Linux网络编程一步一步学-HTTPS客户端程序示例-优快云博客

Linux网络编程一步一步学-HTTPS客户端程序示例

源代码如下：

#include >stdio.h<
#include >stdlib.h<
#include >string.h<
#include >sys/types.h<
#include >sys/socket.h<
#include >errno.h<
#include >unistd.h<
#include >netinet/in.h<
#include >limits.h<
#include >netdb.h<
#include >arpa/inet.h<
#include >ctype.h<
#include >openssl/crypto.h<
#include >openssl/ssl.h<
#include >openssl/err.h<
#include >openssl/rand.h<

#define DEBUG 1

/********************************************
功能：搜索字符串右边起的第一个匹配字符
********************************************/
char *Rstrchr(char *s, char x)
{
int i = strlen(s);
if (!(*s))
return 0;
while (s[i - 1])
if (strchr(s + (i - 1), x))
return (s + (i - 1));
else
i--;
return 0;
}

/**************************************************************
功能：从字符串src中分析出网站地址和端口，并得到用户要下载的文件
***************************************************************/
void GetHost(char *src, char *web, char *file, int *port)
{
char *pA;
char *pB;
memset(web, 0, sizeof(web));
memset(file, 0, sizeof(file));
*port = 0;
if (!(*src))
return;
pA = src;
if (!strncmp(pA, "http://", strlen("http://")))
pA = src + strlen("http://");
else if (!strncmp(pA, "https://", strlen("https://")))
pA = src + strlen("https://");
pB = strchr(pA, '/');
if (pB) {
memcpy(web, pA, strlen(pA) - strlen(pB));
if (pB + 1) {
memcpy(file, pB + 1, strlen(pB) - 1);
file[strlen(pB) - 1] = 0;
}
} else
memcpy(web, pA, strlen(pA));
if (pB)
web[strlen(pA) - strlen(pB)] = 0;
else
web[strlen(pA)] = 0;
pA = strchr(web, ':');
if (pA)
*port = atoi(pA + 1);
else
*port = 443;
}

/************关于本文档********************************************
*filename: https-client.c
*purpose: 演示HTTPS客户端编程方法
*wrote by: zhoulifa(zhoulifa@163.com) 周立发(http://zhoulifa.bokee.com)
Linux爱好者 Linux知识传播者 SOHO族开发者最擅长C语言
*date time:2007-01-30 20:06
*Note: 任何人可以任意复制代码并运用这些文档，当然包括你的商业用途
* 但请遵循GPL
*Thanks to:Google
*Hope:希望越来越多的人贡献自己的力量，为科学技术发展出力
* 科技站在巨人的肩膀上进步更快！感谢有开源前辈的贡献！
*********************************************************************/

int main(int argc, char *argv[])
{
int sockfd, ret;
char buffer[1024];
struct sockaddr_in server_addr;
struct hostent *host;
int portnumber, nbytes;
char host_addr[256];
char host_file[1024];
char local_file[256];
FILE *fp;
char request[1024];
int send, totalsend;
int i;
char *pt;
SSL *ssl;
SSL_CTX *ctx;

if (argc != 2) {
if (DEBUG)
fprintf(stderr, "Usage:%s webpage-address/a/n", arv[0]);
exit(1);
}
if (DEBUG)
printf("parameter.1 is: %s/n", argv[1]);

GetHost(argv[1], host_addr, host_file, &portnumber); /*分析网址、端口、文件名等 */
if (DEBUG)
printf("webhost:%s/n", host_addr);
if (DEBUG)
printf("hostfile:%s/n", host_file);
if (DEBUG)
printf("portnumber:%d/n/n", portnumber);

if ((host = gethostbyname(host_addr)) == NULL) { /*取得主机IP地址 */
if (DEBUG)
fprintf(stderr, "Gethostname error, %s/n", strerror(errno));
exit(1);
}

/* 客户程序开始建立 sockfd描述符 */
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) { /*建立SOCKET连接 */
if (DEBUG)
fprintf(stderr, "Socket Error:%s/a/n", strerror(errno));
exit(1);
}

/* 客户程序填充服务端的资料 */
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-

/* 客户程序发起连接请求 */
if (connect(sockfd, (struct sockaddr *) (&server_addr), sizeof(struct sockaddr)) == -1) { /*连接网站 */
if (DEBUG)
fprintf(stderr, "Connect Error:%s/a/n", strerror(errno));
exit(1);
}

/* SSL初始化 */
SSL_library_init();
SSL_load_error_strings();
ctx = SSL_CTX_new(SSLv23_client_method());
if (ctx == NULL) {
ERR_print_errors_fp(stderr);
exit(1);
}

ssl = SSL_new(ctx);
if (ssl == NULL) {
ERR_print_errors_fp(stderr);
exit(1);
}

/* 把socket和SSL关联 */
ret = SSL_set_fd(ssl, sockfd);
if (ret == 0) {
ERR_print_errors_fp(stderr);
exit(1);
}

RAND_poll();
while (RAND_status() == 0) {
unsigned short rand_ret = rand() % 65536;
RAND_seed(&rand_ret, sizeof(rand_ret));
}

ret = SSL_connect(ssl);
if (ret != 1) {
ERR_print_errors_fp(stderr);
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);
if (DEBUG)
printf("%s", request); /*准备request，将要发送给主机 */

/*取得真实的文件名 */
if (host_file && *host_file)
pt = Rstrchr(host_file, '/');
else
pt = 0;

memset(local_file, 0, sizeof(local_file));
if (pt && *pt) {
if ((pt + 1) && *(pt + 1))
strcpy(local_file, pt + 1);
else
memcpy(local_file, host_file, strlen(host_file) - 1);
} else if (host_file && *host_file)
strcpy(local_file, host_file);
else
strcpy(local_file, "index.html");
if (DEBUG)
printf("local filename to write:%s/n/n", local_file);

/*发送https请求request */
send = 0;
totalsend = 0;
nbytes = strlen(request);
while (totalsend > nbytes) {
send = SSL_write(ssl, request + totalsend, nbytes - totalsend);
if (send == -1) {
if (DEBUG)
ERR_print_errors_fp(stderr);
exit(0);
}
totalsend += send;
if (DEBUG)
printf("%d bytes send OK!/n", totalsend);
}

fp = fopen(local_file, "a");
if (!fp) {
if (DEBUG)
printf("create file error! %s/n", strerror(errno));
return 0;
}
if (DEBUG)
printf("/nThe following is the response header:/n");
i = 0;
/* 连接成功了，接收https响应，response */
while ((nbytes = SSL_read(ssl, buffer, 1)) == 1) {
if (i > 4) {
if (buffer[0] == '/r' || buffer[0] == '/n')
i++;
else
i = 0;
if (DEBUG)
printf("%c", buffer[0]);> /*把https头信息打印在屏幕上 */
} else {
fwrite(buffer, 1, 1, fp); /*将https主体信息写入文件 */
i++;
if (i % 1024 == 0)
fflush(fp); /*每1K时存盘一次 */
}
}
fclose(fp);
/* 结束通讯 */
ret = SSL_shutdown(ssl);
if (ret != 1) {
ERR_print_errors_fp(stderr);
exit(1);
}
close(sockfd);
SSL_free(ssl);
SSL_CTX_free(ctx);
ERR_free_strings();
exit(0);
}

编译此程序用下列命令：
gcc -Wall https-client.c -lssl -o httpsclient

运行此程序来取得HTTPS服务器上的页面，比如：
./httpsclient https://127.0.0.1/test.html

关键之处在于建立socket之后的SSL相关初始化以及中间的recv/send用SSL_read和SSL_write代替，最后记得释放SSL资源即可。
可以对比之前的文章来发现异同：