443 lines
11 KiB
C
443 lines
11 KiB
C
#include <arpa/inet.h>
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#include <errno.h>
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#include <libgen.h>
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#include <netdb.h>
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#include <resolv.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <unistd.h>
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#include <sys/wait.h>
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#include <netinet/in.h>
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#define BUF_SIZE 8192
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#define PORT 9606
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#define MAX_HEADER_SIZE 8192
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char remote_host[128];
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int remote_port;
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int local_port;
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int server_sock;
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int client_sock;
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int remote_sock;
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char * header_buffer ;
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enum
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{
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FLG_NONE = 0, // 正常数据流不进行编解码
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R_C_DEC = 1, // 读取客户端数据仅进行解码
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W_S_ENC = 2 // 发送到服务端进行编码
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};
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static int io_flag; // 网络io的一些标志位
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void handle_client(int client_sock, struct sockaddr_in client_addr);
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void forward_header(int destination_sock);
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void forward_data(int source_sock, int destination_sock);
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void rewrite_header();
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int send_data(int socket,char * buffer,int len );
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int receive_data(int socket, char * buffer, int len);
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void hand_mproxy_info_req(int sock,char * header_buffer) ;
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int create_connection() ;
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int _main(int argc, char *argv[]) ;
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ssize_t readLine(int fd, void *buffer, size_t n)
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{
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ssize_t numRead;
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size_t totRead;
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char *buf;
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char ch;
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if (n <= 0 || buffer == NULL) {
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errno = EINVAL;
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return -1;
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}
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buf = buffer;
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totRead = 0;
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for (;;) {
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numRead = receive_data(fd, &ch, 1);
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if (numRead == -1) {
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if (errno == EINTR)
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continue;
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else
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return -1; // 未知错误
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} else if (numRead == 0) { // EOF
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if (totRead == 0) // No bytes read; return 0
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return 0;
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else // Some bytes read; add '\0'
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break;
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} else {
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if (totRead < n - 1) { // Discard > (n - 1) bytes
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totRead++;
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*buf++ = ch;
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}
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if (ch == '\n')
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break;
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}
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}
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*buf = '\0';
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return totRead;
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}
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int read_header(int fd, void * buffer)
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{
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memset(header_buffer,0,MAX_HEADER_SIZE);
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char line_buffer[2048];
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char * base_ptr = header_buffer;
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for(;;)
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{
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memset(line_buffer,0,2048);
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int total_read = readLine(fd,line_buffer,2048);
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if(total_read <= 0)
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{
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return -1;
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}
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// 防止header缓冲区蛮越界
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if(base_ptr + total_read - header_buffer <= MAX_HEADER_SIZE)
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{
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strncpy(base_ptr,line_buffer,total_read);
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base_ptr += total_read;
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} else
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{
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return -1;
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}
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// 读到了空行，http头结束
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if(strcmp(line_buffer,"\r\n") == 0 || strcmp(line_buffer,"\n") == 0)
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{
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break;
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}
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}
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return 0;
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}
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void extract_server_path(const char * header,char * output)
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{
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char * p = strstr(header,"GET /");
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if(p) {
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char * p1 = strchr(p+4,' ');
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strncpy(output,p+4,(int)(p1 - p - 4) );
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}
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}
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int extract_host(const char * header)
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{
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char * _p = strstr(header,"CONNECT"); // 在 CONNECT 方法中解析 隧道主机名称及端口号
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if(_p)
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{
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char * _p1 = strchr(_p,' ');
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char * _p2 = strchr(_p1 + 1,':');
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char * _p3 = strchr(_p1 + 1,' ');
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if(_p2)
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{
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char s_port[10];
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bzero(s_port,10);
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strncpy(remote_host,_p1+1,(int)(_p2 - _p1) - 1);
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strncpy(s_port,_p2+1,(int) (_p3 - _p2) -1);
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remote_port = atoi(s_port);
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} else
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{
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strncpy(remote_host,_p1+1,(int)(_p3 - _p1) -1);
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remote_port = 80;
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}
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return 0;
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}
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char * p = strstr(header,"Host:");
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if(!p)
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{
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return -1;
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}
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char * p1 = strchr(p,'\n');
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if(!p1)
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{
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return -1;
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}
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char * p2 = strchr(p + 5,':'); // 5是指'Host:'的长度
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if(p2 && p2 < p1)
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{
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int p_len = (int)(p1 - p2 -1);
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char s_port[p_len];
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strncpy(s_port,p2+1,p_len);
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s_port[p_len] = '\0';
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remote_port = atoi(s_port);
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int h_len = (int)(p2 - p -5 -1 );
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strncpy(remote_host,p + 5 + 1 ,h_len); // Host:
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remote_host[h_len] = '\0';
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} else
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{
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int h_len = (int)(p1 - p - 5 -1 -1);
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strncpy(remote_host,p + 5 + 1,h_len);
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remote_host[h_len] = '\0';
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remote_port = 80;
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}
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return 0;
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}
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// 响应隧道连接请求
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int send_tunnel_ok(int client_sock)
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{
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char * resp = "HTTP/1.1 200 Connection Established\r\n\r\n";
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int len = strlen(resp);
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char buffer[len+1];
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strcpy(buffer,resp);
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if(send_data(client_sock,buffer,len) < 0)
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{
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return -1;
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}
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return 0;
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}
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void hand_mproxy_info_req(int sock, char * header) {
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char server_path[255] ;
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char response[8192];
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extract_server_path(header,server_path);
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char info_buf[1024];
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sprintf(response,"HTTP/1.0 200 OK\nServer: CProxy/0.1\n\
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Content-type: text/html; charset=utf-8\n\n\
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<html><body>\
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<pre>%s</pre>\
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</body></html>\n",info_buf);
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write(sock,response,strlen(response));
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}
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// 处理客户端的连接
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void handle_client(int client_sock, struct sockaddr_in client_addr)
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{
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int is_http_tunnel = 0;
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if(strlen(remote_host) == 0) // 未指定远端主机名称从http 请求 HOST 字段中获取
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{
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if(read_header(client_sock,header_buffer) < 0)
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{
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return;
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} else
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{
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char * p = strstr(header_buffer,"CONNECT"); // 判断是否是http 隧道请求
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if(p)
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{
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is_http_tunnel = 1;
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}
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if(strstr(header_buffer,"GET /cproxy") > 0)
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{
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hand_mproxy_info_req(client_sock,header_buffer);
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return;
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}
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if(extract_host(header_buffer) < 0)
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{
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return;
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}
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}
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}
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if ((remote_sock = create_connection()) < 0) {
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return;
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}
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if (fork() == 0) { // 创建子进程用于从客户端转发数据到远端socket接口
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if(strlen(header_buffer) > 0 && !is_http_tunnel)
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{
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forward_header(remote_sock); //普通的http请求先转发header
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}
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forward_data(client_sock, remote_sock);
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exit(0);
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}
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if (fork() == 0) { // 创建子进程用于转发从远端socket接口过来的数据到客户端
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if(io_flag == W_S_ENC)
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{
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io_flag = R_C_DEC; // 发送请求给服务端进行编码，读取服务端的响应则进行解码
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} else if (io_flag == R_C_DEC)
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{
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io_flag = W_S_ENC; //接收客户端请求进行解码，那么响应客户端请求需要编码
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}
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if(is_http_tunnel)
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{
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send_tunnel_ok(client_sock);
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}
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forward_data(remote_sock, client_sock);
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exit(0);
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}
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close(remote_sock);
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close(client_sock);
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}
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void forward_data(int source_sock, int destination_sock) {
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char buffer[BUF_SIZE];
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int n;
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while ((n = receive_data(source_sock, buffer, BUF_SIZE)) > 0)
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{
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send_data(destination_sock, buffer, n);
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}
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shutdown(destination_sock, SHUT_RDWR);
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shutdown(source_sock, SHUT_RDWR);
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}
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void forward_header(int destination_sock)
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{
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rewrite_header();
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int len = strlen(header_buffer);
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send_data(destination_sock,header_buffer,len) ;
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}
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// 代理中的完整URL转发前需改成 path 的形式
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void rewrite_header()
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{
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char * p = strstr(header_buffer,"http://");
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char * p0 = strchr(p,'\0');
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char * p5 = strstr(header_buffer,"HTTP/"); // "HTTP/" 是协议标识 如 "HTTP/1.1"
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int len = strlen(header_buffer);
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if(p)
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{
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char * p1 = strchr(p + 7,'/');
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if(p1 && (p5 > p1))
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{
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// 转换url到 path
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memcpy(p,p1,(int)(p0 -p1));
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int l = len - (p1 - p) ;
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header_buffer[l] = '\0';
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} else
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{
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char * p2 = strchr(p,' '); // GET http://3g.sina.com.cn HTTP/1.1
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memcpy(p + 1,p2,(int)(p0-p2));
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*p = '/'; // url 没有路径使用根
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int l = len - (p2 - p ) + 1;
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header_buffer[l] = '\0';
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}
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}
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}
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int receive_data(int socket, char * buffer, int len)
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{
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int n = recv(socket, buffer, len, 0);
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if(io_flag == R_C_DEC && n > 0)
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{
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int i;
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for(i = 0; i< n; i++ )
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{
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buffer[i] ^= 1;
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}
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}
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return n;
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}
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int send_data(int socket,char * buffer,int len)
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{
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if(io_flag == W_S_ENC)
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{
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int i;
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for(i = 0; i < len ; i++)
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{
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buffer[i] ^= 1;
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}
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}
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return send(socket,buffer,len,0);
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}
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int create_connection() {
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struct sockaddr_in server_addr;
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struct hostent *server;
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int sock;
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if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
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return -1;
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}
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if ((server = gethostbyname(remote_host)) == NULL) {
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errno = EFAULT;
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return -1;
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}
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memset(&server_addr, 0, sizeof(server_addr));
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server_addr.sin_family = AF_INET;
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memcpy(&server_addr.sin_addr.s_addr, server->h_addr, server->h_length);
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server_addr.sin_port = htons(remote_port);
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if (connect(sock, (struct sockaddr *) &server_addr, sizeof(server_addr)) < 0) {
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return -1;
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}
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return sock;
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}
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int _main(int argc, char *argv[])
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{
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header_buffer = (char *) malloc(MAX_HEADER_SIZE);
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int server_sock, optval;
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struct sockaddr_in server_addr;
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if ((server_sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
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return -1;
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}
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if (setsockopt(server_sock, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)) < 0) {
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return -1;
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}
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memset(&server_addr, 0, sizeof(server_addr));
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server_addr.sin_family = AF_INET;
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server_addr.sin_port = htons(PORT);
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server_addr.sin_addr.s_addr = INADDR_ANY;
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if (bind(server_sock, (struct sockaddr*)&server_addr, sizeof(server_addr)) != 0) {
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return -1;
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}
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if (listen(server_sock, 17) < 0) {
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return -1;
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}
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struct sockaddr_in clnt_addr;
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socklen_t clnt_addr_size = sizeof(clnt_addr);
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while (1) {
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int client_socket =
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accept(server_sock, (struct sockaddr *) &clnt_addr,
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&clnt_addr_size);
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if (fork() == 0) { // 创建子进程处理客户端连接请求
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close(server_sock);
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handle_client(client_socket, clnt_addr);
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printf("%s", header_buffer);
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exit(0);
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}
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close(client_socket);
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}
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}
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int main(int argc, char *argv[])
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{
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return _main(argc,argv);
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}
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