Why do I get -1 when recvfrom() from a multicast group address?
1
I am writting a LAN device detect test which can send a request to a multicast group 239.255.255.250 and get response from device where in same LAN as well,
Wireshark tells me, join to group(IGMPv2) is good, sending(UDP) is good, reciving(UDP) is good, BUT in my code, It keeps return -1 when recvfrom(), Whatever I tried, it's always -1...
I ever tried a 3rd party app in windows, it can send&recive normally.
Could anybody gives me a clue ? Thx in advance.
socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP));
setsockopt(socket, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
setsockopt(socket, SOL_SOCKET, SO_IFDEVICE, &i8IfIndex, sizeof(i8IfIndex));
setsockopt(socket, SOL_SOCKET, SO_BROADCAST, &u8On, sizeof(int));
/*all aboved checked alright*/
/*join to multicast group*/
struct ip_mreq mreq;
mreq.imr_multiaddr.s_addr = htonl(0xEFFFFFFA); /*239.255.255.250*/
mreq.imr_interface.s_addr = INADDR_ANY;
setsockopt(socket, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
memset(&socket_address, 0, sizeof(socket_address));
socket_address.sin_addr.s_addr = htonl(0xEFFFFFFA);
socket_address.sin_family = AF_INET;
socket_address.sin_port = htons(37020);
//no help:bind(socket, (PSA) &socket_address, sizeof(socket_address));
memset(&socket_address2, 0, sizeof(socket_address2));
socket_address2.sin_addr.s_addr = INADDR_ANY;
socket_address2.sin_family = AF_INET;
socket_address2.sin_port = 0;
/*send & recv*/
int8 i8Result = 0xcc;
char *inquryStr = "<?xml version="1.0" encoding="utf-8"?><Probe><Uuid>232B1234-FBcC-48B5-AC06-AE1F77051280</Uuid><Types>inquiry</Types></Probe>";
if(i8Result = sendto(socket, inquryStr, strlen(inquryStr), 0, (PSA) &socket_address, sizeof(socket_address))) {
//wireshark detected ,i8Result shows 0x7C sent
if(i8Result = recvfrom(socket, g_HjtOsdComm.u8TRBuf, 1024, 0, (PSA) &socket_address2, sizeof(socket_address2))) {
//wireshark detected ,but i8Result get-1
}
}
/*leave group*/
setsockopt(socket, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
fdClose(HjtOsdSocket);
c multicast
asked Nov 21 '18 at 2:50
jerronjerron
62
add a comment |
1
I am writting a LAN device detect test which can send a request to a multicast group 239.255.255.250 and get response from device where in same LAN as well,
Wireshark tells me, join to group(IGMPv2) is good, sending(UDP) is good, reciving(UDP) is good, BUT in my code, It keeps return -1 when recvfrom(), Whatever I tried, it's always -1...
I ever tried a 3rd party app in windows, it can send&recive normally.
Could anybody gives me a clue ? Thx in advance.
socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP));
setsockopt(socket, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
setsockopt(socket, SOL_SOCKET, SO_IFDEVICE, &i8IfIndex, sizeof(i8IfIndex));
setsockopt(socket, SOL_SOCKET, SO_BROADCAST, &u8On, sizeof(int));
/*all aboved checked alright*/
/*join to multicast group*/
struct ip_mreq mreq;
mreq.imr_multiaddr.s_addr = htonl(0xEFFFFFFA); /*239.255.255.250*/
mreq.imr_interface.s_addr = INADDR_ANY;
setsockopt(socket, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
memset(&socket_address, 0, sizeof(socket_address));
socket_address.sin_addr.s_addr = htonl(0xEFFFFFFA);
socket_address.sin_family = AF_INET;
socket_address.sin_port = htons(37020);
//no help:bind(socket, (PSA) &socket_address, sizeof(socket_address));
memset(&socket_address2, 0, sizeof(socket_address2));
socket_address2.sin_addr.s_addr = INADDR_ANY;
socket_address2.sin_family = AF_INET;
socket_address2.sin_port = 0;
/*send & recv*/
int8 i8Result = 0xcc;
char *inquryStr = "<?xml version="1.0" encoding="utf-8"?><Probe><Uuid>232B1234-FBcC-48B5-AC06-AE1F77051280</Uuid><Types>inquiry</Types></Probe>";
if(i8Result = sendto(socket, inquryStr, strlen(inquryStr), 0, (PSA) &socket_address, sizeof(socket_address))) {
//wireshark detected ,i8Result shows 0x7C sent
if(i8Result = recvfrom(socket, g_HjtOsdComm.u8TRBuf, 1024, 0, (PSA) &socket_address2, sizeof(socket_address2))) {
//wireshark detected ,but i8Result get-1
}
}
/*leave group*/
setsockopt(socket, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
fdClose(HjtOsdSocket);
c multicast
asked Nov 21 '18 at 2:50
jerronjerron
62
And what does the error code say?strerror(errno)
– immibis
Nov 21 '18 at 3:12
Thanks for your clue, it really helps, strerror shows "bad address",then I searched online and found a thread says "last arg of recvfrom is the address of the len instead of len it self"，so problem solved!
– jerron
Nov 21 '18 at 5:15
add a comment |
1
1
1
I am writting a LAN device detect test which can send a request to a multicast group 239.255.255.250 and get response from device where in same LAN as well,
Wireshark tells me, join to group(IGMPv2) is good, sending(UDP) is good, reciving(UDP) is good, BUT in my code, It keeps return -1 when recvfrom(), Whatever I tried, it's always -1...
I ever tried a 3rd party app in windows, it can send&recive normally.
Could anybody gives me a clue ? Thx in advance.
socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP));
setsockopt(socket, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
setsockopt(socket, SOL_SOCKET, SO_IFDEVICE, &i8IfIndex, sizeof(i8IfIndex));
setsockopt(socket, SOL_SOCKET, SO_BROADCAST, &u8On, sizeof(int));
/*all aboved checked alright*/
/*join to multicast group*/
struct ip_mreq mreq;
mreq.imr_multiaddr.s_addr = htonl(0xEFFFFFFA); /*239.255.255.250*/
mreq.imr_interface.s_addr = INADDR_ANY;
setsockopt(socket, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
memset(&socket_address, 0, sizeof(socket_address));
socket_address.sin_addr.s_addr = htonl(0xEFFFFFFA);
socket_address.sin_family = AF_INET;
socket_address.sin_port = htons(37020);
//no help:bind(socket, (PSA) &socket_address, sizeof(socket_address));
memset(&socket_address2, 0, sizeof(socket_address2));
socket_address2.sin_addr.s_addr = INADDR_ANY;
socket_address2.sin_family = AF_INET;
socket_address2.sin_port = 0;
/*send & recv*/
int8 i8Result = 0xcc;
char *inquryStr = "<?xml version="1.0" encoding="utf-8"?><Probe><Uuid>232B1234-FBcC-48B5-AC06-AE1F77051280</Uuid><Types>inquiry</Types></Probe>";
if(i8Result = sendto(socket, inquryStr, strlen(inquryStr), 0, (PSA) &socket_address, sizeof(socket_address))) {
//wireshark detected ,i8Result shows 0x7C sent
if(i8Result = recvfrom(socket, g_HjtOsdComm.u8TRBuf, 1024, 0, (PSA) &socket_address2, sizeof(socket_address2))) {
//wireshark detected ,but i8Result get-1
}
}
/*leave group*/
setsockopt(socket, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
fdClose(HjtOsdSocket);
c multicast
asked Nov 21 '18 at 2:50
jerronjerron
62
I am writting a LAN device detect test which can send a request to a multicast group 239.255.255.250 and get response from device where in same LAN as well,
Wireshark tells me, join to group(IGMPv2) is good, sending(UDP) is good, reciving(UDP) is good, BUT in my code, It keeps return -1 when recvfrom(), Whatever I tried, it's always -1...
I ever tried a 3rd party app in windows, it can send&recive normally.
Could anybody gives me a clue ? Thx in advance.
socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP));
setsockopt(socket, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
setsockopt(socket, SOL_SOCKET, SO_IFDEVICE, &i8IfIndex, sizeof(i8IfIndex));
setsockopt(socket, SOL_SOCKET, SO_BROADCAST, &u8On, sizeof(int));
/*all aboved checked alright*/
/*join to multicast group*/
struct ip_mreq mreq;
mreq.imr_multiaddr.s_addr = htonl(0xEFFFFFFA); /*239.255.255.250*/
mreq.imr_interface.s_addr = INADDR_ANY;
setsockopt(socket, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
memset(&socket_address, 0, sizeof(socket_address));
socket_address.sin_addr.s_addr = htonl(0xEFFFFFFA);
socket_address.sin_family = AF_INET;
socket_address.sin_port = htons(37020);
//no help:bind(socket, (PSA) &socket_address, sizeof(socket_address));
memset(&socket_address2, 0, sizeof(socket_address2));
socket_address2.sin_addr.s_addr = INADDR_ANY;
socket_address2.sin_family = AF_INET;
socket_address2.sin_port = 0;
/*send & recv*/
int8 i8Result = 0xcc;
char *inquryStr = "<?xml version="1.0" encoding="utf-8"?><Probe><Uuid>232B1234-FBcC-48B5-AC06-AE1F77051280</Uuid><Types>inquiry</Types></Probe>";
if(i8Result = sendto(socket, inquryStr, strlen(inquryStr), 0, (PSA) &socket_address, sizeof(socket_address))) {
//wireshark detected ,i8Result shows 0x7C sent
if(i8Result = recvfrom(socket, g_HjtOsdComm.u8TRBuf, 1024, 0, (PSA) &socket_address2, sizeof(socket_address2))) {
//wireshark detected ,but i8Result get-1
}
}
/*leave group*/
setsockopt(socket, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
fdClose(HjtOsdSocket);
c multicast
c multicast
asked Nov 21 '18 at 2:50
jerronjerron
62
asked Nov 21 '18 at 2:50
jerronjerron
62
asked Nov 21 '18 at 2:50
jerronjerron
62
asked Nov 21 '18 at 2:50
jerronjerron
62
asked Nov 21 '18 at 2:50
jerronjerron
62
62
And what does the error code say?strerror(errno)
– immibis
Nov 21 '18 at 3:12
Thanks for your clue, it really helps, strerror shows "bad address",then I searched online and found a thread says "last arg of recvfrom is the address of the len instead of len it self"，so problem solved!
– jerron
Nov 21 '18 at 5:15
add a comment |
And what does the error code say?strerror(errno)
– immibis
Nov 21 '18 at 3:12
Thanks for your clue, it really helps, strerror shows "bad address",then I searched online and found a thread says "last arg of recvfrom is the address of the len instead of len it self"，so problem solved!
– jerron
Nov 21 '18 at 5:15
And what does the error code say?
strerror(errno)– immibis
Nov 21 '18 at 3:12
And what does the error code say?
strerror(errno)– immibis
Nov 21 '18 at 3:12
Thanks for your clue, it really helps, strerror shows "bad address",then I searched online and found a thread says "last arg of recvfrom is the address of the len instead of len it self"，so problem solved!
– jerron
Nov 21 '18 at 5:15
Thanks for your clue, it really helps, strerror shows "bad address",then I searched online and found a thread says "last arg of recvfrom is the address of the len instead of len it self"，so problem solved!
– jerron
Nov 21 '18 at 5:15
add a comment |
0
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And what does the error code say?
strerror(errno)– immibis
Nov 21 '18 at 3:12
Thanks for your clue, it really helps, strerror shows "bad address",then I searched online and found a thread says "last arg of recvfrom is the address of the len instead of len it self"，so problem solved!
– jerron
Nov 21 '18 at 5:15