
type = SOCK_DGRAM;

if((s=socket(AF_INET, type, 0)) <= 0)
error(1, 0, "create socket failed!");
set_address(hname, sname, &local, protocol);
if(setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)))
error(1,errno,"setsocket option failed!");
if(bind(s,(struct sockaddr *)&local,sizeof(local)))
error(1, errno, "bind failed!");
if((type==SOCK_STREAM)&&listen(s,5))
error(1, errno, "listen error!");
return s;
}

//tcpserver.c  子进程

#include
#include
#include
#include
#include
#include
#include
#include
#include
void process_server(int s, struct sockaddr_in * remote) {
int len;
time_t ti;
char buff[128];
printf("connection from: %s:%d/n",inet_ntoa(remote->sin_addr),ntohs(remote->sin_port));
ti=time(NULL);
//snprintf(buff,sizeof(buff),"%s/r/n",ctime(&ti));
while((len=recv(s,buff,sizeof(buff),0))>0) {
buff[len]='/0';
send(s, buff,strlen(buff), 0);
bzero(buff,sizeof(buff));
}
}

void sig_child() {
pid_t pid;
int status;
while((pid=waitpid(-1,&status,WNOHANG))>0)
printf("%d terminated!/n",pid);
// while(wait(&status)>0);
}

int main(int argc, char **argv) {
struct sockaddr_in remote;
char *hname, *sname;
int s, c, len;
pid_t pid;
if(argc < 2)
error(1,0,"parameters less than 2");
else if(argc == 2) {
hname = NULL;
sname = argv[1];
}
else if(argc == 3) {
hname = argv[1];
sname = argv[2];
}
s = server(hname, sname,"tcp");
signal(SIGCHLD,sig_child);
len = sizeof(struct sockaddr);
while(1) {
if((c=accept(s,(struct sockaddr *)&remote,&len))<=0){
if(errno == EINTR)
continue;
error(1,errno,"accept error!");
}
if((pid=fork())>0) {
close(c);
continue;
}
else if(pid < 0)
err(1,0,"fork error!");
close(s);
process_server(c,&remote);
exit(0);
}
close(s);
exit(0);
}

//tcpserver.c 用select

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
void sig_child() {
pid_t pid;
int status;
while((pid=waitpid(-1,&status,WNOHANG))>0)
printf("%d terminated!/n",pid);
// while(wait(&status)>0);
}

int main(int argc, char **argv) {
struct sockaddr_in remote;
char *hname, *sname;
int s, c, len,fd;
pid_t pid;
fd_set rset,allset;
int client[1024];
int i,maxi,maxfd,nready;
char buff[1024];
if(argc < 2)
error(1,0,"parameters less than 2");
else if(argc == 2) {
hname = NULL;
sname = argv[1];
}
else if(argc == 3) {
hname = argv[1];
sname = argv[2];
}

s = server(hname, sname,"tcp");
signal(SIGCHLD,sig_child);
len = sizeof(struct sockaddr);

FD_ZERO(&allset);
FD_ZERO(&rset);
FD_SET(s,&allset);
maxi=0;
maxfd=s;

for(i=0;i<1024;i++)
client[i]=-1;

while(1) {

rset=allset;

if((nready=select(maxfd+1,&rset,NULL,NULL,NULL))<0)
error(1,0,"select error!!");
if(FD_ISSET(s,&rset)) {
if((c=accept(s,(struct sockaddr *)&remote,&len))<=0){
error(1,errno,"accept error!");
}
for(i=0; i<1024; i++) {
if(client[i] != -1)
continue;
else {
client[i]= c;
break;
}
}

if(i == 1024)
error(1,0,"too many clients!!");
FD_SET(c,&allset);
if(c>maxfd)
maxfd = c;
if(i > maxi)
maxi = i;
if(--nready==0)
continue;
}
for(i=0;i<= maxi;i++){

if((fd=client[i])==-1)
continue;
if(FD_ISSET(fd,&rset)){
if((len=recv(fd,buff,sizeof(buff),0))>0) {
buff[len]='/0';
send(fd, buff,strlen(buff), 0);
bzero(buff,sizeof(buff));
}
else {
close(fd);
FD_CLR(fd,&allset);
client[i]=-1;
}
if(--nready==0)
break;
}
}
}
close(s);
exit(0);
}

//udpserver..c

#include
#include
#include
#include
#include
#include

void process_server(int s) {
struct sockaddr_in remote;
char buff[128];
int len,n;
while(1){
n=recvfrom(s,buff,sizeof(buff),0,(struct sockaddr *)&remote,&len);
//printf("%s,%d/n",buff,n);
buff
='/0';
sendto(s,buff,strlen(buff), 0, (struct sockaddr *)&remote,sizeof(remote));
}
}

int main(int argc, char **argv) {
struct sockaddr_in remote;
char *hname, *sname;
int s, c, len;
if(argc < 2)
error(1,0,"parameters less than 2");
else if(argc == 2) {
hname = NULL;
sname = argv[1];
}
else if(argc == 3) {
hname = argv[1];
sname = argv[2];
}
s = server(hname, sname,"udp");
process_server(s);
close(s);
exit(0);
}