int sr_read_from_server(struct sr_instance* sr /* borrowed */)
{
int command, len;
unsigned char *buf = 0;
c_packet_ethernet_header* sr_pkt = 0;
int ret = 0, bytes_read = 0;
/* REQUIRES */
assert(sr);
/*---------------------------------------------------------------------------
Read a command from the server
-------------------------------------------------------------------------*/
bytes_read = 0;
/* attempt to read the size of the incoming packet */
while( bytes_read < 4)
{
do
{ /* -- just in case SIGALRM breaks recv -- */
errno = 0; /* -- hacky glibc workaround -- */
if((ret = recv(sr->sockfd,((uint8_t*)&len) + bytes_read,
4 - bytes_read, 0)) == -1)
{
if ( errno == EINTR )
{ continue; }
perror("recv(..):sr_client.c::sr_read_from_server");
return -1;
}
bytes_read += ret;
} while ( errno == EINTR); /* be mindful of signals */
}
len = ntohl(len);
if ( len > 10000 || len < 0 )
{
fprintf(stderr,"Error: command length to large %d\n",len);
close(sr->sockfd);
return -1;
}
if((buf = malloc(len)) == 0)
{
fprintf(stderr,"Error: out of memory (sr_read_from_server)\n");
return -1;
}
/* set first field of command since we've already read it */
*((int *)buf) = htonl(len);
bytes_read = 0;
/* read the rest of the command */
while ( bytes_read < len - 4)
{
do
{/* -- just in case SIGALRM breaks recv -- */
errno = 0; /* -- hacky glibc workaround -- */
if ((ret = read(sr->sockfd, buf+4+bytes_read, len - 4 - bytes_read)) ==
-1)
{
if ( errno == EINTR )
{ continue; }
fprintf(stderr,"Error: failed reading command body %d\n",ret);
close(sr->sockfd);
return -1;
}
bytes_read += ret;
} while (errno == EINTR); /* be mindful of signals */
}
command = *(((int *)buf)+1) = ntohl(*(((int *)buf)+1));
switch (command)
{
/* ------------- VNSPACKET -------------------- */
case VNSPACKET:
sr_pkt = (c_packet_ethernet_header *)buf;
/* -- check if it is an ARP to another router if so drop -- */
if ( sr_arp_req_not_for_us(sr,
(buf+sizeof(c_packet_header)),
len - sizeof(c_packet_ethernet_header) +
sizeof(struct sr_ethernet_hdr),
(char*)(buf + sizeof(c_base))) )
{ break; }
/* -- log packet -- */
sr_log_packet(sr, buf + sizeof(c_packet_header),
ntohl(sr_pkt->mLen) - sizeof(c_packet_header));
/* -- pass to router, student's code should take over here -- */
sr_handlepacket(sr,
(buf+sizeof(c_packet_header)),
len - sizeof(c_packet_ethernet_header) +
sizeof(struct sr_ethernet_hdr),
(char*)(buf + sizeof(c_base)));
break;
/* ------------- VNSCLOSE -------------------- */
case VNSCLOSE:
fprintf(stderr,"VNS server closed session.\n");
fprintf(stderr,"Reason: %s\n",((c_close*)buf)->mErrorMessage);
sr_session_closed_help();
if(buf)
{ free(buf); }
return 0;
break;
/* ------------- VNSHWINFO -------------------- */
case VNSHWINFO:
sr_handle_hwinfo(sr,(c_hwinfo*)buf);
if(sr_verify_routing_table(sr) != 0)
{
fprintf(stderr,"Routing table not consistent with hardware\n");
return -1;
}
printf(" <-- Ready to process packets --> \n");
break;
default:
Debug("unknown command: %d\n", command);
break;
}/* -- switch -- */
if(buf)
{ free(buf); }
return 1;
}/* -- sr_read_from_server -- */
int sr_read_from_server_expect(struct sr_instance* sr /* borrowed */, int expected_cmd)
{
int command, len;
unsigned char *buf = 0;
c_packet_ethernet_header* sr_pkt = 0;
int ret = 0, bytes_read = 0;
/* REQUIRES */
assert(sr);
/*---------------------------------------------------------------------------
Read a command from the server
-------------------------------------------------------------------------*/
bytes_read = 0;
/* attempt to read the size of the incoming packet */
while( bytes_read < 4)
{
do
{ /* -- just in case SIGALRM breaks recv -- */
errno = 0; /* -- hacky glibc workaround -- */
if((ret = recv(sr->sockfd,((uint8_t*)&len) + bytes_read,
4 - bytes_read, 0)) == -1)
{
if ( errno == EINTR )
{ continue; }
perror("recv(..):sr_client.c::sr_read_from_server");
return -1;
}
bytes_read += ret;
} while ( errno == EINTR); /* be mindful of signals */
}
len = ntohl(len);
if ( len > 10000 || len < 0 )
{
fprintf(stderr,"Error: command length to large %d\n",len);
close(sr->sockfd);
return -1;
}
if((buf = (unsigned char*)malloc(len)) == 0)
{
fprintf(stderr,"Error: out of memory (sr_read_from_server)\n");
return -1;
}
/* set first field of command since we've already read it */
*((int *)buf) = htonl(len);
bytes_read = 0;
/* read the rest of the command */
while ( bytes_read < len - 4)
{
do
{/* -- just in case SIGALRM breaks recv -- */
errno = 0; /* -- hacky glibc workaround -- */
if ((ret = read(sr->sockfd, buf+4+bytes_read, len - 4 - bytes_read)) ==
-1)
{
if ( errno == EINTR )
{ continue; }
fprintf(stderr,"Error: failed reading command body %d\n",ret);
close(sr->sockfd);
return -1;
}
bytes_read += ret;
} while (errno == EINTR); /* be mindful of signals */
}
/* My entry for most unreadable line of code - guido */
/* ... you win - mc */
command = *(((int *)buf)+1) = ntohl(*(((int *)buf)+1));
/* make sure the command is what we expected if we were expecting something */
if(expected_cmd && command!=expected_cmd) {
if(command != VNSCLOSE) { /* VNSCLOSE is always ok */
fprintf(stderr, "Error: expected command %d but got %d\n", expected_cmd, command);
return -1;
}
}
ret = 1;
switch (command)
{
/* ------------- VNSPACKET -------------------- */
case VNSPACKET:
sr_pkt = (c_packet_ethernet_header *)buf;
/* -- log packet -- */
sr_log_packet(sr, buf + sizeof(c_packet_header),
ntohl(sr_pkt->mLen) - sizeof(c_packet_header));
/* -- pass to router, student's code should take over here -- */
sr_integ_input(sr,
(buf+sizeof(c_packet_header)), /* lent */
len - sizeof(c_packet_header),
(const char*)buf + sizeof(c_base)); /* lent */
break;
/* ------------- VNSCLOSE -------------------- */
case VNSCLOSE:
fprintf(stderr,"VNS server closed session.\n");
fprintf(stderr,"Reason: %s\n",((c_close*)buf)->mErrorMessage);
sr_close_instance(sr); /* closes the VNS socket and logfile */
if(buf)
{ free(buf); }
return 0;
break;
/* ------------- VNSBANNER -------------------- */
case VNSBANNER:
fprintf(stderr,"%s",((c_banner*)buf)->mBannerMessage);
break;
/* ------------- VNSHWINFO -------------------- */
case VNSHWINFO:
sr_handle_hwinfo(sr,(c_hwinfo*)buf);
break;
/* ---------------- VNS_RTABLE ---------------- */
case VNS_RTABLE:
fprintf(stderr, "not yet setup to handle VNS_RTABLE message\n");
sr_close_instance(sr);
if(buf) { free(buf); }
return 0;
break;
/* ------------- VNS_AUTH_REQUEST ------------- */
case VNS_AUTH_REQUEST:
if(!sr_handle_auth_request(sr, (c_auth_request*)buf))
ret = -1;
break;
/* ------------- VNS_AUTH_STATUS -------------- */
case VNS_AUTH_STATUS:
if(!sr_handle_auth_status(sr, (c_auth_status*)buf))
ret = -1;
break;
default:
printf("unknown command: %d\n", command);
break;
}/* -- switch -- */
if(buf)
{ free(buf); }
return ret;
}/* -- sr_read_from_server -- */
