diff options
| -rw-r--r-- | src/users.cpp | 116 |
1 files changed, 57 insertions, 59 deletions
diff --git a/src/users.cpp b/src/users.cpp index a86c6f824..ff417a8a3 100644 --- a/src/users.cpp +++ b/src/users.cpp @@ -1120,87 +1120,85 @@ const char* User::GetCIDRMask(int range) #ifdef SUPPORT_IP6LINKS case AF_INET6: { + /* unsigned char s6_addr[16]; */ struct in6_addr v6; - + sockaddr_in6* sin; + int i, bytestozero, extrabits; + char buffer[40]; + if(range > 128) - { - printf("Error, range given (%d) larger than address length (128)\n", range); - return 0; - } - - if(inet_pton(AF_INET6, this->GetIPString(), &v6)) - { - /* unsigned char s6_addr[16]; */ - int i; - int bytestoblank; - int extrabits; - char buffer[64]; + throw "CIDR mask width greater than address width (IPv6, 128 bit)"; - if(range > 0) - { - /* (128 - range) bits must be blanked, so ((128 - range) / 8) of the bytes, working backwards, must be blanked. */ - bytestoblank = (128 - range) / 8; - - /* ((128 - range) % 8) bits of the next byte must also be blanked. */ - extrabits = (128 - range) % 8; - v6.s6_addr[15 - bytestoblank] = (v6.s6_addr[15 - bytestoblank] >> extrabits) << extrabits; - - for(i = 0; i < bytestoblank; i++) - { - v6.s6_addr[15 - i] = 0; - } - } - else - { - for(i = 0; i < 15; i++) - { - v6.s6_addr[i] = 0; - } - } + /* Access the user's IP structure directly */ + sin = (sockaddr_in6*)this->ip; - sprintf(buf, "%s/%d\n", inet_ntop(AF_INET6, &v6, buffer, 64), range); - return buf; + /* To create the CIDR mask we want to set all the bits after 'range' bits of the address + * to zero. This means the last (128 - range) bits of the address must be set to zero. + * Hence this number divided by 8 is the number of whole bytes from the end of the address + * which must be set to zero. + */ + bytestozero = (128 - range) / 8; + + /* Some of the least significant bits of the next most significant byte may also have to + * be zeroed. The number of bits is the remainder of the above division. + */ + extrabits = (128 - range) % 8; + + /* Populate our working struct with the parts of the user's IP which are required in the + * final CIDR mask. Set all the subsequent bytes to zero. + * (16 - bytestozero) is the number of bytes which must be populated with actual IP data. + */ + for(i = 0; i < (16 - bytestozero); i++) + { + v6.s6_addr[i] = sin->sin6_addr.s6_addr[i]; } - else + + /* And zero all the remaining bytes in the IP. */ + for(; i < 16; i++) { - throw "CIDR mask for v6 failed"; + v6.s6_addr[i] = 0; } + + /* And finally, zero the extra bits required. */ + v6.s6_addr[15 - bytestozero] = (v6.s6_addr[15 - bytestozero] >> extrabits) << extrabits; + sprintf(buf, "%s/%d\n", inet_ntop(AF_INET6, &v6, buffer, 40), range); + return buf; } break; #endif case AF_INET: { struct in_addr v4; + sockaddr_in* sin; + uint32_t temp; + char buffer[16]; if (range > 32) - throw "more than 32 bits on an ipv4 connection, can't do that.."; - - if(inet_pton(AF_INET, this->GetIPString(), &v4)) - { - char buffer[16]; - uint32_t temp; - - /* (32 - range) is the number of bits we are *ignoring*. We shift this left and then right to wipe off these bits. */ + throw "CIDR mask width greater than address width (IPv4, 32 bit)"; - if(range > 0) - { - temp = ntohl(v4.s_addr); - temp = (temp >> (32 - range)) << (32 - range); - v4.s_addr = htonl(temp); - } - else - { - v4.s_addr = 0; - } + /* Users already have a sockaddr* pointer (User::ip) which contains either a v4 or v6 structure */ + sin = (sockaddr_in*)this->ip; + v4.s_addr = sin->sin_addr.s_addr; - sprintf(buf, "%s/%d\n", inet_ntop(AF_INET, &v4, buffer, 16), range); - return buf; + /* (32 - range) is the number of bits we are *ignoring*. We shift this left and then right to wipe off these bits. */ + if(range > 0) + { + temp = ntohl(v4.s_addr); + temp = (temp >> (32 - range)) << (32 - range); + v4.s_addr = htonl(temp); } else { - throw "CIDR mask for v4 failed"; + /* a range of zero would cause a 32 bit value to be shifted by 32 bits. + * this has undefined behaviour, but for CIDR purposes the resulting mask + * from a.b.c.d/0 is 0.0.0.0/0 + */ + v4.s_addr = 0; } + + sprintf(buf, "%s/%d\n", inet_ntop(AF_INET, &v4, buffer, 16), range); + return buf; } break; } |