CProxy/cproxy.c

#include "cproxy.h"

char *read_data(int client_sock, char *data, int *data_len)
{
    char *new_data;
    int read_len;

    do {
        new_data = (char *)realloc(data, *data_len + BUF_SIZE + 1);
        if (new_data == NULL) {
            free(data);
            return NULL;
        }
        data = new_data;
        read_len = read(client_sock, data + *data_len, BUF_SIZE);
        if (read_len <= 0) {
            if (read_len == 0 || *data_len == 0 || errno != EAGAIN) {
                free(data);
                return NULL;
            }
            break;
        }
        *data_len += read_len;
    } while (read_len == BUF_SIZE);
    *(data + *data_len) = '\0';

    return data;
}

void servertoclient(int remote_sock, int client_sock, char *complete_data, int *len_complete_data)
{
    while ((*len_complete_data = read(remote_sock, complete_data, BUF_SIZE)) > 0) {
        write(client_sock, complete_data, *len_complete_data);
    }
}

void clienttoserver(int remote_sock, char *complete_data, int *len_complete_data)
{
    write(remote_sock, complete_data, *len_complete_data);
    complete_data = NULL;
    complete_data = 0;
}

// 处理客户端的连接
void handle_client(int client_sock, struct sockaddr_in client_addr, conf *configure)
{
    read_data(client_sock, header_buffer, &len_header_buffer); // 第一次读取客户端(浏览器)数据
    SIGN = request_type(header_buffer); // 获取请求消息类型
    extract_host(header_buffer); // 提取真实Host
    replacement_http_head(header_buffer, remote_host, &remote_port, &SIGN, configure);

    //printf("%s", header_buffer);
    //printf("%s\n", remote_host);
    //printf("%d\n", remote_port);

    if ((remote_sock = create_connection(configure, SIGN)) < 0) {
        return;
    }

    if (fork() == 0) {
        if (SIGN == HTTP_CONNECT) {
            clienttoserver(remote_sock, header_buffer, &len_header_buffer);
            forward_data(client_sock, remote_sock);
        } else if (SIGN == HTTP_OTHERS || SIGN == HTTP) {
            forward_header(remote_sock); //普通的http请求先转发header
            forward_data(client_sock, remote_sock);
        }
        exit(0);
    }

    if (fork() == 0) {
        if (SIGN == HTTP_CONNECT) {
            servertoclient(remote_sock, client_sock, complete_data, &len_complete_data);
        } else if (SIGN == HTTP_OTHERS || SIGN == HTTP) {
            forward_data(remote_sock, client_sock);
        }
        exit(0);
    }

    close(client_sock);
    close(remote_sock);
}

int send_data(int socket, char *buffer, int len)
{
    return send(socket, buffer, len, 0);
}

int receive_data(int socket, char *buffer, int len)
{
    int n = recv(socket, buffer, len, 0);
    return n;
}

void forward_data(int source_sock, int destination_sock)
{
    char buffer[BUF_SIZE];
    int n;
    while ((n = receive_data(source_sock, buffer, BUF_SIZE)) > 0) {
        send_data(destination_sock, buffer, n);
    }
    shutdown(destination_sock, SHUT_RDWR);
    shutdown(source_sock, SHUT_RDWR);
}

int create_connection(conf * configure, int SIGN)
{
    struct sockaddr_in server_addr;
    struct hostent *server;
    int sock;

    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        return CLIENT_SOCKET_ERROR;
    }

    if (SIGN == HTTP_CONNECT) {
        if ((server = gethostbyname(configure->https_ip)) == NULL) {
            errno = EFAULT;
            return CLIENT_RESOLVE_ERROR;
        }
    } else if (SIGN == HTTP_OTHERS || SIGN == HTTP) {
        if ((server = gethostbyname(configure->http_ip)) == NULL) {
            errno = EFAULT;
            return CLIENT_RESOLVE_ERROR;
        }
    }

    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    memcpy(&server_addr.sin_addr.s_addr, server->h_addr, server->h_length);

    if (SIGN == HTTP_CONNECT) {
        server_addr.sin_port = htons(configure->https_port);
    } else if (SIGN == HTTP_OTHERS || SIGN == HTTP) {
        server_addr.sin_port = htons(configure->http_port);
    }

    if (connect(sock, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
        return CLIENT_CONNECT_ERROR;
    }

    return sock;
}

int create_server_socket(int port)
{
    int server_sock, optval;
    struct sockaddr_in server_addr;

    if ((server_sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        return SERVER_SOCKET_ERROR;
    }

    if (setsockopt(server_sock, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)) < 0) {
        return SERVER_SETSOCKOPT_ERROR;
    }

    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    server_addr.sin_addr.s_addr = INADDR_ANY;

    if (bind(server_sock, (struct sockaddr *)&server_addr, sizeof(server_addr))
        != 0) {
        return SERVER_BIND_ERROR;
    }

    if (listen(server_sock, 20) < 0) {
        return SERVER_LISTEN_ERROR;
    }

    return server_sock;
}

// 守护
int init_daemon(int nochdir, int noclose, conf * configure)
{
    FILE *fp = fopen(configure->server_pid_file, "w");
    int pid;

    if ((pid = fork()) < 0) {
        return -1;
    } else if (0 != pid) {
        exit(0);
    }
    //child 1 continues...

    //become session leader
    if (setsid() < 0) {
        return -1;
    }

    signal(SIGHUP, SIG_IGN);
    if ((pid = fork()) < 0) {
        return -1;
    } else if (0 != pid) {
        fprintf(fp, "%d", pid);
        exit(0);
    }
    //child 2 continues...

    //change working directory
    if (0 == nochdir) {
        chdir("/");
    }
    //redirect stdin,stdout,stderror to "/dev/null"
    if (0 == noclose) {
        open("/dev/null", O_RDONLY);
        open("/dev/null", O_RDWR);
        open("/dev/null", O_RDWR);
    }
    fclose(fp);
    return 0;
}

// 处理僵尸进程
void sigchld_handler(int signal)
{
    while (waitpid(-1, NULL, WNOHANG) > 0) ;
}

void server_loop(conf * configure)
{
    struct sockaddr_in client_addr;
    socklen_t addrlen = sizeof(client_addr);

    while (1) {
        client_sock =
            accept(server_sock, (struct sockaddr *)&client_addr, &addrlen);

        if (fork() == 0) {      // 创建子进程处理客户端连接请求
            handle_client(client_sock, client_addr, configure);
            close(client_sock);
            exit(0);
        }
    }

    close(server_sock);
}

void start_server(conf * configure)
{
    signal(SIGCHLD, sigchld_handler); // 防止子进程变成僵尸进程

    if ((server_sock = create_server_socket(local_port)) < 0) {
        exit(server_sock);
    }

    server_loop(configure);
}

int _main(int argc, char *argv[])
{
    //初始化全局变量
    header_buffer = (char *)malloc(BUF_SIZE);
    len_header_buffer = strlen(header_buffer);

    complete_data = (char *)malloc(BUF_SIZES);
    len_complete_data = strlen(complete_data);

    char *inifile = "conf/cproxy.ini";
    conf *configure = (struct CONF *)malloc(sizeof(struct CONF));
    read_conf(inifile, configure);

    local_port = configure->server_port;

    int opt;
    char optstrs[] = ":l:dh";
    while (-1 != (opt = getopt(argc, argv, optstrs))) {
        switch (opt) {
        case 'l':
            local_port = atoi(optarg);
            break;
        case 'd':
            init_daemon(1, 1, configure);
            break;
        case 'h':
            help_information();
            exit(0);
            break;
        default:
            ;
        }
    }

    start_server(configure);
    free_conf(configure);
    free(complete_data);
    free(header_buffer);
    return 0;
}

int main(int argc, char *argv[])
{
    return _main(argc, argv);
}