下面是一個用openssl 實現獲取https 網頁內容的demo,整個流程比較簡單,主要封裝的API如下
static int https_init(https_context_t *context,const char* url);
static int https_uninit(https_context_t *context);
static int https_read(https_context_t *context,void* buff,int len);
static int https_write(https_context_t *context,const void* buff,int len);
static int https_get_status_code(https_context_t *context);
static int https_read_content(https_context_t *context,char *resp_contet,int max_len);
通信流程:
1、初始化,解析url資源,創建socket 連接,綁定ssl
2、發送http 請求
3、獲取請求返回的狀態碼
4、獲取請求返回的數據
5、銷燬動態申請的內存資源
我就把整個代碼貼在下面
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <openssl/ssl.h>
#include <openssl/bio.h>
#define HTTP_REQ_LENGTH 512
#define HTTP_RESP_LENGTH 20480
typedef struct
{
int sock_fd;
SSL_CTX *ssl_ct;
SSL *ssl;
//url 解析出來的信息
char *host;
char *path;
int port;
} https_context_t;
static int https_init(https_context_t *context,const char* url);
static int https_uninit(https_context_t *context);
static int https_read(https_context_t *context,void* buff,int len);
static int https_write(https_context_t *context,const void* buff,int len);
static int https_get_status_code(https_context_t *context);
static int https_read_content(https_context_t *context,char *resp_contet,int max_len);
// http 請求頭信息
static char https_header[] =
"GET %s HTTP/1.1\r\n"
"Host: %s:%d\r\n"
"Connection: Close\r\n"
"Accept: */*\r\n"
"\r\n";
static char http_req_content[HTTP_REQ_LENGTH] = {0};
static char https_resp_content[HTTP_RESP_LENGTH+1] = {0};
static int create_request_socket(const char* host,const int port)
{
int sockfd;
struct hostent *server;
struct sockaddr_in serv_addr;
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
{
printf("[http_demo] create_request_socket create socket fail.\n");
return -1;
}
/* lookup the ip address */
server = gethostbyname(host);
if(server == NULL)
{
printf("[http_demo] create_request_socket gethostbyname fail.\n");
close(sockfd);
return -1;
}
memset(&serv_addr,0,sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(port);
memcpy(&serv_addr.sin_addr.s_addr,server->h_addr,server->h_length);
if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
{
printf("[http_demo] create_request_socket connect fail.\n");
close(sockfd);
return -1;
}
return sockfd;
}
/**
* @brief https_parser_url 解析出https 中的域名、端口和路徑
* @param url 需要解析的url
* @param host 解析出來的域名或者ip
* @param port 端口,沒有時默認返回443
* @param path 路徑,指的是域名後面的位置
* @return
*/
static int https_parser_url(const char* url,char **host,int *port,char **path)
{
if(url == NULL || strlen(url) < 9 || host == NULL || path == NULL)
{
printf("[https_demo] url or host or path is null.\n");
return -1;
}
//判斷是不是 https://
int i = 0;
char https_prefix[] = "https://";
for(i=0;i<8;i++)
{
if(url[i] != https_prefix[i])
{
printf("[https_demo] illegal url = %s.\n",url);
return -1;
}
}
const char *temp = url+i;
while(*temp != '/') //next /
{
if(*temp == '\0') //
{
printf("[https_demo] illegal url = %s.\n",url);
return -1;
}
temp++;
}
const char *host_port = url+i;
while(*host_port != ':' && *host_port != '/') //找到 :或者 / 結束
{
host_port ++;
}
int host_len = host_port-url-i; //減掉https://
int path_len = strlen(temp);
char *host_temp = (char *)malloc(host_len + 1); //多一個字符串結束標識 \0
if(host_temp == NULL)
{
printf("[https_demo] malloc host fail.\n");
return -1;
}
if(*host_port++ == ':') //url 中有端口
{
*port = 0;
while(*host_port !='/' && *host_port !='\0') //十進制字符串轉成數字
{
*port *= 10;
*port += (*host_port - '0');
host_port ++;
}
}
else
{
*port = 443;
}
char *path_temp = (char *)malloc(path_len + 1); //多一個字符串結束標識 \0
if(path_temp == NULL)
{
printf("[https_demo] malloc path fail.\n");
free(host_temp);
return -1;
}
memcpy(host_temp,url+i,host_len);
memcpy(path_temp,temp,path_len);
host_temp[host_len] = '\0';
path_temp[path_len] = '\0';
*host = host_temp;
*path = path_temp;
return 0;
}
static int https_init(https_context_t *context,const char* url)
{
if(context == NULL)
{
printf("[https_demo] init https_context_t is null.\n");
return -1;
}
if(https_parser_url(url,&(context->host),&(context->port),&(context->path)))
{
printf("[https_demo] https_parser_url fail.\n");
return -1;
}
context->sock_fd = create_request_socket(context->host,context->port);
if(context->sock_fd < 0)
{
printf("[https_demo] create_request_socket fail.\n");
goto https_init_fail;
}
context->ssl_ct = SSL_CTX_new(SSLv23_method());
if(context->ssl_ct == NULL)
{
printf("[https_demo] SSL_CTX_new fail.\n");
goto https_init_fail;
}
context->ssl = SSL_new(context->ssl_ct);
if(context->ssl == NULL)
{
printf("[https_demo] SSL_new fail.\n");
goto https_init_fail;
}
if(SSL_set_fd(context->ssl,context->sock_fd)<0)
{
printf("[https_demo] SSL_set_fd fail \n");
}
if(SSL_connect(context->ssl) == -1)
{
printf("[https_demo] SSL_connect fail.\n");
goto https_init_fail;
}
return 0;
https_init_fail:
https_uninit(context);
return -1;
}
static int https_read(https_context_t *context,void* buff,int len)
{
if(context == NULL || context->ssl == NULL)
{
printf("[https_demo] read https_context_t or ssl is null.\n");
return -1;
}
return SSL_read(context->ssl,buff,len);
}
static int https_write(https_context_t *context,const void* buff,int len)
{
if(context == NULL || context->ssl == NULL)
{
printf("[https_demo] write https_context_t or ssl is null.\n");
return -1;
}
return SSL_write(context->ssl,buff,len);
}
static int https_get_status_code(https_context_t *context)
{
if(context == NULL || context->ssl == NULL)
{
printf("[https_demo] get status https_context_t or ssl is null.\n");
return -1;
}
int ret;
int flag =0;
int recv_len = 0;
char res_header[1024] = {0};
while(recv_len<1023)
{
ret = SSL_read(context->ssl, res_header+recv_len, 1);
if(ret<1) // recv fail
{
break;
}
//找到響應頭的頭部信息, 兩個"\r\n"爲分割點
if((res_header[recv_len]=='\r'&&(flag==0||flag==2))||(res_header[recv_len]=='\n'&&(flag==1||flag==3)))
{
flag++;
}
else
{
flag = 0;
}
recv_len+=ret;
if(flag==4)
{
break;
}
}
//printf("[http_demo] recv_len=%d res_header = %s.\n",recv_len,res_header);
/*獲取響應頭的信息*/
int status_code = -1;
char *pos = strstr(res_header, "HTTP/");
if(pos)
{
sscanf(pos, "%*s %d", &status_code);//返回狀態碼
}
return status_code;
}
static int https_read_content(https_context_t *context,char *resp_contet,int max_len)
{
if(context == NULL || context->ssl == NULL)
{
printf("[https_demo] read content https_context_t or ssl is null.\n");
return -1;
}
int ret ;
int recv_size = 0;
while(recv_size < max_len)
{
ret = SSL_read(context->ssl,resp_contet + recv_size,max_len-recv_size);
if(ret < 1)
{
break;
}
recv_size += ret;
}
return recv_size;
}
static int https_uninit(https_context_t *context)
{
if(context == NULL)
{
printf("[https_demo] uninit https_context_t is null.\n");
return -1;
}
if(context->host != NULL)
{
free(context->host);
context->host = NULL;
}
if(context->path != NULL)
{
free(context->path);
context->path = NULL;
}
if(context->ssl != NULL)
{
SSL_shutdown(context->ssl);
//SSl_free(context->ssl);
context->ssl = NULL;
}
if(context->ssl_ct != NULL)
{
SSL_CTX_free(context->ssl_ct);
context->ssl_ct = NULL;
}
if(context->sock_fd > 0)
{
close(context->sock_fd);
context->sock_fd = -1;
}
return 0;
}
int main()
{
https_context_t https_ct = {0};
int ret = SSL_library_init();
printf("[https_demo] SSL_library_init ret = %d.\n",ret);
https_init(&https_ct,"https://www.baidu.com/");
ret = snprintf(http_req_content,HTTP_REQ_LENGTH,https_header,https_ct.path,https_ct.host,https_ct.port);
ret = https_write(&https_ct,http_req_content,ret);
printf("[https_demo] https_write ret = %d.\n",ret);
if(https_get_status_code(&https_ct) == 200)
{
ret = https_read_content(&https_ct,https_resp_content,HTTP_RESP_LENGTH);
if(ret > 0)
{
https_resp_content[ret] = '\0'; //字符串結束標識
printf("[https_demo] https_write https_resp_content = \n %s.\n",https_resp_content);
}
}
https_uninit(&https_ct);
return 0;
}