snep.cpp

00001 
00002 #include "snep.h"
00003 #include "PN532_debug.h"
00004 
00005 int8_t SNEP::write(const uint8_t *buf, uint8_t len, uint16_t timeout)
00006 {
00007     if (0 >= llcp.activate(timeout)) {
00008         DMSG("failed to activate PN532 as a target\n");
00009         return -1;
00010     }
00011 
00012     if (0 >= llcp.connect(timeout)) {
00013         DMSG("failed to set up a connection\n");
00014         return -2;
00015     }
00016 
00017     // response a success SNEP message
00018     headerBuf[0] = SNEP_DEFAULT_VERSION;
00019     headerBuf[1] = SNEP_REQUEST_PUT;
00020     headerBuf[2] = 0;
00021     headerBuf[3] = 0;
00022     headerBuf[4] = 0;
00023     headerBuf[5] = len;
00024     if (0 >= llcp.write(headerBuf, 6, buf, len)) {
00025         return -3;
00026     }
00027 
00028     uint8_t rbuf[16];
00029     if (6 > llcp.read(rbuf, sizeof(rbuf))) {
00030         return -4;
00031     }
00032 
00033     // check SNEP version
00034     if (SNEP_DEFAULT_VERSION != rbuf[0]) {
00035         DMSG("The received SNEP message's major version is different\n");
00036         // To-do: send Unsupported Version response
00037         return -4;
00038     }
00039 
00040     // expect a put request
00041     if (SNEP_RESPONSE_SUCCESS != rbuf[1]) {
00042         DMSG("Expect a success response\n");
00043         return -4;
00044     }
00045 
00046     llcp.disconnect(timeout);
00047 
00048     return 1;
00049 }
00050 
00051 int16_t SNEP::read(uint8_t *buf, uint8_t len, uint16_t timeout)
00052 {
00053     if (0 >= llcp.activate(timeout)) {
00054         DMSG("failed to activate PN532 as a target\n");
00055         return -1;
00056     }
00057 
00058     if (0 >= llcp.waitForConnection(timeout)) {
00059         DMSG("failed to set up a connection\n");
00060         return -2;
00061     }
00062 
00063     uint16_t status = llcp.read(buf, len);
00064     if (6 > status) {
00065         return -3;
00066     }
00067 
00068 
00069     // check SNEP version
00070     if (SNEP_DEFAULT_VERSION != buf[0]) {
00071         DMSG("The received SNEP message's major version is different\n");
00072         // To-do: send Unsupported Version response
00073         return -4;
00074     }
00075 
00076     // expect a put request
00077     if (SNEP_REQUEST_PUT != buf[1]) {
00078         DMSG("Expect a put request\n");
00079         return -4;
00080     }
00081 
00082     // check message's length
00083     uint32_t length = (buf[2] << 24) + (buf[3] << 16) + (buf[4] << 8) + buf[5];
00084     // length should not be more than 244 (header + body < 255, header = 6 + 3 + 2)
00085     if (length > (status - 6)) {
00086         DMSG("The SNEP message is too large: "); 
00087         DMSG_INT(length);
00088         DMSG_INT(status - 6);
00089         DMSG("\n");
00090         return -4;
00091     }
00092     for (uint8_t i = 0; i < length; i++) {
00093         buf[i] = buf[i + 6];
00094     }
00095 
00096     // response a success SNEP message
00097     headerBuf[0] = SNEP_DEFAULT_VERSION;
00098     headerBuf[1] = SNEP_RESPONSE_SUCCESS;
00099     headerBuf[2] = 0;
00100     headerBuf[3] = 0;
00101     headerBuf[4] = 0;
00102     headerBuf[5] = 0;
00103     llcp.write(headerBuf, 6);
00104 
00105     return length;
00106 }