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Text File | 1991-02-19 | 28.4 KB | 904 lines

;;************************************************************************* ;; ip.inc ip.inc ;;************************************************************************* ;; ;; Copyright (C) 1989 Northwestern University, Vance Morrison ;; ;; ;; Permission to view, compile, and modify for LOCAL (intra-organization) ;; USE ONLY is hereby granted, provided that this copyright and permission ;; notice appear on all copies. Any other use by permission only. ;; ;; Northwestern University makes no representations about the suitability ;; of this software for any purpose. It is provided "as is" without expressed ;; or implied warranty. See the copywrite notice file for complete details. ;; ;;***************************************************************************** ;; ;; Routines provided by this module ;; ;; IP_DECLARE name, router, dls, icmp ;; IP_DEFINE name ;; IP_R_READ name, code_label ;; IP_R_RETURN name ;; IP_R_SRC_in_SI_ES_out_AX_BX_const_CX_DX_BP_SI_DI_ES name ;; IP_R_BROAD_in_SI_ES_const_CX_DX_BP_SI_DI_ES name, broadcast ;; IP_R_HEADER_in_ES_out_SI_const_BX_CX_DX_BP_DI_ES name ;; IP_W_ACCESS_in_AX_BX_CX_DL_out_AX_DI_ES name ;; IP_W_WRITE_in_CX name ;; IP_COMPUTE_NET_in_AX_BX_out_AX_BX_const_CX_DX_BP_SI_DI_ES dls ;; ;; Variables Provided by this Module (READ ONLY!!!) ;; ;; ip_&name&_dls ;; 1..dls are the names of the IP_DL objects ;; ;;***************************************************************************** ;; IP packet header def ;; masks for the Flag field IP_DONT_FRAG = 4000H IP_MORE_FRAG = 2000H SWAPPED_IP_DONT_FRAG = 40H SWAPPED_IP_MORE_FRAG = 20H ip STRUC ;; and IP packet ip_ver_size DB ? ip_tos DB ? ip_length DW ? ip_id DW ? ip_frag DW ? ip_ttl DB ? ip_proto DB ? ip_check DW ? ip_src DD ? ip_dst DD ? ip ENDS ip_data STRUC ip_write_dst DD ? ip_write_src DD ? ip_write_off DW ? ip_write_seg DW ? ip_write_gate DW ? ip_write_proto DB ? ip_write_dl DB ? ip_write_id DW ? ip_packet DW (dl_ip_max_mtu/2 + 16) dup (0) ip_header DW 32 dup (0) ip_broadcast DB ? ip_read_head DW ? ip_read_jmp DW 32 dup (0) ip_data ENDS ;;****************************************************************************** ;; IP_DECLARE name, dls ;; IP_DECLARE declares a network ojbect that will route packets ;; using 'router' as its routing table to the Data Link objects ;; 1..dls. ;; IP_DECLARE MACRO name, router, dls, icmp .DATA ip_&name&_dls = dls ip_&name&_router = router ip_&name&_icmp = icmp global ip_&name&_data:ip_data .CODE IRP idx, <1,2,3,4,5,6,7,8> if idx le ip_&name&_dls IP_DECLARE_HELPER name, idx endif endm global ip_&name&_read_packet:near global ip_&name&_prot_unreach:near global ip_&name&_w_access:near global ip_&name&_w_write:near global ip_&name&_real_define:near ENDM IP_DECLARE_HELPER MACRO name, dl global ip_&name&_dl_&dl&_read_start:near ENDM ;;***************************************************************************** ;; IP_DEFINE name ;; IP_DEFINE defines all of the data structures needed by IP and ;; initializes them. ;; IP_DEFINE MACRO name call ip_&name&_real_define ENDM IP_REAL_DEFINE MACRO name local around, skip .errb <name> ifdef ip_&name&_dls .DATA ip_&name&_data ip_data <> .CODE ip_&name&_real_define: jmp around ;; declare the 'this node' IP packet processor ip_&name&_read_packet: IP_PACKET_in_AX_BX_CX_ES name RET ip_&name&_prot_unreach: cmp ip_&name&_data.ip_broadcast, 0 jnz skip mov SI, BX IP_R_HEADER_in_ES_out_SI_const_BX_CX_DX_BP_DI_ES name ICMP_ERROR_in_SI_ES %ip_&name&_icmp, ICMP_UNREACHABLE, ICMP_UNREACH_PROTO, name skip: RET ip_&name&_w_access: IP_REAL_W_ACCESS_in_AX_BX_CX_DL_out_AX_DI_ES name RET ip_&name&_w_write: IP_REAL_W_WRITE_in_CX name, %ip_&name&_w_write RET around: ;; initialize the jump table mov AX, DS ;; initialize jump table mov ES, AX mov DI, offset ip_&name&_data.ip_read_jmp mov AX, offset ip_&name&_prot_unreach mov CX, 32 rep stosw ;; do all per DL initilization IRP idx, <1,2,3,4,5,6,7,8> if idx le ip_&name&_dls IP_INIT_DL name, idx endif endm RET endif ENDM ;;***************************************************************************** ;; IP_R_READ name, proto, code_label ;; IP_READ declares that the code starting at 'code_label' should ;; be called when a IP packet with protocol 'proto' is read in ;; The data in the IP packet is passed to the object in BX:ES the ;; protocol type in AX and the length of the data in CX. ;; When the code is done it should execute a RET instruction ;; If the source address is requires IP_R_SRC should be called ;; IP_R_READ MACRO name, proto, code_label .errb <code_label> mov word ptr ip_&name&_data.ip_read_jmp+2*(proto mod 32), offset code_label ENDM ;;***************************************************************************** ;; IP_R_SRC_in_SI_ES_out_AX_BX name ;; IP_R_SRC returns the source of the IP data packet pointed to by SI:ES ;; that was given to the IP_R_READ routine. The IP address is put in ;; AX,BX ;; IP_R_SRC_in_SI_ES_out_AX_BX_const_CX_DX_BP_SI_DI_ES MACRO name .errb <name> push SI IP_R_HEADER_in_ES_out_SI_const_BX_CX_DX_BP_DI_ES name add SI, ip_src mov AX, word ptr ES:[SI] mov BX, word ptr ES:[SI+2] pop SI ENDM ;;***************************************************************************** ;; IP_R_BROAD_in_SI_ES name, broadcast ;; IP_R_BROAD jumps to 'broadcast' if the IP packet pointed to by SI:ES ;; is a broadcast. ;; IP_R_BROAD_in_SI_ES_const_CX_DX_BP_SI_DI_ES MACRO name, broadcast .errb <name> cmp ip_&name&_data.ip_broadcast, 0 jnz broadcast ENDM ;;***************************************************************************** ;; IP_R_HEADER_in_ES_out_SI_const_BX_CX_DX_BP_DI_ES name ;; IP_R_HEADER_in_SI_ES_out_DI returns the IP header for the packet pointed ;; to by SI:ES. This routine must only be called in the routine specified ;; in R_READ. (this is meant so that you can send ICMP packets) ;; IP_R_HEADER_in_ES_out_SI_const_BX_CX_DX_BP_DI_ES MACRO name .errb <name> mov SI, word ptr ip_&name&_data.ip_read_head ;; save header pointer ENDM ;;***************************************************************************** ;; IP_W_ACCESS_in_AX_BX_CX_DL_out_AX_DI_ES name ;; IP_W_ACCESS retrieves a buffer to write the data for an IP packet. ;; AX,BX holds the destination IP address of the packet and DL holds ;; the protocol number of the packet. The output buffer is returned ;; in DI:ES. This routine might fail if CX exceeds the MTU of the ;; interface. Thus it is only guarenteed to succeed when ;; CX <= dl_ip_min_mtu. AX is 0 if everything was successful. ;; IP_W_ACCESS_in_AX_BX_CX_DL_out_AX_DI_ES MACRO name local call_OK CALL ip_&name&_w_access ENDM ;;***************************************************************************** ;; IP_REAL_W_ACCESS is the real provider of the W_ACCESS service. ;; IP_REAL_W_ACCESS_in_AX_BX_CX_DL_out_AX_DI_ES MACRO name local done, jmp_table, fail, return, forme .errb <name> .DATA ;; declare the jump table jmp_table dw done ;; dl 0 is undefined IRP idx, <1,2,3,4,5,6,7,8> if idx le ip_&name&_dls IP_INIT_DL_JMP_TAB name, idx, write_access endif endm .CODE mov word ptr ip_&name&_data.ip_write_dst, AX ;; save address mov word ptr ip_&name&_data.ip_write_dst+2, BX mov byte ptr ip_&name&_data.ip_write_proto, DL mov BP, CX ;; save CX mov CX, BX IP_COMPUTE_NET_in_AX_BX_out_AX_BX_const_CX_DX_BP_SI_DI_ES %ip_&name&_dls ROUTE_FIND_in_AX_BX_CX_out_AX_DL_const_BP_ES %ip_&name&_router, forme, fail mov byte ptr ip_&name&_data.ip_write_dl, DL mov word ptr ip_&name&_data.ip_write_gate, AX xor DH, DH ;; set up jump to proper DL shl DX, 1 mov DI, offset jmp_table add DI, DX jmp [DI] forme: fail: xor AX, AX dec AX jmp return ;; the above jump goes to one of the code fragments below IRP idx, <1,2,3,4,5,6,7,8> if idx le ip_&name&_dls IP_INIT_DL_LABEL name, idx, write_access IP_SAVE_SRC name, idx mov CX, BP ;; restore CX cmp CX, dl_ip_min_mtu ;; enforce length restriction ja fail DL_IP_W_ACCESS_in_CX_out_DI_ES_const_CX_BP idx, fail jmp done endif endm ;; the above code does NOT fall through done: mov word ptr ip_&name&_data.ip_write_off, DI mov word ptr ip_&name&_data.ip_write_seg, ES add DI, size ip xor AX, AX return: ENDM IP_SAVE_SRC MACRO name, dl mov AX, word ptr dl_ip_&dl&_ip mov word ptr ip_&name&_data.ip_write_src, AX mov AX, word ptr dl_ip_&dl&_ip+2 mov word ptr ip_&name&_data.ip_write_src+2, AX ENDM ;;***************************************************************************** ;; IP_W_WRITE_in_CX name ;; IP_W_WRITE tells the IP interface to send the PACKET that is been ;; loaded into the buffer DI:ES. The length of the packet is in CX ;; note that this IP level does NOT support fragmentation, so CX better ;; be less than the dl_ip_min_mtu ;; IP_W_WRITE_in_CX MACRO name .errb <name> CALL ip_&name&_w_write ENDM ;;***************************************************************************** ;; ;; IP_REAL_W_WRITE_in_CX is the real provider of the W_WRITE service. ;; it is identical in function to IP_W_WRITE. ;; IP_REAL_W_WRITE_in_CX MACRO name local done, jmp_table .errb <name> .DATA ;; declare the jump table jmp_table dw done ;; dl 0 is undefined IRP idx, <1,2,3,4,5,6,7,8> if idx le ip_&name&_dls IP_INIT_DL_JMP_TAB name, idx, write_it endif endm .CODE les DI, dword ptr ip_&name&_data.ip_write_off mov AX, 0045H ;; byte swapped length = 5 version = 4 tos = 0 mov BX, AX stosw add CX, size ip mov AX, CX ;; the length xchg AL, AH add BX, AX stosw mov AX, word ptr ip_&name&_data.ip_write_id adc BX, AX stosw inc AX mov word ptr ip_&name&_data.ip_write_id, AX mov AX, 0 stosw mov AL, 100 ;; the time to live mov AH, byte ptr ip_&name&_data.ip_write_proto adc BX, AX stosw inc DI inc DI ;; skip checksum mov SI, offset ip_&name&_data.ip_write_src lodsw adc BX, AX stosw lodsw adc BX, AX stosw mov SI, offset ip_&name&_data.ip_write_dst lodsw adc BX, AX stosw lodsw adc BX, AX adc BX, 0 stosw sub DI, 10 not BX mov AX, BX stosw ;; set out the packet mov AX, word ptr ip_&name&_data.ip_write_gate xor DH, DH ;; set up jump to proper DL mov DL, byte ptr ip_&name&_data.ip_write_dl shl DX, 1 mov DI, offset jmp_table add DI, DX jmp [DI] ;; the above jump goes to one of the code fragments below IRP idx, <1,2,3,4,5,6,7,8> if idx le ip_&name&_dls IP_INIT_DL_LABEL name, idx, write_it DL_IP_W_WRITE_in_AX_CX_const_BP idx jmp done endif endm ;; the above code does NOT fall through done: ENDM ;;***************************************************************************** ;; IP_INIT_DL name, dl ;; IP_INIT_DL initializes the data link interface 'dl' IP_INIT_DL MACRO name, dl local around .errb <dl> jmp around ;; This stuff can be compiled seperately ; IP_DL_PACKET_in_BX_ES name, dl ; DL_IP_R_RETURN dl ;; This does NOT fall through around: mov AX, DS ;; add the route for each directly connected interface mov ES, AX xor CX, CX mov SI, offset dl_ip_&dl&_net mov DI, offset dl_ip_&dl&_ip ROUTE_ADD_in_CX_SI_DI_ES_const_DI_ES %ip_&name&_router DL_IP_R_READ dl, ip_&name&_dl_&dl&_read_start ;; schedule the read ENDM ;;***************************************************************************** ;; IP_DL_PACKET_in_BX_ES name, read_dl ;; IP_DL_PACKET_in_BX_ES does the proessing of a packet that came from ;; a data link interface BX:ES points to the begining of the IP packet. ;; this is the routeine that does the routing and if it for this node ;; calls IP_PACKET_in_BX_ES ;; IP_DL_PACKET_in_BX_ES MACRO name, read_dl local forme, jmp_table, drop, ip_write_sav, ip_write_gate, ip_write_size local ip_write_sav_seg local drop_ttl, drop_route, broad_forme, redirect, continue_forme, ip_ok .errb <read_dl> .DATA ;; declare the jump table jmp_table dw drop ;; dl 0 is undefined IRP idx, <1,2,3,4,5,6,7,8> if idx le ip_&name&_dls IP_INIT_DL_JMP_TAB name, idx, read_dl&_write_start endif endm ip_write_size DW ? ip_write_sav DW ? ip_write_sav_seg DW ? ip_write_gate DW ? .CODE ip_&name&_dl_&read_dl&_read_start: mov ip_write_sav, BX mov CX, word ptr ES:[BX+ip_length] ;; make sure length reasonable xchg CH, CL ;; byte swap cmp CX, dl_ip_&read_dl&_mtu ja drop mov ip_write_size, CX DL_IP_IS_BROADCAST_in_BX_ES_const_AX_BX_CX_DX_BP_DI_ES read_dl jnz broad_forme mov BP, BX ;; save BX mov AX, word ptr ES:[BX+ip_dst] ;; get an IP packet mov BX, word ptr ES:[BX+ip_dst+2] mov CX, BX IP_COMPUTE_NET_in_AX_BX_out_AX_BX_const_CX_DX_BP_SI_DI_ES %ip_&name&_dls ROUTE_FIND_in_AX_BX_CX_out_AX_DL_const_BP_ES %ip_&name&_router, forme, drop_route mov word ptr ip_write_gate, AX mov SI, BP ;; restore pointer IP_DEC_TTL_in_SI_ES_const_BX_CX_DX_BP_SI_DI_ES drop_ttl xor DH, DH ;; set up jump to proper DL shl DX, 1 mov DI, offset jmp_table add DI, DX jmp [DI] ;; jump to proper DL ;; the above jump goes to one of the code fragments below IRP idx, <1,2,3,4,5,6,7,8> if idx le ip_&name&_dls IP_INIT_DL_LABEL name, idx, read_dl&_write_start if idx eq read_dl mov word ptr ip_write_sav_seg, ES endif IP_DL_TEST_BROAD_in_AX idx, drop mov BP, word ptr ip_write_sav IP_SEND_PACKET_in_BP_ES name, read_dl, idx, ip_write_gate if idx eq read_dl IP_DL_TEST_FLAGS idx, NO_REDIRECT jnz drop mov SI, word ptr ip_write_sav mov ES, word ptr ip_write_sav_seg IP_DL_ADDRESS_out_AX_const_BX_CX_DX_BP_SI_DI idx mov BX, word ptr ip_write_gate jmp redirect else jmp drop endif endif endm ;; the above code does NOT fall through drop_route: mov SI, BP ICMP_ERROR_in_SI_ES %ip_&name&_icmp, ICMP_UNREACHABLE, ICMP_UNREACH_HOST, name jmp drop redirect: ICMP_REDIRECT_in_AX_BX_SI_ES %ip_&name&_icmp, ICMP_REDIRECT_HOST, name jmp drop drop_ttl: ICMP_ERROR_in_SI_ES %ip_&name&_icmp, ICMP_TIME, ICMP_TIME_TTL, name jmp drop broad_forme: mov ip_&name&_data.ip_broadcast, 1 jmp continue_forme forme: mov ip_&name&_data.ip_broadcast, 0 continue_forme: mov BX, ip_write_sav mov CX, ip_write_size DL_IP_R_CONT_in_BX_CX_ES_const_BX_CX_DX_BP_SI_DI_ES read_dl, ip_ok mov SI, BX mov DI, offset ip_&name&_data.ip_packet mov DX, DS mov ES, DX DL_IP_COPY_in_CX_SI_DI_ES_out_SI_DI_const_BX_BP_ES read_dl mov BX, offset ip_&name&_data.ip_packet mov CX, ip_write_size ip_ok: CALL ip_&name&_read_packet drop: ENDM ;; this macro simply returns the first two bytes of IP address of 'mydl' IP_DL_ADDRESS_out_AX_const_BX_CX_DX_BP_SI_DI MACRO mydl mov AX, word ptr dl_ip_&mydl&_ip ENDM ;; this macro tests if the flag bit 'mybit' of the DL_IP 'name' is set IP_DL_TEST_FLAGS MACRO name, mybit test dl_ip_&name&_flags, mybit ENDM ;; This macro tests if the dest AX should be droped because it is a broadcast IP_DL_TEST_BROAD_in_AX MACRO name, drop local forward cmp AX, word ptr dl_ip_&name&_broad+2 ;; should we forward jnz forward test dl_ip_&name&_flags, NO_DIR_BROAD jnz drop forward: ENDM ;;***************************************************************************** ;; IP_INIT_DL_LABEL generates a code lable for use in a jump table for ;; 'name', 'dl'. 'suffix' is a unique suffix ;; IP_INIT_DL_LABEL MACRO name, dl, suffix ip_&name&_dl_&dl&_&suffix: ENDM ;;***************************************************************************** ;; IP_INIT_DL_JMP_TAB generates the table entry for the entry 'name', 'dl' ;; 'suffix' is a unique suffix. ;; This is meant for use in a .DATA section ;; IP_INIT_DL_JMP_TAB MACRO name, dl, suffix dw ip_&name&_dl_&dl&_&suffix ENDM ;;**************************************************************************** ;; IP_SEND_PACKET sends the packet pointed to by BP:ES of from the ;; DL 'read_dl' to the dl 'write_dl'. 'gate' is an address that contains ;; the last two bytes of the IP address. This is the routine that handles ;; IP fragmentation ;; IP_SEND_PACKET_in_BP_ES MACRO name, read_dl, write_dl, gate local done, frag_loop, size_ok, fragment, ip_head_len .DATA ip_head_len DW ? .CODE mov CX, ES:[BP+ip_length] xchg CH, CL if dl_ip_&read_dl&_mtu gt dl_ip_&write_dl&_mtu ;;is fragmenting EVER needed cmp CX, dl_ip_&write_dl&_mtu ja fragment endif DL_IP_W_ACCESS_in_CX_out_DI_ES_const_CX_BP write_dl, done mov SI, BP ;; restore SI mov BX, CX ;; save CX DL_IP_COPY_in_CX_SI_DI_ES_out_SI_DI_const_BX_BP_ES read_dl mov CX, BX ;; restore CX mov AX, word ptr gate DL_IP_W_WRITE_in_AX_CX_const_BP write_dl if dl_ip_&read_dl&_mtu gt dl_ip_&write_dl&_mtu ;;is fragmenting EVER needed jmp done fragment: test byte ptr ES:[SI+ip_frag], SWAPPED_IP_DONT_FRAG ;; OK to fragment? jnz done ;; compute the header size xor CX, CX ;; make CX hold the size of the IP header mov CL, ES:[BP+ip_ver_size] and CL, 0FH shl CL, 1 shl CL, 1 mov word ptr ip_head_len, CX mov AX, DS ;; copy the header mov ES, AX mov SI, BP mov DI, offset ip_&name&_data.ip_header DL_IP_COPY_in_CX_SI_DI_ES_out_SI_DI_const_BX_BP_ES read_dl mov BP, SI ;; save SI ;; fix checksum so it is correct when ip_frag = ip_len = 0 mov AX, word ptr ip_&name&_data.ip_header.ip_check add AX, word ptr ip_&name&_data.ip_header.ip_frag adc AX, word ptr ip_&name&_data.ip_header.ip_length adc AX, 0 mov word ptr ip_&name&_data.ip_header.ip_check, AX frag_loop: mov CX, dl_ip_&write_dl&_mtu ;; ask for biggest buffer DL_IP_W_ACCESS_in_CX_out_DI_ES_const_CX_BP write_dl, done mov DX, word ptr ip_head_len ;; copy the header mov CX, DX mov SI, offset ip_&name&_data.ip_header shr CX, 1 rep movsw sub DI, DX ;; make DI point to begining of the packet mov AX, word ptr ES:[DI+ip_frag] xchg AH, AL mov CX, word ptr ES:[DI+ip_length] xchg CH, CL cmp CX, dl_ip_&write_dl&_mtu ;; can we send it jbe size_ok mov CX, dl_ip_&write_dl&_mtu sub CX, DX ;; subtract the IP header length and CX, 0FFF8H ;; make multiple of 8 add CX, DX ;; add the IP header length or AX, IP_MORE_FRAG ;; indicate not the last size_ok: xchg CH, CL mov word ptr ES:[DI+ip_length], CX xchg AH, AL mov word ptr ES:[DI+ip_frag], AX mov BX, word ptr ES:[DI+ip_check] ;; fix up checksum sub BX, CX sbb BX, AX sbb BX, 0 mov word ptr ES:[DI+ip_check], BX ;; set up stuff for next round xchg CH, CL sub CX, DX ;; subtract the IP header length mov BX, CX shr BX, 1 shr BX, 1 shr BX, 1 mov AX, word ptr ip_&name&_data.ip_header.ip_frag xchg AH, AL add AX, BX xchg AH, AL mov word ptr ip_&name&_data.ip_header.ip_frag, AX mov BX, word ptr ip_&name&_data.ip_header.ip_length xchg BH, BL sub BX, CX xchg BH, BL mov word ptr ip_&name&_data.ip_header.ip_length, BX mov SI, BP ;; restore SI add DI, DX ;; restore DI mov BX, CX add BX, DX ;; BX holds total Lenght DL_IP_COPY_in_CX_SI_DI_ES_out_SI_DI_const_BX_BP_ES read_dl mov BP, SI ;; save SI mov AX, word ptr gate mov CX, BX DL_IP_W_WRITE_in_AX_CX_const_BP write_dl mov BX, word ptr ip_&name&_data.ip_header.ip_length xchg BH, BL cmp BX, word ptr ip_head_len ja frag_loop endif done: ENDM ;;****************************************************************************** ;; IP_DEC_TTL_in_BX_ES ;; IP_DEC_TTL decrements the TTL of the IP packet pointed to by SI:ES ;; and jumps to 'drop' if the TTL has expired. ;; IP_DEC_TTL_in_SI_ES_const_BX_CX_DX_BP_SI_DI_ES MACRO drop mov AL, byte ptr ES:[SI+ip_ttl] ;; decrement ttl sub AL, 01 ;; can't use dec (need carry) jbe drop mov byte ptr ES:[SI+ip_ttl], AL mov AX, word ptr ES:[SI+ip_check] ;; fix up checksum add AX, 1 ;; add 1 in 1's complement adc AX, 0 mov word ptr ES:[SI+ip_check], AX ENDM ;;****************************************************************************** ;; IP_COMPUTE_NET ;; IP_COMPUTE_NET takes an IP address in AX,BX and given the ip address ;; and the dl list 1..dls and computes the network part of the IP address ;; and returns it in AX,BX. ;; IP_COMPUTE_NET_in_AX_BX_out_AX_BX_const_CX_DX_BP_SI_DI_ES MACRO dls local done .errb <dls> IRP idx, <8,7,6,5,4,3,2,1> if idx le dls IP_CHECK_SUBNET_in_AX_BX_out_AX_BX_const_CX_DX_BP_SI_DI_ES idx, done endif endm IP_COMP_NET_in_AX_BX_out_AX_BX_const_CX_DX_BP_SI_DI_ES dls done: ENDM ;;****************************************************************************** ;; IP_COMP_NET is like IP_COMPUTE_NET but it does its computation based ONLY ;; on the Class of the IP address (No subnet checking ;; IP_COMP_NET_in_AX_BX_out_AX_BX_const_CX_DX_BP_SI_DI_ES MACRO dls local class_A, class_B, class_C test AL, 80h ;; normal IP network interpretation jz class_A test AL, 40h jz class_B jmp class_C class_A: xor AH, AH class_B: xor BL, BL class_C: xor BH, BH ENDM ;;****************************************************************************** ;; IP_CHECK_SUBNET ;; Check_subnet checks if the IP address in AX,BX matches the subnet of ;; the Data link interface 'dl'. If it does, it computes the network part ;; and returns it in AX,BX and then jumps to 'success' ;; IP_CHECK_SUBNET_in_AX_BX_out_AX_BX_const_CX_DX_BP_SI_DI_ES MACRO dl, success local fail, mask_it .errb <success> cmp AL, byte ptr dl_ip_&dl&_ip jnz fail test AL, 80H jz mask_it cmp AH, byte ptr dl_ip_&dl&_ip+1 jnz fail test AL, 40H jz mask_it cmp BL, byte ptr dl_ip_&dl&_ip+2 jnz fail mask_it: and BX, word ptr dl_ip_&dl&_mask+2 jmp success fail: ENDM ;;***************************************************************************** ;; IP_PACKET_in_BX_ES name ;; IP_PACKET_in_BX_ES does all the proessing of a packet that is destined ;; for this node. BX:ES points to the begining of the IP packet. ;; AX holds the hardware protocol number and CX holds the length of ;; the packet. ;; Basicly this routine just dispatches it to the proper READ routine ;; IP_PACKET_in_AX_BX_CX_ES MACRO name local drop .errb <name> test word ptr ES:[BX+ip_frag], 3FFFH ;; if fragmented jnz drop xor AH, AH mov AL, byte ptr ES:[BX+ip_proto] ;; load protocol mov word ptr ip_&name&_data.ip_read_head, BX ;; save header pointer xor DX, DX ;; compute the size of the header mov DL, ES:[BX+ip_ver_size] and DL, 0FH shl DX, 1 shl DX, 1 sub CX, DX add BX, DX mov DX, AX ;; jump to proper routine and DL, 1FH shl DX, 1 mov SI, offset ip_&name&_data.ip_read_jmp add SI, DX jmp [SI] ;; note this is NOT a call, ;; so when the code returns ;; it will return to the caller ;; of this routine drop: ENDM ;;***************************************************************************** ;; IP_ASCII_in_SI_DI_ES_out_DI converts the IP address stored at SI:DS ;; to ASCII dot notation in the buffer ENDING at DI:ES. DI:ES returns the ;; begining of the string generated. ;; IP_ASCII_in_SI_DI_ES_out_DI_const_BX_BP_ES MACRO local ip_loop, ip_loop_done std ;; count down mov CX, 4 add SI, 3 dec DI ip_loop: lodsb TO_ASCII_in_AL_DI_ES_out_DI_const_BX_CX_BP_SI_ES dec CX jz ip_loop_done mov AL, '.' stosb jmp ip_loop ip_loop_done: inc DI cld ;; count up again ENDM ;;***************************************************************************** ;; TO_ASCII converts the number in AL to ascii (decimal) and puts the resulting ;; string in the buffer whose END is pointed to by DI:ES. DI points to the ;; BEGINING of the string when it is done. THIS ROUTINE ASSUMES THE DIRECTION ;; FLAG IS COUNTING DOWN ;; TO_ASCII_in_AL_DI_ES_out_DI_const_BX_CX_BP_SI_ES MACRO local loop_write mov DL, 10 loop_write: ;; write in the number xor AH, AH idiv DL ;; AH = AL % 10 AL = AL / 10 xchg AL, AH add AL, 48 ;; add ascii '0' stosb mov AL, AH and AL, AL jnz loop_write ENDM