crest42
commented
5 years ago My check function in sock_udp_recv:
memcpy(data, pkt->data, pkt->size);
res = (int)pkt->size;
if (pkt->size == 48 && memcmp(data, pkt->data, pkt->size) != 0)
{
printf("%p-%p: ",data,(char *)data+pkt->size);
for (int i = 0; i < 48; i++)
{
printf("%02x",((char *)data)[i]);
}
printf("\n");
printf("%p-%p: ",pkt->data,(char *)pkt->data+pkt->size);
for (int i = 0; i < 48; i++)
{
printf("%02x",((char *)pkt->data)[i]);
}
printf("\n");
unsigned char *d = ((unsigned char *)data);
uint32_t tmp;
d = d + (3*sizeof(uint32_t));
memcpy(&tmp, d, sizeof(uint32_t));
uint32_t len = ntohl(tmp);
assert(len < 1000);
} In the case of an error the memcmp returns != 0 and the printed buffer are different. I try to reproduce and send the corresponding output.
kaspar030
stale[bot]
Description
When using gnrc_sock_udp in my application after a certain amount of hosts in the network (and thus a certain amount of packets/s on a single host), the buffer content returned by sock_udp_recv is filled with garbage. My message format is defined to be 4 bytes + 4 bytes + 4 bytes + 4 bytes (message type, app src id, app dst id, length of the remainder data).
As an example: A message of type 11 always sends a static sized buffer with size 32 and thus the message "header" would look like this: 0x0000000b 0x00000001 0x00000002 0x00000020. (Second and third 4 bytes can differ)
Sometimes if many hosts are joining the network it happens very seldom that a single host instead read something like: 0x0000000b 0xfe80aaf0 0x00000000 0x00afbb20
Two intresting observations here:
The first 4 bytes always are correct. The second 4 bytes always contains fe80something (Maybe i am just paranoid but this looks like the beginning of a link local ipv6 address)
Further debugging:
Steps to reproduce the issue
Reading content from a udp socket and sending a lots (TBD) of messages. Testing the read buffer for correctness. Sadly no better way yet than try and wait.
Expected results
Content of buffer is correct
Actual results
Buffer content is garbage
Versions
Operating System Environment
Installed compiler toolchains
riscv-none-embed-gcc: missing clang: clang version 7.0.0 (tags/RELEASE_700/final)
Installed compiler libs
arm-none-eabi-newlib: "3.0.0" mips-mti-elf-newlib: missing riscv-none-embed-newlib: missing avr-libc: "2.0.0" ("20150208")
Installed development tools