How to make an epoll-based HTTP client
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Makefile
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# @author KISHI Yasuhiro
# $Id: Makefile,v 1.2 2008/11/23 12:30:13 ykishi Exp ykishi $
CC = gcc
OBJS = epoll-client.o getSocket.o setNonblocking.o
LIBS =
INCLUDES =
TARGET = epoll-client
$(TARGET): $(OBJS)
$(CC) -o $@ $(OBJS) $(LIBS) && strip $(TARGET)
.c.o:
$(CC) -c $< $(INCLUDES)
clean:
rm -f $(TARGET) $(OBJS) *~ *.c.orig
indent:
astyle -a -P --mode=java *.c
getSocket.o: getSocket.h
setNoblocking.o: setNonblocking.h
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getSocket.h
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/*
* $Id: getSocket.h,v 1.1 2008/11/23 12:18:50 ykishi Exp ykishi $
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <unistd.h>
int getSocket (char *hostname, int portNumber);
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setNonblocking.h
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/epoll.h>
#include <netinet/in.h>
/**
* $Source: /home/ykishi/C-test/epoll-client/RCS/setNonblocking.h,v $
*/
void setNonblocking (int sock);
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epoll-client.c
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/epoll.h>
#include <netinet/in.h>
/**
* $Source: /home/ykishi/C-test/epoll-client/RCS/epoll-client.c,v $
*/
int
main ( int argc, char **argv ) {
char *host;
int port;
char *requestURI;
int i = 0;
int maxClients = 0;
if ( argc != 5 ) {
fprintf ( stderr, "Usage: %s [host] [port] [requestURI] [maxClients]\n", argv[0] );
return -1;
}
host = argv[1];
port = atoi ( argv[2] );
requestURI = argv[3];
maxClients = atoi(argv[4]);
//--------------------------------------------------
// create epoll's descriptors
//--------------------------------------------------
int epfd;
if ( ( epfd = epoll_create ( maxClients ) ) < 0 ) {
perror ( "epoll_create" );
exit ( 1 );
}
//--------------------------------------------------
// create as many socket handles as needed
//--------------------------------------------------
int sock[maxClients];
for ( i = 0; i < maxClients; i++ ) {
sock[i] = getSocket ( host, port );
setNonblocking ( sock[i] );
fprintf ( stderr, "... socket handle created ... \n" );
}
//--------------------------------------------------
// add all the sockets into epoll
//--------------------------------------------------
struct epoll_event ev;
struct epoll_event events[maxClients];
for ( i = 0; i < maxClients; i++ ) {
memset ( &ev, 0, sizeof ev );
ev.events = EPOLLIN | EPOLLOUT | EPOLLET;
ev.data.fd = sock[i];
if ( epoll_ctl ( epfd, EPOLL_CTL_ADD, sock[i], &ev ) < 0 ) {
fprintf ( stderr, "epoll_ctl()\n" );
exit ( 2 );
}
}
//--------------------------------------------------------------
// wait for the available status of each epoll descriptor
//--------------------------------------------------------------
int nfd;
while ( 1 ) {
nfd = epoll_wait ( epfd, events, maxClients, -1 );
for ( i = 0; i < nfd; ++i ) {
fprintf ( stderr, "*** now polling *** i=%d\n", i );
int client = events[i].data.fd;
char message[1024];
if ( events[i].events & EPOLLOUT ) {
sprintf ( message, "GET %s HTTP/1.1\r\nHost: %s:%d\r\n\r\n",
requestURI, host, port );
int write_len = write ( client, message, strlen ( message ) );
printf ( "write_len=%d\n", write_len );
}
if ( events[i].events & EPOLLIN ) {
memset ( message, 0, sizeof message );
int read_len = read ( client, message, sizeof message );
printf ( "read_len=%d\n", read_len );
// detached
epoll_ctl ( epfd, EPOLL_CTL_DEL, client, &ev );
// close socket
close ( client );
// add new descriptor
int newSock = getSocket ( host, port );
setNonblocking ( newSock );
memset ( &ev, 0, sizeof ev );
ev.events = EPOLLIN | EPOLLOUT | EPOLLET;
ev.data.fd = newSock;
if ( epoll_ctl ( epfd, EPOLL_CTL_ADD, newSock, &ev ) < 0 ) {
fprintf ( stderr, "epoll_ctl()\n" );
exit ( 3 );
}
}
}
}
return 0;
}
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getSocket.c
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/*
* $Id: getSocket.c,v 1.4 2008/11/23 13:24:02 ykishi Exp ykishi $
*/
#include "getSocket.h"
int
getSocket ( char *hostname, int portNumber ) {
struct sockaddr_in addr;
struct hostent *he;
int sock;
if ( hostname == NULL ) {
perror ( "host is undefined!" );
exit ( 1 );
}
if ( ( sock = socket ( AF_INET, SOCK_STREAM, 0 ) ) < 0 ) {
perror ( "socket" );
exit ( 2 );
}
bzero ( ( char * ) &addr, sizeof ( addr ) );
if ( ( he = gethostbyname ( hostname ) ) == NULL ) {
perror ( "No such host" );
exit ( 3 );
}
bcopy ( he->h_addr, &addr.sin_addr, he->h_length );
addr.sin_family = AF_INET;
addr.sin_port = htons ( portNumber );
if ( connect ( sock, ( struct sockaddr * ) &addr, sizeof ( addr ) ) < 0 ) {
perror ( "connect" );
exit ( 4 );
}
return sock;
}
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setNonblocking.c
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#include "setNonblocking.h"
/**
* $Source: /home/ykishi/C-test/epoll-client/RCS/setNonblocking.c,v $
*/
void
setNonblocking ( int sock ) {
int flag = fcntl ( sock, F_GETFL, 0 );
fcntl ( sock, F_SETFL, flag | O_NONBLOCK );
}
[ykishi@foo-bar-machine epoll-client]$
[ykishi@foo-bar-machine epoll-client]$ ./epoll-client 10.181.168.72 80 / 100
... snip ...
*** now polling *** i=22
write_len=42
read_len=366
*** now polling *** i=23
write_len=42
*** now polling *** i=24
write_len=42
*** now polling *** i=25
write_len=42
read_len=366
*** now polling *** i=26
write_len=42
read_len=366
*** now polling *** i=27
write_len=42
*** now polling *** i=28
write_len=42
*** now polling *** i=29
write_len=42
read_len=366
*** now polling *** i=30
[root@foo-bar-machine logs]# tail -f access_log
... snip ...
10.181.168.72 - - [24/Nov/2008:13:54:44 +0900] "GET / HTTP/1.1" 200 103 "-" "-"
10.181.168.72 - - [24/Nov/2008:13:54:44 +0900] "GET / HTTP/1.1" 200 103 "-" "-"
10.181.168.72 - - [24/Nov/2008:13:54:44 +0900] "GET / HTTP/1.1" 200 103 "-" "-"
10.181.168.72 - - [24/Nov/2008:13:54:44 +0900] "GET / HTTP/1.1" 200 103 "-" "-"
10.181.168.72 - - [24/Nov/2008:13:54:44 +0900] "GET / HTTP/1.1" 200 103 "-" "-"
10.181.168.72 - - [24/Nov/2008:13:54:44 +0900] "GET / HTTP/1.1" 200 103 "-" "-"
10.181.168.72 - - [24/Nov/2008:13:54:44 +0900] "GET / HTTP/1.1" 200 103 "-" "-"