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mmexternal: new solid external plugin response reader

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we can now read arbitrary long responses; PoC code replaced.
This commit is contained in:
Rainer Gerhards 2014-04-02 13:09:37 +02:00
parent 58677f210e
commit 2996241346
1 changed files with 45 additions and 14 deletions
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59
plugins/mmexternal/mmexternal.c
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@ -70,6 +70,10 @@ typedef struct wrkrInstanceData {
int fdPipeOut; /* file descriptor to write to */
int fdPipeIn; /* fd we receive messages from the program (if we want to) */
int bIsRunning; /* is binary currently running? 0-no, 1-yes */
char *respBuf; /* buffer to read exernal plugin's response */
int maxLenRespBuf; /* (current) maximum length of response buffer */
int lenRespBuf; /* actual nbr of chars in response buffer */
int idxRespBuf; /* last char read from response buffer */
} wrkrInstanceData_t;
typedef struct configSettings_s {
@ -111,6 +115,10 @@ CODESTARTcreateWrkrInstance
pWrkrData->fdPipeOut = -1;
pWrkrData->fdOutput = -1;
pWrkrData->bIsRunning = 0;
pWrkrData->respBuf = NULL;
pWrkrData->maxLenRespBuf = 0;
pWrkrData->lenRespBuf = 0;
pWrkrData->idxRespBuf = 0;
ENDcreateWrkrInstance
@ -137,6 +145,7 @@ ENDfreeInstance
BEGINfreeWrkrInstance
CODESTARTfreeWrkrInstance
free(pWrkrData->respBuf);
ENDfreeWrkrInstance
@ -187,34 +196,56 @@ done: return;
}
/* Get reply from external program. Note that we *must* receive one
* reply for each message sent (half-duplex protocol).
* reply for each message sent (half-duplex protocol). As such, the last
* char we read MUST be \n ... we cannot have multiple LF as this is
* forbidden by the plugin interface. We cannot have multiple responses
* for multiple messages, as we are in half-duplex mode! This makes
* things quite a bit simpler. So don't think the simple code does
* not handle those border-cases that are describe to cannot exist!
*/
static void
processProgramReply(wrkrInstanceData_t *__restrict__ const pWrkrData, msg_t *const pMsg)
{
char buf[4096];
char errStr[1024];
ssize_t r;
int numCharsRead;
char *newptr;
dbgprintf("mmexternal: checking prog output, fd %d\n", pWrkrData->fdPipeIn);
numCharsRead = 0;
do {
r = read(pWrkrData->fdPipeIn, buf, sizeof(buf)-1);
if(r > 0)
buf[r] = '\0'; /* space reserved in read! */
else
buf[0] = '\0';
dbgprintf("mmexternal: read state %lld, data '%s'\n", (long long) r, buf);
if(pWrkrData->maxLenRespBuf < numCharsRead + 256) { /* 256 to permit at least a decent read */
pWrkrData->maxLenRespBuf += 4096;
if((newptr = realloc(pWrkrData->respBuf, pWrkrData->maxLenRespBuf)) == NULL) {
DBGPRINTF("mmexternal: error realloc responseBuf: %s\n",
rs_strerror_r(errno, errStr, sizeof(errStr)));
/* emergency - fake no update */
strcpy(pWrkrData->respBuf, "{}\n");
numCharsRead = 3;
break;
}
pWrkrData->respBuf = newptr;
}
r = read(pWrkrData->fdPipeIn, pWrkrData->respBuf+numCharsRead,
pWrkrData->maxLenRespBuf-numCharsRead-1);
if(r > 0) {
numCharsRead += r;
pWrkrData->respBuf[numCharsRead] = '\0'; /* space reserved in read! */
} else {
/* emergency - fake no update */
strcpy(pWrkrData->respBuf, "{}\n");
numCharsRead = 3;
}
dbgprintf("mmexternal: read state %lld, data '%s'\n", (long long) r, pWrkrData->respBuf);
if(Debug && r == -1) {
DBGPRINTF("mmexternal: error reading from external program: %s\n",
rs_strerror_r(errno, errStr, sizeof(errStr)));
}
if(r > 0) {
writeOutputDebug(pWrkrData, buf, r);
MsgSetPropsViaJSON(pMsg, (uchar*)buf);
}
} while(0); // TODO: change this so that we actually read one line!
} while(pWrkrData->respBuf[numCharsRead-1] != '\n');
writeOutputDebug(pWrkrData, pWrkrData->respBuf, numCharsRead);
MsgSetPropsViaJSON(pMsg, (uchar*)pWrkrData->respBuf);
return;
}