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app: Remove extra <CRLF> from AT response #182

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app: Remove extra <CRLF> from AT response #182

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75 changes: 3 additions & 72 deletions app/src/sm_at_host.c
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Original file line number Diff line number Diff line change
Expand Up @@ -466,72 +466,6 @@ static int cmd_grammar_check(const char *cmd, size_t length)
return 0;
}

static char *strrstr(const char *str1, const char *str2)
{
size_t len1;
size_t len2;

if (str1 == NULL || str2 == NULL) {
return NULL;
}

len1 = strlen(str1);
len2 = strlen(str2);

if (len2 > len1 || len1 == 0 || len2 == 0) {
return NULL;
}

for (int i = len1 - len2; i >= 0; i--) {
if (strncmp(str1 + i, str2, len2) == 0) {
return (char *)str1 + i;
}
}

return NULL;
}

static void format_final_result(char *buf, size_t buf_len, size_t buf_max_len)
{
static const char ok_str[] = "OK\r\n";
static const char error_str[] = "ERROR\r\n";
static const char cme_error_str[] = "+CME ERROR:";
static const char cms_error_str[] = "+CMS ERROR:";
char *result = NULL;

result = strrstr(buf, ok_str);
if (result == NULL) {
result = strrstr(buf, error_str);
}

if (result == NULL) {
result = strrstr(buf, cme_error_str);
}

if (result == NULL) {
result = strrstr(buf, cms_error_str);
}

if (result == NULL) {
LOG_WRN("Final result not found");
return;
}

/* insert CRLF before final result if there is information response before it */
if (result != buf + strlen(CRLF_STR)) {
if (buf_len + strlen(CRLF_STR) < buf_max_len) {
memmove((void *)(result + strlen(CRLF_STR)), (void *)result,
strlen(result));
result[0] = CR;
result[1] = LF;
buf_len += strlen(CRLF_STR);
buf[buf_len] = '\0';
} else {
LOG_WRN("No room to insert CRLF");
}
}
}

static int sm_at_send_internal(const uint8_t *data, size_t len, bool urc,
enum sm_debug_print print_debug)
{
Expand Down Expand Up @@ -669,12 +603,9 @@ static void cmd_send(uint8_t *buf, size_t cmd_length, size_t buf_size, bool *sto
*/
buf[0] = CR;
buf[1] = LF;
if (strlen(buf) > strlen(CRLF_STR)) {
format_final_result(buf, strlen(buf), buf_size);
err = sm_at_send_str(buf);
if (err) {
LOG_ERR("AT command response failed: %d", err);
}
err = sm_at_send_str(buf);
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@MarkusLassila MarkusLassila Feb 13, 2026

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This works well for the AT+ and AT%, but the SM AT# commands still send the additional \r\n:

OK
Ready
at#xsocket=1,1,0

#XSOCKET: 0,1,6

OK
at+cereg?

+CEREG: 0,4
OK

The first \r\n comes from:
https://github.com/nrfconnect/ncs-serial-modem/blob/main/app/src/sm_at_socket.c#L542

And the second one from lines above this. The first one should be removed from all the commands.

if (err) {
LOG_ERR("AT command response failed: %d", err);
}
}

Expand Down