/* values */
// 判断压力测试是否到达设定时间
volatile int timerexpired = 0;
int speed = 0;  // 记录进程成功得到服务器相应的数量，即成功数
int failed = 0; // 记录失败的数目
int bytes = 0;  // 记录进程成功读取的字节数，当force = 0时有效
/* globals */
// HTTP协议版本，默认为HTTP 1.0
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"
// HTTP 默认请求方式为GET，也支持HEAD，OPTION，TRACE
int method = METHOD_GET;
int clients = 1;        // 并发数目，-c N 参数N表示并发数，默认为1个进程
int force = 0;          // 是否等待读取从Server返回的数据，0表示要等待读取
int force_reload = 0;   // 是否使用缓存，1表示不缓存，0表示缓存
int proxyport = 80;     // (代理)服务器端口
char *proxyhost = NULL; // 代理服务器地址
int benchtime = 30;     // 压力测试时间，通过-t参数设置，默认为30s
/* internal */
// 管道，用于父子进程通信
int mypipe[2];
char host[MAXHOSTNAMELEN]; // 目标主机地址
#define REQUEST_SIZE 2048
char request[REQUEST_SIZE]; // 发送的构造的HTTP请求

// 长选项，getopt_long的参数
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);

// timerexpired = 1 时，定时结束
static void alarm_handler(int signal)
{
    timerexpired = 1;
}

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[])
{
    // getopt_long 的返回字符
    int opt = 0;
    // getopt_long 的第五个参数，一般为0
    int options_index = 0;
    char *tmp = NULL;

    if (argc == 1)
    {
        usage();
        return 2;
    }

    // 依次读取命令行参数，并通过optarg返回值赋值
    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);
        // -t 后跟压力测试时间，optarg返回，使用atoi转换成整数
        case 't':
            benchtime = atoi(optarg);
            break;
        case 'p':
            /* proxy server parsing server:port */
            tmp = strrchr(optarg, ':'); // server:Port
            proxyhost = optarg;
            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'; // 获得代理地址
            proxyport = atoi(tmp + 1);
            break; // 获得代理端口

        case ':':
        case 'h':
        case '?':
            usage();
            return 2;
            break;
        // 并发数目 -c N
        case 'c':
            clients = atoi(optarg);
            break;
        }
    }

    // optind 返回第一个不包含选项的命令行参数，此处为URL值
    if (optind == argc)
    {
        fprintf(stderr, "webbench: Missing URL!\n");
        usage();
        return 2;
    }

    // 此处多做一次判断，可预防BUG，因为上文并发数目用户可能写0
    if (clients == 0)
        clients = 1;
    // 压力测试时间默认为30S，如果用户写成0，则默认为60S
    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");
    // 构造HTTP请求头
    build_request(argv[optind]); // 参数为URL值
    /* print bench info */
    printf("\nBenchmarking: ");

    /*
     * 以下打印压力测试各种参数信息，如HTTP协议，请求方式，并发个数，请求时间等。
     */

    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");
    // bench() 压力测试的核心代码
    return bench();
}

// 构造HTTP请求头
void build_request(const char *url)
{
    char tmp[10];
    int i;

    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;
    // 该请求方法的相应不能缓存
    case METHOD_OPTIONS:
        strcpy(request, "OPTIONS");
        break;
    case METHOD_TRACE:
        strcpy(request, "TRACE");
        break;
    }

    strcat(request, " ");

    if (NULL == strstr(url, "://"))
    {
        fprintf(stderr, "\n%s: is not a valid URL.\n", url);
        exit(2);
    }

    if (strlen(url) > 1500)
    {
        fprintf(stderr, "URL is too long.\n");
        exit(2);
    }

    if (proxyhost == NULL)
        if (0 != strncasecmp("http://", url, 7)) // 未使用代理服务器的情况下，只允许HTTP协议
        {
            fprintf(stderr, "\nOnly HTTP protocol is directly supported, set --proxy for others.\n");
            exit(2);
        }
    /* protocol/host delimiter */
    // 指向"://"后的第一个字母
    i = strstr(url, "://") - url + 3;
    /* printf("%d\n",i); */
    // URL后必须得'/'
    if (strchr(url + i, '/') == NULL)
    {
        fprintf(stderr, "\nInvalid URL syntax - hostname don't ends with '/'.\n");
        exit(2);
    }
    // 如果未使用代理服务器，就表示肯定是HTTP协议
    if (proxyhost == NULL)
    {
        /* get port from hostname */
        // 如果是server : port 形式，解析主机和端口
        if (index(url + i, ':') != NULL &&
            index(url + i, ':') < index(url + i, '/'))
        {
            // 获取主机地址
            strncpy(host, url + i, strchr(url + i, ':') - url - i);
            bzero(tmp, 10);
            strncpy(tmp, index(url + i, ':') + 1, strchr(url + i, '/') - index(url + i, ':') - 1);
            /* printf("tmp=%s\n",tmp); */
            // 目标端口
            proxyport = atoi(tmp);
            if (proxyport == 0)
                proxyport = 80;
        }
        else
        {
            strncpy(host, url + i, strcspn(url + i, "/"));
        }
        // printf("Host=%s\n",host);
        // url + i + strcspn(url+i,"/") 得到域名后面的目标地址
        strcat(request + strlen(request), url + i + strcspn(url + i, "/"));
    }
    else
    {
        // printf("ProxyHost=%s\nProxyPort=%d\n",proxyhost,proxyport);
        // 如若使用代理服务器
        strcat(request, url);
    }

    if (http10 == 1)
        strcat(request, " HTTP/1.0");
    else if (http10 == 2)
        strcat(request, " HTTP/1.1");
    // 完成如 GET / HTTP1.1 后，添加"\r\n"
    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");
    }
    // force_reload = 1 和存在代理服务器，则不缓存
    if (force_reload && proxyhost != NULL)
    {
        strcat(request, "Pragma: no-cache\r\n");
    }
    // 如果为HTTP1.1，则存在长连接，应将Connection置为close
    if (http10 > 1)
        strcat(request, "Connection: close\r\n");
    /* add empty line at end */
    // 别忘记在请求后添加"\r\n"
    if (http10 > 0)
        strcat(request, "\r\n");
    // printf("Req=%s\n",request);
}

/* vraci system rc error kod */
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 */
    // 根据并发数创建子进程
    for (i = 0; i < clients; i++)
    {
        pid = fork();
        if (pid <= (pid_t)0)
        {
            /* child process or error*/
            // 注意这里子进程sleep(1)
            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;
    }

    // 子进程则调用benchcore函数
    if (pid == (pid_t)0)
    {
        /* I am a child */
        if (proxyhost == NULL)
            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); */
        // 子进程将speed failed bytes写进管道
        fprintf(f, "%d %d %d\n", speed, failed, bytes);
        fclose(f);
        return 0;
    }
    else //父进程
    {
        f = fdopen(mypipe[0], "r"); //mypipe[0]与标准流相结合
        if (f == NULL)
        {
            perror("open pipe for reading failed.");
            return 3;
        }
        setvbuf(f, NULL, _IONBF, 0); //设置无缓冲区
        speed = 0;
        failed = 0;
        bytes = 0;

        while (1)
        {
            // 通过f从管道读取数据，注意fscanf为阻塞式函数
            pid = fscanf(f, "%d %d %d", &i, &j, &k);
            if (pid < 2)
            {
                fprintf(stderr, "Some of our childrens died.\n");
                break;
            }
            // 父进程利用管道负责统计子进程的三种数据和
            speed += i;
            failed += j;
            bytes += k;
            /* fprintf(stderr,"*Knock* %d %d read=%d\n",speed,failed,pid); */
            // 当子进程数据读完后，就退出
            if (--clients == 0)
                break;
        }
        fclose(f);

        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;
}

// 子进程进行压力测试，每个子进程皆会调用
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 */
    // 设置alarm定时器处理函数
    sa.sa_handler = alarm_handler;
    sa.sa_flags = 0;
    // sigaction 成功则返回0，失败则返回-1
    // 超时会产生信号SIGALRM，用sa中的指定函数处理
    if (sigaction(SIGALRM, &sa, NULL))
        exit(3);
    alarm(benchtime); // 开始计时

    rlen = strlen(req);
nexttry:
    while (1)
    {
        // 超时则返回
        if (timerexpired)
        {
            if (failed > 0)
            {
                /* fprintf(stderr,"Correcting failed by signal\n"); */
                failed--;
            }
            return;
        }
        s = Socket(host, port);
        if (s < 0)
        {
            failed++;
            continue;
        } // 连接失败，failed数加一
        if (rlen != write(s, req, rlen))
        {
            failed++;
            close(s);
            continue;
        }                // header大小与发送的不相等，则失败
        if (http10 == 0) // 针对HTTP0.9的特殊处理，关闭s的写功能，成功则返回0，错误则返回-1
            if (shutdown(s, 1))
            {
                failed++;
                close(s);
                continue;
            }
        // 发出请求后需要等待服务器的响应结果
        if (force == 0) // force = 0表示等待从Server返回的数据
        {
            /* read all available data from socket */
            while (1)
            {
                if (timerexpired)
                    break;              // timerexpired默认为0，在规定时间内读取当为1时表示定时结束
                i = read(s, buf, 1500); // 从socket读取返回数据
                                        /* fprintf(stderr,"%d\n",i); */
                if (i < 0)
                {
                    failed++;
                    close(s);
                    goto nexttry;
                }
                else if (i == 0)
                    break;
                else
                    bytes += i;
            }
        }
        if (close(s))
        {
            failed++;
            continue;
        }
        speed++;
    }
}

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;

    // 将字符串转换为32位二进制网络字节序的IPv4地址
    inaddr = inet_addr(host);
    if (inaddr != INADDR_NONE)
        memcpy(&ad.sin_addr, &inaddr, sizeof(inaddr));
    else
    {
        // 使用域名或主机名获取ip地址
        hp = gethostbyname(host);
        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;
    if (connect(sock, (struct sockaddr *)&ad, sizeof(ad)) < 0)
        return -1;
    return sock;
}