The problem is you can't just call tcp_tmr repeatedly in a loop as you're doing. The docs for the function (in the code) say it should be called every 250mS.
Bill From: [email protected] [mailto:[email protected]] On Behalf Of Chen Sent: Thursday, February 05, 2009 8:53 AM To: [email protected] Subject: Re: Re: [lwip-users] Struggleing to build a TCP echo server Simon, Thanks to your reply, I am so new to the forum, I am not sure if this the right way to to reply on the forum. <<There is an example (very simple) HTTP server for the raw API in the contrib module (there is also a port for unix and win32 for easy development/debugging). The contrib module for lwIP 1.3.0 is availaible in the download section at savannah or via CVS.>> Could you show me how to get to the download section? <<As you mentioned you used ATMEL sample projects: be aware ATMEL could have an older version of lwIP, which is not really supported on this list. Oh, and when using the raw API: be aware the functions may only be called from one thread, the lwIP core is NOT thread safe (use sockets/netconn if you want that).>> ATMEL also has a working HTTP sample which I believed is based on lwIP version 1.3 , but I just can't figure out how to extract the pieces to construct a telnet server from it. Based on my previous experience with Dynamic C (see the end of this email for the example), I assume I could build something similar from lwIP (btw, I still couldn't find any sample using tcp_* under lwIP). Based on your suggested reading, I struggle to come up something like this. When running, it acted like a TCP black hole: I can open connection to port 23 once, JUST ONCE, and type until the socket is closed due to time out. Problem: 1) From Ethereal, it accepted Telnet connection with SYN, ACK, and after that it does nothing, never ACK to the incoming data anymore 2) I have no idea how to test number of data in the receive buffer 3) The state machine doesn't totally agree with Dynamic C's and I have no clue how to deal with them due to lack of documentation Could you be so kind to give me some pointers on this? Thank you very very much for your time! Regards, Chen >>>>>> My unsuccessful try under lwIP >>>>>> int len; int i; struct netbuf *buf; struct lwip_socket *sock; struct tcp_pcb *ptel_pcb; ptel_pcb = tcp_new(); tcp_bind(ptel_pcb, IP_ADDR_ANY, 23); ptel_pcb = tcp_listen(ptel_pcb); tcp_accept(ptel_pcb, NULL); while(1){ tcp_tmr(); switch(ptel_pcb->state){ case CLOSED: break; case LISTEN: break; case SYN_SENT: break; case SYN_RCVD: break; case ESTABLISHED: break; case FIN_WAIT_1: break; case FIN_WAIT_2: break; case CLOSE_WAIT: break; case CLOSING: break; case LAST_ACK: break; case TIME_WAIT: break; } >>>>>>>>>A working TCP Echo Server from Dynamic C>>>>>>>>>>>>> #define VS_INIT 0 /* closed or never opened */ #define VS_LISTEN 1 /* waiting for a connection */ #define VS_OPENING 2 /* wait while we open a connection */ #define VS_OPEN 3 /* we have a connection */ #define VS_WAITCLOSE 4 /* wait for the connection to be torn down */ typedef struct { int state; tcp_Socket socket; } VsState; VsState vs_state; void vs_init(VsState* vs_state) { vs_state->state=VS_INIT; memcpy(&vs_info,&factory_defaults,sizeof(vs_info)); } void vs_handler(VsState* state) { auto tcp_Socket* socket; auto int ch, bytes_written; auto int bytes_to_write; socket=&state->socket; if(state->state!=VS_INIT && tcp_tick(socket)==0) { state->state=VS_INIT; state->open_timeout=vs_info.open_timeout; } switch(state->state) { case VS_INIT: tcp_listen(socket,TCP_PORT,0,0,NULL,0); state->state=VS_LISTEN; break; case VS_LISTEN: case VS_OPENING: if(sock_established(socket)) { state->state=VS_OPEN; sock_mode(socket,TCP_MODE_BINARY); } break; case VS_OPEN: iread=sock_dataready(socket); //iread bytes are ready to read ... i=sock_read(socket, input, x ); //read x bytes to input[] ... j=sock_tbleft(socket); //j bytes available on output buffer ... sock_fastwrite(socket,buffer, y); //transmit y bytes from buffer[] break; case VS_WAITCLOSE: break; default: state->state=VS_INIT; break; } } void main() { sock_init(); vs_init(&vs_state); while (1) { tcp_tick(NULL); //this is similar to tcp_tmr in lwIP, I think vs_handler(&vs_state); } }
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