Webbench源代码分析
Web Bench是一个网站压力测试的工具。其最后更新时间是2004年，已经十年多了。其源代码总共才500多行，全部使用C语言编写，最多可以模拟上万个并发连接。
其原理也比较简单，就是使用fork创建子进程，通过子进程来测试http连接，把测试结果写到管道，再有父进程读取管道信息来计算测试结果。流程图下：
其源代码有2个文件组成
socket.c是创建socket连接的。主要的代码在webbench.c中。
webbench.c中有几个主要的函数。
static void usage(void)是在使用出错时提示怎么使用本程序。
void build_request(const char *url)是用来创建http连接请求的。
static int bench(void)中创建管道和子进程，调用测试http函数。
void benchcore(const char *host,const int port,const char *req)对http请求进行测试。
socket.c源代码及注释：
/* $Id: socket.c 1.1 1995/01/01 07:11:14 cthuang Exp $
*
* This module has been modified by Radim Kolar for OS/2 emx
*/
/***********************************************************************
module: socket.c
program: popclient
SCCS ID: @(#)socket.c 1.5 4/1/94
programmer: Virginia Tech Computing Center
compiler: DEC RISC C compiler (Ultrix 4.1)
environment: DEC Ultrix 4.3
description: UNIX sockets code.
***********************************************************************/
#include <sys/types.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <sys/time.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
/***********
功能：通过地址和端口建立网络连接
@host:网络地址
@clientPort:端口
Return：建立的socket连接。
如果返回-1，表示建立连接失败
************/
int Socket(const char *host, int clientPort)
{
int sock;
unsigned long inaddr;
struct sockaddr_in ad;
struct hostent *hp;
memset(&ad, 0, sizeof(ad));
ad.sin_family = AF_INET;
inaddr = inet_addr(host);//将点分的十进制的IP转为无符号长整形
if (inaddr != INADDR_NONE)
memcpy(&ad.sin_addr, &inaddr, sizeof(inaddr));
else//如果host是域名
{
hp = gethostbyname(host);//用域名获取IP
if (hp == NULL)
return -1;
memcpy(&ad.sin_addr, hp->h_addr, hp->h_length);
}
ad.sin_port = htons(clientPort);
sock = socket(AF_INET, SOCK_STREAM, 0);
if (sock < 0)
return sock;
//连接
if (connect(sock, (struct sockaddr *)&ad, sizeof(ad)) < 0)
return -1;
return sock;
}
/*
* (C) Radim Kolar 1997-2004
* This is free software, see GNU Public License version 2 for
* details.
*
* Simple forking WWW Server benchmark:
*
* Usage:
* webbench --help
*
* Return codes:
* 0 - sucess
* 1 - benchmark failed (server is not on-line)
* 2 - bad param
* 3 - internal error, fork failed
*
*/
#include "socket.c"
#include <unistd.h>
#include <sys/param.h>
#include <rpc/types.h>
#include <getopt.h>
#include <strings.h>
#include <time.h>
#include <signal.h>
/* values */
volatile int timerexpired=0;
int speed=0;
int failed=0;
int bytes=0;
/* globals */
//http协议的版本号
int http10=1; /* 0 - http/0.9, 1 - http/1.0, 2 - http/1.1 */
/* Allow: GET, HEAD, OPTIONS, TRACE */
#define METHOD_GET 0
#define METHOD_HEAD 1
#define METHOD_OPTIONS 2
#define METHOD_TRACE 3
#define PROGRAM_VERSION "1.5"
int method=METHOD_GET;//全局变量，指定http方法
int clients=1;//并发数
int force=0;//是否等待服务器应答。默认为不等待
int force_reload=0;
int proxyport=80;//代理服务器端口号。默认为80
char *proxyhost=NULL;//代理服务器的地址
int benchtime=30;//运行多久。默认为30s。可以通过-t指定
/* internal */
int mypipe[2];
char host[MAXHOSTNAMELEN];
#define REQUEST_SIZE 2048
char request[REQUEST_SIZE];
//struct option结构体，配合getopt_long函数使用
static const struct option long_options[]=
{
{"force",no_argument,&force,1},
{"reload",no_argument,&force_reload,1},
{"time",required_argument,NULL,'t'},
{"help",no_argument,NULL,'?'},
{"http09",no_argument,NULL,'9'},
{"http10",no_argument,NULL,'1'},
{"http11",no_argument,NULL,'2'},
{"get",no_argument,&method,METHOD_GET},
{"head",no_argument,&method,METHOD_HEAD},
{"options",no_argument,&method,METHOD_OPTIONS},
{"trace",no_argument,&method,METHOD_TRACE},
{"version",no_argument,NULL,'V'},
{"proxy",required_argument,NULL,'p'},
{"clients",required_argument,NULL,'c'},
{NULL,0,NULL,0}
};
/* prototypes */
static void benchcore(const char* host,const int port, const char *request);
static int bench(void);
static void build_request(const char *url);
static void alarm_handler(int signal)
{
timerexpired=1;
}
/**************
程序使用方法
***************/
static void usage(void)
{
fprintf(stderr,
"webbench [option]... URL\n"
" -f|--force Don't wait for reply from server.\n"
" -r|--reload Send reload request - Pragma: no-cache.\n"
" -t|--time <sec> Run benchmark for <sec> seconds. Default 30.\n"
" -p|--proxy <server:port> Use proxy server for request.\n"
" -c|--clients <n> Run <n> HTTP clients at once. Default one.\n"
" -9|--http09 Use HTTP/0.9 style requests.\n"
" -1|--http10 Use HTTP/1.0 protocol.\n"
" -2|--http11 Use HTTP/1.1 protocol.\n"
" --get Use GET request method.\n"
" --head Use HEAD request method.\n"
" --options Use OPTIONS request method.\n"
" --trace Use TRACE request method.\n"
" -?|-h|--help This information.\n"
" -V|--version Display program version.\n"
);
};
int main(int argc, char *argv[])
{
int opt=0;
int options_index=0;
char *tmp=NULL;
if(argc==1)//使用方法不合适
{
usage();
return 2;
}
//检查输入参数，并设置对应选项
while((opt=getopt_long(argc,argv,"912Vfrt:p:c:?h",long_options,&options_index))!=EOF )
{
switch(opt)
{
case 0 : break;
case 'f': force=1;break;
case 'r': force_reload=1;break;
case '9': http10=0;break;
case '1': http10=1;break;
case '2': http10=2;break;
case 'V': printf(PROGRAM_VERSION"\n");exit(0);//输入版本号
case 't': benchtime=atoi(optarg);break; //optarg表示命令后的参数，例如-c 100，optarg为100。
//atoi表示把字符串转换成长整型。
case 'p':
/* proxy server parsing server:port */
tmp=strrchr(optarg,':');
proxyhost=optarg;//设定地址
if(tmp==NULL)
{
break;
}
if(tmp==optarg)
{
fprintf(stderr,"Error in option --proxy %s: Missing hostname.\n",optarg);
return 2;
}
if(tmp==optarg+strlen(optarg)-1)
{
fprintf(stderr,"Error in option --proxy %s Port number is missing.\n",optarg);
return 2;
}
*tmp='\0';
proxyport=atoi(tmp+1);break;//重设端口号
case ':':
case 'h':
case '?': usage();return 2;break;
case 'c': clients=atoi(optarg);break;//并发数
}
}
//optind为对应参数的下标位置
if(optind==argc) {
fprintf(stderr,"webbench: Missing URL!\n");
usage();
return 2;
}
if(clients==0) clients=1;
if(benchtime==0) benchtime=60;
/* Copyright */
fprintf(stderr,"Webbench - Simple Web Benchmark "PROGRAM_VERSION"\n"
"Copyright (c) Radim Kolar 1997-2004, GPL Open Source Software.\n"
);
//使用中，最后为URL，所以optind应该是URL的位置
build_request(argv[optind]);
/* print bench info */
printf("\nBenchmarking: ");
switch(method)
{
case METHOD_GET:
default:
printf("GET");break;
case METHOD_OPTIONS:
printf("OPTIONS");break;
case METHOD_HEAD:
printf("HEAD");break;
case METHOD_TRACE:
printf("TRACE");break;
}
printf(" %s",argv[optind]);
switch(http10)
{
case 0: printf(" (using HTTP/0.9)");break;
case 2: printf(" (using HTTP/1.1)");break;
}
printf("\n");
if(clients==1) printf("1 client");
else
printf("%d clients",clients);
printf(", running %d sec", benchtime);
if(force) printf(", early socket close");
if(proxyhost!=NULL) printf(", via proxy server %s:%d",proxyhost,proxyport);
if(force_reload) printf(", forcing reload");
printf(".\n");
return bench();
}
/****************
创建URL请求连接
@url:url地址
创建好的请求放在全局变量request中
****************/
void build_request(const char *url)
{
char tmp[10];
int i;
//请求地址和请求连接清零
bzero(host,MAXHOSTNAMELEN);
bzero(request,REQUEST_SIZE);
if(force_reload && proxyhost!=NULL && http10<1) http10=1;
if(method==METHOD_HEAD && http10<1) http10=1;
if(method==METHOD_OPTIONS && http10<2) http10=2;
if(method==METHOD_TRACE && http10<2) http10=2;
switch(method)
{
default:
case METHOD_GET: strcpy(request,"GET");break;
case METHOD_HEAD: strcpy(request,"HEAD");break;
case METHOD_OPTIONS: strcpy(request,"OPTIONS");break;
case METHOD_TRACE: strcpy(request,"TRACE");break;
}
strcat(request," ");
if(NULL==strstr(url,"://"))//找“://”在URL中的位置
{
fprintf(stderr, "\n%s: is not a valid URL.\n",url);
exit(2);
}
if(strlen(url)>1500)//url是否太长
{
fprintf(stderr,"URL is too long.\n");
exit(2);
}
if(proxyhost==NULL)//代理服务器是否为空
if (0!=strncasecmp("http://",url,7)) //比较前7个字符串
{ fprintf(stderr,"\nOnly HTTP protocol is directly supported, set --proxy for others.\n");
exit(2);
}
/* protocol/host delimiter */
i=strstr(url,"://")-url+3;//i指向http://后第一个位置
/* printf("%d\n",i); */
if(strchr(url+i,'/')==NULL) {
fprintf(stderr,"\nInvalid URL syntax - hostname don't ends with '/'.\n");
exit(2);
}
if(proxyhost==NULL)
{
/* get port from hostname */
if(index(url+i,':')!=NULL &&
index(url+i,':')<index(url+i,'/'))//判断url中是否指定了端口号
{
strncpy(host,url+i,strchr(url+i,':')-url-i);//取出主机地址
bzero(tmp,10);
strncpy(tmp,index(url+i,':')+1,strchr(url+i,'/')-index(url+i,':')-1);
/* printf("tmp=%s\n",tmp); */
proxyport=atoi(tmp);//端口号转换为int
if(proxyport==0) proxyport=80;
} else
{
strncpy(host,url+i,strcspn(url+i,"/"));
}
// printf("Host=%s\n",host);
strcat(request+strlen(request),url+i+strcspn(url+i,"/"));
} else
{
// printf("ProxyHost=%s\nProxyPort=%d\n",proxyhost,proxyport);
strcat(request,url);
}
if(http10==1)//版本号
strcat(request," HTTP/1.0");
else if (http10==2)
strcat(request," HTTP/1.1");
strcat(request,"\r\n");
if(http10>0)
strcat(request,"User-Agent: WebBench "PROGRAM_VERSION"\r\n");
if(proxyhost==NULL && http10>0)
{
strcat(request,"Host: ");
strcat(request,host);
strcat(request,"\r\n");
}
if(force_reload && proxyhost!=NULL)
{
strcat(request,"Pragma: no-cache\r\n");
}
if(http10>1)
strcat(request,"Connection: close\r\n");
/* add empty line at end */
if(http10>0) strcat(request,"\r\n");
// printf("Req=%s\n",request);
}
/* vraci system rc error kod */
/**********************
创建管道和子进程，对http请求进行测试
**********************/
static int bench(void)
{
int i,j,k;
pid_t pid=0;
FILE *f;
/* check avaibility of target server */
i=Socket(proxyhost==NULL?host:proxyhost,proxyport);
if(i<0) {
fprintf(stderr,"\nConnect to server failed. Aborting benchmark.\n");
return 1;
}
close(i);
/* create pipe */
if(pipe(mypipe))
{
perror("pipe failed.");
return 3;
}
/* not needed, since we have alarm() in childrens */
/* wait 4 next system clock tick */
/*
cas=time(NULL);
while(time(NULL)==cas)
sched_yield();
*/
/* fork childs */
for(i=0;i<clients;i++)
{
pid=fork();
if(pid <= (pid_t) 0)
{
/* child process or error*/
sleep(1); /* make childs faster */
break;
}
}
if( pid< (pid_t) 0)
{
fprintf(stderr,"problems forking worker no. %d\n",i);
perror("fork failed.");
return 3;
}
if(pid== (pid_t) 0)
{
/* I am a child */
if(proxyhost==NULL)//是否使用proxyhost
benchcore(host,proxyport,request);
else
benchcore(proxyhost,proxyport,request);
/* write results to pipe */
f=fdopen(mypipe[1],"w");
if(f==NULL)
{
perror("open pipe for writing failed.");
return 3;
}
/* fprintf(stderr,"Child - %d %d\n",speed,failed); */
fprintf(f,"%d %d %d\n",speed,failed,bytes);//把每个子进程运行的结果放到管道。
fclose(f);
return 0;
} else
{
f=fdopen(mypipe[0],"r");
if(f==NULL)
{
perror("open pipe for reading failed.");
return 3;
}
setvbuf(f,NULL,_IONBF,0);
speed=0;
failed=0;
bytes=0;
while(1)//父进程读取管道数据，并做加法
{
pid=fscanf(f,"%d %d %d",&i,&j,&k);
if(pid<2)
{
fprintf(stderr,"Some of our childrens died.\n");
break;
}
speed+=i;
failed+=j;
bytes+=k;
/* fprintf(stderr,"*Knock* %d %d read=%d\n",speed,failed,pid); */
if(--clients==0) break;
}
fclose(f);
//输出测试结果
printf("\nSpeed=%d pages/min, %d bytes/sec.\nRequests: %d susceed, %d failed.\n",
(int)((speed+failed)/(benchtime/60.0f)),
(int)(bytes/(float)benchtime),
speed,
failed);
}
return i;
}
/******************************
这里才是测试http的地方
@host:地址
@port：端口
@req：http格式方法
********************************/
void benchcore(const char *host,const int port,const char *req)
{
int rlen;
char buf[1500];
int s,i;
struct sigaction sa;
/* setup alarm signal handler */
sa.sa_handler=alarm_handler;//定时器方法
sa.sa_flags=0;
if(sigaction(SIGALRM,&sa,NULL))
exit(3);
alarm(benchtime);
rlen=strlen(req);
nexttry:while(1)
{
if(timerexpired)//定时器到时后，会设定timerexpired=1，函数就会返回
{
if(failed>0)
{
/* fprintf(stderr,"Correcting failed by signal\n"); */
failed--;
}
return;
}
s=Socket(host,port); //创建连接
if(s<0) { failed++;continue;} //连接失败，failed加1
if(rlen!=write(s,req,rlen)) {failed++;close(s);continue;}//发送失败
if(http10==0)
if(shutdown(s,1)) { failed++;close(s);continue;}
if(force==0) //force等于0表示要读取http请求数据
{
/* read all available data from socket */
while(1)
{
if(timerexpired) break;
i=read(s,buf,1500);
/* fprintf(stderr,"%d\n",i); */
if(i<0)
{
failed++;
close(s);
goto nexttry;
}
else
if(i==0) break;
else
bytes+=i;//读取字节数增加
}
}
if(close(s)) {failed++;continue;}
speed++;//http测试成功一次，speed加1
}
}