linux下c/c++实例之十socket简单应用
2017-09-29 16:29
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转自：http://blog.csdn.net/taiyang1987912/article/details/49738351
通过socket扫描本机打开的tcp端口号，模拟用户名、密码登录服务器的过程、socket文件传输及模仿http服务器。
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// 端口扫描程序，只支持扫描TCP端口
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
// 定义一个端口区间信息
typedef struct _port_segment {
struct in_addr dest_ip; // 目标IP
unsigned short int min_port; // 起始端口
unsigned short int max_port; // 最大端口
} port_segment;
/*自定义的错误处理函数*/
void my_err(const char * err_string, int line)
{
fprintf(stderr, "line:%d ", line);
perror(err_string);
exit(1);
}
/*
* 描 述：扫描某一IP地址上的某一个端口的函数
* 返回值：-1 出错
* 0 目标端口未打开
* 1 目标端口已打开
*/
int do_scan(struct sockaddr_in serv_addr)
{
int conn_fd;
int ret;
// 创建一个TCP套接字
conn_fd = socket(AF_INET, SOCK_STREAM,0);
if (conn_fd < 0) {
my_err("socket", __LINE__);
}
// 向服务器端发送连接请求
if ((ret = connect(conn_fd, (struct sockaddr *)&serv_addr, sizeof (struct sockaddr))) < 0 ) {
if (errno == ECONNREFUSED) { // 目标端口未打开
close(conn_fd);
return 0;
} else { // 其他错误
close(conn_fd);
return -1;
}
} else if (ret == 0){
printf("port %d found in %s\n", ntohs(serv_addr.sin_port),
inet_ntoa(serv_addr.sin_addr));
close(conn_fd);
return 1;
}
return -1; // 实际执行不到这里，只是为了消除编译程序时产生的警告
}
// 执行扫描的线程，扫描某一区间的端口
void * scaner(void *arg)
{
unsigned short int i;
struct sockaddr_in serv_addr;
port_segment portinfo; // 端口信息
// 读取端口区间信息
memcpy(&portinfo, arg, sizeof(struct _port_segment));
// 初始化服务器端地址结构
memset(&serv_addr, 0, sizeof (struct sockaddr_in));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = portinfo.dest_ip.s_addr;
//printf("******serv_addr.sin_addr.s_addr=%s\n", serv_addr.sin_addr.s_addr);
//printf("*******portinfo.min_port=%d, portinfo.max_port=%d\n", portinfo.min_port, portinfo.max_port);
for (i=portinfo.min_port; i<=portinfo.max_port; i++) {
serv_addr.sin_port = htons(i);
if (do_scan(serv_addr) < 0) {
continue; // 出错则退出进程
}
}
return NULL;
}
/*
* 命令行参数：-m 最大端口， -a 目标主机的IP地址, -n 最大线程数
*/
int main(int argc, char **argv)
{
pthread_t* thread; // 指向所有的线程ID
int max_port; // 最大端口号
int thread_num; // 最大线程数
int seg_len; // 端口区间长度
struct in_addr dest_ip; // 目标主机IP
int i;
// 检查参数个数
if (argc != 7) {
printf("Usage: [-m] [max_port] [-a] [serv_address] [-n] [thread_number]\n");
exit(1);
}
// 解析命令行参数
for (i=1; i<argc; i++) {
if (strcmp("-m", argv[i]) == 0) {
max_port = atoi(argv[i+1]); // 将字符串转化为对应的整数
if (max_port < 0 || max_port >= 65535) { //65535会导致死循环
printf("Usage:invalid max dest port\n");
exit(1);
}
continue;
}
if (strcmp("-a", argv[i]) == 0) {
if (inet_aton(argv[i+1], &dest_ip) == 0) {
printf("Usage:invalid dest ip address\n");
exit(1);
}
continue;
}
if (strcmp("-n", argv[i]) == 0) {
thread_num = atoi(argv[i+1]);
if (thread_num <= 0) {
printf("Usage:invalid thread_number\n");
exit(1);
}
continue;
}
}
// 如果输入的最大端口号小于线程数，则将线程数设为最大端口号
if (max_port < thread_num) {
thread_num = max_port;
}
seg_len = max_port / thread_num;
if ( (max_port%thread_num) != 0 ) {
thread_num += 1;
}
//printf("max_port=%d, seg_len=%d, thread_num = %d\n", max_port, seg_len, thread_num);
// 分配存储所有线程ID的内存空间
thread = (pthread_t*)malloc(thread_num*sizeof(pthread_t));
// 创建线程，根据最大端口号和线程数分配每个线程扫描的端口区间
port_segment *portinfo = (port_segment*)malloc(thread_num * sizeof(port_segment));
for (i=0; i<thread_num; i++) {
portinfo[i].dest_ip = dest_ip;
portinfo[i].min_port = i*seg_len + 1;
//printf("portinfo.min_port=%d, seg_len=%d, i = %d\n", portinfo[i].min_port, seg_len, i);
if (i == thread_num - 1) {
portinfo[i].max_port = max_port;
} else {
portinfo[i].max_port = portinfo[i].min_port + seg_len - 1;
}
// 创建线程
//if (pthread_create(&thread[i], NULL, scaner, (void *)(portinfo + i)) != 0) {
if (pthread_create(&thread[i], NULL, scaner, (void *)(&portinfo[i])) != 0) {
my_err("pthread_create", __LINE__);
}
}
for (i=0; i<thread_num; i++) {
// 主线程等待子线程结束
pthread_join(thread[i], NULL);
}
free(portinfo);
return 0;
}
（2）编译运行
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gcc -o scanport scanport.c -lpthread
./scanport -m 65534 -a 127.0.0.1 -n 1
可以通过netstat查看网络相关信息，netstat -tnlp或netstat -tnlpc比较打开的tcp端口号。
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// Client/Server模型的服务器端
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <stdlib.h>
#define BUFSIZE 1024
#define SERV_PORT 4507 // 服务器端的端口
#define LISTENQ 12 // 连接请求队列的最大长度
#define INVALID_USERINFO 'n' // 用户信息无效
#define VALID_USERINFO 'y' // 用户信息有效
#define USERNAME 0 // 接收到的是用户名
#define PASSWORD 1 // 接收到的是密码
struct userinfo { // 保存用户名和密码的结构体
char username[32];
char password[32];
};
struct userinfo users[ ] = {
{"linux", "unix"},
{"4507", "4508"},
{"clh", "clh"},
{"xl", "xl"},
{" "," "} // 以只含一个空格的字符串作为数组的结束标志
};
/*自定义的错误处理函数*/
void my_err(const char * err_string, int line)
{
fprintf(stderr, "line:%d ", line);
perror(err_string);
exit(1);
}
/*
* 函数名: my_recv
* 描 述 : 从套接字上读取一次数据(以'\n'为结束标志)
* 参 数 : conn_fd -- 从该连接套接字上接收数据
* data_buf -- 读取到的数据保存在此缓冲中
* len -- data_buf所指向的空间长度
* 返回值: 出错返回-1， 服务器端已关闭连接则返回0， 成功返回读取的字节数
*/
int my_recv(int conn_fd, char *data_buf, int len)
{
static char recv_buf[BUFSIZE]; // 自定义缓冲区，BUFSIZE定义在my_recv.h中
static char *pread; // 指向下一次读取数据的位置
static int len_remain = 0; // 自定义缓冲区中剩余字节数
int i;
// 如果自定义缓冲区中没有数据，则从套接字读取数据
if (len_remain <= 0) {
if ((len_remain =recv(conn_fd, recv_buf, sizeof (recv_buf), 0)) < 0) {
my_err("recv", __LINE__);
} else if (len_remain == 0) { // 目的计算机端的socket连接关闭
return 0;
}
pread = recv_buf; // 重新初始化pread指针
}
// 从自定义缓冲区中读取一次数据
for (i=0; *pread != '\n'; i++) {
if (i > len) { // 防止指针越界
return -1;
}
data_buf[i] = *pread++;
len_remain--;
}
// 去除结束标志
len_remain--;
pread++;
return i; // 读取成功
}
// 查找用户名是否存在，存在返回该用户名的下标,不存在则返回-1，出错返回-2
int find_name(const char *name)
{
int i;
if (name == NULL) {
printf("in find_name, NULL pointer");
return -2;
}
for (i=0; users[i].username[0] != ' ';i++) {
if (strncmp(users[i].username, name, strlen(users[i].username)) == 0) {
return i;
}
}
return -1;
}
// 发送数据
void send_data(int conn_fd, const char *string)
{
if (send(conn_fd, string, strlen(string), 0) < 0) {
my_err("send", __LINE__); // my_err函数在my_recv.h中声明
}
}
int main()
{
int sock_fd, conn_fd;
int optval;
int flag_recv = USERNAME; // 标识接收到的是用户还是密码
int ret;
int name_num;
pid_t pid;
socklen_t cli_len;
struct sockaddr_in cli_addr, serv_addr;
char recv_buf[128];
// 创建一个TCP套接字
sock_fd = socket(AF_INET, SOCK_STREAM,0);
if (sock_fd < 0) {
my_err("socket", __LINE__);
}
// 设置该套接字使之可以重新绑定端口
optval = 1;
if (setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR,
(void *)&optval, sizeof(int)) < 0) {
my_err("setsockopt", __LINE__);
}
// 初始化服务器端地址结构
memset(&serv_addr, 0, sizeof (struct sockaddr_in));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(SERV_PORT);
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
// 将套接字绑定到本地端口
if (bind(sock_fd, (struct sockaddr *)&serv_addr,
sizeof (struct sockaddr_in)) < 0) {
my_err("bind", __LINE__);
}
// 将套接字转化为监听套接字
if (listen(sock_fd, LISTENQ) < 0) {
my_err("listen", __LINE__);
}
cli_len = sizeof (struct sockaddr_in);
while (1) {
// 通过accept接受客户端的连接请求，并返回连接套接字用于收发数据
conn_fd = accept(sock_fd, (struct sockaddr *)&cli_addr, &cli_len);
if (conn_fd < 0) {
my_err("accept", __LINE__);
}
printf("accept a new client, ip:%s\n", inet_ntoa(cli_addr.sin_addr));
// 创建一个子进程处理刚刚接受的连接请求
if ( (pid = fork()) == 0 ) { // 子进程
while(1) {
memset(recv_buf, 0, sizeof(recv_buf));
if ((ret = recv(conn_fd, recv_buf, sizeof (recv_buf), 0)) < 0) {
perror("recv");
exit(1);
}
recv_buf[ret-1] = '\0'; // 将数据结束标志'\n'替换成字符串结束标志
if (flag_recv == USERNAME) { // 接收到的是用户名
name_num = find_name(recv_buf);
switch (name_num) {
case -1:
send_data(conn_fd, "n\n");
break;
case -2:
exit(1);
break;
default:
send_data(conn_fd, "y\n");
flag_recv = PASSWORD;
break;
}
} else if (flag_recv == PASSWORD) { // 接收到的是密码
if (strncmp(users[name_num].password, recv_buf, strlen(users[name_num].password)) == 0) {
send_data(conn_fd, "y\n");
send_data(conn_fd, "Welcome login my tcp server\n");
printf("%s login\n", users[name_num].username);
break; // 跳出while循环
} else
send_data(conn_fd, "n\n");
}
}
close(sock_fd);
close(conn_fd);
exit(0); // 结束子进程
} else { // 父进程关闭刚刚接受的连接请求，执行accept等待其他连接请求
close(conn_fd);
}
}
return 0;
}
（2）客户端client.c：
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#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define BUFSIZE 1024
#define INVALID_USERINFO 'n' // 用户信息无效
#define VALID_USERINFO 'y' // 用户信息有效
/*自定义的错误处理函数*/
void my_err(const char * err_string, int line)
{
fprintf(stderr, "line:%d ", line);
perror(err_string);
exit(1);
}
/*
* 函数名: my_recv
* 描 述 : 从套接字上读取一次数据(以'\n'为结束标志)
* 参 数 : conn_fd -- 从该连接套接字上接收数据
* data_buf -- 读取到的数据保存在此缓冲中
* len -- data_buf所指向的空间长度
* 返回值: 出错返回-1， 服务器端已关闭连接则返回0， 成功返回读取的字节数
*/
int my_recv(int conn_fd, char *data_buf, int len)
{
static char recv_buf[BUFSIZE]; // 自定义缓冲区，BUFSIZE定义在my_recv.h中
static char *pread; // 指向下一次读取数据的位置
static int len_remain = 0; // 自定义缓冲区中剩余字节数
int i;
// 如果自定义缓冲区中没有数据，则从套接字读取数据
if (len_remain <= 0) {
if ((len_remain =recv(conn_fd, recv_buf, sizeof (recv_buf), 0)) < 0) {
my_err("recv", __LINE__);
} else if (len_remain == 0) { // 目的计算机端的socket连接关闭
return 0;
}
pread = recv_buf; // 重新初始化pread指针
}
// 从自定义缓冲区中读取一次数据
for (i=0; *pread != '\n'; i++) {
if (i > len) { // 防止指针越界
return -1;
}
data_buf[i] = *pread++;
len_remain--;
}
// 去除结束标志
len_remain--;
pread++;
return i; // 读取成功
}
/*获取用户输入存入到buf，buf的长度为len，用户输入数据以'\n'为结束标志*/
int get_userinfo(char *buf, int len)
{
int i;
int c;
if (buf == NULL) {
return -1;
}
i = 0;
while ( ((c = getchar()) != '\n') && (c != EOF) && (i < len-2) ) {
buf[i++] = c;
}
buf[i++] = '\n';
buf[i++] = '\0';
return 0;
}
// 输入用户名,然后通过fd发送出去
void input_userinfo(int conn_fd, const char *string)
{
char input_buf[32];
char recv_buf[BUFSIZE];
int flag_userinfo;
int count = 0;
// 输入用户信息直到正确为止
do {
printf("%s:", string);
if (get_userinfo(input_buf, 32) < 0) {
printf("error return from get_userinfo\n");
exit(1);
}
if (send(conn_fd, input_buf, strlen(input_buf), 0) < 0) {
my_err("send", __LINE__);
}
// 从连接套接字上读取一次数据
if (my_recv(conn_fd, recv_buf, sizeof (recv_buf)) < 0) {
printf("data is too long\n");
exit(1);
}
if (recv_buf[0] == VALID_USERINFO) {
flag_userinfo = VALID_USERINFO;
} else {
count++;
if (count >= 3) {
printf("input %s error for three times,exit!\n", string);
exit(-1);
}
printf("%s error,input again!\n", string);
flag_userinfo= INVALID_USERINFO;
}
} while(flag_userinfo == INVALID_USERINFO);
}
int main(int argc, char **argv)
{
int i;
int ret;
int conn_fd;
int serv_port;
struct sockaddr_in serv_addr;
char recv_buf[BUFSIZE];
// 检查参数个数
if (argc != 5) {
printf("Usage: [-p] [serv_port] [-a] [serv_address]\n");
exit(1);
}
// 初始化服务器端地址结构
memset(&serv_addr, 0, sizeof (struct sockaddr_in));
serv_addr.sin_family = AF_INET;
// 从命令行获取服务器端的端口与地址
for (i=1; i<argc; i++) {
if (strcmp("-p", argv[i]) == 0) {
serv_port = atoi(argv[i+1]);
if (serv_port < 0 || serv_port > 65535) {
printf("invalid serv_addr.sin_port\n");
exit(1);
} else {
serv_addr.sin_port = htons(serv_port);
}
continue;
}
if (strcmp("-a", argv[i]) == 0) {
if (inet_aton(argv[i+1], &serv_addr.sin_addr) == 0) {
printf("invalid server ip address\n");
exit(1);
}
continue;
}
}
// 检测是否少输入了某项参数
if (serv_addr.sin_port == 0 || serv_addr.sin_addr.s_addr == 0) {
printf("Usage: [-p] [serv_addr.sin_port] [-a][serv_address]\n");
exit(1);
}
// 创建一个TCP套接字
conn_fd = socket(AF_INET, SOCK_STREAM,0);
if (conn_fd < 0) {
my_err("socket", __LINE__);
}
// 向服务器端发送连接请求
if (connect(conn_fd, (struct sockaddr *)&serv_addr, sizeof (struct sockaddr)) < 0) {
my_err("connect", __LINE__);
}
// 输入用户名和密码
input_userinfo(conn_fd, "username");
input_userinfo(conn_fd, "password");
// 读取欢迎信息并打印出来
if ((ret = my_recv(conn_fd, recv_buf, sizeof (recv_buf))) < 0) {
printf("data is too long\n");
exit(1);
}
for (i=0; i<ret; i++) {
printf("%c", recv_buf[i]);
}
printf("\n");
close(conn_fd);
return 0;
}
（3）编译运行：
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gcc -o server server.c
./server
gcc -o client client.c
./client -p 4507 -a 127.0.0.1
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#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <strings.h>
#define HELLO_WORLD_SERVER_PORT 6666
#define LENGTH_OF_LISTENQ_QUEUE 20
#define BUFFER_SIZE 1024
#define FILE_NAME_MAX_SIZE 512
int main(int argc, char *argv[])
{
struct sockaddr_in server_addr;
bzero(&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = htons(INADDR_ANY);
server_addr.sin_port = htons(HELLO_WORLD_SERVER_PORT);
int server_socket = socket(AF_INET, SOCK_STREAM, 0);
if (server_socket < 0) {
printf("create socket failed!\n");
exit(1);
}
if (bind(server_socket, (struct sockaddr*)&server_addr, sizeof(server_addr))) {
printf("bind socket failed!\n");
exit(1);
}
if (listen(server_socket, LENGTH_OF_LISTENQ_QUEUE)) {
printf("listen socket failed!\n");
exit(1);
}
while (1) {
struct sockaddr_in client_addr;
socklen_t length = sizeof(client_addr);
int new_server_scoket = accept(server_socket, (struct sockaddr*)&client_addr, &length);
if (new_server_scoket < 0) {
printf("accept socket failed!\n");
break;
}
char buffer[BUFFER_SIZE];
bzero(buffer, BUFFER_SIZE);
length = recv(new_server_scoket, buffer, BUFFER_SIZE, 0);
if (length < 0) {
printf("recv data failed!\n");
break;
}
char file_name[FILE_NAME_MAX_SIZE + 1];
bzero(file_name, FILE_NAME_MAX_SIZE + 1);
strncpy(file_name, buffer, strlen(file_name) > FILE_NAME_MAX_SIZE ? FILE_NAME_MAX_SIZE : strlen(buffer));
FILE *fp = fopen(file_name, "r");
if (fp == NULL) {
printf("File: %s not found\n", file_name);
}
else {
bzero(buffer, BUFFER_SIZE);
int file_length = 0;
while((file_length = fread(buffer, sizeof(char), BUFFER_SIZE, fp)) > 0) {
printf("file_length = %d\n", file_length);
if (send(new_server_scoket, buffer, file_length, 0) < 0) {
printf("send file: %s failed\n", file_name);
break;
}
bzero(buffer, BUFFER_SIZE);
}
fclose(fp);
printf("file: %s trandfer finished\n", file_name);
}
close(new_server_scoket);
}
close(server_socket);
return 0;
}
（2）file_client.c：
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#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <strings.h>
#define HELLO_WORLD_SERVER_PORT 6666
#define BUFFER_SIZE 1024
#define FILE_NAME_MAX_SIZE 512
int main(int argc, char *argv[])
{
if (argc != 2) {
printf("use:[./run][server_ipaddress]\n");
exit(1);
}
struct sockaddr_in client_addr;
bzero(&client_addr,sizeof(client_addr));
client_addr.sin_family = AF_INET;
if (inet_aton(argv[1], &client_addr.sin_addr) == 0) {
printf("server ip address error!\n");
exit(1);
}
client_addr.sin_port = htons(HELLO_WORLD_SERVER_PORT);
socklen_t client_addr_length = sizeof(client_addr);
int client_socket = socket(AF_INET, SOCK_STREAM, 0);
if (client_socket < 0) {
printf("create socket failed\n");
exit(1);
}
if (connect(client_socket, (struct sockaddr*)&client_addr, client_addr_length) < 0) {
printf("can not connect to address\n");
exit(1);
}
char file_name[FILE_NAME_MAX_SIZE + 1];
bzero(file_name, FILE_NAME_MAX_SIZE + 1);
printf("please input file name:");
scanf("%s", file_name);
char buffer[BUFFER_SIZE];
bzero(buffer, BUFFER_SIZE);
strncpy(buffer, file_name, strlen(file_name) > BUFFER_SIZE ? BUFFER_SIZE : strlen(file_name));
send(client_socket, buffer, BUFFER_SIZE, 0);
FILE *fp = fopen(file_name, "w");
if (fp == NULL) {
printf("file can not open\n");
exit(1);
}
bzero(buffer, BUFFER_SIZE);
int length = 0;
while (length = recv(client_socket, buffer, BUFFER_SIZE, 0)) {
if (length < 0) {
printf("recv failed\n");
break;
}
int write_length = fwrite(buffer, sizeof(char), length, fp);
if (write_length < length) {
printf("file write failed\n");
break;
}
bzero(buffer, BUFFER_SIZE);
}
printf("recieve file: %s from server %s finished!\n", file_name, argv[1]);
close(fp);
close(client_socket);
return 0;
}
（3）编译运行
[html] view
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gcc -o server file_server.c
./server
gcc -o client file_client.c
./client 127.0.0.1
server显示：
client显示：
注：server和client放在不同的目录下，需要传输的文件yang.txt与server在同一目录下。
[html] view
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#include <stdarg.h>
#include <errno.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <resolv.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <signal.h>
#include <strings.h>
#define DEFAULTIP "127.0.0.1"
#define DEFAULTPORT "4040"
#define DEFAULTBACK "10"
#define DEFAULTDIR "/tmp/http/dir"
#define DEFAULTLOG "/tmp/http/log"
void prterrmsg(char *msg);
#define prterrmsg(msg) { perror(msg); abort(); }
void wrterrmsg(char *msg);
#define wrterrmsg(msg) { fputs(msg, logfp); fputs(strerror(errno), logfp);fflush(logfp); abort(); }
void prtinfomsg(char *msg);
#define prtinfomsg(msg) { fputs(msg, stdout); }
void wrtinfomsg(char *msg);
#define wrtinfomsg(msg) { fputs(msg, logfp); fflush(logfp);}
#define MAXBUF 1024
char buffer[MAXBUF + 1];
char *host = 0;
char *port = 0;
char *back = 0;
char *dirroot = 0;
char *logdir = 0;
unsigned char daemon_y_n = 0;
FILE *logfp;
#define MAXPATH 150
/*----------------------------------------
*--- dir_up - 查找dirpath所指目录的上一级目录
*----------------------------------------
*/
char *dir_up(char *dirpath)
{
static char Path[MAXPATH];
int len;
strcpy(Path, dirpath);
len = strlen(Path);
if (len > 1 && Path[len - 1] == '/')
len--;
while (Path[len - 1] != '/' && len > 1)
len--;
Path[len] = 0;
return Path;
}
/*------------------------------------------------------
*--- AllocateMemory - 分配空间并把d所指的内容复制
*------------------------------------------------------
*/
void AllocateMemory(char **s, int l, char *d)
{
*s = (char *)malloc(l + 1);
bzero(*s, l + 1);
memcpy(*s, d, l);
}
/*------------------------------------------------------
*--- GiveResponse - 把Path所指的内容发送到client_sock去
*-------------------如果Path是一个目录，则列出目录内容
*-------------------如果Path是一个文件，则下载文件
*------------------------------------------------------
*/
void GiveResponse(FILE * client_sock, char *Path)
{
struct dirent *dirent;
struct stat info;
char Filename[MAXPATH];
DIR *dir;
int fd, len, ret;
char *p, *realPath, *realFilename, *nport;
/* 获得实际工作目录或文件 */
len = strlen(dirroot) + strlen(Path) + 1;
realPath = (char *)malloc(len + 1);
bzero(realPath, len + 1);
sprintf(realPath, "%s/%s", dirroot, Path);
/* 获得实际工作端口 */
len = strlen(port) + 1;
nport = (char *)malloc(len + 1);
bzero(nport, len + 1);
sprintf(nport, ":%s", port);
/* 获得实际工作目录或文件的信息以判断是文件还是目录 */
if (stat(realPath, &info)) {
fprintf(client_sock,
"HTTP/1.1 200 OK\r\nServer: DAS by Centos\r\nConnection: close\r\n\r\n"
"<html>"
"<meta charset=\"UTF-8\"/>"
"<head><title>%d - %s</title></head>"
"<body><font size=+4>Linux下目录访问服务器</font><br><hr width=\"100%%\"><br><center>"
"<table border cols=3 width=\"100%%\">"
, errno, strerror(errno));
fprintf(client_sock,
"</table><font color=\"CC0000\" size=+2>请向管理员咨询为何出现如下错误提示：\n%s %s</font></body></html>",
Path, strerror(errno));
goto out;
}
/* 处理浏览文件请求，即下载文件 */
if (S_ISREG(info.st_mode)) {
fd = open(realPath, O_RDONLY);
len = lseek(fd, 0, SEEK_END);
p = (char *) malloc(len + 1);
bzero(p, len + 1);
lseek(fd, 0, SEEK_SET);
ret = read(fd, p, len);
close(fd);
fprintf(client_sock,
"HTTP/1.1 200 OK\r\nServer: DAS by Centos\r\nConnection: keep-alive\r\nContent-type: application/*\r\nContent-Length:%d\r\n\r\n",
len);
fwrite(p, len, 1, client_sock);
free(p);
} else if (S_ISDIR(info.st_mode)) {
/* 处理浏览目录请求 */
dir = opendir(realPath);
fprintf(client_sock,
"HTTP/1.1 200 OK\r\nServer: DAS by Centos\r\nConnection: close\r\n\r\n"
"<html>"
"<meta charset=\"UTF-8\"/>"
"<head><title>%s</title></head>"
"<body><font size=+4>Linux下目录访问服务器</font><br><hr width=\"100%%\"><br><center>"
"<table border cols=3 width=\"100%%\">", Path);
fprintf(client_sock,
"<caption><font size=+3>目录 %s</font></caption>\n",
Path);
fprintf(client_sock,
"<tr><td>名称</td><td>大小</td><td>修改时间</td></tr>\n");
if (dir == 0) {
fprintf(client_sock,
"</table><font color=\"CC0000\" size=+2>%s</font></body></html>",
strerror(errno));
return;
}
/* 读取目录里的所有内容 */
while ((dirent = readdir(dir)) != 0) {
if (strcmp(Path, "/") == 0)
sprintf(Filename, "/%s", dirent->d_name);
else
sprintf(Filename, "%s/%s", Path, dirent->d_name);
fprintf(client_sock, "<tr>");
len = strlen(dirroot) + strlen(Filename) + 1;
realFilename = (char *)malloc(len + 1);
bzero(realFilename, len + 1);
sprintf(realFilename, "%s/%s", dirroot, Filename);
if (stat(realFilename, &info) == 0) {
if (strcmp(dirent->d_name, "..") == 0)
fprintf(client_sock,
"<td><a href=\"http://%s%s%s\">(parent)</a></td>",
host, atoi(port) == 80 ? "" : nport,
dir_up(Path));
else
fprintf(client_sock,
"<td><a href=\"http://%s%s%s\">%s</a></td>",
host, atoi(port) == 80 ? "" : nport, Filename,
dirent->d_name);
if (S_ISDIR(info.st_mode))
fprintf(client_sock, "<td>目录</td>");
else if (S_ISREG(info.st_mode))
fprintf(client_sock, "<td>%d</td>", info.st_size);
else if (S_ISLNK(info.st_mode))
fprintf(client_sock, "<td>链接</td>");
else if (S_ISCHR(info.st_mode))
fprintf(client_sock, "<td>字符设备</td>");
else if (S_ISBLK(info.st_mode))
fprintf(client_sock, "<td>块设备</td>");
else if (S_ISFIFO(info.st_mode))
fprintf(client_sock, "<td>FIFO</td>");
else if (S_ISSOCK(info.st_mode))
fprintf(client_sock, "<td>Socket</td>");
else
fprintf(client_sock, "<td>(未知)</td>");
fprintf(client_sock, "<td>%s</td>", ctime(&info.st_ctime));
}
fprintf(client_sock, "</tr>\n");
free(realFilename);
}
fprintf(client_sock, "</table></center></body></html>");
} else {
/* 既非常规文件又非目录，禁止访问 */
fprintf(client_sock,
"HTTP/1.1 200 OK\r\nServer: DAS by Centos\r\nConnection: close\r\n\r\n"
"<html>"
"<meta charset=\"UTF-8\"/>"
"<head><title>permission denied</title></head>"
"<body><font size=+4>Linux下目录访问服务器</font><br><hr width=\"100%%\"><br><center>"
"<table border cols=3 width=\"100%%\">");
fprintf(client_sock,
"</table><font color=\"CC0000\" size=+2>你访问的资源'%s'被禁止访问，请联系管理员解决！</font></body></html>",
Path);
}
out:
free(realPath);
free(nport);
}
/*------------------------------------------------------
*--- getoption - 分析取出程序的参数
*------------------------------------------------------
*/
void getoption(int argc, char **argv)
{
// int c, len;
// char *p = 0;
//
// opterr = 0;
// while (1) {
// int option_index = 0;
// static struct option long_options[] = {
// {"host", 1, 0, 0},
// {"port", 1, 0, 0},
// {"back", 1, 0, 0},
// {"dir", 1, 0, 0},
// {"log", 1, 0, 0},
// {"daemon", 0, 0, 0},
// {0, 0, 0, 0}
// };
// /* 本程序支持如一些参数：
// * --host IP地址 或者 -H IP地址
// * --port 端口 或者 -P 端口
// * --back 监听数量 或者 -B 监听数量
// * --dir 网站根目录 或者 -D 网站根目录
// * --log 日志存放路径 或者 -L 日志存放路径
// * --daemon 使程序进入后台运行模式
// */
// c = getopt_long(argc, argv, "H:P:B:D:L",
// long_options, &option_index);
// if (c == -1 || c == '?')
// break;
//
// if(optarg) len = strlen(optarg);
// else len = 0;
//
// if ((!c && !(strcasecmp(long_options[option_index].name, "host")))
// || c == 'H')
// p = host = malloc(len + 1);
// else if ((!c
// &&
// !(strcasecmp(long_options[option_index].name, "port")))
// || c == 'P')
// p = port = malloc(len + 1);
// else if ((!c
// &&
// !(strcasecmp(long_options[option_index].name, "back")))
// || c == 'B')
// p = back = malloc(len + 1);
// else if ((!c
// && !(strcasecmp(long_options[option_index].name, "dir")))
// || c == 'D')
// p = dirroot = malloc(len + 1);
// else if ((!c
// && !(strcasecmp(long_options[option_index].name, "log")))
// || c == 'L')
// p = logdir = malloc(len + 1);
// else if ((!c
// &&
// !(strcasecmp
// (long_options[option_index].name, "daemon")))) {
// daemon_y_n = 1;
// continue;
// }
// else
// break;
// bzero(p, len + 1);
// memcpy(p, optarg, len);
// }
}
int main(int argc, char **argv)
{
struct sockaddr_in addr;
int sock_fd, addrlen;
/* 获得程序工作的参数，如 IP 、端口、监听数、网页根目录、目录存放位置等 */
//getoption(argc, argv);
if (!host) {
addrlen = strlen(DEFAULTIP);
AllocateMemory(&host, addrlen, DEFAULTIP);
}
if (!port) {
addrlen = strlen(DEFAULTPORT);
AllocateMemory(&port, addrlen, DEFAULTPORT);
}
if (!back) {
addrlen = strlen(DEFAULTBACK);
AllocateMemory(&back, addrlen, DEFAULTBACK);
}
if (!dirroot) {
addrlen = strlen(DEFAULTDIR);
AllocateMemory(&dirroot, addrlen, DEFAULTDIR);
}
if (!logdir) {
addrlen = strlen(DEFAULTLOG);
AllocateMemory(&logdir, addrlen, DEFAULTLOG);
}
printf
("host=%s port=%s back=%s dirroot=%s logdir=%s %s是后台工作模式(进程ID：%d)\n",
host, port, back, dirroot, logdir, daemon_y_n?"":"不", getpid());
/* fork() 两次处于后台工作模式下 */
if (daemon_y_n) {
if (fork())
exit(0);
if (fork())
exit(0);
close(0), close(1), close(2);
logfp = fopen(logdir, "a+");
if (!logfp)
exit(0);
}
/* 处理子进程退出以免产生僵尸进程 */
signal(SIGCHLD, SIG_IGN);
/* 创建 socket */
if ((sock_fd = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
if (!daemon_y_n) {
prterrmsg("socket()");
} else {
wrterrmsg("socket()");
}
}
/* 设置端口快速重用 */
addrlen = 1;
setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, &addrlen,
sizeof(addrlen));
addr.sin_family = AF_INET;
addr.sin_port = htons(atoi(port));
addr.sin_addr.s_addr = htonl(INADDR_ANY);//htonl(INADDR_ANY);
addrlen = sizeof(struct sockaddr_in);
/* 绑定地址、端口等信息 */
if (bind(sock_fd, (struct sockaddr *) &addr, addrlen) < 0) {
if (!daemon_y_n) {
prterrmsg("bind()");
} else {
wrterrmsg("bind()");
}
}
/* 开启临听 */
if (listen(sock_fd, atoi(back)) < 0) {
if (!daemon_y_n) {
prterrmsg("listen()");
} else {
wrterrmsg("listen()");
}
}
while (1) {
int len;
int new_fd;
addrlen = sizeof(struct sockaddr_in);
/* 接受新连接请求 */
new_fd = accept(sock_fd, (struct sockaddr *) &addr, (socklen_t *)&addrlen);
if (new_fd < 0) {
if (!daemon_y_n) {
prterrmsg("accept()");
} else {
wrterrmsg("accept()");
}
break;
}
bzero(buffer, MAXBUF + 1);
sprintf(buffer, "连接来自于: %s:%d\n",
inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
if (!daemon_y_n) {
prtinfomsg(buffer);
} else {
wrtinfomsg(buffer);
}
/* 产生一个子进程去处理请求，当前进程继续等待新的连接到来 */
if (!fork()) {
bzero(buffer, MAXBUF + 1);
puts("recving...");
if ((len = recv(new_fd, buffer, MAXBUF, 0)) > 0) {
FILE *ClientFP = fdopen(new_fd, "w");
if (ClientFP == NULL) {
if (!daemon_y_n) {
prterrmsg("fdopen()");
} else {
prterrmsg("fdopen()");
}
} else {
char Req[MAXPATH + 1] = "";
sscanf(buffer, "GET %s HTTP", Req);
bzero(buffer, MAXBUF + 1);
sprintf(buffer, "请求取文件: \"%s\"\n", Req);
if (!daemon_y_n) {
prtinfomsg(buffer);
} else {
wrtinfomsg(buffer);
}
/* 处理用户请求 */
GiveResponse(ClientFP, Req);
fclose(ClientFP);
}
}
puts("go out");
exit(0);
}
close(new_fd);
}
close(sock_fd);
return 0;
}
（2）编译运行（浏览器为客户端）：
[html] view
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gcc -o server server.c
./server
服务器运行：
在浏览器中输入：http://127.0.0.1:4040
注：需建立/tmp/http/dir和/tmp/http/log文件夹，并在dir下建立目录树。
然后在浏览器中点击文件即可下载文件，点击目录可进一步进行查看。点击parent可以返回到上一级目录。
（3）http客户端client.c（从服务器上下载文件并重新命名）
[html] view
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#include <stdlib.h>
#include <stdio.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <strings.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include<errno.h>
int main(int argc, char *argv[])
{
char buffer[1024] = {0};
char host_addr[256] = {0};
char host_file[256] = {0};
char local_file[256] = {0};
int sockfd;
int send, totalsend;
int nbytes;
char request[1024] = {0};
struct sockaddr_in server_addr;
struct hostent *host;
if (argc != 2) {
fprintf(stderr, "Usage:%s web-address!\n", argv[0]);
exit(1);
}
int portnumber = 4040;
strcpy(host_addr, argv[1]);
strcpy(host_file, "server.c");
if ((host = gethostbyname(argv[1])) == NULL) {
fprintf(stderr,"Gethostname error\n", strerror(errno));
exit(1);
}
char ip_str[32] = {0};
printf("address: %s\n", inet_ntop(host->h_addrtype, host->h_addr, ip_str, sizeof(ip_str)));
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
fprintf(stderr,"Socket Error:%s!\n",strerror(errno));
exit(1);
}
bzero(&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(portnumber);
server_addr.sin_addr = *((struct in_addr *)host->h_addr);
if (connect(sockfd, (struct sockaddr *)(&server_addr), sizeof(struct sockaddr)) == -1) {
fprintf(stderr,"Connect Error:%s!\n",strerror(errno));
exit(1);
}
sprintf(request, "GET /%s HTTP/1.1\r\nAccept: */*\r\nAccept-Language: zh-cn\r\n \
User-Agent: Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)\r\n \
Host: %s:%d\r\nConnection: Close\r\n\r\n", host_file, host_addr, portnumber);
strcpy(local_file, "local.txt");
send = 0;
totalsend = 0;
nbytes = strlen(request);
while (totalsend < nbytes) {
send = write(sockfd, request + totalsend, nbytes - totalsend);
if (send == -1) {
printf("send error:%s!\n", strerror(errno));
exit(0);
}
totalsend += send;
printf("%d bytes send OK!\n", totalsend);
}
FILE * fp = fopen(local_file, "a");
if(!fp) {
printf("create file error:%s!\n", strerror(errno));
return 0;
}
//printf("The following is the response header:\n");
int i = 0;
/* 连接成功了，接收http响应，response */
while((nbytes = read(sockfd, buffer, 1)) == 1) {
if (i < 4) {
if (buffer[0] == '\r' || buffer[0] == '\n')
i++;
else
i = 0;
//printf("%c", buffer[0]);
}
else {
fwrite(buffer, 1, 1, fp);/*将http主体信息写入文件*/
//printf("%c", buffer[0]);
i++;
if(i % 1024 == 0)
fflush(fp); /**每1K时存盘一次**/
}
}
printf("\n");
fclose(fp);
/* 结束通讯 */
close(sockfd);
return 0;
}
在客户端程序的当前的目录下下载了local.txt，其中的内容是服务器上server.c文件的内容。
（1）上述代码在centos上测试通过，只是功能实现，代码执行效率暂未考虑。
（2）若有建议，请留言，在此先感谢！
一、简介
通过socket扫描本机打开的tcp端口号，模拟用户名、密码登录服务器的过程、socket文件传输及模仿http服务器。
二、详解
1、Linux下tcp端口扫描
（1）scanport.c：[html] view
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// 端口扫描程序，只支持扫描TCP端口
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
// 定义一个端口区间信息
typedef struct _port_segment {
struct in_addr dest_ip; // 目标IP
unsigned short int min_port; // 起始端口
unsigned short int max_port; // 最大端口
} port_segment;
/*自定义的错误处理函数*/
void my_err(const char * err_string, int line)
{
fprintf(stderr, "line:%d ", line);
perror(err_string);
exit(1);
}
/*
* 描 述：扫描某一IP地址上的某一个端口的函数
* 返回值：-1 出错
* 0 目标端口未打开
* 1 目标端口已打开
*/
int do_scan(struct sockaddr_in serv_addr)
{
int conn_fd;
int ret;
// 创建一个TCP套接字
conn_fd = socket(AF_INET, SOCK_STREAM,0);
if (conn_fd < 0) {
my_err("socket", __LINE__);
}
// 向服务器端发送连接请求
if ((ret = connect(conn_fd, (struct sockaddr *)&serv_addr, sizeof (struct sockaddr))) < 0 ) {
if (errno == ECONNREFUSED) { // 目标端口未打开
close(conn_fd);
return 0;
} else { // 其他错误
close(conn_fd);
return -1;
}
} else if (ret == 0){
printf("port %d found in %s\n", ntohs(serv_addr.sin_port),
inet_ntoa(serv_addr.sin_addr));
close(conn_fd);
return 1;
}
return -1; // 实际执行不到这里，只是为了消除编译程序时产生的警告
}
// 执行扫描的线程，扫描某一区间的端口
void * scaner(void *arg)
{
unsigned short int i;
struct sockaddr_in serv_addr;
port_segment portinfo; // 端口信息
// 读取端口区间信息
memcpy(&portinfo, arg, sizeof(struct _port_segment));
// 初始化服务器端地址结构
memset(&serv_addr, 0, sizeof (struct sockaddr_in));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = portinfo.dest_ip.s_addr;
//printf("******serv_addr.sin_addr.s_addr=%s\n", serv_addr.sin_addr.s_addr);
//printf("*******portinfo.min_port=%d, portinfo.max_port=%d\n", portinfo.min_port, portinfo.max_port);
for (i=portinfo.min_port; i<=portinfo.max_port; i++) {
serv_addr.sin_port = htons(i);
if (do_scan(serv_addr) < 0) {
continue; // 出错则退出进程
}
}
return NULL;
}
/*
* 命令行参数：-m 最大端口， -a 目标主机的IP地址, -n 最大线程数
*/
int main(int argc, char **argv)
{
pthread_t* thread; // 指向所有的线程ID
int max_port; // 最大端口号
int thread_num; // 最大线程数
int seg_len; // 端口区间长度
struct in_addr dest_ip; // 目标主机IP
int i;
// 检查参数个数
if (argc != 7) {
printf("Usage: [-m] [max_port] [-a] [serv_address] [-n] [thread_number]\n");
exit(1);
}
// 解析命令行参数
for (i=1; i<argc; i++) {
if (strcmp("-m", argv[i]) == 0) {
max_port = atoi(argv[i+1]); // 将字符串转化为对应的整数
if (max_port < 0 || max_port >= 65535) { //65535会导致死循环
printf("Usage:invalid max dest port\n");
exit(1);
}
continue;
}
if (strcmp("-a", argv[i]) == 0) {
if (inet_aton(argv[i+1], &dest_ip) == 0) {
printf("Usage:invalid dest ip address\n");
exit(1);
}
continue;
}
if (strcmp("-n", argv[i]) == 0) {
thread_num = atoi(argv[i+1]);
if (thread_num <= 0) {
printf("Usage:invalid thread_number\n");
exit(1);
}
continue;
}
}
// 如果输入的最大端口号小于线程数，则将线程数设为最大端口号
if (max_port < thread_num) {
thread_num = max_port;
}
seg_len = max_port / thread_num;
if ( (max_port%thread_num) != 0 ) {
thread_num += 1;
}
//printf("max_port=%d, seg_len=%d, thread_num = %d\n", max_port, seg_len, thread_num);
// 分配存储所有线程ID的内存空间
thread = (pthread_t*)malloc(thread_num*sizeof(pthread_t));
// 创建线程，根据最大端口号和线程数分配每个线程扫描的端口区间
port_segment *portinfo = (port_segment*)malloc(thread_num * sizeof(port_segment));
for (i=0; i<thread_num; i++) {
portinfo[i].dest_ip = dest_ip;
portinfo[i].min_port = i*seg_len + 1;
//printf("portinfo.min_port=%d, seg_len=%d, i = %d\n", portinfo[i].min_port, seg_len, i);
if (i == thread_num - 1) {
portinfo[i].max_port = max_port;
} else {
portinfo[i].max_port = portinfo[i].min_port + seg_len - 1;
}
// 创建线程
//if (pthread_create(&thread[i], NULL, scaner, (void *)(portinfo + i)) != 0) {
if (pthread_create(&thread[i], NULL, scaner, (void *)(&portinfo[i])) != 0) {
my_err("pthread_create", __LINE__);
}
}
for (i=0; i<thread_num; i++) {
// 主线程等待子线程结束
pthread_join(thread[i], NULL);
}
free(portinfo);
return 0;
}
（2）编译运行
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gcc -o scanport scanport.c -lpthread
./scanport -m 65534 -a 127.0.0.1 -n 1
可以通过netstat查看网络相关信息，netstat -tnlp或netstat -tnlpc比较打开的tcp端口号。
2、模拟用户名、密码登录
（1）服务器server.c：[html] view
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// Client/Server模型的服务器端
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <stdlib.h>
#define BUFSIZE 1024
#define SERV_PORT 4507 // 服务器端的端口
#define LISTENQ 12 // 连接请求队列的最大长度
#define INVALID_USERINFO 'n' // 用户信息无效
#define VALID_USERINFO 'y' // 用户信息有效
#define USERNAME 0 // 接收到的是用户名
#define PASSWORD 1 // 接收到的是密码
struct userinfo { // 保存用户名和密码的结构体
char username[32];
char password[32];
};
struct userinfo users[ ] = {
{"linux", "unix"},
{"4507", "4508"},
{"clh", "clh"},
{"xl", "xl"},
{" "," "} // 以只含一个空格的字符串作为数组的结束标志
};
/*自定义的错误处理函数*/
void my_err(const char * err_string, int line)
{
fprintf(stderr, "line:%d ", line);
perror(err_string);
exit(1);
}
/*
* 函数名: my_recv
* 描 述 : 从套接字上读取一次数据(以'\n'为结束标志)
* 参 数 : conn_fd -- 从该连接套接字上接收数据
* data_buf -- 读取到的数据保存在此缓冲中
* len -- data_buf所指向的空间长度
* 返回值: 出错返回-1， 服务器端已关闭连接则返回0， 成功返回读取的字节数
*/
int my_recv(int conn_fd, char *data_buf, int len)
{
static char recv_buf[BUFSIZE]; // 自定义缓冲区，BUFSIZE定义在my_recv.h中
static char *pread; // 指向下一次读取数据的位置
static int len_remain = 0; // 自定义缓冲区中剩余字节数
int i;
// 如果自定义缓冲区中没有数据，则从套接字读取数据
if (len_remain <= 0) {
if ((len_remain =recv(conn_fd, recv_buf, sizeof (recv_buf), 0)) < 0) {
my_err("recv", __LINE__);
} else if (len_remain == 0) { // 目的计算机端的socket连接关闭
return 0;
}
pread = recv_buf; // 重新初始化pread指针
}
// 从自定义缓冲区中读取一次数据
for (i=0; *pread != '\n'; i++) {
if (i > len) { // 防止指针越界
return -1;
}
data_buf[i] = *pread++;
len_remain--;
}
// 去除结束标志
len_remain--;
pread++;
return i; // 读取成功
}
// 查找用户名是否存在，存在返回该用户名的下标,不存在则返回-1，出错返回-2
int find_name(const char *name)
{
int i;
if (name == NULL) {
printf("in find_name, NULL pointer");
return -2;
}
for (i=0; users[i].username[0] != ' ';i++) {
if (strncmp(users[i].username, name, strlen(users[i].username)) == 0) {
return i;
}
}
return -1;
}
// 发送数据
void send_data(int conn_fd, const char *string)
{
if (send(conn_fd, string, strlen(string), 0) < 0) {
my_err("send", __LINE__); // my_err函数在my_recv.h中声明
}
}
int main()
{
int sock_fd, conn_fd;
int optval;
int flag_recv = USERNAME; // 标识接收到的是用户还是密码
int ret;
int name_num;
pid_t pid;
socklen_t cli_len;
struct sockaddr_in cli_addr, serv_addr;
char recv_buf[128];
// 创建一个TCP套接字
sock_fd = socket(AF_INET, SOCK_STREAM,0);
if (sock_fd < 0) {
my_err("socket", __LINE__);
}
// 设置该套接字使之可以重新绑定端口
optval = 1;
if (setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR,
(void *)&optval, sizeof(int)) < 0) {
my_err("setsockopt", __LINE__);
}
// 初始化服务器端地址结构
memset(&serv_addr, 0, sizeof (struct sockaddr_in));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(SERV_PORT);
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
// 将套接字绑定到本地端口
if (bind(sock_fd, (struct sockaddr *)&serv_addr,
sizeof (struct sockaddr_in)) < 0) {
my_err("bind", __LINE__);
}
// 将套接字转化为监听套接字
if (listen(sock_fd, LISTENQ) < 0) {
my_err("listen", __LINE__);
}
cli_len = sizeof (struct sockaddr_in);
while (1) {
// 通过accept接受客户端的连接请求，并返回连接套接字用于收发数据
conn_fd = accept(sock_fd, (struct sockaddr *)&cli_addr, &cli_len);
if (conn_fd < 0) {
my_err("accept", __LINE__);
}
printf("accept a new client, ip:%s\n", inet_ntoa(cli_addr.sin_addr));
// 创建一个子进程处理刚刚接受的连接请求
if ( (pid = fork()) == 0 ) { // 子进程
while(1) {
memset(recv_buf, 0, sizeof(recv_buf));
if ((ret = recv(conn_fd, recv_buf, sizeof (recv_buf), 0)) < 0) {
perror("recv");
exit(1);
}
recv_buf[ret-1] = '\0'; // 将数据结束标志'\n'替换成字符串结束标志
if (flag_recv == USERNAME) { // 接收到的是用户名
name_num = find_name(recv_buf);
switch (name_num) {
case -1:
send_data(conn_fd, "n\n");
break;
case -2:
exit(1);
break;
default:
send_data(conn_fd, "y\n");
flag_recv = PASSWORD;
break;
}
} else if (flag_recv == PASSWORD) { // 接收到的是密码
if (strncmp(users[name_num].password, recv_buf, strlen(users[name_num].password)) == 0) {
send_data(conn_fd, "y\n");
send_data(conn_fd, "Welcome login my tcp server\n");
printf("%s login\n", users[name_num].username);
break; // 跳出while循环
} else
send_data(conn_fd, "n\n");
}
}
close(sock_fd);
close(conn_fd);
exit(0); // 结束子进程
} else { // 父进程关闭刚刚接受的连接请求，执行accept等待其他连接请求
close(conn_fd);
}
}
return 0;
}
（2）客户端client.c：
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#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define BUFSIZE 1024
#define INVALID_USERINFO 'n' // 用户信息无效
#define VALID_USERINFO 'y' // 用户信息有效
/*自定义的错误处理函数*/
void my_err(const char * err_string, int line)
{
fprintf(stderr, "line:%d ", line);
perror(err_string);
exit(1);
}
/*
* 函数名: my_recv
* 描 述 : 从套接字上读取一次数据(以'\n'为结束标志)
* 参 数 : conn_fd -- 从该连接套接字上接收数据
* data_buf -- 读取到的数据保存在此缓冲中
* len -- data_buf所指向的空间长度
* 返回值: 出错返回-1， 服务器端已关闭连接则返回0， 成功返回读取的字节数
*/
int my_recv(int conn_fd, char *data_buf, int len)
{
static char recv_buf[BUFSIZE]; // 自定义缓冲区，BUFSIZE定义在my_recv.h中
static char *pread; // 指向下一次读取数据的位置
static int len_remain = 0; // 自定义缓冲区中剩余字节数
int i;
// 如果自定义缓冲区中没有数据，则从套接字读取数据
if (len_remain <= 0) {
if ((len_remain =recv(conn_fd, recv_buf, sizeof (recv_buf), 0)) < 0) {
my_err("recv", __LINE__);
} else if (len_remain == 0) { // 目的计算机端的socket连接关闭
return 0;
}
pread = recv_buf; // 重新初始化pread指针
}
// 从自定义缓冲区中读取一次数据
for (i=0; *pread != '\n'; i++) {
if (i > len) { // 防止指针越界
return -1;
}
data_buf[i] = *pread++;
len_remain--;
}
// 去除结束标志
len_remain--;
pread++;
return i; // 读取成功
}
/*获取用户输入存入到buf，buf的长度为len，用户输入数据以'\n'为结束标志*/
int get_userinfo(char *buf, int len)
{
int i;
int c;
if (buf == NULL) {
return -1;
}
i = 0;
while ( ((c = getchar()) != '\n') && (c != EOF) && (i < len-2) ) {
buf[i++] = c;
}
buf[i++] = '\n';
buf[i++] = '\0';
return 0;
}
// 输入用户名,然后通过fd发送出去
void input_userinfo(int conn_fd, const char *string)
{
char input_buf[32];
char recv_buf[BUFSIZE];
int flag_userinfo;
int count = 0;
// 输入用户信息直到正确为止
do {
printf("%s:", string);
if (get_userinfo(input_buf, 32) < 0) {
printf("error return from get_userinfo\n");
exit(1);
}
if (send(conn_fd, input_buf, strlen(input_buf), 0) < 0) {
my_err("send", __LINE__);
}
// 从连接套接字上读取一次数据
if (my_recv(conn_fd, recv_buf, sizeof (recv_buf)) < 0) {
printf("data is too long\n");
exit(1);
}
if (recv_buf[0] == VALID_USERINFO) {
flag_userinfo = VALID_USERINFO;
} else {
count++;
if (count >= 3) {
printf("input %s error for three times,exit!\n", string);
exit(-1);
}
printf("%s error,input again!\n", string);
flag_userinfo= INVALID_USERINFO;
}
} while(flag_userinfo == INVALID_USERINFO);
}
int main(int argc, char **argv)
{
int i;
int ret;
int conn_fd;
int serv_port;
struct sockaddr_in serv_addr;
char recv_buf[BUFSIZE];
// 检查参数个数
if (argc != 5) {
printf("Usage: [-p] [serv_port] [-a] [serv_address]\n");
exit(1);
}
// 初始化服务器端地址结构
memset(&serv_addr, 0, sizeof (struct sockaddr_in));
serv_addr.sin_family = AF_INET;
// 从命令行获取服务器端的端口与地址
for (i=1; i<argc; i++) {
if (strcmp("-p", argv[i]) == 0) {
serv_port = atoi(argv[i+1]);
if (serv_port < 0 || serv_port > 65535) {
printf("invalid serv_addr.sin_port\n");
exit(1);
} else {
serv_addr.sin_port = htons(serv_port);
}
continue;
}
if (strcmp("-a", argv[i]) == 0) {
if (inet_aton(argv[i+1], &serv_addr.sin_addr) == 0) {
printf("invalid server ip address\n");
exit(1);
}
continue;
}
}
// 检测是否少输入了某项参数
if (serv_addr.sin_port == 0 || serv_addr.sin_addr.s_addr == 0) {
printf("Usage: [-p] [serv_addr.sin_port] [-a][serv_address]\n");
exit(1);
}
// 创建一个TCP套接字
conn_fd = socket(AF_INET, SOCK_STREAM,0);
if (conn_fd < 0) {
my_err("socket", __LINE__);
}
// 向服务器端发送连接请求
if (connect(conn_fd, (struct sockaddr *)&serv_addr, sizeof (struct sockaddr)) < 0) {
my_err("connect", __LINE__);
}
// 输入用户名和密码
input_userinfo(conn_fd, "username");
input_userinfo(conn_fd, "password");
// 读取欢迎信息并打印出来
if ((ret = my_recv(conn_fd, recv_buf, sizeof (recv_buf))) < 0) {
printf("data is too long\n");
exit(1);
}
for (i=0; i<ret; i++) {
printf("%c", recv_buf[i]);
}
printf("\n");
close(conn_fd);
return 0;
}
（3）编译运行：
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gcc -o server server.c
./server
gcc -o client client.c
./client -p 4507 -a 127.0.0.1
3、socket文件传输（从server端下载文件）
（1）file_server.c：[html] view
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#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <strings.h>
#define HELLO_WORLD_SERVER_PORT 6666
#define LENGTH_OF_LISTENQ_QUEUE 20
#define BUFFER_SIZE 1024
#define FILE_NAME_MAX_SIZE 512
int main(int argc, char *argv[])
{
struct sockaddr_in server_addr;
bzero(&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = htons(INADDR_ANY);
server_addr.sin_port = htons(HELLO_WORLD_SERVER_PORT);
int server_socket = socket(AF_INET, SOCK_STREAM, 0);
if (server_socket < 0) {
printf("create socket failed!\n");
exit(1);
}
if (bind(server_socket, (struct sockaddr*)&server_addr, sizeof(server_addr))) {
printf("bind socket failed!\n");
exit(1);
}
if (listen(server_socket, LENGTH_OF_LISTENQ_QUEUE)) {
printf("listen socket failed!\n");
exit(1);
}
while (1) {
struct sockaddr_in client_addr;
socklen_t length = sizeof(client_addr);
int new_server_scoket = accept(server_socket, (struct sockaddr*)&client_addr, &length);
if (new_server_scoket < 0) {
printf("accept socket failed!\n");
break;
}
char buffer[BUFFER_SIZE];
bzero(buffer, BUFFER_SIZE);
length = recv(new_server_scoket, buffer, BUFFER_SIZE, 0);
if (length < 0) {
printf("recv data failed!\n");
break;
}
char file_name[FILE_NAME_MAX_SIZE + 1];
bzero(file_name, FILE_NAME_MAX_SIZE + 1);
strncpy(file_name, buffer, strlen(file_name) > FILE_NAME_MAX_SIZE ? FILE_NAME_MAX_SIZE : strlen(buffer));
FILE *fp = fopen(file_name, "r");
if (fp == NULL) {
printf("File: %s not found\n", file_name);
}
else {
bzero(buffer, BUFFER_SIZE);
int file_length = 0;
while((file_length = fread(buffer, sizeof(char), BUFFER_SIZE, fp)) > 0) {
printf("file_length = %d\n", file_length);
if (send(new_server_scoket, buffer, file_length, 0) < 0) {
printf("send file: %s failed\n", file_name);
break;
}
bzero(buffer, BUFFER_SIZE);
}
fclose(fp);
printf("file: %s trandfer finished\n", file_name);
}
close(new_server_scoket);
}
close(server_socket);
return 0;
}
（2）file_client.c：
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#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <strings.h>
#define HELLO_WORLD_SERVER_PORT 6666
#define BUFFER_SIZE 1024
#define FILE_NAME_MAX_SIZE 512
int main(int argc, char *argv[])
{
if (argc != 2) {
printf("use:[./run][server_ipaddress]\n");
exit(1);
}
struct sockaddr_in client_addr;
bzero(&client_addr,sizeof(client_addr));
client_addr.sin_family = AF_INET;
if (inet_aton(argv[1], &client_addr.sin_addr) == 0) {
printf("server ip address error!\n");
exit(1);
}
client_addr.sin_port = htons(HELLO_WORLD_SERVER_PORT);
socklen_t client_addr_length = sizeof(client_addr);
int client_socket = socket(AF_INET, SOCK_STREAM, 0);
if (client_socket < 0) {
printf("create socket failed\n");
exit(1);
}
if (connect(client_socket, (struct sockaddr*)&client_addr, client_addr_length) < 0) {
printf("can not connect to address\n");
exit(1);
}
char file_name[FILE_NAME_MAX_SIZE + 1];
bzero(file_name, FILE_NAME_MAX_SIZE + 1);
printf("please input file name:");
scanf("%s", file_name);
char buffer[BUFFER_SIZE];
bzero(buffer, BUFFER_SIZE);
strncpy(buffer, file_name, strlen(file_name) > BUFFER_SIZE ? BUFFER_SIZE : strlen(file_name));
send(client_socket, buffer, BUFFER_SIZE, 0);
FILE *fp = fopen(file_name, "w");
if (fp == NULL) {
printf("file can not open\n");
exit(1);
}
bzero(buffer, BUFFER_SIZE);
int length = 0;
while (length = recv(client_socket, buffer, BUFFER_SIZE, 0)) {
if (length < 0) {
printf("recv failed\n");
break;
}
int write_length = fwrite(buffer, sizeof(char), length, fp);
if (write_length < length) {
printf("file write failed\n");
break;
}
bzero(buffer, BUFFER_SIZE);
}
printf("recieve file: %s from server %s finished!\n", file_name, argv[1]);
close(fp);
close(client_socket);
return 0;
}
（3）编译运行
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gcc -o server file_server.c
./server
gcc -o client file_client.c
./client 127.0.0.1
server显示：
client显示：
注：server和client放在不同的目录下，需要传输的文件yang.txt与server在同一目录下。
4、模拟http服务器
（1）http服务器server.c：[html] view
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#include <stdarg.h>
#include <errno.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <resolv.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <signal.h>
#include <strings.h>
#define DEFAULTIP "127.0.0.1"
#define DEFAULTPORT "4040"
#define DEFAULTBACK "10"
#define DEFAULTDIR "/tmp/http/dir"
#define DEFAULTLOG "/tmp/http/log"
void prterrmsg(char *msg);
#define prterrmsg(msg) { perror(msg); abort(); }
void wrterrmsg(char *msg);
#define wrterrmsg(msg) { fputs(msg, logfp); fputs(strerror(errno), logfp);fflush(logfp); abort(); }
void prtinfomsg(char *msg);
#define prtinfomsg(msg) { fputs(msg, stdout); }
void wrtinfomsg(char *msg);
#define wrtinfomsg(msg) { fputs(msg, logfp); fflush(logfp);}
#define MAXBUF 1024
char buffer[MAXBUF + 1];
char *host = 0;
char *port = 0;
char *back = 0;
char *dirroot = 0;
char *logdir = 0;
unsigned char daemon_y_n = 0;
FILE *logfp;
#define MAXPATH 150
/*----------------------------------------
*--- dir_up - 查找dirpath所指目录的上一级目录
*----------------------------------------
*/
char *dir_up(char *dirpath)
{
static char Path[MAXPATH];
int len;
strcpy(Path, dirpath);
len = strlen(Path);
if (len > 1 && Path[len - 1] == '/')
len--;
while (Path[len - 1] != '/' && len > 1)
len--;
Path[len] = 0;
return Path;
}
/*------------------------------------------------------
*--- AllocateMemory - 分配空间并把d所指的内容复制
*------------------------------------------------------
*/
void AllocateMemory(char **s, int l, char *d)
{
*s = (char *)malloc(l + 1);
bzero(*s, l + 1);
memcpy(*s, d, l);
}
/*------------------------------------------------------
*--- GiveResponse - 把Path所指的内容发送到client_sock去
*-------------------如果Path是一个目录，则列出目录内容
*-------------------如果Path是一个文件，则下载文件
*------------------------------------------------------
*/
void GiveResponse(FILE * client_sock, char *Path)
{
struct dirent *dirent;
struct stat info;
char Filename[MAXPATH];
DIR *dir;
int fd, len, ret;
char *p, *realPath, *realFilename, *nport;
/* 获得实际工作目录或文件 */
len = strlen(dirroot) + strlen(Path) + 1;
realPath = (char *)malloc(len + 1);
bzero(realPath, len + 1);
sprintf(realPath, "%s/%s", dirroot, Path);
/* 获得实际工作端口 */
len = strlen(port) + 1;
nport = (char *)malloc(len + 1);
bzero(nport, len + 1);
sprintf(nport, ":%s", port);
/* 获得实际工作目录或文件的信息以判断是文件还是目录 */
if (stat(realPath, &info)) {
fprintf(client_sock,
"HTTP/1.1 200 OK\r\nServer: DAS by Centos\r\nConnection: close\r\n\r\n"
"<html>"
"<meta charset=\"UTF-8\"/>"
"<head><title>%d - %s</title></head>"
"<body><font size=+4>Linux下目录访问服务器</font><br><hr width=\"100%%\"><br><center>"
"<table border cols=3 width=\"100%%\">"
, errno, strerror(errno));
fprintf(client_sock,
"</table><font color=\"CC0000\" size=+2>请向管理员咨询为何出现如下错误提示：\n%s %s</font></body></html>",
Path, strerror(errno));
goto out;
}
/* 处理浏览文件请求，即下载文件 */
if (S_ISREG(info.st_mode)) {
fd = open(realPath, O_RDONLY);
len = lseek(fd, 0, SEEK_END);
p = (char *) malloc(len + 1);
bzero(p, len + 1);
lseek(fd, 0, SEEK_SET);
ret = read(fd, p, len);
close(fd);
fprintf(client_sock,
"HTTP/1.1 200 OK\r\nServer: DAS by Centos\r\nConnection: keep-alive\r\nContent-type: application/*\r\nContent-Length:%d\r\n\r\n",
len);
fwrite(p, len, 1, client_sock);
free(p);
} else if (S_ISDIR(info.st_mode)) {
/* 处理浏览目录请求 */
dir = opendir(realPath);
fprintf(client_sock,
"HTTP/1.1 200 OK\r\nServer: DAS by Centos\r\nConnection: close\r\n\r\n"
"<html>"
"<meta charset=\"UTF-8\"/>"
"<head><title>%s</title></head>"
"<body><font size=+4>Linux下目录访问服务器</font><br><hr width=\"100%%\"><br><center>"
"<table border cols=3 width=\"100%%\">", Path);
fprintf(client_sock,
"<caption><font size=+3>目录 %s</font></caption>\n",
Path);
fprintf(client_sock,
"<tr><td>名称</td><td>大小</td><td>修改时间</td></tr>\n");
if (dir == 0) {
fprintf(client_sock,
"</table><font color=\"CC0000\" size=+2>%s</font></body></html>",
strerror(errno));
return;
}
/* 读取目录里的所有内容 */
while ((dirent = readdir(dir)) != 0) {
if (strcmp(Path, "/") == 0)
sprintf(Filename, "/%s", dirent->d_name);
else
sprintf(Filename, "%s/%s", Path, dirent->d_name);
fprintf(client_sock, "<tr>");
len = strlen(dirroot) + strlen(Filename) + 1;
realFilename = (char *)malloc(len + 1);
bzero(realFilename, len + 1);
sprintf(realFilename, "%s/%s", dirroot, Filename);
if (stat(realFilename, &info) == 0) {
if (strcmp(dirent->d_name, "..") == 0)
fprintf(client_sock,
"<td><a href=\"http://%s%s%s\">(parent)</a></td>",
host, atoi(port) == 80 ? "" : nport,
dir_up(Path));
else
fprintf(client_sock,
"<td><a href=\"http://%s%s%s\">%s</a></td>",
host, atoi(port) == 80 ? "" : nport, Filename,
dirent->d_name);
if (S_ISDIR(info.st_mode))
fprintf(client_sock, "<td>目录</td>");
else if (S_ISREG(info.st_mode))
fprintf(client_sock, "<td>%d</td>", info.st_size);
else if (S_ISLNK(info.st_mode))
fprintf(client_sock, "<td>链接</td>");
else if (S_ISCHR(info.st_mode))
fprintf(client_sock, "<td>字符设备</td>");
else if (S_ISBLK(info.st_mode))
fprintf(client_sock, "<td>块设备</td>");
else if (S_ISFIFO(info.st_mode))
fprintf(client_sock, "<td>FIFO</td>");
else if (S_ISSOCK(info.st_mode))
fprintf(client_sock, "<td>Socket</td>");
else
fprintf(client_sock, "<td>(未知)</td>");
fprintf(client_sock, "<td>%s</td>", ctime(&info.st_ctime));
}
fprintf(client_sock, "</tr>\n");
free(realFilename);
}
fprintf(client_sock, "</table></center></body></html>");
} else {
/* 既非常规文件又非目录，禁止访问 */
fprintf(client_sock,
"HTTP/1.1 200 OK\r\nServer: DAS by Centos\r\nConnection: close\r\n\r\n"
"<html>"
"<meta charset=\"UTF-8\"/>"
"<head><title>permission denied</title></head>"
"<body><font size=+4>Linux下目录访问服务器</font><br><hr width=\"100%%\"><br><center>"
"<table border cols=3 width=\"100%%\">");
fprintf(client_sock,
"</table><font color=\"CC0000\" size=+2>你访问的资源'%s'被禁止访问，请联系管理员解决！</font></body></html>",
Path);
}
out:
free(realPath);
free(nport);
}
/*------------------------------------------------------
*--- getoption - 分析取出程序的参数
*------------------------------------------------------
*/
void getoption(int argc, char **argv)
{
// int c, len;
// char *p = 0;
//
// opterr = 0;
// while (1) {
// int option_index = 0;
// static struct option long_options[] = {
// {"host", 1, 0, 0},
// {"port", 1, 0, 0},
// {"back", 1, 0, 0},
// {"dir", 1, 0, 0},
// {"log", 1, 0, 0},
// {"daemon", 0, 0, 0},
// {0, 0, 0, 0}
// };
// /* 本程序支持如一些参数：
// * --host IP地址 或者 -H IP地址
// * --port 端口 或者 -P 端口
// * --back 监听数量 或者 -B 监听数量
// * --dir 网站根目录 或者 -D 网站根目录
// * --log 日志存放路径 或者 -L 日志存放路径
// * --daemon 使程序进入后台运行模式
// */
// c = getopt_long(argc, argv, "H:P:B:D:L",
// long_options, &option_index);
// if (c == -1 || c == '?')
// break;
//
// if(optarg) len = strlen(optarg);
// else len = 0;
//
// if ((!c && !(strcasecmp(long_options[option_index].name, "host")))
// || c == 'H')
// p = host = malloc(len + 1);
// else if ((!c
// &&
// !(strcasecmp(long_options[option_index].name, "port")))
// || c == 'P')
// p = port = malloc(len + 1);
// else if ((!c
// &&
// !(strcasecmp(long_options[option_index].name, "back")))
// || c == 'B')
// p = back = malloc(len + 1);
// else if ((!c
// && !(strcasecmp(long_options[option_index].name, "dir")))
// || c == 'D')
// p = dirroot = malloc(len + 1);
// else if ((!c
// && !(strcasecmp(long_options[option_index].name, "log")))
// || c == 'L')
// p = logdir = malloc(len + 1);
// else if ((!c
// &&
// !(strcasecmp
// (long_options[option_index].name, "daemon")))) {
// daemon_y_n = 1;
// continue;
// }
// else
// break;
// bzero(p, len + 1);
// memcpy(p, optarg, len);
// }
}
int main(int argc, char **argv)
{
struct sockaddr_in addr;
int sock_fd, addrlen;
/* 获得程序工作的参数，如 IP 、端口、监听数、网页根目录、目录存放位置等 */
//getoption(argc, argv);
if (!host) {
addrlen = strlen(DEFAULTIP);
AllocateMemory(&host, addrlen, DEFAULTIP);
}
if (!port) {
addrlen = strlen(DEFAULTPORT);
AllocateMemory(&port, addrlen, DEFAULTPORT);
}
if (!back) {
addrlen = strlen(DEFAULTBACK);
AllocateMemory(&back, addrlen, DEFAULTBACK);
}
if (!dirroot) {
addrlen = strlen(DEFAULTDIR);
AllocateMemory(&dirroot, addrlen, DEFAULTDIR);
}
if (!logdir) {
addrlen = strlen(DEFAULTLOG);
AllocateMemory(&logdir, addrlen, DEFAULTLOG);
}
printf
("host=%s port=%s back=%s dirroot=%s logdir=%s %s是后台工作模式(进程ID：%d)\n",
host, port, back, dirroot, logdir, daemon_y_n?"":"不", getpid());
/* fork() 两次处于后台工作模式下 */
if (daemon_y_n) {
if (fork())
exit(0);
if (fork())
exit(0);
close(0), close(1), close(2);
logfp = fopen(logdir, "a+");
if (!logfp)
exit(0);
}
/* 处理子进程退出以免产生僵尸进程 */
signal(SIGCHLD, SIG_IGN);
/* 创建 socket */
if ((sock_fd = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
if (!daemon_y_n) {
prterrmsg("socket()");
} else {
wrterrmsg("socket()");
}
}
/* 设置端口快速重用 */
addrlen = 1;
setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, &addrlen,
sizeof(addrlen));
addr.sin_family = AF_INET;
addr.sin_port = htons(atoi(port));
addr.sin_addr.s_addr = htonl(INADDR_ANY);//htonl(INADDR_ANY);
addrlen = sizeof(struct sockaddr_in);
/* 绑定地址、端口等信息 */
if (bind(sock_fd, (struct sockaddr *) &addr, addrlen) < 0) {
if (!daemon_y_n) {
prterrmsg("bind()");
} else {
wrterrmsg("bind()");
}
}
/* 开启临听 */
if (listen(sock_fd, atoi(back)) < 0) {
if (!daemon_y_n) {
prterrmsg("listen()");
} else {
wrterrmsg("listen()");
}
}
while (1) {
int len;
int new_fd;
addrlen = sizeof(struct sockaddr_in);
/* 接受新连接请求 */
new_fd = accept(sock_fd, (struct sockaddr *) &addr, (socklen_t *)&addrlen);
if (new_fd < 0) {
if (!daemon_y_n) {
prterrmsg("accept()");
} else {
wrterrmsg("accept()");
}
break;
}
bzero(buffer, MAXBUF + 1);
sprintf(buffer, "连接来自于: %s:%d\n",
inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
if (!daemon_y_n) {
prtinfomsg(buffer);
} else {
wrtinfomsg(buffer);
}
/* 产生一个子进程去处理请求，当前进程继续等待新的连接到来 */
if (!fork()) {
bzero(buffer, MAXBUF + 1);
puts("recving...");
if ((len = recv(new_fd, buffer, MAXBUF, 0)) > 0) {
FILE *ClientFP = fdopen(new_fd, "w");
if (ClientFP == NULL) {
if (!daemon_y_n) {
prterrmsg("fdopen()");
} else {
prterrmsg("fdopen()");
}
} else {
char Req[MAXPATH + 1] = "";
sscanf(buffer, "GET %s HTTP", Req);
bzero(buffer, MAXBUF + 1);
sprintf(buffer, "请求取文件: \"%s\"\n", Req);
if (!daemon_y_n) {
prtinfomsg(buffer);
} else {
wrtinfomsg(buffer);
}
/* 处理用户请求 */
GiveResponse(ClientFP, Req);
fclose(ClientFP);
}
}
puts("go out");
exit(0);
}
close(new_fd);
}
close(sock_fd);
return 0;
}
（2）编译运行（浏览器为客户端）：
[html] view
plain copy
gcc -o server server.c
./server
服务器运行：
在浏览器中输入：http://127.0.0.1:4040
注：需建立/tmp/http/dir和/tmp/http/log文件夹，并在dir下建立目录树。
然后在浏览器中点击文件即可下载文件，点击目录可进一步进行查看。点击parent可以返回到上一级目录。
（3）http客户端client.c（从服务器上下载文件并重新命名）
[html] view
plain copy
#include <stdlib.h>
#include <stdio.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <strings.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include<errno.h>
int main(int argc, char *argv[])
{
char buffer[1024] = {0};
char host_addr[256] = {0};
char host_file[256] = {0};
char local_file[256] = {0};
int sockfd;
int send, totalsend;
int nbytes;
char request[1024] = {0};
struct sockaddr_in server_addr;
struct hostent *host;
if (argc != 2) {
fprintf(stderr, "Usage:%s web-address!\n", argv[0]);
exit(1);
}
int portnumber = 4040;
strcpy(host_addr, argv[1]);
strcpy(host_file, "server.c");
if ((host = gethostbyname(argv[1])) == NULL) {
fprintf(stderr,"Gethostname error\n", strerror(errno));
exit(1);
}
char ip_str[32] = {0};
printf("address: %s\n", inet_ntop(host->h_addrtype, host->h_addr, ip_str, sizeof(ip_str)));
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
fprintf(stderr,"Socket Error:%s!\n",strerror(errno));
exit(1);
}
bzero(&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(portnumber);
server_addr.sin_addr = *((struct in_addr *)host->h_addr);
if (connect(sockfd, (struct sockaddr *)(&server_addr), sizeof(struct sockaddr)) == -1) {
fprintf(stderr,"Connect Error:%s!\n",strerror(errno));
exit(1);
}
sprintf(request, "GET /%s HTTP/1.1\r\nAccept: */*\r\nAccept-Language: zh-cn\r\n \
User-Agent: Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)\r\n \
Host: %s:%d\r\nConnection: Close\r\n\r\n", host_file, host_addr, portnumber);
strcpy(local_file, "local.txt");
send = 0;
totalsend = 0;
nbytes = strlen(request);
while (totalsend < nbytes) {
send = write(sockfd, request + totalsend, nbytes - totalsend);
if (send == -1) {
printf("send error:%s!\n", strerror(errno));
exit(0);
}
totalsend += send;
printf("%d bytes send OK!\n", totalsend);
}
FILE * fp = fopen(local_file, "a");
if(!fp) {
printf("create file error:%s!\n", strerror(errno));
return 0;
}
//printf("The following is the response header:\n");
int i = 0;
/* 连接成功了，接收http响应，response */
while((nbytes = read(sockfd, buffer, 1)) == 1) {
if (i < 4) {
if (buffer[0] == '\r' || buffer[0] == '\n')
i++;
else
i = 0;
//printf("%c", buffer[0]);
}
else {
fwrite(buffer, 1, 1, fp);/*将http主体信息写入文件*/
//printf("%c", buffer[0]);
i++;
if(i % 1024 == 0)
fflush(fp); /**每1K时存盘一次**/
}
}
printf("\n");
fclose(fp);
/* 结束通讯 */
close(sockfd);
return 0;
}
在客户端程序的当前的目录下下载了local.txt，其中的内容是服务器上server.c文件的内容。
三、总结
（1）上述代码在centos上测试通过，只是功能实现，代码执行效率暂未考虑。（2）若有建议，请留言，在此先感谢！
内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理 
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