diff --git a/src/libui_sdl/LAN_Socket.cpp b/src/libui_sdl/LAN_Socket.cpp index b8944177..4fbfd9ae 100644 --- a/src/libui_sdl/LAN_Socket.cpp +++ b/src/libui_sdl/LAN_Socket.cpp @@ -380,6 +380,9 @@ void HandleDNSFrame(u8* data, int len) u8* udpheader = &data[0x22]; u8* dnsbody = &data[0x2A]; + u32 srcip = ntohl(*(u32*)&ipheader[12]); + u16 srcport = ntohs(*(u16*)&udpheader[0]); + u16 id = ntohs(*(u16*)&dnsbody[0]); u16 flags = ntohs(*(u16*)&dnsbody[2]); u16 numquestions = ntohs(*(u16*)&dnsbody[4]); @@ -390,33 +393,174 @@ void HandleDNSFrame(u8* data, int len) printf("DNS: ID=%04X, flags=%04X, Q=%d, A=%d, auth=%d, add=%d\n", id, flags, numquestions, numanswers, numauth, numadd); + // for now we only take 'simple' DNS requests + if (flags & 0x8000) return; + if (numquestions != 1 || numanswers != 0) return; + + u8 resp[1024]; + u8* out = &resp[0]; + + // ethernet + memcpy(out, &data[6], 6); out += 6; + memcpy(out, kServerMAC, 6); out += 6; + *(u16*)out = htons(0x0800); out += 2; + + // IP + u8* resp_ipheader = out; + *out++ = 0x45; + *out++ = 0x00; + *(u16*)out = 0; out += 2; // total length + *(u16*)out = htons(IPv4ID); out += 2; IPv4ID++; + *out++ = 0x00; + *out++ = 0x00; + *out++ = 0x80; // TTL + *out++ = 0x11; // protocol (UDP) + *(u16*)out = 0; out += 2; // checksum + *(u32*)out = htonl(kDNSIP); out += 4; // source IP + *(u32*)out = htonl(srcip); out += 4; // destination IP + + // UDP + u8* resp_udpheader = out; + *(u16*)out = htons(53); out += 2; // source port + *(u16*)out = htons(srcport); out += 2; // destination port + *(u16*)out = 0; out += 2; // length + *(u16*)out = 0; out += 2; // checksum + + // DNS + u8* resp_body = out; + *(u16*)out = htons(id); out += 2; // ID + *(u16*)out = htons(0x8000); out += 2; // flags + *(u16*)out = htons(numquestions); out += 2; // num questions + *(u16*)out = htons(numquestions); out += 2; // num answers + *(u16*)out = 0; out += 2; // num authority + *(u16*)out = 0; out += 2; // num additional + u32 curoffset = 12; + for (u16 i = 0; i < numquestions; i++) + { + if (curoffset >= (len-0x2A)) return; + + u8 bitlength = 0; + while ((bitlength = dnsbody[curoffset++]) != 0) + curoffset += bitlength; + + curoffset += 4; + } + + u32 qlen = curoffset-12; + if (qlen > 512) return; + memcpy(out, &dnsbody[12], qlen); out += qlen; + + curoffset = 12; for (u16 i = 0; i < numquestions; i++) { - // Assemble the requested domain name + // assemble the requested domain name u8 bitlength = 0; char domainname[256] = ""; int o = 0; while ((bitlength = dnsbody[curoffset++]) != 0) { - if ((o+bitlength) >= 255) break; + if ((o+bitlength) >= 255) + { + // welp. atleast try not to explode. + domainname[o++] = '\0'; + break; + } strncpy(&domainname[o], (const char *)&dnsbody[curoffset], bitlength); o += bitlength; curoffset += bitlength; if (dnsbody[curoffset] != 0) - { domainname[o++] = '.'; - } + else + domainname[o++] = '\0'; } - printf("- q%d: %s", i, domainname); + u16 type = ntohs(*(u16*)&dnsbody[curoffset]); + u16 cls = ntohs(*(u16*)&dnsbody[curoffset+2]); - // TODO: get answer + printf("- q%d: %04X %04X %s", i, type, cls, domainname); + + // get answer + struct addrinfo dns_hint; + struct addrinfo* dns_res; + u32 addr_res; + + memset(&dns_hint, 0, sizeof(dns_hint)); + dns_hint.ai_family = AF_INET; // TODO: other address types (INET6, etc) + if (getaddrinfo(domainname, "0", &dns_hint, &dns_res) == 0) + { + struct addrinfo* p = dns_res; + while (p) + { + struct sockaddr_in* addr = (struct sockaddr_in*)p->ai_addr; + printf(" -> %d.%d.%d.%d", + addr->sin_addr.S_un.S_un_b.s_b1, addr->sin_addr.S_un.S_un_b.s_b2, + addr->sin_addr.S_un.S_un_b.s_b3, addr->sin_addr.S_un.S_un_b.s_b4); + + addr_res = addr->sin_addr.S_un.S_addr; + p = p->ai_next; + } + } + else + { + printf(" shat itself :("); + addr_res = 0; + } printf("\n"); curoffset += 4; + + // TODO: betterer support + // (under which conditions does the C00C marker work?) + *(u16*)out = htons(0xC00C); out += 2; + *(u16*)out = htons(type); out += 2; + *(u16*)out = htons(cls); out += 2; + *(u32*)out = htonl(3600); out += 4; // TTL (hardcoded for now) + *(u16*)out = htons(4); out += 2; // address length + *(u32*)out = addr_res; out += 4; // address } + + // lengths + u32 framelen = (u32)(out - &resp[0]); + if (framelen & 1) { *out++ = 0; framelen++; } + *(u16*)&resp_ipheader[2] = htons(framelen - 0xE); + *(u16*)&resp_udpheader[4] = htons(framelen - (0xE + 0x14)); + + // IP checksum + u32 tmp = 0; + + for (int i = 0; i < 20; i += 2) + tmp += ntohs(*(u16*)&resp_ipheader[i]); + while (tmp >> 16) + tmp = (tmp & 0xFFFF) + (tmp >> 16); + tmp ^= 0xFFFF; + *(u16*)&resp_ipheader[10] = htons(tmp); + + // UDP checksum + // (note: normally not mandatory, but some older sgIP versions require it) + tmp = 0; + tmp += ntohs(*(u16*)&resp_ipheader[12]); + tmp += ntohs(*(u16*)&resp_ipheader[14]); + tmp += ntohs(*(u16*)&resp_ipheader[16]); + tmp += ntohs(*(u16*)&resp_ipheader[18]); + tmp += ntohs(0x1100); + tmp += (u32)(out - resp_udpheader); + for (u8* i = resp_udpheader; i < out; i += 2) + tmp += ntohs(*(u16*)i); + while (tmp >> 16) + tmp = (tmp & 0xFFFF) + (tmp >> 16); + tmp ^= 0xFFFF; + if (tmp == 0) tmp = 0xFFFF; + *(u16*)&resp_udpheader[6] = htons(tmp); + + // TODO: if there is already a packet queued, this will overwrite it + // that being said, this will only happen during DHCP setup, so probably + // not a big deal + + PacketLen = framelen; + memcpy(PacketBuffer, resp, PacketLen); + RXNum = 1; } void HandleIPFrame(u8* data, int len)