STM32 + W5500 实现HTTPS !

两点：

1. 让我们先站在操作系统之上的网络协议栈再之上来思考……

2. 我们先简单粗暴地理解为：http + (加密）= https

先弄一个简单的HTTP网络客户端，连接服务器并读取默认页面。该应用程序可能如下所示：

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdio.h>
#include <netdb.h>#define SERVER_PORT 80
#define SERVER_NAME "localhost"
#define GET_REQUEST "GET / HTTP/1.0\r\n\r\n"int main( void )
{int ret, len, server_fd;unsigned char buf[1024];struct sockaddr_in server_addr;struct hostent *server_host;/** Start the connection*/printf( "\n  . Connecting to tcp/%s/%4d...", SERVER_NAME,SERVER_PORT );fflush( stdout );if( ( server_host = gethostbyname( SERVER_NAME ) ) == NULL ){printf( " failed\n  ! gethostbyname failed\n\n");goto exit;}if( ( server_fd = socket( AF_INET, SOCK_STREAM, IPPROTO_IP) ) < 0 ){printf( " failed\n  ! socket returned %d\n\n", server_fd );goto exit;}memcpy( (void *) &server_addr.sin_addr,(void *) server_host->h_addr,server_host->h_length );server_addr.sin_family = AF_INET;server_addr.sin_port = htons( SERVER_PORT );if( ( ret = connect( server_fd, (struct sockaddr *) &server_addr,sizeof( server_addr ) ) ) < 0 ){printf( " failed\n  ! connect returned %d\n\n", ret );goto exit;}printf( " ok\n" );/** Write the GET request*/print