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Page 3 of 11

Chapter 2

Page 38 Python HTTP Server

from http.server import HTTPServer, BaseHTTPRequestHandler
from io import BytesIO

class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):

    def sendResponse(self, cmd):
        content_length = int(self.headers['Content-Length'])
        body = self.rfile.read(content_length)
        self.send_response(200)
        self.end_headers()
        response = BytesIO()
        response.write(b'This is a '+bytes(cmd, 'utf-8')+
                                               b' request. ')
        response.write(b'Received: ')
        response.write(body)
        self.wfile.write(response.getvalue())

    def do_GET(self):
        self.send_response(200)
        self.end_headers()
        self.wfile.write(b'Hello, world!')


    def do_HEAD(self):
        self.send_response(200)
        self.end_headers()

    def do_POST(self):
        self.sendResponse("POST")

    def do_PUT(self):
        self.sendResponse("PUT")

    def do_DELETE(self):
        self.sendResponse("DELETE")

    def do_PATCH(self):
        self.sendResponse("PATCH")


httpd = HTTPServer(('', 8080), SimpleHTTPRequestHandler)
httpd.serve_forever()

Page 42  Simple HTTP Client using standard  lwipopts.h and cmakelists.txt 

#include <stdio.h>
#include "pico/stdlib.h"
#include "pico/cyw43_arch.h"
#include "setupWifi.h"
#include "lwip/tcp.h"

#define BUF_SIZE 2048
char myBuff[BUF_SIZE];
char header[] = "GET /index.html HTTP/1.1\r\nHOST:example.com\r\nConnection: close\r\n\r\n";

err_t recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
{
 if (p != NULL)
 {
 printf("recv total %d  this buffer %d next %d err %d\n", p->tot_len, p->len, p->next, err);
 pbuf_copy_partial(p, myBuff, p->tot_len, 0);
 myBuff[p->tot_len] = 0;
 printf("Buffer= %s\n", myBuff);
 tcp_recved(pcb, p->tot_len);
 pbuf_free(p);
 }
 return ERR_OK;
}

static err_t connected(void *arg, struct tcp_pcb *pcb, err_t err)
{
 err = tcp_write(pcb, header, strlen(header), 0);
 err = tcp_output(pcb);
 return ERR_OK;
}

int main()
{

 stdio_init_all();
 connect();

    struct tcp_pcb *pcb = tcp_new();
    tcp_recv(pcb, recv);
    ip_addr_t ip;
    IP4_ADDR(&ip, 93, 184, 216, 34);
    cyw43_arch_lwip_begin();
    err_t err = tcp_connect(pcb, &ip, 80, connected);
    cyw43_arch_lwip_end();
    while (true)
    {
        sleep_ms(500);
    }
}

Page 44 Simple HTTP Client Using ALTCP

#include <stdio.h>
#include "pico/stdlib.h"
#include "pico/cyw43_arch.h"
#include "setupWifi.h"
#include "lwip/altcp.h"

#define BUF_SIZE 2048
char myBuff[BUF_SIZE];
char header[] = "GET /index.html HTTP/1.1\r\nHOST:example.com\r\n\r\n";

err_t recv(void *arg, struct altcp_pcb *pcb, struct pbuf *p, err_t err)
{

    if (p != NULL)
    {
        printf("recv total %d  this buffer %d next %d err %d\n", p->tot_len, p->len, p->next, err);
        pbuf_copy_partial(p, myBuff, p->tot_len, 0);
        myBuff[p->tot_len] = 0;
        printf("Buffer= %s\n", myBuff);
        altcp_recved(pcb, p->tot_len);
        pbuf_free(p);
    }
    return ERR_OK;
}

static err_t altcp_client_connected(void *arg, struct altcp_pcb *pcb, err_t err)
{
    err = altcp_write(pcb, header, strlen(header), 0);
    err = altcp_output(pcb);
    return ERR_OK;
}

int main()
{

    stdio_init_all();
    connect();

    struct altcp_pcb *pcb = altcp_new(NULL);
    altcp_recv(pcb, recv);

    ip_addr_t ip;
    IP4_ADDR(&ip, 93, 184, 216, 34);
    cyw43_arch_lwip_begin();
    err_t err = altcp_connect(pcb, &ip, 80, altcp_client_connected);
    cyw43_arch_lwip_end();

    while (true)
    {
        sleep_ms(500);
    }
}
 

Add to the end of lwipopts.h

#define LWIP_ALTCP 1
 

 

Page 45 Not listed in full in book
Final Practical HTTP Client main.c - standard cmakelists.txt and lwipopts.h with  #define LWIP_ALTCP 1

#include <stdio.h>
#include "pico/stdlib.h"
#include "pico/cyw43_arch.h"
#include "setupWifi.h"
#include "lwip/altcp.h"

#define BUF_SIZE 2048
char myBuff[BUF_SIZE];
char header[] = "GET /index.html HTTP/1.1\r\nHOST:example.com\r\n\r\n";

err_t recv(void *arg, struct altcp_pcb *pcb, struct pbuf *p, err_t err)
{

    if (p != NULL)
    {
        printf("recv total %d  this buffer %d next %d err %d\n", p->tot_len, p->len, p->next, err);
                if ((p->tot_len) > 2)
        {
        pbuf_copy_partial(p, myBuff, p->tot_len, 0);
        myBuff[p->tot_len] = 0;        
        printf("Buffer= %s\n", myBuff);
        altcp_recved(pcb, p->tot_len);
        }
        pbuf_free(p);
    }    else
    {
        printf("Connection Closed");
        altcp_close(pcb);
    }
    return ERR_OK;
}

err_t sent(void *arg, struct altcp_pcb *pcb, u16_t len)
{
    printf("data sent %d\n", len);
}

void err(void *arg, err_t err)
{
    if (err != ERR_ABRT)
    {
        printf("client_err %d\n", err);
    }
}

err_t altcp_client_connected(void *arg, struct altcp_pcb *pcb, err_t err)
{
    err = altcp_write(pcb, header, strlen(header), 0);
    err = altcp_output(pcb);

    return ERR_OK;
}

err_t poll(void *arg, struct altcp_pcb *pcb){
        printf("Connection Closed");
        altcp_close(pcb);
}


int main()
{

    stdio_init_all();
    connect();

    struct altcp_pcb *pcb = altcp_new(NULL);
    altcp_recv(pcb, recv);
    altcp_sent(pcb, sent);
    altcp_err(pcb, err);
    altcp_poll(pcb, poll,10);

    ip_addr_t ip;
    IP4_ADDR(&ip, 93, 184, 216, 34);
    cyw43_arch_lwip_begin();
    err_t err = altcp_connect(pcb, &ip, 80, altcp_client_connected);
    cyw43_arch_lwip_end();

    while (true)
    {
        sleep_ms(500);
    }
}