From a62fcf786a0484e55e98861d52e31a83353373d6 Mon Sep 17 00:00:00 2001 From: Vadim Yanitskiy Date: Fri, 9 Mar 2018 03:24:08 +0700 Subject: [PATCH] Transceiver.cpp: use pointer arithmetics for CMD parsing It looks like the author of control command parsing code was not familar with simple pointer arithmetics, so excessive amount of memory and useless memcopying was used to parse a single command. Let's introduce two pointers, one of which will point to the beginning of a command, another to the beginning of its arguments. Also, let's simplify the command matching by using a separate function called 'MATCH_CMD'. Change-Id: I226ca0771e63228cf5e04ef9766057d4107fdd11 --- Transceiver52M/Transceiver.cpp | 115 ++++++++++++++++++--------------- 1 file changed, 64 insertions(+), 51 deletions(-) diff --git a/Transceiver52M/Transceiver.cpp b/Transceiver52M/Transceiver.cpp index 8f41c5e4..4b4fefe6 100644 --- a/Transceiver52M/Transceiver.cpp +++ b/Transceiver52M/Transceiver.cpp @@ -659,10 +659,40 @@ void Transceiver::reset() #define MAX_PACKET_LENGTH 100 +/** + * Matches a buffer with a command. + * @param buf a buffer to look command in + * @param cmd a command to look in buffer + * @param params pointer to arguments, or NULL + * @return true if command matches, otherwise false + */ +static bool match_cmd(char *buf, + const char *cmd, char **params) +{ + size_t cmd_len = strlen(cmd); + + /* Check a command itself */ + if (strncmp(buf, cmd, cmd_len)) + return false; + + /* A command has arguments */ + if (params != NULL) { + /* Make sure there is a space */ + if (buf[cmd_len] != ' ') + return false; + + /* Update external pointer */ + *params = buf + cmd_len + 1; + } + + return true; +} + void Transceiver::driveControl(size_t chan) { char buffer[MAX_PACKET_LENGTH + 1]; char response[MAX_PACKET_LENGTH + 1]; + char *command, *params; int msgLen; /* Attempt to read from control socket */ @@ -673,22 +703,20 @@ void Transceiver::driveControl(size_t chan) /* Zero-terminate received string */ buffer[msgLen] = '\0'; - char cmdcheck[4]; - char command[MAX_PACKET_LENGTH]; - - sscanf(buffer,"%3s %s",cmdcheck,command); - - if (strcmp(cmdcheck,"CMD")!=0) { + /* Verify a command signature */ + if (strncmp(buffer, "CMD ", 4)) { LOG(WARNING) << "bogus message on control interface"; return; } - LOG(INFO) << "command is " << buffer; - if (strcmp(command,"POWEROFF")==0) { + /* Set command pointer */ + command = buffer + 4; + LOG(INFO) << "command is " << command; + + if (match_cmd(command, "POWEROFF", NULL)) { stop(); sprintf(response,"RSP POWEROFF 0"); - } - else if (strcmp(command,"POWERON")==0) { + } else if (match_cmd(command, "POWERON", NULL)) { if (!start()) { sprintf(response,"RSP POWERON 1"); } else { @@ -698,41 +726,35 @@ void Transceiver::driveControl(size_t chan) mHandover[i][j] = false; } } - } - else if (strcmp(command,"HANDOVER")==0){ + } else if (match_cmd(command, "HANDOVER", ¶ms)) { int ts=0,ss=0; - sscanf(buffer,"%3s %s %d %d",cmdcheck,command,&ts,&ss); + sscanf(params, "%d %d", &ts, &ss); mHandover[ts][ss] = true; sprintf(response,"RSP HANDOVER 0 %d %d",ts,ss); - } - else if (strcmp(command,"NOHANDOVER")==0){ + } else if (match_cmd(command, "NOHANDOVER", ¶ms)) { int ts=0,ss=0; - sscanf(buffer,"%3s %s %d %d",cmdcheck,command,&ts,&ss); + sscanf(params, "%d %d", &ts, &ss); mHandover[ts][ss] = false; sprintf(response,"RSP NOHANDOVER 0 %d %d",ts,ss); - } - else if (strcmp(command,"SETMAXDLY")==0) { + } else if (match_cmd(command, "SETMAXDLY", ¶ms)) { //set expected maximum time-of-arrival int maxDelay; - sscanf(buffer,"%3s %s %d",cmdcheck,command,&maxDelay); + sscanf(params, "%d", &maxDelay); mMaxExpectedDelayAB = maxDelay; // 1 GSM symbol is approx. 1 km sprintf(response,"RSP SETMAXDLY 0 %d",maxDelay); - } - else if (strcmp(command,"SETMAXDLYNB")==0) { + } else if (match_cmd(command, "SETMAXDLYNB", ¶ms)) { //set expected maximum time-of-arrival int maxDelay; - sscanf(buffer,"%3s %s %d",cmdcheck,command,&maxDelay); + sscanf(params, "%d", &maxDelay); mMaxExpectedDelayNB = maxDelay; // 1 GSM symbol is approx. 1 km sprintf(response,"RSP SETMAXDLYNB 0 %d",maxDelay); - } - else if (strcmp(command,"SETRXGAIN")==0) { + } else if (match_cmd(command, "SETRXGAIN", ¶ms)) { //set expected maximum time-of-arrival int newGain; - sscanf(buffer,"%3s %s %d",cmdcheck,command,&newGain); + sscanf(params, "%d", &newGain); newGain = mRadioInterface->setRxGain(newGain, chan); sprintf(response,"RSP SETRXGAIN 0 %d",newGain); - } - else if (strcmp(command,"NOISELEV")==0) { + } else if (match_cmd(command, "NOISELEV", NULL)) { if (mOn) { float lev = mStates[chan].mNoiseLev; sprintf(response,"RSP NOISELEV 0 %d", @@ -741,26 +763,23 @@ void Transceiver::driveControl(size_t chan) else { sprintf(response,"RSP NOISELEV 1 0"); } - } - else if (!strcmp(command, "SETPOWER")) { + } else if (match_cmd(command, "SETPOWER", ¶ms)) { int power; - sscanf(buffer, "%3s %s %d", cmdcheck, command, &power); + sscanf(params, "%d", &power); power = mRadioInterface->setPowerAttenuation(power, chan); mStates[chan].mPower = power; sprintf(response, "RSP SETPOWER 0 %d", power); - } - else if (!strcmp(command,"ADJPOWER")) { + } else if (match_cmd(command, "ADJPOWER", ¶ms)) { int power, step; - sscanf(buffer, "%3s %s %d", cmdcheck, command, &step); + sscanf(params, "%d", &step); power = mStates[chan].mPower + step; power = mRadioInterface->setPowerAttenuation(power, chan); mStates[chan].mPower = power; sprintf(response, "RSP ADJPOWER 0 %d", power); - } - else if (strcmp(command,"RXTUNE")==0) { + } else if (match_cmd(command, "RXTUNE", ¶ms)) { // tune receiver int freqKhz; - sscanf(buffer,"%3s %s %d",cmdcheck,command,&freqKhz); + sscanf(params, "%d", &freqKhz); mRxFreq = freqKhz * 1e3; if (!mRadioInterface->tuneRx(mRxFreq, chan)) { LOG(ALERT) << "RX failed to tune"; @@ -768,11 +787,10 @@ void Transceiver::driveControl(size_t chan) } else sprintf(response,"RSP RXTUNE 0 %d",freqKhz); - } - else if (strcmp(command,"TXTUNE")==0) { + } else if (match_cmd(command, "TXTUNE", ¶ms)) { // tune txmtr int freqKhz; - sscanf(buffer,"%3s %s %d",cmdcheck,command,&freqKhz); + sscanf(params, "%d", &freqKhz); mTxFreq = freqKhz * 1e3; if (!mRadioInterface->tuneTx(mTxFreq, chan)) { LOG(ALERT) << "TX failed to tune"; @@ -780,11 +798,10 @@ void Transceiver::driveControl(size_t chan) } else sprintf(response,"RSP TXTUNE 0 %d",freqKhz); - } - else if (!strcmp(command,"SETTSC")) { + } else if (match_cmd(command, "SETTSC", ¶ms)) { // set TSC unsigned TSC; - sscanf(buffer, "%3s %s %d", cmdcheck, command, &TSC); + sscanf(params, "%d", &TSC); if (TSC > 7) { sprintf(response, "RSP SETTSC 1 %d", TSC); } else { @@ -792,12 +809,11 @@ void Transceiver::driveControl(size_t chan) mTSC = TSC; sprintf(response,"RSP SETTSC 0 %d", TSC); } - } - else if (strcmp(command,"SETSLOT")==0) { + } else if (match_cmd(command, "SETSLOT", ¶ms)) { // set slot type int corrCode; int timeslot; - sscanf(buffer,"%3s %s %d %d",cmdcheck,command,×lot,&corrCode); + sscanf(params, "%d %d", ×lot, &corrCode); if ((timeslot < 0) || (timeslot > 7)) { LOG(WARNING) << "bogus message on control interface"; sprintf(response,"RSP SETSLOT 1 %d %d",timeslot,corrCode); @@ -806,17 +822,14 @@ void Transceiver::driveControl(size_t chan) mStates[chan].chanType[timeslot] = (ChannelCombination) corrCode; setModulus(timeslot, chan); sprintf(response,"RSP SETSLOT 0 %d %d",timeslot,corrCode); - - } - else if (strcmp(command,"_SETBURSTTODISKMASK")==0) { + } else if (match_cmd(command, "_SETBURSTTODISKMASK", ¶ms)) { // debug command! may change or disapear without notice // set a mask which bursts to dump to disk int mask; - sscanf(buffer,"%3s %s %d",cmdcheck,command,&mask); + sscanf(params, "%d", &mask); mWriteBurstToDiskMask = mask; sprintf(response,"RSP _SETBURSTTODISKMASK 0 %d",mask); - } - else { + } else { LOG(WARNING) << "bogus command " << command << " on control interface."; sprintf(response,"RSP ERR 1"); }