with gwan server, is it possible to get the request string... ie. the arguments.
given http://myserver.com/main.cpp?arg1=one&arg2=two
im looking to obtain a char string arg1=one&arg2=two
according to docs, it should be
REQ_ENTITY, // char *ENTITY // "arg=x&arg=y..."
but doing this gives me an empty string (using args on the above url)
char * req = (char*) get_env(argv, REQ_ENTITY);
xbuf_cat(get_reply(argv), req);;
aha. i should add that get_arg( "arg1" ...) works no problem on that exact same url string (suggesting that its in there somewhere. perhaps the raw query string
a hint or pointer to an example might be all thats needed. also it would be nice to have that work with a mapping/redirect at some point.
http://myserver.com/main/arg1=one&arg2=two
regards
A quick note about REQ_ENTITY.
Your sample above doesn't have a REQ_ENTITY since you are only doing a GET request. If a request have an Entity Body (Like POST) you can get the Entity Body using REQ_ENTITY but usually you don't need to since you can access it using your sample (stepping through argv) or by using get_arg().
get_arg() sample
This nice snippet of code works for my purpose. found in the docs.
Just concat them. so love working in c on the server.
int i = 0;
while(i < argc)
{
xbuf_xcat(get_reply(argv), "argv[%u] '%s' <br>", i, argv[i]);
i++;
}
and adapted it to the following:
string concatArgs(void) {
stringstream ss;
int i = 0;
while(i < argc) {
ss << argv[i++];
}
return ss.str();
}
Related
Im try to add to my sketch a dynamic way to setup the ethernet info (mac, ip, gateway, subnet) from a configuration file (config.txt). So running a webserver and serving htm files from sd card, user can go to setting page, fill a form with these info and when posted , the webserver parse the http form and save (update) the config.txt file. After that system do a restart, in order to start with the new settings (by read the config.txt file)
I have create succesfully all the parts (sd, ethernet, webserver, webclient, create the config file from posted form data) except the get params by reading the config.txt file.
I can read line by line the config, I can split the line to param & value, and now I need to fill some byte variables with the readed data. I can (after a month of google searching) to read IPs (decimal values) to byte array. Im stack to read the MAC ADDRESS hex into byte array. The config file contains the:
mac=8f:2c:2b:19:e0:b7;
ip=192.168.1.200;
netmask=255.255.255.0;
gateway=192.168.1.254;
dns=8.8.8.8;
posturl=192.168.1.157;
postport=8080;
postscript=/itherm/update.php;
interval=60000;
and the code that I use to read is:
byte myMAC[6];
byte myIP[4];
File fset;
fset = SD.open("config.txt");
if (fset){
char ff[40];
while (fset.available()>1){
bool eol=false;
for (int i=0; !eol;i++){
ff[i]=fset.read();
if (ff[i]=='\n'){
eol=true;
}
}
String par="";
bool DONE=false;
for (int i=0; !DONE;i++){
par+=ff[i];
if (ff[i]== '='){DONE=true;}
}
String pval="";
DONE=false;
//------------------------
if (par=="ip=" ){
int x=0;
while(!DONE){
for(int i=3;i<=i+21;i++){
if(ff[i]=='.'){
myIP[x]=pval.toInt();
x++;
i++;
pval="";
}
else if(ff[i]==';' || i>20){
myIP[x]=pval.toInt();
DONE=true;
break;
}
pval+=ff[i];
}
}
}
} //while (fset.available()>1)
} //if (fset)
I will appreciate any help. Please no answers with simple use of Serial.print(). I have found hundreds of suggestions but none, that work properly to read all the parameters (dec, hex, strings). After a month of effort & searching, I wonder why something so necessary and useful does not exist as an example in the community, completely functional !!
Best regards
Okay so here is a complete set of routines to do what you want -I think you misunderstood the concept of char arrays vs a single char[0] The routines are documented and self explanatory. I recomend not to finish lines with ; but with '\n' which in your example is there anyway (also you can not see the new line terminator) To get the mac address I need three lines:
if (strncmp(cfgLine, "mac=", 4) == 0) {
strcpy (macAddr, cfgLine + 4);
}
line one compares the first 4 characters and if it is 0 (meaning its a fit)
line two copies the chars from the fifth to the last char from the lineBuffer to the target array, which can actually be used as param for functions.
The file structure should be with no ; as you would have to parse ; and \n
mac=8f:2c:2b:19:e0:b7
ip=192.168.1.200
....
postport=8080
To convert a char array to eg int we use atoi(), to convert a single char[0] to a single number we use int singleDigit = char[0]-48;
const char configurationFilePath [] = "/someconfig.txt";
char cfgLine[128] = {'\0'}; // this is a global temp char array to hold the read lines (lenght= chars longest line +1)
char numBuffer[16] = {'\0'}; // this is a global temo char array to help to convert char to number
char macAddr [18] = {'\0'}; // this is a global char array to hold the mac address
char ipAddr [16] = {'\0'}; // this is a global char array to hold the IP address - max xxx.xxx.xxx.xxx
int postport=0;
// .... you can easyly implement for all other data you want to store/retrieve
// Counts the lines of a file
uint16_t countLines() {
uint16_t currentLineCount = 0;
File cfgFile = SD.open(configurationFilePath, "r");
if (!cfgFile) {
Serial.println(F("Config file open failed on read"));
} else {
while (cfgFile.available()) {
/** Lets read line by line from the file */
if (cfgFile.read() == '\n') currentLineCount ++; // Lines are delimited by '\n'
}
cfgFile.close();
}
return currentLineCount;
}
//Load the config file from SD/SPIFFS/LittleFS
bool loadConfigFile() {
uint16_t lineCounter = countLines();
if (lineCounter <= 0) {
Serial.print(F("No config data stored in file ")); Serial.println(configurationFilePath);
return false;
}
else {
File cfgFile = SD.open(configurationFilePath, "r");
while (cfgFile.available()) {
strcpy (cfgLine, (cfgFile.readStringUntil('\n').c_str())); // normaly you use new line, we copy one line at a time
// Serial.println(cfgLine); /** Printing for debuging purpose */
while (cfgLine[0] != '\0') { /* Block refilling of cfgLine till processed */
loadSingleCfgLine();
}
}
cfgFile.close();
Serial.println(F("[Success] Loaded config !"));
return true;
}
}
//Load the data of a single line into a char array
void loadSingleCfgLine() {
if (strncmp(cfgLine, "mac=", 4) == 0) {
strcpy (macAddr, cfgLine + 4);
}
if (strncmp(cfgLine, "ip=", 3) == 0) {
strcpy (ipAddr, cfgLine + 3);
}
if (strncmp(cfgLine, "postport=", 9) == 0) {
strcpy (numBuffer, cfgLine + 9);
postport = atoi(numBuffer); // One extra step to convert to int
}
// ... easy to implement for all other data
}
I divided the routines into small independend functions, so its easy adaptable for different uses. I'm sorry for not digging into your code as it is hard to follow and unclear what you want todo.As an added bonus we do not use the String class. These Strings tend to fragment heap - causing resets/crashes while the global char arrays are compiled to flash and don't show this behavior.
I'm trying to concatenate the current DateTime to my devices Mac Address in the following format: aa:bb:cc:dd:ee:ffYYmmDDhhMMss so I can hash it and send it to a web service every time I collect new data (so I'll have to hash it in every loop)
I managed to concatenate the two values (mac address + datetime) and converted it to char array
addressDateTime.toCharArray(thisThing, 28);
However, I'm kind of lost as to how to continue.
I've also tried to read the resulting char* with this cycle but I'm not understanding why it doesn't work:
void loop() {
while (!timeClient.update()) {
timeClient.forceUpdate();
}
String addressDateTime = getPayload(); //this gets the *aa:bb:cc:dd:ee:ffYYmmDDhhMMss* string
char* hashThis;
addressDateTime.toCharArray(hashThis, 28);
for (int i = 0; i < sizeof(hashThis); i++) {
char str[3];
sprintf(str, "%02x", hashThis[i]);
Serial.print(str);
}
delay(5000);
}
Am I converting the String to char* correctly?
How should I go about Hashing the char*?
Or can I Hash the String without converting it to to char*?
Update:
My code's looking like this atm
while (!timeClient.update()) {
timeClient.forceUpdate();
}
String addressDateTime = getPayload();
char hashThis[30];
addressDateTime.toCharArray(hashThis, 30);
for (int i = 0; i < sizeof(hashThis); i++) {
Serial.printf("%02x", hashThis[i]);
}
delay(5000);
}
So I managed to convert the String to Char* Except that the output is looking like this 33433a37313a42463a31443a34323a463431393035303531343038323700 instead of (for example) aa:bb:cc:dd:ee:ff190505141037
After figuring out why my char* array outputs like that I still have to hash it.
Thanks for helping me get this far, I still have ways to go
You're not allocating space to store the C string that you're getting from addressDateTime.
hashThis is a char* which is a pointer to a character. It hasn't been set to anything so it's just... random. Which will almost certainly make your program crash or at least misbehave badly.
Given your code, the quickest fix is to change
char* hashThis;
to
char hasThis[30];
addressDateTime.toCharArray(hashThis, 30);
I changed 28 to 30 because aa:bb:cc:dd:ee:ffYYmmDDhhMMss is actually 29 characters long and also requires an extra byte for the C string null terminator character. I'm not 100% sure if the toCharArray() method sets the null terminator; if it doesn't, you'd need to add
hasThis[29] = '\0';
You can avoid that by just using the String c_str() method, which returns a char* to the internal buffer that String uses to hold the string.
In that case you could rewrite
char* hashThis;
addressDateTime.toCharArray(hashThis, 28);
as
char* hashThis = addressDateTime.c_str();
By the way, you can also just do
Serial.printf("%02x", hashThis[i]);
and dispense with the snprintf(). Kudos on getting the right buffer size there, though!
UPDATE
In your updated question, you said that you're expecting to see output that looks like:
aa:bb:cc:dd:ee:ff190505141037
instead of:
33433a37313a42463a31443a34323a463431393035303531343038323700
Your code is
for (int i = 0; i < sizeof(hashThis); i++) {
Serial.printf("%02x", hashThis[i]);
}
You're writing each character as a two digit hexadecimal number, so you're going to see the number in hexadecimal that represents the character, not the character itself. If you want to see the characters, do:
for (int i = 0; i < strlen(hashThis); i++) {
Serial.printf("%c", hashThis[i]);
}
or (better)
for (int i = 0; i < strlen(hashThis); i++) {
Serial.print(hashThis[i]);
}
or (best)
Serial.println(hashThis);
Note that I changed your sizeof to a strlen. If for some reason you put a shorter string in hashThis, strlen will do the right thing whereas sizeof will always return the length that hashThis was declared with rather than the length of the string in it.
I am trying to create a software lighting desk by using Qt and Arduino with a DMX Shield. I've been able to establish communication between these two and can send commands over to Arduino Mega (at the moment the communication goes only one way). I am periodically (every 200 ms) sending values of 11 faders to Mega as a String.
eg.: A123 B234 C050 ... J222 M255
The values in the string above are variables based on the position of the sliders and should be used to adjust the values of light intensities saved into each fader on the Mega side. The Letters in each section identify corresponding fader. A = fader1, B = fader2, ... Just for clarity: I can bring up a light/s at a specific intensity -> these intensities are then assigned to a fader and when that fader is moved I want these values to adjust and be sent out to the actual lights/dimmers. The calculations work fine but my Mega would eventually become unresponsive.
I think my problem is parsing the incoming string. I have tried the strtok() method and readStringUntil() to no avail. It is also difficult to monitor the incoming strings in Serial Monitor as this is used for the communication with Qt.
Would be happy for any kind of help. Please ask questions if anything is unclear.
Edit:
This is one of my attempts at solutions
const char delim[2] = " ";
char *token;
if(Serial.available())
{
//incomingMessage = Serial.readString();
incomingMessage = Serial.readStringUntil("\n"); // read the whole string until newline
//Serial.println(incomingMessage);
const char* str = incomingMessage.c_str(); // convert it to a C String terminated by a null character "\0"
//Serial.println(str);
token = strtok(str, delim); // first part is a first section until delimiter occurs "-space- "
//Serial.println(token);
LX_Rated.commandLineResolve(token); // resolve it
while( token != NULL ) { // continue splitting and resolving the incoming message until it reaches the end
token = strtok(NULL, delim);
LX_Rated.commandLineResolve(token);
}
}
Edit2:
I have confirmed that I receive the whole string sent by Qt. When I try to tokenise it using the strtok() function and print out the first token I get back the whole string, the other tokens are empty. I don't see any mistake in my code here. I even tried to slow down the sending of the string from Qt to one per 5 sec. Does anybody have any idea what is going on? I don't see why this standard function doesn't work as expected. Please see the amended code below.
if(Serial.available()) {
incomingMessage = Serial.readStringUntil("\n");
Serial.println("ok");
Serial.flush();
char* nullTerminatedIncomingMessage = incomingMessage.c_str();
const char delimiter = " ";
char* token;
char* token1;
char* token2;
//char* secondToken;
token = strtok(nullTerminatedIncomingMessage, delimiter);
token1 = strtok(NULL, delimiter);
token2 = strtok(NULL, delimiter);
Serial.println(token); // print the first section
//Serial.println(incomingMessage);
Serial.flush();
Serial.println(token1);
Serial.flush();
Serial.println(token2);
Serial.flush();
//while(token != NULL)
// secondToken = strtok(NULL, delimiter);
//Serial.println(secondToken);
//Serial.flush();
incomingMessage = "";
}
Your mistake - at the very least - is in assuming that all the input is available when you expect it. You need to defer processing until an entire line has been assembled. Serial.readStringUntil blocks until an entire line is available, and that's not what you expect. You essentially need to replace Serial.available() with Serial.lineAvailable(), except the latter is not implemented.
This answer contains a complete solution to your issue - including both Qt and Arduino code - and an Arudino emulation layer. It might be a good starting point, especially that you can easily co-debug both Qt and Arduino projects from within one application and using one debugger!
As for difficulty in monitoring communication, you can(in Qt) dump everything you read into console and do the same for everything you write into the serial port. It will show in the console tab of QtCreator
#include <QDebug>
...
qDebug() << "whatever" << endl;
Aso for parsing the data you read from to serial port, take a look at this to see how to easily split the sliders info into individual strings(with QRegExp)
How Can I Split a String According To Delimiters in Qt?
I can't possibly guess why your arduino would be unresponsive without the code.
EDIT:
Is it possible, when you generate the string in Qt, that you separate the tokens by something other than space? Maybe tab("\t") or something? strtok accepts multiple delimiters in the delimiter string, may be something to try.
If that is not the case, there is the unlikely possibility that something's wrong with the strtok(...) function(btw. it modifies the original string, that in itself could be a problem). Also, strtok could return a NULL pointer, you don't seem to handle that case(some wrong input - print a message). You could try this as an alternative to normal strtok:
/**
* #brief custom strtok replacement with the same interface
* It does not modify the original string
* Token length is limited to 63 characters
* #param ptr pointer to the string or NULL
* #param delim delimiting character(only the first character will be used)
*/
const char * my_strtok(const char * ptr, const char * delim) {
// Persistent variables, it will remember pointer to the processed string
static const char * src;
static char buffer[64]; // Token is limited to 63 characters
if(ptr) { // Remember the pointer, if a new one was supplied
src = ptr;
}
if(src == NULL || *src == '\0')// Invalid / empty string / no next token - return NULL
return NULL;
char i = 0;
for(i = 0; i < 63 && *src != delim[0]; i++) {// Copy token until delimiter or end of buffer
buffer[i] = *(src++);
}
if(*src == delim[0]) // Skip over the delimiter to the begining of the next token
++src;
buffer[i] = '\0'; // Any returned string must be terminated
return buffer;
}
#include <cstdlib>
#include <cstring>
#include <cassert>
void test() {
const char * str1 = "123 456 asdf jkl;";
assert(strcmp("123", my_strtok(str1, " ")) == 0);
assert(strcmp("456", my_strtok(NULL, " ")) == 0);
assert(strcmp("asdf", my_strtok(NULL, " ")) == 0);
assert(strcmp("jkl;", my_strtok(NULL, " ")) == 0);
assert(NULL == my_strtok(NULL, " "));
assert(NULL == my_strtok(NULL, " "));
assert(strcmp("123", my_strtok(str1, " ")) == 0);
}
I know Qt has a lot of good methods for reading file.But in my work , I have to open a file by using Qt and get a pointer pointing to the start address of the file.So how to do that?
Here is my codes:
char *buffer;
if(file.open(QIODevice::ReadOnly))
{
QByteArray dataArray=file.readAll();
buffer=dataArray.data();
}
char test[1024];
for(int i=0;i<1024;i++)
{
test[i]=*buffer;
buffer++;
}
I use QByteArray QIODevice::readAll()to read all available data from the device, and returns it as a byte array.
Then I use char * QByteArray::data() to set my pointer buffer.
But when I try to read the data by a for loop,my Qt debugger throw me an error:read access violation,so how would this happen?
BTW , the file to be read is very big so I can't use a buffer to read them all once. Instead , I have to do as what I did here. When I read a 7kb-sizes-file ,my codes runs well. When I read a 700kb-sizes-file , here comes the problem.
The reason you are getting access violation is that dataArray is declared inside if code block and goes out of scope. You want to declare the dataArray outside of that block, eg:
QByteArray dataArray;
if(file.open(QIODevice::ReadOnly))
{
dataArray = file.readAll();
}
else
{
// give error
}
char *buffer = dataArray.data();
char test[1024];
for(int i = 0; i < 1024; i++)
{
test[i] = *buffer;
buffer++;
}
There are other potential problems in your code though:
First, what if the size of data read from the file is less than 1024? Then you will be reading past the end of the buffer (more access violations).
Second, what if the file is really big? Reading all that data at once may cause swapping/paging.
In QT have the following code that starts a thread to send out commands. The thread takes a char * and int as arguments. In the "run" I use the pointer that is given by the constuctor. The code is:
MyThread::MyThread(char * payld, int payld_size)
{
payload_size = payld_size;
payload_p = payld;
}
void MyThread::run()
{
while(...)
{
sendCommand(payload_p, payload_size);
}
}
Unfortunately this doesn´t work and my application crashes when I try to use thread.start(). But when I change it to:
MyThread::MyThread(char * payld, int payld_size)
{
payload_size = payld_size;
payload_p = payld;
for(int i=0; i<payload_size; i++)
{
payload[i] = payld[i];
}
}
void MyThread::run()
{
while(...)
{
sendCommand(payload, payload_size);
}
}
The code does run and only crashes sometimes (looks pretty random to me). Can anybody Explain me why version one doesnt work and version two does? And any ideas on why the second code sometimes crashes? Could it be because the size of payload is not predefined (in the header file I defined it as
char payload[];
When I define it as:
char payload[10];
it seems to work better, but it is annoying to test since the crashes are pretty random.
instead of fiddling with char*, I would switch to QString (since you're using Qt). It takes a bit of learning, but it's almost mandatory to get code working smoothly in this framework. Then declare
QString payload;
and depending on sendCommand implementation, use one of the member functions QString to get the char*, like payload.toLatin1()