Upgraded part15-tcpip to include code for serving web pages

part15-tcpip-webserver/README.md

@@ -0,0 +1,94 @@
+Writing a "bare metal" operating system for Raspberry Pi 4 (Part 15)
+====================================================================
+
+Adding a TCP/IP stack
+---------------------
+Having achieved "proof of life" from our Ethernet module in _part14-spi-ethernet_, you're doubtless wondering how to go from there to serving web pages, posting tweets on Twitter or perhaps even just simply responding to a ping!
+
+This is where you'll need a fully-fledged TCP/IP stack that goes way beyond handcrafted ARPs, implementing many more protocols to achieve efficient bi-directional communication.
+
+In this part we make use of some code from Guido Socher of [tuxgraphics.org](http://tuxgraphics.org/), designed to be a lightweight TCP/IP stack for embedded devices. I chose this because it was super simple to get working (or "port"), but you might want to look at [LwIP](https://en.wikipedia.org/wiki/LwIP) if you need something more advanced.
+
+The code
+--------
+Most of the new code is in the _tcpip/_ subdirectory. I actually came across it in [this tarball](http://tuxgraphics.org/common/src2/article09051/eth_tcp_client_server-dhcp-5.10.tar.gz) and, again, made only a very few cosmetic changes (`diff` is your friend!).
+
+It did require me to expose the `strlen()` function we implemented in _lib/fb.c_, so that's added to _include/fb.h_. Similarly, we expose the `memcpy()` function we implemented in _kernel/kernel.c_, so that's added to _kernel/kernel.h_.
+
+I also needed a single function that tells the ENC to send a packet. Nothing new here, just different packaging:
+
+```c
+void enc28j60PacketSend(unsigned short buflen, void *buffer) {
+   if (ENC_RestoreTXBuffer(&handle, buflen) == 0) {
+      ENC_WriteBuffer((unsigned char *) buffer, buflen);
+      handle.transmitLength = buflen;
+      ENC_Transmit(&handle);
+   }
+}
+```
+
+This was also added to _kernel/kernel.h_.
+
+What happened to _arp.c_?
+-------------------------
+You'll notice that I've merged _arp.c_ and _kernel.c_. We still initialise the network card in exactly the same way but, when we're done, we call this function in Guido's code:
+
+```c
+init_udp_or_www_server(myMAC, deviceIP);
+```
+
+This tells the TCP/IP library who we are, so we're all on the same page!
+
+Finally, and aside from a little cleanup (eg. moving the HAL timer functions to _io.c_ with the commensurate changes to _io.h_), the major change is the new `serve()` function:
+
+```c
+void serve(void)
+{
+   while (1) {
+      while (!ENC_GetReceivedFrame(&handle));
+
+      uint8_t *buf = (uint8_t *)handle.RxFrameInfos.buffer;
+      uint16_t len = handle.RxFrameInfos.length;
+      uint16_t dat_p = packetloop_arp_icmp_tcp(buf, len);
+
+      if (dat_p != 0) {
+         debugstr("Incoming web request... ");
+
+         if (strncmp("GET ", (char *)&(buf[dat_p]), 4) != 0) {
+            debugstr("not GET");
+            dat_p = fill_tcp_data(buf, 0, "HTTP/1.0 401 Unauthorized\r\nContent-Type: text/html\r\n\r\n<h1>ERROR</h1>");
+         } else {
+            if (strncmp("/ ", (char *)&(buf[dat_p+4]), 2) == 0) {
+               // just one web page in the "root directory" of the web server
+               debugstr("GET root");
+               dat_p = fill_tcp_data(buf, 0, "HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n<h1>Hello world!</h1>");
+            } else {
+               // just one web page not in the "root directory" of the web server
+               debugstr("GET not root");
+               dat_p = fill_tcp_data(buf, 0, "HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n<h1>Goodbye cruel world.</h1>");
+            }
+         }
+
+         www_server_reply(buf, dat_p); // send web page data
+         debugcrlf();
+      }
+   }
+}
+```
+
+This is an infinite loop which waits for an incoming packet and then firstly passes it to Guido's `packetloop_arp_icmp_tcp()` function. This function implements some useful things, like responding to pings. I modified the routine to print a message to the screen when it sends a "pong" (look from line 1371 of _tcpip/ip_arp_udp_tcp.c_), so we can see when it's in action!
+
+Examining the return value of `packetloop_arp_icmp_tcp()` then allows us to check whether there is an incoming web request, since we've configured the TCP/IP library to be a web server in _tcpip/ip_config.h_ with `#define WWW_server`.
+
+We then serve responses based on three possible cases:
+
+ * The incoming request is not a GET request (eg. maybe it's a HEAD request) - you can simulate this using the `curl` tool: `curl -I 192.168.0.66`
+ * The incoming request is a GET request for the root web page `/` - `curl 192.168.0.66/`
+ * The incoming request is a GET request for any non-root web page - eg. `curl 192.168.0.66/isometimes/monkey`
+
+I recommend reading [this page](http://tuxgraphics.org/electronics/200905/embedded-tcp-ip-stack.shtml) for a full explanation. The code I have ported is very similar to what you see there.
+
+_Imagine my excitement when I built, ran and could ping my RPi4 at 192.168.0.66 and get a web response to my browser on both my laptop and my iPhone!_
+
+![Pinging from my iPhone](images/15-tcpip-webserver-pinging.jpg)
+![Browsing from my laptop](images/15-tcpip-webserver-browser.png)

part15-tcpip-webserver/include/io.h

@@ -17,3 +17,5 @@ void gpio_setPinOutputBool(unsigned int pin_number, unsigned int onOrOff);
 void gpio_initOutputPinWithPullNone(unsigned int pin_number);
 void uart_hex(unsigned int d);
 void uart_byte(unsigned char b);
+unsigned long HAL_GetTick(void);
+void HAL_Delay(unsigned int ms);

part15-tcpip-webserver/kernel/kernel.c

@@ -1,17 +1,8 @@
-#include "../net/enc28j60.h"
 #include "../include/fb.h"
+#include "../include/spi.h"
+#include "../net/enc28j60.h"
 #include "../tcpip/ip_arp_udp_tcp.h"
 
-ENC_HandleTypeDef handle;
-
-// MAC address to be assigned to the ENC28J60
-
-unsigned char myMAC[6] = { 0xc0, 0xff, 0xee, 0xc0, 0xff, 0xee };
-
-// IP address to be assigned to the ENC28J60
-
-unsigned char deviceIP[4] = { 192, 168, 0, 66 };
-
 // HELPER FUNCTIONS
 
 void *memset(void *dest, unsigned char val, unsigned short len)
@@ -45,27 +36,31 @@ uint8_t memcmp(void *str1, void *str2, unsigned count)
     return 0;
 }
 
-void enc28j60PacketSend(unsigned short buflen, void *buffer) {
+int strncmp(const char *s1, const char *s2, unsigned short n)
-   if (ENC_RestoreTXBuffer(&handle, buflen) == 0) {
-      ENC_WriteBuffer((unsigned char *) buffer, buflen);
-      handle.transmitLength = buflen;
-      ENC_Transmit(&handle);
-   }
-}
-
-// MAIN FUNCTIONS
-
-void net_test(void)
 {
-   while (1) {
+    unsigned char u1, u2;
-      while (!ENC_GetReceivedFrame(&handle));
+
-  
+    while (n-- > 0)
-      uint16_t len = handle.RxFrameInfos.length;
+    {
-      uint8_t *buffer = (uint8_t *)handle.RxFrameInfos.buffer;
+       u1 = (unsigned char) *s1++;
-      packetloop_arp_icmp_tcp(buffer, len);
+       u2 = (unsigned char) *s2++;
-   }
+       if (u1 != u2) return u1 - u2;
+       if (u1 == '\0') return 0;
+    }
+
+    return 0;
 }
 
+// NETWORKING GLOBALS AND FUNCTIONS
+
+ENC_HandleTypeDef handle;
+
+// MAC address to be assigned to the ENC28J60
+unsigned char myMAC[6] = { 0xc0, 0xff, 0xee, 0xc0, 0xff, 0xee };
+
+// IP address to be assigned to the ENC28J60
+unsigned char deviceIP[4] = { 192, 168, 0, 66 };
+
 void init_network(void)
 {
    handle.Init.DuplexMode = ETH_MODE_HALFDUPLEX;
@@ -100,3 +95,61 @@ void init_network(void)
    debugstr("done.");
    debugcrlf();
 }
+
+void enc28j60PacketSend(unsigned short buflen, void *buffer) {
+   if (ENC_RestoreTXBuffer(&handle, buflen) == 0) {
+      ENC_WriteBuffer((unsigned char *) buffer, buflen);
+      handle.transmitLength = buflen;
+      ENC_Transmit(&handle);
+   }
+}
+
+void serve(void)
+{
+   while (1) {
+      while (!ENC_GetReceivedFrame(&handle));
+
+      uint8_t *buf = (uint8_t *)handle.RxFrameInfos.buffer;
+      uint16_t len = handle.RxFrameInfos.length;
+      uint16_t dat_p = packetloop_arp_icmp_tcp(buf, len);
+
+      if (dat_p != 0) {
+         debugstr("Incoming web request... ");
+
+         if (strncmp("GET ", (char *)&(buf[dat_p]), 4) != 0) {
+            debugstr("not GET");
+            dat_p = fill_tcp_data(buf, 0, "HTTP/1.0 401 Unauthorized\r\nContent-Type: text/html\r\n\r\n<h1>ERROR</h1>");
+         } else {
+            if (strncmp("/ ", (char *)&(buf[dat_p+4]), 2) == 0) {
+               // just one web page in the "root directory" of the web server
+               debugstr("GET root");
+               dat_p = fill_tcp_data(buf, 0, "HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n<h1>Hello world!</h1>");
+            } else {
+               // just one web page not in the "root directory" of the web server
+               debugstr("GET not root");
+               dat_p = fill_tcp_data(buf, 0, "HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n<h1>Goodbye cruel world.</h1>");
+            }
+         }
+
+         www_server_reply(buf, dat_p); // send web page data
+         debugcrlf();
+      }
+   }
+}
+
+// MAIN FUNCTION
+
+void main(void)
+{
+    fb_init();
+
+    // Init network and serve web pages
+
+    spi_init();
+    init_network();
+    serve();
+
+    // Catch us if we fall
+
+    while(1);
+}

part15-tcpip-webserver/kernel/kernel.h

@@ -0,0 +1,2 @@
+void enc28j60PacketSend(unsigned short buflen, void *buffer);
+void *memcpy(void *dest, const void *src, unsigned short len);

part15-tcpip-webserver/lib/io.c

@@ -197,3 +197,33 @@ void uart_byte(unsigned char b) {
     }
     uart_writeByteBlockingActual(' ');
 }
+
+// TIMER
+
+struct timer_regs {
+    volatile unsigned int control_status;
+    volatile unsigned int counter_lo;
+    volatile unsigned int counter_hi;
+    volatile unsigned int compare[4];
+};
+
+#define REGS_TIMER ((struct timer_regs *)(PERIPHERAL_BASE + 0x00003000))
+
+unsigned long HAL_GetTick(void) {
+    unsigned int hi = REGS_TIMER->counter_hi;
+    unsigned int lo = REGS_TIMER->counter_lo;
+
+    //double check hi value didn't change after setting it...
+    if (hi != REGS_TIMER->counter_hi) {
+        hi = REGS_TIMER->counter_hi;
+        lo = REGS_TIMER->counter_lo;
+    }
+
+    return ((unsigned long)hi << 32) | lo;
+}
+
+void HAL_Delay(unsigned int ms) {
+    unsigned long start = HAL_GetTick();
+
+    while(HAL_GetTick() < start + (ms * 1000));
+}

part15-tcpip-webserver/net/enc28j60.c

@@ -81,6 +81,7 @@ Errata 18 is implemented in lwip stack
 /* Includes ------------------------------------------------------------------*/
 #include "enc28j60.h"
 #include "../include/fb.h"
+#include "../include/io.h"
 
 /** @addtogroup BSP
   * @{
@@ -1171,6 +1172,8 @@ void ENC_Transmit(ENC_HandleTypeDef *handle)
             enc_waitwhilegreg(ENC_EIR, EIR_TXIF | EIR_TXERIF, 0);
 #endif
 
+            HAL_Delay(20); // Added by AGB - fixes weird timing bug
+
             /* Stop transmission */
             enc_bfcgreg(ENC_ECON1, ECON1_TXRTS);
 

part15-tcpip-webserver/net/enc28j60.h

@@ -61,11 +61,6 @@
 #define MIN_FRAMELEN      64
 #define MAX_FRAMELEN      1518
 
-
-/* External functions --------------------------------------------------------*/
-void HAL_Delay(volatile uint32_t Delay);
-uint32_t HAL_GetTick(void);
-
 /* Callback  functions  *********************************************************/
 
 /**

part15-tcpip-webserver/tcpip/ip_arp_udp_tcp.c

@@ -2,7 +2,7 @@
  * vim:sw=8:ts=8:si:et
  * To use the above modeline in vim you must have "set modeline" in your .vimrc
  *
- * Author: Guido Socher
+ * Author: Guido Socher 
  * Copyright:LGPL V2
  * See http://www.gnu.org/licenses/old-licenses/lgpl-2.0.html
  *
@@ -16,27 +16,29 @@
  * large pages.
  *
  *********************************************/
-
+#include "net.h"
+#include "../net/enc28j60.h"
+#include "../kernel/kernel.h"
+#include "../include/fb.h"
 #include "ip_config.h"
-#include "ip_arp_udp_tcp.h"
 
 // I use them to debug stuff:
 #define LEDOFF PORTB|=(1<<PORTB1)
 #define LEDON PORTB&=~(1<<PORTB1)
+#define LEDISOFF PORTB&(1<<PORTB1)
 //
 static uint8_t macaddr[6];
 static uint8_t ipaddr[4]={0,0,0,0};
-//static uint8_t seqnum=0xa; // my initial tcp sequence number
+static uint8_t seqnum=0xa; // my initial tcp sequence number
 static void (*icmp_callback)(uint8_t *ip);
-
 //
 #if defined (NTP_client) || defined (UDP_client) || defined (TCP_client) || defined (PING_client)
 #define ARP_MAC_resolver_client 1
 #define ALL_clients 1
 #endif
-#if defined (WWW_client) || defined (TCP_client)
+#if defined (WWW_client) || defined (TCP_client) 
 // just lower byte, the upper byte is TCPCLIENT_SRC_PORT_H:
-static uint8_t tcpclient_src_port_l=1;
+static uint8_t tcpclient_src_port_l=1; 
 static uint8_t tcp_fd=0; // a file descriptor, will be encoded into the port
 static uint8_t tcp_otherside_ip[4];
 static uint8_t tcp_dst_mac[6]; // normally the gateway via which we want to send
@@ -59,10 +61,10 @@ static uint16_t (*client_tcp_datafill_callback)(uint8_t);
 static uint8_t www_fd=0;
 static uint8_t browsertype=0; // 0 = get, 1 = post
 static void (*client_browser_callback)(uint16_t,uint16_t,uint16_t); // the fields are: uint16_t webstatuscode,uint16_t datapos,uint16_t len; datapos is start of http data and len the the length of that data
-static const prog_char *client_additionalheaderline;
+static const char *client_additionalheaderline_p; // null pointer or pointer to a string in progmem
 static char *client_postval;
-static const prog_char *client_urlbuf;
+static const char *client_urlbuf_p; // null pointer or pointer to a string in progmem
-static const char *client_urlbuf_var;
+static char *client_urlbuf_var;
 static const char *client_hoststr;
 static uint8_t *bufptr=0; // ugly workaround for backward compatibility
 #endif
@@ -89,6 +91,8 @@ static uint16_t info_data_len=0;
 
 #if defined (ALL_clients)
 static uint8_t ipnetmask[4]={255,255,255,255};
+#endif
+#if defined (ALL_clients) || defined (WOL_client)
 static uint8_t ipid=0x2; // IP-identification, it works as well if you do not change it but it is better to fill the field, we count this number up and wrap.
 const char iphdr[] ={0x45,0,0,0x82,0,0,0x40,0,0x20}; // 0x82 is the total len on ip, 0x20 is ttl (time to live), the second 0,0 is IP-identification and may be changed.
 #endif
@@ -107,7 +111,7 @@ const char ntpreqhdr[] ={0xe3,0,4,0xfa,0,1,0,0,0,1};
 // the calculation.
 // len for ip is 20.
 //
-// For UDP/TCP we do not make up the required pseudo header. Instead we
+// For UDP/TCP we do not make up the required pseudo header. Instead we 
 // use the ip.src and ip.dst fields of the real packet:
 // The udp checksum calculation starts with the ip.src field
 // Ip.src=4bytes,Ip.dst=4 bytes,Udp header=8bytes + data length=16+len
@@ -129,7 +133,7 @@ uint16_t checksum(uint8_t *buf, uint16_t len,uint8_t type){
         //      2=tcp
         uint32_t sum = 0;
 
-        //if(type==0){
+        //if(type==0){    
         //        // do not add anything, standard IP checksum as described above
         //        // Usable for ICMP and IP header
         //}
@@ -140,7 +144,7 @@ uint16_t checksum(uint8_t *buf, uint16_t len,uint8_t type){
                 sum+=len-8; // = real udp len
         }
         if(type==2){
-                sum+=IP_PROTO_TCP_V;
+                sum+=IP_PROTO_TCP_V; 
                 // the length here is the length of tcp (data+header len)
                 // =length given to this function - (IP.scr+IP.dst length)
                 sum+=len-8; // = real tcp len
@@ -185,14 +189,14 @@ void client_ifconfig(uint8_t *ip,uint8_t *netmask)
 // returns 1 if destip must be routed via the GW. Returns 0 if destip is on the local LAN
 uint8_t route_via_gw(uint8_t *destip)
 {
-    uint8_t i=0;
+	uint8_t i=0;
-    while(i<4){
+	while(i<4){
-        if ((destip[i] & ipnetmask[i]) != (ipaddr[i] & ipnetmask[i])){
+		if ((destip[i] & ipnetmask[i]) != (ipaddr[i] & ipnetmask[i])){
-            return(1);
+			return(1);
-        }
+		}
-        i++;
+		i++;
-    }
+	}
-    return(0);
+	return(0);
 }
 #endif
 
@@ -211,11 +215,11 @@ uint8_t check_ip_message_is_from(uint8_t *buf,uint8_t *ip)
 
 uint8_t eth_type_is_arp_and_my_ip(uint8_t *buf,uint16_t len){
         uint8_t i=0;
-        //
+        //  
         if (len<41){
                 return(0);
         }
-        if(buf[ETH_TYPE_H_P] != ETHTYPE_ARP_H_V ||
+        if(buf[ETH_TYPE_H_P] != ETHTYPE_ARP_H_V || 
            buf[ETH_TYPE_L_P] != ETHTYPE_ARP_L_V){
                 return(0);
         }
@@ -234,7 +238,7 @@ uint8_t eth_type_is_ip_and_my_ip(uint8_t *buf,uint16_t len){
         if (len<42){
                 return(0);
         }
-        if(buf[ETH_TYPE_H_P]!=ETHTYPE_IP_H_V ||
+        if(buf[ETH_TYPE_H_P]!=ETHTYPE_IP_H_V || 
            buf[ETH_TYPE_L_P]!=ETHTYPE_IP_L_V){
                 return(0);
         }
@@ -364,7 +368,7 @@ void make_arp_answer_from_request(uint8_t *buf)
                 i++;
         }
         // eth+arp is 42 bytes:
-        enc28j60PacketSend(42,buf);
+        enc28j60PacketSend(42,buf); 
 }
 
 void make_echo_reply_from_request(uint8_t *buf,uint16_t len)
@@ -382,7 +386,7 @@ void make_echo_reply_from_request(uint8_t *buf,uint16_t len)
         enc28j60PacketSend(len,buf);
 }
 
-// do some basic length calculations
+// do some basic length calculations 
 uint16_t get_tcp_data_len(uint8_t *buf)
 {
         int16_t i;
@@ -412,20 +416,6 @@ uint16_t fill_tcp_data_p(uint8_t *buf,uint16_t pos, const uint8_t *progmem_s)
         return(pos);
 }
 
-uint16_t fill_tcp_data_string(uint8_t *buf,uint16_t pos, char *reply)
-{
-//        char c;
-        // fill in tcp data at position pos
-        //
-        // with no options the data starts after the checksum + 2 more bytes (urgent ptr)
-        while ( !(*reply == '\n') ) {
-                buf[TCP_CHECKSUM_L_P+3+pos] = *reply;
-                reply++;
-                pos++;
-        }
-        return(pos);
-}
-
 // fill a binary string of len data into the tcp packet
 uint16_t fill_tcp_data_len(uint8_t *buf,uint16_t pos, const uint8_t *s, uint8_t len)
 {
@@ -450,7 +440,7 @@ uint16_t fill_tcp_data(uint8_t *buf,uint16_t pos, const char *s)
 }
 
 // Make just an ack packet with no tcp data inside
-// This will modify the eth/ip/tcp header
+// This will modify the eth/ip/tcp header 
 void make_tcp_ack_from_any(uint8_t *buf,int16_t datlentoack,uint8_t addflags)
 {
         uint16_t j;
@@ -458,7 +448,7 @@ void make_tcp_ack_from_any(uint8_t *buf,int16_t datlentoack,uint8_t addflags)
         // fill the header:
         buf[TCP_FLAGS_P]=TCP_FLAGS_ACK_V|addflags;
         if (addflags==TCP_FLAGS_RST_V){
-                make_tcphead(buf,datlentoack,1);
+                make_tcphead(buf,datlentoack,1); 
         }else{
                 if (datlentoack==0){
                         // if there is no data then we must still acknoledge one packet
@@ -468,7 +458,7 @@ void make_tcp_ack_from_any(uint8_t *buf,int16_t datlentoack,uint8_t addflags)
                 make_tcphead(buf,datlentoack,1); // no options
         }
         // total length field in the IP header must be set:
-        // 20 bytes IP + 20 bytes tcp (when no options)
+        // 20 bytes IP + 20 bytes tcp (when no options) 
         j=IP_HEADER_LEN+TCP_HEADER_LEN_PLAIN;
         buf[IP_TOTLEN_H_P]=j>>8;
         buf[IP_TOTLEN_L_P]=j& 0xff;
@@ -597,10 +587,10 @@ void make_tcp_synack_from_syn(uint8_t *buf)
         // put an inital seq number
         buf[TCP_SEQ_H_P+0]= 0;
         buf[TCP_SEQ_H_P+1]= 0;
-        // we step only the second byte, this allows us to send packts
+        // we step only the second byte, this allows us to send packts 
         // with 255 bytes, 512  or 765 (step by 3) without generating
         // overlapping numbers.
-        buf[TCP_SEQ_H_P+2]= seqnum;
+        buf[TCP_SEQ_H_P+2]= seqnum; 
         buf[TCP_SEQ_H_P+3]= 0;
         // step the inititial seq num by something we will not use
         // during this tcp session:
@@ -629,7 +619,7 @@ void make_tcp_synack_from_syn(uint8_t *buf)
 
 // you must have initialized info_data_len at some time before calling this function
 //
-// This info_data_len initialisation is done automatically if you call
+// This info_data_len initialisation is done automatically if you call 
 // packetloop_icmp_tcp(buf,enc28j60PacketReceive(BUFFER_SIZE, buf));
 // and test the return value for non zero.
 //
@@ -644,28 +634,27 @@ void www_server_reply(uint8_t *buf,uint16_t dlen)
         // This code requires that we send only one data packet
         // because we keep no state information. We must therefore set
         // the fin here:
-        buf[TCP_FLAGS_P]=TCP_FLAGS_ACK_V|TCP_FLAGS_PUSH_V;//|TCP_FLAGS_FIN_V;
+        buf[TCP_FLAGS_P]=TCP_FLAGS_ACK_V|TCP_FLAGS_PUSH_V|TCP_FLAGS_FIN_V;
         make_tcp_ack_with_data_noflags(buf,dlen); // send data
 }
 
 #endif // WWW_server
 
-#if defined (ALL_clients)
+#if defined (ALL_clients) || defined (GRATARP) || defined (WOL_client)
 // fill buffer with a prog-mem string
-void fill_buf_p(uint8_t *buf,uint16_t len, const char *progmem_s)
+void fill_buf_p(uint8_t *buf,uint16_t len, const char *progmem_str_p)
 {
-        uint8_t i=0;
-
         while (len){
-                *buf= progmem_s[i];
+                *buf= pgm_read_byte(progmem_str_p);
                 buf++;
-                len--; i++;
+                progmem_str_p++;
+                len--;
         }
 }
-#endif
+#endif 
 
 #ifdef PING_client
-// icmp echo, matchpat is a pattern that has to be sent back by the
+// icmp echo, matchpat is a pattern that has to be sent back by the 
 // host answering the ping.
 // The ping is sent to destip  and mac dstmac
 void client_icmp_request(uint8_t *buf,uint8_t *destip,uint8_t *dstmac)
@@ -697,14 +686,14 @@ void client_icmp_request(uint8_t *buf,uint8_t *destip,uint8_t *dstmac)
         buf[ICMP_CHECKSUM_H_P]=0;
         buf[ICMP_CHECKSUM_L_P]=0;
         // a possibly unique id of this host:
-        buf[ICMP_IDENT_H_P]=5; // some number
+        buf[ICMP_IDENT_H_P]=5; // some number 
         buf[ICMP_IDENT_L_P]=ipaddr[3]; // last byte of my IP
         //
         buf[ICMP_IDENT_L_P+1]=0; // seq number, high byte
         buf[ICMP_IDENT_L_P+2]=1; // seq number, low byte, we send only 1 ping at a time
         // copy the data:
         i=0;
-        while(i<56){
+        while(i<56){ 
                 buf[ICMP_DATA_P+i]=PINGPATTERN;
                 i++;
         }
@@ -725,6 +714,7 @@ void client_ntp_request(uint8_t *buf,uint8_t *ntpip,uint8_t srcport,uint8_t *dst
 {
         uint8_t i=0;
         uint16_t ck;
+        if (!enc28j60linkup())return;
         //
         while(i<6){
                 buf[ETH_DST_MAC +i]=dstmac[i]; // gw mac in local lan or host mac
@@ -756,7 +746,7 @@ void client_ntp_request(uint8_t *buf,uint8_t *ntpip,uint8_t srcport,uint8_t *dst
         // copy the data:
         i=0;
         // most fields are zero, here we zero everything and fill later
-        while(i<48){
+        while(i<48){ 
                 buf[UDP_DATA_P+i]=0;
                 i++;
         }
@@ -772,7 +762,7 @@ void client_ntp_request(uint8_t *buf,uint8_t *ntpip,uint8_t srcport,uint8_t *dst
 // return 1 on sucessful processing of answer
 uint8_t client_ntp_process_answer(uint8_t *buf,uint32_t *time,uint8_t dstport_l){
         if (dstport_l){
-                if (buf[UDP_DST_PORT_L_P]!=dstport_l){
+                if (buf[UDP_DST_PORT_L_P]!=dstport_l){ 
                         return(0);
                 }
         }
@@ -787,9 +777,9 @@ uint8_t client_ntp_process_answer(uint8_t *buf,uint32_t *time,uint8_t dstport_l)
 #endif
 
 #ifdef UDP_client
-// -------------------- send a spontanious UDP packet to a server
+// -------------------- send a spontanious UDP packet to a server 
 // There are two ways of using this:
-// 1) you call send_udp_prepare, you fill the data yourself into buf starting at buf[UDP_DATA_P],
+// 1) you call send_udp_prepare, you fill the data yourself into buf starting at buf[UDP_DATA_P], 
 // you send the packet by calling send_udp_transmit
 //
 // 2) You just allocate a large enough buffer for you data and you call send_udp and nothing else
@@ -820,9 +810,9 @@ void send_udp_prepare(uint8_t *buf,uint16_t sport, const uint8_t *dip, uint16_t
         }
         // done in transmit: fill_ip_hdr_checksum(buf);
         buf[UDP_DST_PORT_H_P]=(dport>>8);
-        buf[UDP_DST_PORT_L_P]=0xff&dport;
+        buf[UDP_DST_PORT_L_P]=0xff&dport; 
         buf[UDP_SRC_PORT_H_P]=(sport>>8);
-        buf[UDP_SRC_PORT_L_P]=sport&0xff;
+        buf[UDP_SRC_PORT_L_P]=sport&0xff; 
         buf[UDP_LEN_H_P]=0;
         // done in transmit: buf[UDP_LEN_L_P]=UDP_HEADER_LEN+datalen;
         // zero the checksum
@@ -912,7 +902,7 @@ void send_wol(uint8_t *buf,uint8_t *wolmac)
         buf[UDP_CHECKSUM_L_P]=0;
         // copy the data (102 bytes):
         i=0;
-        while(i<6){
+        while(i<6){ 
                 buf[UDP_DATA_P+i]=0xff;
                 i++;
         }
@@ -920,7 +910,7 @@ void send_wol(uint8_t *buf,uint8_t *wolmac)
         pos=UDP_DATA_P+6;
         while (m<16){
                 i=0;
-                while(i<6){
+                while(i<6){ 
                         buf[pos]=wolmac[i];
                         i++;
                         pos++;
@@ -960,7 +950,7 @@ uint8_t gratutious_arp(uint8_t *buf)
         buf[ETH_TYPE_L_P] = ETHTYPE_ARP_L_V;
         // arp request and reply are the same execept for
         // the opcode:
-        fill_buf_p(&buf[ETH_ARP_P],8,arpreqhdr);
+        fill_buf_p(&buf[ETH_ARP_P],8,arpreqhdr); 
         //buf[ETH_ARP_OPCODE_L_P]=ETH_ARP_OPCODE_REPLY_L_V; // reply
         i=0;
         while(i<6){
@@ -982,8 +972,8 @@ uint8_t gratutious_arp(uint8_t *buf)
 
 #if ARP_MAC_resolver_client
 // make a arp request
-// Note: you must have initialized the stack with
+// Note: you must have initialized the stack with 
-// init_udp_or_www_server or client_ifconfig
+// init_udp_or_www_server or client_ifconfig 
 // before you can use this function
 void client_arp_whohas(uint8_t *buf,uint8_t *ip_we_search)
 {
@@ -1025,8 +1015,8 @@ uint8_t get_mac_with_arp_wait(void)
 
 // reference_number is something that is just returned in the callback
 // to make matching and waiting for a given ip/mac address pair easier
-// Note: you must have initialized the stack with
+// Note: you must have initialized the stack with 
-// init_udp_or_www_server or client_ifconfig
+// init_udp_or_www_server or client_ifconfig 
 // before you can use this function
 void get_mac_with_arp(uint8_t *ip, uint8_t reference_number,void (*arp_result_callback)(uint8_t *ip,uint8_t reference_number,uint8_t *mac))
 {
@@ -1039,7 +1029,7 @@ void get_mac_with_arp(uint8_t *ip, uint8_t reference_number,void (*arp_result_ca
                 i++;
         }
 }
-#endif
+#endif 
 
 #if defined (TCP_client)
 // Make a tcp syn packet
@@ -1076,12 +1066,12 @@ void tcp_client_syn(uint8_t *buf,uint8_t srcport,uint16_t dstport)
                 buf[TCP_SEQ_H_P+i]=0;
                 i++;
         }
-        // -- header ready
+        // -- header ready 
         // put inital seq number
-        // we step only the second byte, this allows us to send packts
+        // we step only the second byte, this allows us to send packts 
         // with 255 bytes 512 (if we step the initial seqnum by 2)
         // or 765 (step by 3)
-        buf[TCP_SEQ_H_P+2]= seqnum;
+        buf[TCP_SEQ_H_P+2]= seqnum; 
         // step the inititial seq num by something we will not use
         // during this tcp session:
         seqnum+=3;
@@ -1110,7 +1100,7 @@ void tcp_client_syn(uint8_t *buf,uint8_t srcport,uint16_t dstport)
 }
 #endif // TCP_client
 
-#if defined (TCP_client)
+#if defined (TCP_client) 
 // This is how to use the tcp client:
 //
 // Declare a callback function to get the result (tcp data from the server):
@@ -1126,16 +1116,16 @@ void tcp_client_syn(uint8_t *buf,uint8_t srcport,uint16_t dstport)
 // output such that this will be the only packet.
 //
 // close_tcp_session=1 means close the session now. close_tcp_session=0
-// read all data and leave it to the other side to close it.
+// read all data and leave it to the other side to close it. 
 // If you connect to a web server then you want close_tcp_session=0.
 // If you connect to a modbus/tcp equipment then you want close_tcp_session=1
 //
-// Declare a callback function to be called in order to fill in the
+// Declare a callback function to be called in order to fill in the 
 //
 // request (tcp data sent to the server):
 // uint16_t your_client_tcp_datafill_callback(uint8_t fd){...your code;return(len_of_data_filled_in);}
 //
-// Now call:
+// Now call: 
 // fd=client_tcp_req(&your_client_tcp_result_callback,&your_client_tcp_datafill_callback,portnumber);
 //
 // fd is a file descriptor like number that you get back in the fill and result
@@ -1171,7 +1161,7 @@ uint8_t client_tcp_req(uint8_t (*result_callback)(uint8_t fd,uint8_t statuscode,
 }
 #endif //  TCP_client
 
-#if defined (WWW_client)
+#if defined (WWW_client) 
 uint16_t www_client_internal_datafill_callback(uint8_t fd){
         char strbuf[5];
         uint16_t len=0;
@@ -1179,27 +1169,27 @@ uint16_t www_client_internal_datafill_callback(uint8_t fd){
                 if (browsertype==0){
                         // GET
                         len=fill_tcp_data_p(bufptr,0,PSTR("GET "));
-                        len=fill_tcp_data_p(bufptr,len,client_urlbuf);
+                        len=fill_tcp_data_p(bufptr,len,client_urlbuf_p);
                         len=fill_tcp_data(bufptr,len,client_urlbuf_var);
                         // I would prefer http/1.0 but there is a funny
                         // bug in some apache webservers which causes
                         // them to send two packets (fragmented PDU)
                         // if we don't use HTTP/1.1 + Connection: close
                         len=fill_tcp_data_p(bufptr,len,PSTR(" HTTP/1.1\r\nHost: "));
-                        len=fill_tcp_data(bufptr,len,client_hoststr);
+                        len=fill_tcp_data_p(bufptr,len,client_hoststr);
-                        len=fill_tcp_data_p(bufptr,len,PSTR("\r\nUser-Agent: tgr/1.1\r\nAccept: text/html\r\nConnection: close\r\n\r\n"));
+                        len=fill_tcp_data_p(bufptr,len,PSTR("\r\nUser-Agent: tgr/1.1\r\nAccept: text/html\r\n\r\n"));
                 }else{
                         // POST
                         len=fill_tcp_data_p(bufptr,0,PSTR("POST "));
-                        len=fill_tcp_data_p(bufptr,len,client_urlbuf);
+                        len=fill_tcp_data_p(bufptr,len,client_urlbuf_p);
                         len=fill_tcp_data(bufptr,len,client_urlbuf_var);
                         len=fill_tcp_data_p(bufptr,len,PSTR(" HTTP/1.1\r\nHost: "));
-                        len=fill_tcp_data(bufptr,len,client_hoststr);
+                        len=fill_tcp_data_p(bufptr,len,client_hoststr);
-                        if (client_additionalheaderline){
+                        if (client_additionalheaderline_p){
                                 len=fill_tcp_data_p(bufptr,len,PSTR("\r\n"));
-                                len=fill_tcp_data_p(bufptr,len,client_additionalheaderline);
+                                len=fill_tcp_data_p(bufptr,len,client_additionalheaderline_p);
                         }
-                        len=fill_tcp_data_p(bufptr,len,PSTR("\r\nUser-Agent: tgr/1.1\r\nAccept: */*\r\nConnection: close\r\n"));
+                        len=fill_tcp_data_p(bufptr,len,PSTR("\r\nUser-Agent: tgr/1.1\r\nAccept: */*\r\n"));
                         len=fill_tcp_data_p(bufptr,len,PSTR("Content-Length: "));
                         itoa(strlen(client_postval),strbuf,10);
                         len=fill_tcp_data(bufptr,len,strbuf);
@@ -1213,7 +1203,7 @@ uint16_t www_client_internal_datafill_callback(uint8_t fd){
 
 uint8_t www_client_internal_result_callback(uint8_t fd, uint8_t statuscode, uint16_t datapos, uint16_t len_of_data){
         uint16_t web_statuscode=0; // tcp status is OK but we need to check http layer too
-        uint8_t i=0;
+        uint8_t i=0; 
         if (fd!=www_fd){
                 (*client_browser_callback)(500,0,0);
                 return(0);
@@ -1222,7 +1212,7 @@ uint8_t www_client_internal_result_callback(uint8_t fd, uint8_t statuscode, uint
                 // we might have a http status code
                 // http status codes are 3digit numbers as ascii text. See http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
                 // The buffer would look like this: HTTP/1.1 200 OK\r\n
-                // web_statuscode=0 means we got a corrupted answer
+                // web_statuscode=0 means we got a corrupted answer 
                 if (client_browser_callback){
                         if (isblank(bufptr[datapos+8]) && isdigit(bufptr[datapos+9])&& isdigit(bufptr[datapos+11])){ // e.g 200 OK, a status code has 3 digits from datapos+9 to datapos+11, copy over the web/http status code to web_statuscode:
                                 while(i<2){
@@ -1260,10 +1250,10 @@ uint8_t www_client_internal_result_callback(uint8_t fd, uint8_t statuscode, uint
 // The string buffers to which urlbuf_varpart and hoststr are pointing
 // must not be changed until the callback is executed.
 //
-void client_browse_url(const prog_char *urlbuf,const char *urlbuf_varpart,const char *hoststr,void (*callback)(uint16_t,uint16_t,uint16_t),uint8_t *dstip,uint8_t *dstmac)
+void client_browse_url(const char *urlbuf_p,char *urlbuf_varpart,const char *hoststr,void (*callback)(uint16_t,uint16_t,uint16_t),uint8_t *dstip,uint8_t *dstmac)
 {
         if (!enc28j60linkup())return;
-        client_urlbuf=urlbuf;
+        client_urlbuf_p=urlbuf_p;
         client_urlbuf_var=urlbuf_varpart;
         client_hoststr=hoststr;
         browsertype=0;
@@ -1272,19 +1262,19 @@ void client_browse_url(const prog_char *urlbuf,const char *urlbuf_varpart,const
 }
 
 // client web browser using http POST operation:
-// additionalheaderline must be set to NULL if not used.
+// additionalheaderline_p must be set to NULL if not used.
 // The string buffers to which urlbuf_varpart and hoststr are pointing
 // must not be changed until the callback is executed.
-// postval is a string buffer which can only be de-allocated by the caller
+// postval is a string buffer which can only be de-allocated by the caller 
 // when the post operation was really done (e.g when callback was executed).
 // postval must be urlencoded.
-void client_http_post(const prog_char *urlbuf, const char *urlbuf_varpart,const char *hoststr, const prog_char *additionalheaderline,char *postval,void (*callback)(uint16_t,uint16_t,uint16_t),uint8_t *dstip,uint8_t *dstmac)
+void client_http_post(const char *urlbuf_p, char *urlbuf_varpart,const char *hoststr, const char *additionalheaderline_p,char *postval,void (*callback)(uint16_t,uint16_t,uint16_t),uint8_t *dstip,uint8_t *dstmac)
 {
         if (!enc28j60linkup())return;
-        client_urlbuf=urlbuf;
+        client_urlbuf_p=urlbuf_p;
         client_hoststr=hoststr;
         client_urlbuf_var=urlbuf_varpart;
-        client_additionalheaderline=additionalheaderline;
+        client_additionalheaderline_p=additionalheaderline_p;
         client_postval=postval;
         browsertype=1;
         client_browser_callback=callback;
@@ -1314,18 +1304,18 @@ uint8_t packetloop_icmp_checkreply(uint8_t *buf,uint8_t *ip_monitoredhost)
 #endif // PING_client
 
 
-// return 0 to just continue in the packet loop and return the position
+// return 0 to just continue in the packet loop and return the position 
 // of the tcp data if there is tcp data part
 uint16_t packetloop_arp_icmp_tcp(uint8_t *buf,uint16_t plen)
 {
-//        uint16_t len;
+        uint16_t len;
 #if defined (TCP_client)
         uint8_t send_fin=0;
         uint16_t tcpstart;
         uint16_t save_len;
 #endif
 #ifdef ARP_MAC_resolver_client
-        //plen will be unequal to zero if there is a valid
+        //plen will be unequal to zero if there is a valid 
         // packet (without crc error):
         if(plen==0){
                 if (arpip_state == (WGW_ACCEPT_ARP_REPLY|WGW_INITIAL_ARP) && arp_delaycnt==0 ){
@@ -1352,17 +1342,17 @@ uint16_t packetloop_arp_icmp_tcp(uint8_t *buf,uint16_t plen)
         }
 #endif // ARP_MAC_resolver_client
         // arp is broadcast if unknown but a host may also
-        // verify the mac address by sending it to
+        // verify the mac address by sending it to 
         // a unicast address.
         if(eth_type_is_arp_and_my_ip(buf,plen)){
                 if (buf[ETH_ARP_OPCODE_L_P]==ETH_ARP_OPCODE_REQ_L_V){
-                        // is it an arp request
+                        // is it an arp request 
                         make_arp_answer_from_request(buf);
                 }
 #ifdef ARP_MAC_resolver_client
                 if ((arpip_state & WGW_ACCEPT_ARP_REPLY) && (buf[ETH_ARP_OPCODE_L_P]==ETH_ARP_OPCODE_REPLY_L_V)){
-                        // is it an arp reply
+                        // is it an arp reply 
-                        if (memcmp(&buf[ETH_ARP_SRC_IP_P],arpip,4)!=0) return(0); // not an arp reply for the IP we were searching
+                        if (memcmp(&buf[ETH_ARP_SRC_IP_P],arpip,4)!=0) return(0); // not an arp reply for the IP we were searching           
                         (*client_arp_result_callback)(arpip,arp_reference_number,buf+ETH_ARP_SRC_MAC_P);
                         arpip_state=WGW_HAVE_MAC;
                 }
@@ -1379,13 +1369,13 @@ uint16_t packetloop_arp_icmp_tcp(uint8_t *buf,uint16_t plen)
                         (*icmp_callback)(&(buf[IP_SRC_P]));
                 }
                 // a ping packet, let's send pong
-                debugstr("Sending ping reply...");
+                debugstr("Replying to ping..."); debugcrlf();
-                debugcrlf();
                 make_echo_reply_from_request(buf,plen);
                 return(0);
         }
-        if (plen<54 && buf[IP_PROTO_P]!=IP_PROTO_TCP_V ){
+        // this is an important check to avoid working on the wrong packets:
-                // smaller than the smallest TCP packet and not tcp port
+        if (plen<54 || buf[IP_PROTO_P]!=IP_PROTO_TCP_V ){
+                // smaller than the smallest TCP packet (TCP packet with no options section) or not tcp port
                 return(0);
         }
 #if defined (TCP_client)
@@ -1393,7 +1383,7 @@ uint16_t packetloop_arp_icmp_tcp(uint8_t *buf,uint16_t plen)
         if ( buf[TCP_DST_PORT_H_P]==TCPCLIENT_SRC_PORT_H){
 #if defined (WWW_client)
                 // workaround to pass pointer to www_client_internal..
-                bufptr=buf;
+                bufptr=buf; 
 #endif // WWW_client
                 if (check_ip_message_is_from(buf,tcp_otherside_ip)==0){
                         return(0);
@@ -1404,7 +1394,7 @@ uint16_t packetloop_arp_icmp_tcp(uint8_t *buf,uint16_t plen)
                                 // parameters in client_tcp_result_callback: fd, status, buf_start, len
                                 (*client_tcp_result_callback)((buf[TCP_DST_PORT_L_P]>>5)&0x7,3,0,0);
                         }
-                        tcp_client_state=5;
+                        tcp_client_state=6;
                         return(0);
                 }
                 len=get_tcp_data_len(buf);
@@ -1418,7 +1408,7 @@ uint16_t packetloop_arp_icmp_tcp(uint8_t *buf,uint16_t plen)
                                 // still have a valid tcp-ack in the buffer. In other words
                                 // you have just called make_tcp_ack_from_any(buf,0).
                                 if (client_tcp_datafill_callback){
-                                        // in this case it is src port because the above
+                                        // in this case it is src port because the above 
                                         // make_tcp_ack_from_any swaps the dst and src port:
                                         len=(*client_tcp_datafill_callback)((buf[TCP_SRC_PORT_L_P]>>5)&0x7);
                                 }else{
@@ -1447,7 +1437,7 @@ uint16_t packetloop_arp_icmp_tcp(uint8_t *buf,uint16_t plen)
                 }
                 // in tcp_client_state==3 we will normally first get an empty
                 // ack-packet and then a ack-packet with data.
-                if (tcp_client_state==3 && len>0){
+                if (tcp_client_state==3 && len>0){ 
                         // our first real data packet
                         tcp_client_state=4;
                         // return the data we received
@@ -1470,11 +1460,25 @@ uint16_t packetloop_arp_icmp_tcp(uint8_t *buf,uint16_t plen)
                         }
                 }
                 if(tcp_client_state==5){
-                        // no more ack
+                        // we get one more final ack to our fin-ack:
+                        if (buf[TCP_FLAGS_P] & TCP_FLAGS_ACK_V){
+                                tcp_client_state=6; // in state 6 communication should be finished
+                        }
+                        return(0);
+                }
+                if(tcp_client_state==6){
+                        // something wrong, can't deal with this, reset the connection
+                        len++;
+                        if (buf[TCP_FLAGS_P] & TCP_FLAGS_ACK_V) len=0; // if packet was an ack then do not step the ack number
+                        make_tcp_ack_from_any(buf,len,TCP_FLAGS_RST_V);
+                        // just a single reset, do not repeat if more messages:
+                        tcp_client_state=7;
                         return(0);
                 }
                 if (buf[TCP_FLAGS_P] & TCP_FLAGS_FIN_V){
-                        make_tcp_ack_from_any(buf,len+1,TCP_FLAGS_PUSH_V|TCP_FLAGS_FIN_V);
+                        // this normally a fin ack message but it could be
+                        // any message with fin we answer with fin-ack:
+                        make_tcp_ack_from_any(buf,len+1,TCP_FLAGS_FIN_V);
                         tcp_client_state=5; // connection terminated
                         return(0);
                 }
@@ -1490,7 +1494,7 @@ uint16_t packetloop_arp_icmp_tcp(uint8_t *buf,uint16_t plen)
         //
 #ifdef WWW_server
         // tcp port web server start
-        if (buf[IP_PROTO_P]==IP_PROTO_TCP_V && buf[TCP_DST_PORT_H_P]==wwwport_h && buf[TCP_DST_PORT_L_P]==wwwport_l){
+        if (buf[TCP_DST_PORT_H_P]==wwwport_h && buf[TCP_DST_PORT_L_P]==wwwport_l){
                 if (buf[TCP_FLAGS_P] & TCP_FLAGS_SYN_V){
                         make_tcp_synack_from_syn(buf);
                         // make_tcp_synack_from_syn does already send the syn,ack

part15-tcpip-webserver/tcpip/ip_arp_udp_tcp.h

@@ -12,10 +12,6 @@
 #ifndef IP_ARP_UDP_TCP_H
 #define IP_ARP_UDP_TCP_H 1
 
-#include "net.h"
-#include "../net/enc28j60.h"
-#include "../kernel/kernel.h"
-#include "../include/fb.h"
 #include "ip_config.h"
 
 // set my own mac address:

part15-tcpip-webserver/tcpip/ip_config.h

@@ -22,7 +22,7 @@
 // a server answering to UDP messages
 #define UDP_server
 // a web server
-#undef WWW_server
+#define WWW_server
 
 // to send out a ping:
 #undef PING_client

part15-tcpip/README.md

@@ -1,63 +0,0 @@
-Writing a "bare metal" operating system for Raspberry Pi 4 (Part 15)
-====================================================================
-
-Adding a TCP/IP stack
----------------------
-Having achieved "proof of life" from our Ethernet module in _part14-spi-ethernet_, you're doubtless wondering how to go from there to serving web pages, posting tweets on Twitter or perhaps even just simply responding to a ping!
-
-This is where you'll need a fully-fledged TCP/IP stack that goes way beyond handcrafted ARPs, implementing many more protocols to achieve efficient bi-directional communication.
-
-In this part we make use of some code from Guido Socher of [tuxgraphics.org](http://tuxgraphics.org/), designed to be a lightweight TCP/IP stack for embedded devices. I chose this because it was super simple to get working (or "port"), but you might want to look at [LwIP](https://en.wikipedia.org/wiki/LwIP) if you need something more advanced.
-
-The code
---------
-Most of the new code is in the _tcpip/_ subdirectory. I actually came across it in [this Github repository](https://github.com/ussserrr/maglev-ti-rtos) and, again, made only a very few cosmetic changes (`diff` is your friend!).
-
-It did require me to expose the `strlen()` function we implemented in _lib/fb.c_, so that's added to _include/fb.h_. Similarly, we expose the `memcpy()` function we implemented in _kernel/kernel.c_, so that's added to _kernel/kernel.h_.
-
-I also needed a single function that tells the ENC to send a packet. Nothing new here, just different packaging:
-
-```c
-void enc28j60PacketSend(unsigned short buflen, void *buffer) {
-   if (ENC_RestoreTXBuffer(&handle, buflen) == 0) {
-      ENC_WriteBuffer((unsigned char *) buffer, buflen);
-      handle.transmitLength = buflen;
-      ENC_Transmit(&handle);
-   }
-}
-```
-
-This was also added to _kernel/kernel.h_. Finally, _kernel/kernel.c_ now calls a function called `net_test()` instead of our original `arp_test()`.
-
-The changes to _arp.c_
-----------------------
-We initialise the network card in exactly the same way but, when we're done, we call this function in Guido's code:
-
-```c
-init_udp_or_www_server(myMAC, deviceIP);
-```
-
-This tells the TCP/IP library who we are, so we're all on the same page!
-
-Finally, and aside from a little cleanup, the major change is the new `net_test()` function:
-
-```c
-void net_test(void)
-{
-   while (1) {
-      while (!ENC_GetReceivedFrame(&handle));
-
-      uint16_t len = handle.RxFrameInfos.length;
-      uint8_t *buffer = (uint8_t *)handle.RxFrameInfos.buffer;
-      packetloop_arp_icmp_tcp(buffer, len);
-   }
-}
-```
-
-This is an infinite loop which waits for an incoming packet and then simply passes it to Guido's `packetloop_arp_icmp_tcp()` function. This function implements some useful things, like responding to pings. I modified the routine to print a message to the screen when it sends a "pong" (look from line 1381 of _tcpip/ip_arp_udp_tcp.c_), so we can see when it's in action!
-
-_Imagine my excitement when I built, ran and could ping my RPi4 at 192.168.0.66 and get a response to both my laptop and my iPhone!_
-
-I recommend reading [this page](http://tuxgraphics.org/electronics/200905/embedded-tcp-ip-stack.shtml) to give you some ideas about what else you might achieve with Guido's library...
-
-![Pinging from my iPhone](images/15-tcpip-pinging.jpg)

part15-tcpip/kernel/irq.c

@@ -1,27 +0,0 @@
-#include "kernel.h"
-
-void enable_interrupt_controller() {
-    REGS_IRQ->irq0_enable_0 = SYS_TIMER_IRQ_1 | SYS_TIMER_IRQ_3;
-}
-
-void disable_interrupt_controller() {
-    REGS_IRQ->irq0_enable_0 = 0;
-}
-
-void handle_irq() {
-    unsigned int irq = REGS_IRQ->irq0_pending_0;
-
-    while(irq) {
-        if (irq & SYS_TIMER_IRQ_1) {
-            irq &= ~SYS_TIMER_IRQ_1;
-
-            handle_timer_1();
-        }
-
-        if (irq & SYS_TIMER_IRQ_3) {
-            irq &= ~SYS_TIMER_IRQ_3;
-
-            handle_timer_3();
-        }
-    }
-}

part15-tcpip/kernel/irqentry.S

@@ -1,160 +0,0 @@
-#define SYNC_INVALID_EL1t		0 
-#define IRQ_INVALID_EL1t		1 
-#define FIQ_INVALID_EL1t		2 
-#define ERROR_INVALID_EL1t		3 
-
-#define SYNC_INVALID_EL1h		4 
-#define IRQ_INVALID_EL1h		5 
-#define FIQ_INVALID_EL1h		6 
-#define ERROR_INVALID_EL1h		7 
-
-#define SYNC_INVALID_EL0_64		8 
-#define IRQ_INVALID_EL0_64		9 
-#define FIQ_INVALID_EL0_64		10 
-#define ERROR_INVALID_EL0_64		11 
-
-#define SYNC_INVALID_EL0_32		12 
-#define IRQ_INVALID_EL0_32		13 
-#define FIQ_INVALID_EL0_32		14 
-#define ERROR_INVALID_EL0_32		15 
-
-//stack frame size
-#define S_FRAME_SIZE			256
-
-.macro kernel_entry
-	sub 	sp, sp, #S_FRAME_SIZE
-	stp 	x0, x1, [sp, #16 * 0]
-	stp 	x2, x3, [sp, #16 * 1]
-	stp	x4, x5, [sp, #16 * 2]
-	stp	x6, x7, [sp, #16 * 3]
-	stp	x8, x9, [sp, #16 * 4]
-	stp	x10, x11, [sp, #16 * 5]
-	stp	x12, x13, [sp, #16 * 6]
-	stp	x14, x15, [sp, #16 * 7]
-	stp	x16, x17, [sp, #16 * 8]
-	stp	x18, x19, [sp, #16 * 9]
-	stp	x20, x21, [sp, #16 * 10]
-	stp	x22, x23, [sp, #16 * 11]
-	stp	x24, x25, [sp, #16 * 12]
-	stp	x26, x27, [sp, #16 * 13]
-	stp	x28, x29, [sp, #16 * 14]
-	str	x30, [sp, #16 * 15] 
-.endm
-
-.macro kernel_exit
-	ldp	x0, x1, [sp, #16 * 0]
-	ldp	x2, x3, [sp, #16 * 1]
-	ldp	x4, x5, [sp, #16 * 2]
-	ldp	x6, x7, [sp, #16 * 3]
-	ldp	x8, x9, [sp, #16 * 4]
-	ldp	x10, x11, [sp, #16 * 5]
-	ldp	x12, x13, [sp, #16 * 6]
-	ldp	x14, x15, [sp, #16 * 7]
-	ldp	x16, x17, [sp, #16 * 8]
-	ldp	x18, x19, [sp, #16 * 9]
-	ldp	x20, x21, [sp, #16 * 10]
-	ldp	x22, x23, [sp, #16 * 11]
-	ldp	x24, x25, [sp, #16 * 12]
-	ldp	x26, x27, [sp, #16 * 13]
-	ldp	x28, x29, [sp, #16 * 14]
-	ldr	x30, [sp, #16 * 15] 
-	add	sp, sp, #S_FRAME_SIZE
-	eret
-.endm
-
-.macro handle_invalid_entry type
-	kernel_entry
-	mov	x0, #\type
-	mrs	x1, esr_el1
-	mrs	x2, elr_el1
-
-        // We could pass this to a function to print an error here
-        // e.g. bl show_invalid_entry_message
-        //
-        // For now we'll just hang
-
-	b	err_hang
-.endm
-
-.macro	ventry	label
-.align	7
-	b	\label
-.endm
-
-//Exception vectors table
-.align	11
-.globl vectors 
-vectors:
-	ventry	sync_invalid_el1t			// Synchronous EL1t
-	ventry	irq_invalid_el1t			// IRQ EL1t
-	ventry	fiq_invalid_el1t			// FIQ EL1t
-	ventry	error_invalid_el1t			// Error EL1t
-
-	ventry	sync_invalid_el1h			// Synchronous EL1h
-	ventry	handle_el1_irq				// IRQ EL1h
-	ventry	fiq_invalid_el1h			// FIQ EL1h
-	ventry	error_invalid_el1h			// Error EL1h
-
-	ventry	sync_invalid_el0_64			// Synchronous 64-bit EL0
-	ventry	irq_invalid_el0_64			// IRQ 64-bit EL0
-	ventry	fiq_invalid_el0_64			// FIQ 64-bit EL0
-	ventry	error_invalid_el0_64			// Error 64-bit EL0
-
-	ventry	sync_invalid_el0_32			// Synchronous 32-bit EL0
-	ventry	irq_invalid_el0_32			// IRQ 32-bit EL0
-	ventry	fiq_invalid_el0_32			// FIQ 32-bit EL0
-	ventry	error_invalid_el0_32			// Error 32-bit EL0
-
-
-sync_invalid_el1t:
-	handle_invalid_entry  SYNC_INVALID_EL1t
-
-irq_invalid_el1t:
-	handle_invalid_entry  IRQ_INVALID_EL1t
-
-fiq_invalid_el1t:
-	handle_invalid_entry  FIQ_INVALID_EL1t
-
-error_invalid_el1t:
-	handle_invalid_entry  ERROR_INVALID_EL1t
-
-sync_invalid_el1h:
-	handle_invalid_entry  SYNC_INVALID_EL1h
-
-fiq_invalid_el1h:
-	handle_invalid_entry  FIQ_INVALID_EL1h
-
-error_invalid_el1h:
-	handle_invalid_entry  ERROR_INVALID_EL1h
-
-sync_invalid_el0_64:
-	handle_invalid_entry  SYNC_INVALID_EL0_64
-
-irq_invalid_el0_64:
-	handle_invalid_entry  IRQ_INVALID_EL0_64
-
-fiq_invalid_el0_64:
-	handle_invalid_entry  FIQ_INVALID_EL0_64
-
-error_invalid_el0_64:
-	handle_invalid_entry  ERROR_INVALID_EL0_64
-
-sync_invalid_el0_32:
-	handle_invalid_entry  SYNC_INVALID_EL0_32
-
-irq_invalid_el0_32:
-	handle_invalid_entry  IRQ_INVALID_EL0_32
-
-fiq_invalid_el0_32:
-	handle_invalid_entry  FIQ_INVALID_EL0_32
-
-error_invalid_el0_32:
-	handle_invalid_entry  ERROR_INVALID_EL0_32
-
-handle_el1_irq:
-	kernel_entry 
-	bl	handle_irq
-	kernel_exit 
-
-.globl err_hang
-err_hang: b err_hang

part15-tcpip/kernel/kernel.c

@@ -1,167 +0,0 @@
-#include "../include/fb.h"
-#include "../include/io.h"
-#include "../include/spi.h"
-#include "../include/multicore.h"
-#include "kernel.h"
-
-void initProgress(void)
-{
-    drawRect(0, 0, 301, 50, 0x0f, 0);
-    drawString(309, 21, "Core 0", 0x0f, 1);
-
-    drawRect(0, 60, 301, 110, 0x0f, 0);
-    drawString(309, 81, "Core 1", 0x0f, 1);
-
-    drawRect(0, 120, 301, 170, 0x0f, 0);
-    drawString(309, 141, "Timer 1", 0x0f, 1);
-
-    drawRect(0, 180, 301, 230, 0x0f, 0);
-    drawString(309, 201, "Timer 3", 0x0f, 1);
-}
-
-void drawProgress(unsigned int core, unsigned int val) {
-    unsigned char col = (core + 1) + ((core + 1) << 4);
-
-    // val should be 0-100
-    if (val == 0) drawRect(1, (60 * core) + 1, 300, (60 * core) + 49, 0x00, 1);
-    if (val > 0) drawRect(1, (60 * core) + 1, (val * 3), (60 * core) + 49, col, 1);
-}
-
-void core3_main(void) {
-    clear_core3();                // Only run once
-
-    // Test the network card
-
-    spi_init();
-    init_network();
-    net_test();
-
-    while(1);
-}
-
-void core0_main(void)
-{
-    unsigned int core0_val = 0;
-
-    while (core0_val <= 100) {
-       wait_msec(0x100000);
-       drawProgress(0, core0_val);
-       core0_val++;
-    }
-
-    debugstr("Core 0 done.");
-    debugcrlf();
-}
-
-void core1_main(void)
-{
-    unsigned int core1_val = 0;
-
-    clear_core1();                // Only run once
-
-    while (core1_val <= 100) {
-       wait_msec(0x3FFFF);
-       drawProgress(1, core1_val);
-       core1_val++;
-    }
-
-    debugstr("Core 1 done.");
-    debugcrlf();
- 
-    while(1);
-}
-
-// TIMER FUNCTIONS
-
-const unsigned int timer1_int = CLOCKHZ;
-const unsigned int timer3_int = CLOCKHZ / 4;
-unsigned int timer1_val = 0;
-unsigned int timer3_val = 0;
-
-void timer_init() {
-    timer1_val = REGS_TIMER->counter_lo;
-    timer1_val += timer1_int;
-    REGS_TIMER->compare[1] = timer1_val;
-
-    timer3_val = REGS_TIMER->counter_lo;
-    timer3_val += timer3_int;
-    REGS_TIMER->compare[3] = timer3_val;
-}
-
-void handle_timer_1() {
-    timer1_val += timer1_int;
-    REGS_TIMER->compare[1] = timer1_val;
-    REGS_TIMER->control_status |= SYS_TIMER_IRQ_1;
-
-    unsigned int progval = timer1_val / timer1_int;
-    if (progval <= 100) {
-       drawProgress(2, progval);
-    } else {
-       debugstr("Timer 1 done.");
-       debugcrlf();
-    }
-}
-
-void handle_timer_3() {
-    timer3_val += timer3_int;
-    REGS_TIMER->compare[3] = timer3_val;
-    REGS_TIMER->control_status |= SYS_TIMER_IRQ_3;
-
-    unsigned int progval = timer3_val / timer3_int;
-    if (progval <= 100) drawProgress(3, progval);
-}
-
-unsigned long HAL_GetTick(void) {
-    unsigned int hi = REGS_TIMER->counter_hi;
-    unsigned int lo = REGS_TIMER->counter_lo;
-
-    //double check hi value didn't change after setting it...
-    if (hi != REGS_TIMER->counter_hi) {
-        hi = REGS_TIMER->counter_hi;
-        lo = REGS_TIMER->counter_lo;
-    }
-
-    return ((unsigned long)hi << 32) | lo;
-}
-
-void HAL_Delay(unsigned int ms) {
-    unsigned long start = HAL_GetTick();
-
-    while(HAL_GetTick() < start + (ms * 1000));
-}
-
-void main(void)
-{
-    fb_init();
-
-    unsigned int i=0;
-    while (i++<30) debugcrlf();
-
-    initProgress();
-
-    // Kick it off on core 1
-
-    start_core1(core1_main);
-
-    // Kick off the timers
-
-    irq_init_vectors();
-    enable_interrupt_controller();
-    irq_enable();
-    timer_init();
-
-    // Kick it off on core 3
-
-    start_core3(core3_main);
-
-    // Kick it off on core 0
-
-    core0_main();
-
-    // Disable IRQs and loop endlessly
-
-    irq_disable();
-    disable_interrupt_controller();
-
-    while(1);
-}

part15-tcpip/kernel/kernel.h

@@ -1,51 +0,0 @@
-#define PERIPHERAL_BASE 0xFE000000
-#define CLOCKHZ 1000000
-
-struct timer_regs {
-    volatile unsigned int control_status;
-    volatile unsigned int counter_lo;
-    volatile unsigned int counter_hi;
-    volatile unsigned int compare[4];
-};
-
-#define REGS_TIMER ((struct timer_regs *)(PERIPHERAL_BASE + 0x00003000))
-
-struct arm_irq_regs_2711 {
-    volatile unsigned int irq0_pending_0;
-    volatile unsigned int irq0_pending_1;
-    volatile unsigned int irq0_pending_2;
-    volatile unsigned int res0;
-    volatile unsigned int irq0_enable_0;
-    volatile unsigned int irq0_enable_1;
-    volatile unsigned int irq0_enable_2;
-    volatile unsigned int res1;
-    volatile unsigned int irq0_disable_0;
-    volatile unsigned int irq0_disable_1;
-    volatile unsigned int irq0_disable_2;
-};
-
-typedef struct arm_irq_regs_2711 arm_irq_regs;
-
-#define REGS_IRQ ((arm_irq_regs *)(PERIPHERAL_BASE + 0x0000B200))
-
-enum vc_irqs {
-    SYS_TIMER_IRQ_0 = 1,
-    SYS_TIMER_IRQ_1 = 2,
-    SYS_TIMER_IRQ_2 = 4,
-    SYS_TIMER_IRQ_3 = 8,
-    AUX_IRQ = (1 << 29)
-};
-
-void irq_init_vectors();
-void irq_enable();
-void irq_disable();
-void enable_interrupt_controller();
-void disable_interrupt_controller();
-
-void handle_timer_1();
-void handle_timer_3();
-
-void init_network(void);
-void net_test(void);
-void enc28j60PacketSend(unsigned short buflen, void *buffer);
-void *memcpy(void *dest, const void *src, unsigned short len);

part15-tcpip/kernel/utils.S

@@ -1,15 +0,0 @@
-.globl irq_init_vectors
-irq_init_vectors:
-    adr x0, vectors
-    msr vbar_el1, x0
-    ret
-
-.globl irq_enable
-irq_enable:
-    msr daifclr, #2
-    ret
-
-.globl irq_disable
-irq_disable:
-    msr daifset, #2
-    ret