I used ubuntu16 socat to generate a pair of virtual serial ports and wrote code to try Modbus RTU communication, but the host got an error reading slave map holdover register address: read error: Operation not permitted
master.c
ret = modbus_read_registers(mb, 2000, 3, table);
if(ret == 3)
printf("read success : 0x%02x 0x%02x 0x%02x \n", table[0], table[1], table[2]);
else
{
printf("read error: %s\n", modbus_strerror(errno));
break;
}
slave.c
mb_mapping = modbus_mapping_new_start_address(0, 0, 0, 0, 2000, 3, 0, 0);
if(mb_mapping == NULL)
{
modbus_free(mb);
printf("new mapping failed: %s\n", modbus_strerror(errno));
return 0;
}
//保持寄存器数据
mb_mapping->tab_registers[0] = 0x1001;
mb_mapping->tab_registers[1] = 0x1002;
mb_mapping->tab_registers[2] = 0x1003;
socat:
error:
I consulted a lot of materials and tried to solve the problem, but in the end there was no result
Related
using Linux (ubuntu 20.04) machine, openssl 3.0.7 is installed , running a sample code for signing.
we followed below procedure for signing. getting segmentation fault in EVP_DigestFinal_ex.
segmentation fault is happening due to mdctx->algctx=0x0. while debugging the code mdctx->algctx is updated in EVP_DigestInit_ex but latter it was freed in EVP_DigestSignInit. not sure what we are missing and how to update mdctx->algctx to avoid the crash.
#include <stdio.h>
#include <string.h>
#include <openssl/evp.h>
#include <openssl/provider.h>
EVP_PKEY *pkey = NULL;
generate_key(){
EVP_PKEY_CTX *ctx=NULL;
pkey=EVP_PKEY_new();
ctx=EVP_PKEY_CTX_new(pkey,NULL);
ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_RSA, NULL);
if (!ctx)
printf(" key gen failed");
if (EVP_PKEY_keygen_init(ctx) <= 0)
printf(" key gen failed");
if (EVP_PKEY_CTX_set_rsa_keygen_bits(ctx, 512) <= 0)
printf(" key gen failed");
/* Generate key */
if (EVP_PKEY_keygen(ctx, &pkey) <= 0)
printf(" key gen failed");
}
int main(int argc, char *argv[])
{
EVP_MD_CTX *mdctx;
const EVP_MD *m_md;
const EVP_MD *md;
EVP_PKEY *m_key;
EVP_PKEY *ed_pkey = NULL;
EVP_PKEY_CTX *ed_pctx = NULL;
// OSSL_PROVIDER *default;
size_t sign_len = 0;
u_int8_t m_sign_buf[2048];
int ret = 0;
char mess1[] = "Test Message\n";
char mess2[] = "Hello World\n";
unsigned char *outdigest = NULL;
unsigned int md_len = 0, i;
printf("args : %s\n",argv[1]);
//default = OSSL_PROVIDE_load(NULL, "default");
//md = EVP_get_digestbyname("SHA256");
//md = EVP_sha256();
md = EVP_MD_fetch(NULL, "SHA256", NULL); //;
if (md == NULL) {
printf("Unknown message digest %s\n", argv[1]);
exit(1);
}
generate_key();
printf("value of md %s\n",md);
mdctx = EVP_MD_CTX_new();
if((EVP_DigestInit_ex(mdctx, md, NULL)) != 1)
printf("EVP_DigestInit_ex failed \n");
if((EVP_DigestSignInit(mdctx, NULL, md, NULL, pkey)) != 1)
printf("EVP_DigestSignInit failed \n");
if((EVP_DigestSignUpdate(mdctx, mess1, strlen(mess1))) != 1)
printf("EVP_DigestSignUpdate failed \n");
//EVP_DigestUpdate(mdctx, mess2, strlen(mess2));
if((EVP_DigestSignFinal(mdctx, (u_int8_t*)NULL, &sign_len)) != 1)
printf("EVP_DigestSignFinal failed \n");
if((EVP_DigestSignFinal(mdctx, m_sign_buf, &sign_len)) != 1)
printf("EVP_DigestSignFinal 2 failed \n");
/* Allocate the output buffer */
outdigest = OPENSSL_malloc(EVP_MD_get_size(md));
if (outdigest == NULL)
printf("outdigest failed \n");
if((EVP_DigestFinal_ex(mdctx, outdigest, &md_len)) != 1)
printf("EVP_DigestFinal_ex failed \n");
EVP_MD_CTX_free(mdctx);
/* Print out the digest result */
BIO_dump_fp(stdout, outdigest, &md_len);
exit(0);
}
`
```
Thanks,
while debugging the code mdctx->algctx is updated in EVP_DigestInit_ex but latter it was freed in EVP_DigestSignInit. not sure what we are missing and how to update mdctx->algctx to avoid the crash.
CRASH Info:
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7d99422 in SHA256_Final (md=0x5555555a88d0 "\250UUU\005", c=0x0)
at ../openssl-3.0.7/include/crypto/md32_common.h:194
194 size_t n = c->num;
(gdb) bt
#0 0x00007ffff7d99422 in SHA256_Final (md=0x5555555a88d0 "\250UUU\005", c=0x0)
at ../openssl-3.0.7/include/crypto/md32_common.h:194
#1 0x00007ffff7e2628c in sha256_internal_final (ctx=0x0, out=0x5555555a88d0 "\250UUU\005", outl=0x7fffffffda98,
outsz=32) at ../openssl-3.0.7/providers/implementations/digests/sha2_prov.c:72
#2 0x00007ffff7cbadf6 in EVP_DigestFinal_ex (ctx=0x555555580d80, md=0x5555555a88d0 "\250UUU\005",
isize=0x7fffffffdad8) at ../openssl-3.0.7/crypto/evp/digest.c:446
#3 0x000055555555575f in main (argc=1, argv=0x7fffffffe458) at test2.c:90
I want to use PJSIP's C API to record the incoming audio to a file on a machine with no hardware sound device .
I'm unsure about the details, but the sparse documentation for PJSIP suggests it should be
possible through the pjsua_set_null_snd_dev() call.
In the fully functioning (Windows biased) example below the call pjmedia_aud_dev_default_param(PJMEDIA_AUD_DEFAULT_CAPTURE_DEV, ¶m) returns PJMEDIA_AUD_INVALID_DEV in the status.
The code generates this same error on Linux (Ubuntu 14) and Windows 10 when there are no hardware audio devices present.
If there is an hardware audio device driver installed the exact same code works fine on both OSes.
I have compiled the PJSIP libraries with PJMEDIA_AUDIO_DEV_HAS_NULL_AUDIO enabled.
On Linux the presence of the module snd-dummy does not help.
How do I get access to the audio data stream from a SIP call after calling pjsua_set_null_snd_dev()?
#include <pjlib.h>
#include <pjlib-util.h>
#include <pjnath.h>
#include <pjsip.h>
#include <pjsip_ua.h>
#include <pjsip_simple.h>
#include <pjsua-lib/pjsua.h>
#include <pjmedia.h>
#include <pjmedia-codec.h>
#include <pj/log.h>
#include <pj/os.h>
int main(int, char **)
{
// Create pjsua first!
pj_status_t status = pjsua_create();
if (status != PJ_SUCCESS)
{
fprintf(stderr,"pjsua_create error\n");
return -1;
}
// Init pjsua
pjsua_config cfg;
pjsua_logging_config log_cfg;
pjsua_config_default(&cfg);
pjsua_logging_config_default(&log_cfg);
log_cfg.console_level = 4;
status = pjsua_init(&cfg, &log_cfg, NULL);
if (status != PJ_SUCCESS)
{
fprintf(stderr,"pjsua_init error\n");
return -1;
}
// Proactively list known audio devices so we are sure there are NONE
pjmedia_aud_dev_info info[64];
unsigned info_count = 64;
pjsua_enum_aud_devs(info, &info_count);
fprintf(stderr,"Listing known sound devices, total of [%u]\n", info_count);
for (unsigned i = 0; i<info_count; ++i)
{
fprintf(stderr,"Name [%s]", info[i].name);
}
// Add transport
pjsua_transport_config tcfg;
pjsua_transport_id trans_id;
pjsua_transport_config_default(&tcfg);
tcfg.port = 5060;
status = pjsua_transport_create(PJSIP_TRANSPORT_UDP, &tcfg, &trans_id);
if (status != PJ_SUCCESS)
{
fprintf(stderr, "pjsua_transport_create error\n");
return -1;
}
// Initialization is done, now start pjsua
status = pjsua_start();
if (status != PJ_SUCCESS)
{
fprintf(stderr, "pjsua_start error\n");
return -1;
}
// Set NULL sound
status = pjsua_set_null_snd_dev();
if (status != PJ_SUCCESS)
{
fprintf(stderr, "pjsua_set_null_snd_dev error");
return -1;
}
// Register to a SIP server by creating SIP account, I happen use use Asterisk
pjsua_acc_id acc_id;
fprintf(stderr, "Setting up SIP server registration\n");
{
pjsua_acc_config cfg;
pjsua_acc_config_default(&cfg);
cfg.id = pj_str("sip:6001#10.0.0.21");
cfg.reg_uri = cfg.id; // same as ID
cfg.cred_count = 1;
cfg.cred_info[0].realm = pj_str("*");
cfg.cred_info[0].scheme = pj_str("digest");
cfg.cred_info[0].username = pj_str("6001");
cfg.cred_info[0].data_type = PJSIP_CRED_DATA_PLAIN_PASSWD;
cfg.cred_info[0].data = pj_str("teddy");
status = pjsua_acc_add(&cfg, PJ_TRUE, &acc_id);
if (status != PJ_SUCCESS)
{
fprintf(stderr, "pjsua_acc_add error\n");
return -1;
}
}
fprintf(stderr, "Waiting for SIP server registration to complete....\n");
Sleep(2000); // sleep 2 seconds
// Call extension 9 on my Asterisk server at 10.0.0.21:5060
pj_str_t sip_target(pj_str("sip:9#10.0.0.21"));
fprintf(stderr, "Making call to [%s]\n", sip_target.ptr);
pjsua_call_id call_id;
status = pjsua_call_make_call(acc_id, &sip_target, 0, NULL, NULL, &call_id);
if (status != PJ_SUCCESS)
{
fprintf(stderr, "pjsua_call_make_call error\n");
return -1;
}
pj_pool_t * pool = nullptr;
pjmedia_port * wav = nullptr;
pjmedia_aud_stream *strm = nullptr;
pool = pj_pool_create(pjmedia_aud_subsys_get_pool_factory(), "wav-audio", 1000, 1000, NULL);
if (nullptr == pool)
{
fprintf(stderr,"Pool creation failed\n");
return -1;
}
// 8kHz, single channel 16bit MS WAV format file
status = pjmedia_wav_writer_port_create(pool, "test.wav", 8000, 1, 320, 16, PJMEDIA_FILE_WRITE_PCM, 0, &wav);
if (status != PJ_SUCCESS)
{
fprintf(stderr, "Error creating WAV file\n");
return -1;
}
pjmedia_aud_param param;
//////////////////////////////////////////////////////
// FAILURE HERE : This is the function call which returns PJMEDIA_AUD_INVALID_DEV
//////////////////////////////////////////////////////
status = pjmedia_aud_dev_default_param(PJMEDIA_AUD_DEFAULT_CAPTURE_DEV, ¶m);
if (status != PJ_SUCCESS)
{
fprintf(stderr, "pjmedia_aud_dev_default_param()");
return -1;
}
param.dir = PJMEDIA_DIR_CAPTURE;
param.clock_rate = PJMEDIA_PIA_SRATE(&wav->info);
param.samples_per_frame = PJMEDIA_PIA_SPF(&wav->info);
param.channel_count = PJMEDIA_PIA_CCNT(&wav->info);
param.bits_per_sample = PJMEDIA_PIA_BITS(&wav->info);
status = pjmedia_aud_stream_create(¶m, &test_rec_cb, &test_play_cb, wav, &strm);
if (status != PJ_SUCCESS)
{
fprintf(stderr, "Error opening the sound stream");
return -1;
}
status = pjmedia_aud_stream_start(strm);
if (status != PJ_SUCCESS)
{
fprintf(stderr, "Error starting the sound device");
return -1;
}
// Spend some time allowing the called party to pick up and recording to proceed
Sleep(10000); // sleep 10 seconds
// Clean up code omitted
return 0;
}
Apologies to the pure of heart for the mix of C and C++ above.
Solved this by loading the Alsa module snd-dummy.
Look in /lib/modules/YOUR_KERNEL_VERSION/modules.dep if its mentioned.
If you have it then load it with modprobe snd-dummy
Otherwise recompile your Kernel to include it as a module or follow the installation in the link above.
Im trying to use memory map I/O netlink to transfer bulk packets from kernel to user space, and I followed a guide document from Patrick McHardy 1. However, when I try to setup the shared ring buffer in user space by using:
setsockopt(sock_fd, SOL_NETLINK, NETLINK_RX_RING, &req, sizeof(req));
setsockopt(sock_fd, SOL_NETLINK, NETLINK_TX_RING, &req, sizeof(req));
Both functions return -1, and the errno is 1, which means the descriptor is invalid. Im confused about that because I also referred to many other source codes and they can setup the ring successfully.
My code is almost the same as Patrick's 1:
int sock_fd = -1;
sock_fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_DECODE);
if (sock_fd < 0)
return -1;
bind(sock_fd, (struct sockaddr *)&src_addr, sizeof(src_addr));
/* init the mmap buffer */
unsigned int block_size = 16 * getpagesize();
struct nl_mmap_req req = {
.nm_block_size = block_size,
.nm_block_nr = 64,
.nm_frame_size = 16384,
.nm_frame_nr = 64 * block_size / 16384,
};
/* Configure ring parameters */
if (setsockopt(sock_fd, SOL_NETLINK, NETLINK_RX_RING, &req, sizeof(req)) < 0){
if(errno > 0)
printf("%d\n", errno);
}
if (setsockopt(sock_fd, SOL_NETLINK, NETLINK_TX_RING, &req, sizeof(req)) < 0){
if(errno > 0)
printf("%d", errno);
exit(1);
}
This code is built in Ubuntu 14.04, and kernel version is 3.13.0-74-generic.
Anyone idea about it? Thanks a lot.
I have a program which goes this way.
{
memset(&hints, 0, sizeof(struct addrinfo));
/* fill the hints struct */
hints.ai_flags = AI_PASSIVE;
hints.ai_socktype = SOCK_STREAM;
//hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = 0;
//hints.ai_protocol = IPPROTO_UDP;
hints.ai_canonname = NULL;
hints.ai_addr = NULL;
hints.ai_next = NULL;
if(iFamily == AF_INET)
hints.ai_family = AF_INET;
else if(iFamily == AF_INET6)
hints.ai_family = AF_INET6;
/* Code for getting gettaddressinfo */
if(iFamily == AF_INET)
{
iRet = bind(SockIPC, res->ai_addr, sizeof(struct sockaddr_in));
char sBuff[1024];
sprintf(sBuff, "errno [%d] ", errno);
fp=fopen("debug.log","a+");
fprintf(fp,"IPv4 bind error\n ");
fprintf(fp,"bind error = %s\n",sBuff);
fclose(fp);
fflush(stdout);
}
}
In the above piece of code I am trying to bind a UDP socket created.
I am getting the following bind error
bind error = 266
Which is address already in use.
Can anyone
let me know where I am going wrong.
There's no evidence of a problem here. It's only valid to evaluate errno if the immediately prior system call has returned -1, and perror("bind"); would have been a lot simpler:
if (bind(...) == -1)
{
perror("bind");
}
else // continue with execution
However there almost certainly was an error, if not 266: EADDRINUSE is 98, not 266. SOCK_STREAM and IPPROTO_UDP don't go together. You need SOCK_DGRAM and IPPROTO_UDP.
We are using libmodbus library to read register values from energy meter EM6400 which supports Modbus over RTU. We are facing the following two issues.
1) We are facing an issue with modbus_read_registers API, this API returns -1 and the error message is:
ERROR Connection timed out: select.
After debugging the library, we found this issue is due to the echo of request bytes in the response message.
read() API call in _modbus_rtu_recv returns request bytes first followed by response bytes. As a result, length_to_read is calculated in compute_data_length_after_meta() based on the request bytes instead of response bytes (which contains the number of bytes read) and connection timed out issue occurs.
We tried to use both 3.0.6 and 3.1.2 libmodbus versions but same issue occurs in both the versions.
2) modbus_rtu_set_serial_mode (ctx, MODBUS_RTU_RS485) returns "BAD file descriptor".
Please confirm if there is any API call missing or any parameter is not set correctly.
Our sample code to read register value is as follows.
int main()
{
modbus_t *ctx;
uint16_t tab_reg[2] = {0,0};
float avgVLL = -1;;
int res = 0;
int rc;
int i;
struct timeval response_timeout;
uint32_t tv_sec = 0;
uint32_t tv_usec = 0;
response_timeout.tv_sec = 5;
response_timeout.tv_usec = 0;
ctx = modbus_new_rtu("/dev/ttyUSB0", 19200, 'E', 8, 1);
if (NULL == ctx)
{
printf("Unable to create libmodbus context\n");
res = 1;
}
else
{
printf("created libmodbus context\n");
modbus_set_debug(ctx, TRUE);
//modbus_set_error_recovery(ctx, MODBUS_ERROR_RECOVERY_LINK |MODBUS_ERROR_RECOVERY_PROTOCOL);
rc = modbus_set_slave(ctx, 1);
printf("modbus_set_slave return: %d\n",rc);
if (rc != 0)
{
printf("modbus_set_slave: %s \n",modbus_strerror(errno));
}
/* Commented - Giving 'Bad File Descriptor' issue
rc = modbus_rtu_set_serial_mode(ctx, MODBUS_RTU_RS485);
printf("modbus_rtu_set_serial_mode: %d \n",rc);
if (rc != 0)
{
printf("modbus_rtu_set_serial_mode: %s \n",modbus_strerror(errno));
}
*/
// This code is for version 3.0.6
modbus_get_response_timeout(ctx, &response_timeout);
printf("Default response timeout:%ld sec %ld usec \n", response_timeout.tv_sec, response_timeout.tv_usec );
response_timeout.tv_sec = 60;
response_timeout.tv_usec = 0;
modbus_set_response_timeout(ctx, &response_timeout);
modbus_get_response_timeout(ctx, &response_timeout);
printf("Set response timeout:%ld sec %ld usec \n", response_timeout.tv_sec, response_timeout.tv_usec );
/* This code is for version 3.1.2
modbus_get_response_timeout(ctx, &tv_sec, &tv_usec);
printf("Default response timeout:%d sec %d usec \n",tv_sec,tv_usec );
tv_sec = 60;
tv_usec = 0;
modbus_set_response_timeout(ctx, tv_sec,tv_usec);
modbus_get_response_timeout(ctx, &tv_sec, &tv_usec);
printf("Set response timeout:%d sec %d usec \n",tv_sec,tv_usec );
*/
rc = modbus_connect(ctx);
printf("modbus_connect: %d \n",rc);
if (rc == -1) {
printf("Connection failed: %s\n", modbus_strerror(errno));
res = 1;
}
rc = modbus_read_registers(ctx, 3908, 2, tab_reg);
printf("modbus_read_registers: %d \n",rc);
if (rc == -1) {
printf("Read registers failed: %s\n", modbus_strerror(errno));
res = 1;
}
for (i=0; i < 2; i++) {
printf("reg[%d]=%d (0x%X)\n", i, tab_reg[i], tab_reg[i]);
}
avgVLL = modbus_get_float(tab_reg);
printf("Average Line to Line Voltage = %f\n", avgVLL);
modbus_close(ctx);
modbus_free(ctx);
}
}
Output of this sample is as follows:
created libmodbus context
modbus_set_slave return: 0
modbus_rtu_set_serial_mode: -1
modbus_rtu_set_serial_mode: Bad file descriptor
Default response timeout:0 sec 500000 usec
Set response timeout:60 sec 0 usec
Opening /dev/ttyUSB0 at 19200 bauds (E, 8, 1)
modbus_connect: 0
[01][03][0F][44][00][02][87][0A]
Waiting for a confirmation...
ERROR Connection timed out: select
<01><03><0F><44><00><02><87><0A><01><03><04><C4><5F><43><D4><C6><7E>modbus_read_registers: -1
Read registers failed: Connection timed out
reg[0]=0 (0x0)
reg[1]=0 (0x0)
Average Line to Line Voltage = 0.000000
Issue 1) is probably a hardware issue, with "local echo" enabled in your RS-485 adapter. Local echo is sometimes used to confirm sending of data bytes on the bus. You need to disable it, or find another RS-485 adapter.
I have written about this in the documentation of my MinimalModbus Python library: Local Echo
It lists a few common ways to disable local echo in RS-485 adapters.