HTTPS客户端纯C语言不用库,从TCP到HTTPS代码实现-https客户端

C语言实现https请求, 先贴上代码, 以下代码来自<>, 稍作修改

https_client.c

#include

void main(int argc, char **argv)

{

SSL *ssl = NULL;

SSL_CTX *ctx = NULL;

const SSL_METHOD *client_method;

X509 *server_cert;

int sd,err;

char *str,*hostname,outbuf[4096],inbuf[4096],host_header[512];

struct hostent *host_entry;

struct sockaddr_in server_socket_address;

struct in_addr ip;

/* (1) 初始化openssl库 */

SSL_library_init();

ERR_load_crypto_strings();

SSL_load_error_strings();

OpenSSL_add_all_algorithms();

client_method = SSLv23_client_method( );

ctx = SSL_CTX_new(client_method);

if (!ctx) {

fprintf (stderr, "SSL_CTX_new failed:\n");

ERR_print_errors_fp (stderr);

return;

}

printf("(1) SSL context initialized\n\n");

/* (2) 把域名转换成ip地址 */

hostname = argv[1];

host_entry = gethostbyname(hostname);

bcopy(host_entry->h_addr, &(ip.s_addr), host_entry->h_length);

printf("(2) '%s' has IP address '%s'\n\n", hostname, inet_ntoa(ip));

/* (3) 用tcp连接到server的443端口 */

sd = socket(AF_INET, SOCK_STREAM, 0);

memset(&server_socket_address, '\0', sizeof(server_socket_address));

server_socket_address.sin_family = AF_INET;

server_socket_address.sin_port = htons(443);

memcpy(&(server_socket_address.sin_addr.s_addr),

host_entry->h_addr, host_entry->h_length);

err = connect(sd, (struct sockaddr*) &server_socket_address,

sizeof(server_socket_address));

if (err < 0) { perror("can't connect to server port"); exit(1); }

printf("(3) TCP connection open to host '%s', port %d\n\n",

hostname, server_socket_address.sin_port);

/* (4) 在tcp连接上进行ssl握手 */

ssl = SSL_new(ctx); /* 创建ssl句柄，之后的send，recv都在ssl句柄上进行 */

if (!ssl) {

fprintf (stderr, "SSL_new failed:\n");

ERR_print_errors_fp (stderr);

return;

}

SSL_set_fd(ssl, sd); /* 把ssl句柄绑定到scoket */

err = SSL_connect(ssl); /* 启动ssl握手 */

printf("(4) SSL endpoint created & handshake completed\n\n");

/* (5) 打印出协商的好的加密密文 */

printf("(5) SSL connected with cipher: %s\n\n", SSL_get_cipher(ssl));

/* (6) 打印服务器的证书 */

server_cert = SSL_get_peer_certificate(ssl);

printf("(6) server's certificate was received:\n\n");

str = X509_NAME_oneline(X509_get_subject_name(server_cert), 0, 0);

printf(" subject: %s\n", str);

str = X509_NAME_oneline(X509_get_issuer_name(server_cert), 0, 0);

printf(" issuer: %s\n\n", str);

/* 这里对证书进行验证 */

X509_free(server_cert);

/* (7) 握手完成 --- 开始在ssl上发送http请求 */

sprintf(host_header,"Host: %s:443\r\n",hostname);

strcpy(outbuf,"GET / HTTP/1.1\r\n");

strcat(outbuf,host_header);

strcat(outbuf,"Connection: close\r\n");

strcat(outbuf,"\r\n");

err = SSL_write(ssl, outbuf, strlen(outbuf));

shutdown (sd, 1); /* send EOF to server */

printf("(7) sent HTTP request over encrypted channel:\n\n%s\n",outbuf);

/* (8) 通过ssl句柄读取服务器响应 */

printf ("(8) got back %d bytes of HTTP response:\n");

do{

memset(inbuf, 0, sizeof(inbuf));

err = SSL_read(ssl, inbuf, sizeof(inbuf) - 1);

printf ("%s",inbuf);

inbuf[err] = '\0';

}while(err > 0);

/* (9) 释放连接，句柄 */

SSL_shutdown(ssl);

close(sd);

SSL_free(ssl);

SSL_CTX_free(ctx);

printf("(9) all done, cleaned up and closed connection\n\n");

}

编译运行

如果提示找不到openssl的头文件，自行搜索openssl库的安装

gcc -o https_client https_client.c -lssl -lcrypto

访问百度

./https_client www.baidu.com

访问本地, 一般本地domain Name是localhost,

./https_client localhost

如果域名不能解析, 自己代码中去掉域名解析的部分,自己把地址替换成ip