Created
April 30, 2014 22:15
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jmp and call generator
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#include <stdio.h> | |
#include <stdlib.h> | |
#include <string.h> | |
struct OpCode { | |
char* mne; | |
char* opcode; | |
}; | |
struct OpCode opcodes[] = { | |
{ "jmp", "\\xeb" }, | |
{ "long_jmp", "\\xe9" }, | |
{ "je" , "\\x74" }, | |
{ "long_je" , "\\x0f\\x84" }, | |
{ "jne", "\\x75" }, | |
{ "long_jne" , "\\x0f\\x85" }, | |
{ "jle", "\\x7e" }, | |
{ "long_jle", "\\x0f\\x8e" }, | |
{ "jl" , "\\x7c" }, | |
{ "jb" , "\\x72" }, | |
{ "long_jb", "\\x0f\\x82" }, | |
{ "jbe", "\\x76" }, | |
{ "jg" , "\\x7f" }, | |
{ "js" , "\\x78" }, | |
{ "long_js", "\\x0f\\x88" }, | |
{ "jns", "\\x79" }, | |
{ "ja" , "\\x77" }, | |
{ "jae", "\\x73" }, | |
{ "jge", "\\x7d" }, | |
{ "call", "\\xe8" }}; | |
int op_size = sizeof(opcodes) / sizeof(struct OpCode); | |
void generate(struct OpCode,char*,char*); | |
char* | |
getLong(char* op) | |
{ | |
int i; | |
char* tmp = malloc(5 + strlen(op)); | |
sprintf(tmp,"long_%s",op); | |
for(i = 0;i < op_size;i++) | |
if(!strcmp(opcodes[i].mne,tmp)) | |
return opcodes[i].opcode; | |
return NULL; | |
} | |
int | |
main(int argc,char* argv[]) | |
{ | |
int i; | |
if(argc == 4) | |
for(i = 0;i < op_size;i++) | |
if(!strcmp(argv[1],opcodes[i].mne)) | |
generate(opcodes[i],argv[2],argv[3]); | |
printf("* Instruction not found. Available instructions:\n"); | |
for(i = 0;i < op_size;i++) | |
if(strncmp(opcodes[i].mne,"long_",5) && opcodes[i].mne[0] != '*') | |
printf(" - %s\n",opcodes[i].mne); | |
return 0; | |
} | |
void | |
generate(struct OpCode code,char* address0,char* address1) | |
{ | |
int addr0,addr1; | |
unsigned char addr[5]; | |
signed int addr2; | |
if(!address0 || !address1) | |
exit(1); | |
sscanf(address0,"%x",&addr0); | |
sscanf(address1,"%x",&addr1); | |
addr2 = (signed int)(addr1 - addr0); | |
memcpy(addr, &addr2, 4); | |
if(address0[0] == '*') | |
{ | |
if(strcmp(code.mne,"jmp") && strcmp(code.mne,"call")) | |
{ | |
printf("* Error, indirect jump and call only available with jmp and call.\n"); | |
exit(1); | |
} | |
sscanf(address0 + 1,"%x",&addr0); | |
memcpy(addr, &addr0, 4); | |
printf("%s\\x%02x\\x%02x\\x%02x\\x%02x\n", | |
(!strcmp(code.mne,"jmp")) ? "\\xff\\x25" : "\\xff\\x15" , addr[0],addr[1],addr[2],addr[3]); | |
exit(0); | |
} | |
if(address0[0] == '%') | |
{ | |
printf("\\xff"); | |
if(!strcmp(address0, "%eax")) | |
printf("\\x%02x\n", ( code.mne[0] == 'j' ? 0xe0 : 0xd0 )); | |
else if(!strcmp(address0, "%ecx")) | |
printf("\\x%02x\n", ( code.mne[0] == 'j' ? 0xe1 : 0xd1 )); | |
else if(!strcmp(address0, "%edx")) | |
printf("\\x%02x\n", ( code.mne[0] == 'j' ? 0xe2 : 0xd2 )); | |
else if(!strcmp(address0, "%ebx")) | |
printf("\\x%02x\n", ( code.mne[0] == 'j' ? 0xe3 : 0xd3 )); | |
else if(!strcmp(address0, "%esp")) | |
printf("\\x%02x\n", ( code.mne[0] == 'j' ? 0xe4 : 0xd4 )); | |
else if(!strcmp(address0, "%ebp")) | |
printf("\\x%02x\n", ( code.mne[0] == 'j' ? 0xe5 : 0xd5 )); | |
else if(!strcmp(address0, "%esi")) | |
printf("\\x%02x\n", ( code.mne[0] == 'j' ? 0xe6 : 0xd6 )); | |
else if(!strcmp(address0, "%edi")) | |
printf("\\x%02x\n", ( code.mne[0] == 'j' ? 0xe7 : 0xd7 )); | |
exit(0); | |
} | |
if(!strcmp(code.mne,"call")) | |
{ | |
printf("%s\\x%02x\\x%02x\\x%02x\\x%02x\n", code.opcode, addr[0],addr[1],addr[2],addr[3]); | |
exit(0); | |
} | |
if(addr2 >= -99 && (addr2 <= 0xff)) | |
printf("%s\\x%02x\n",code.opcode, (unsigned char) addr[0]); | |
else | |
printf("%s\\x%02x\\x%02x\\x%02x\\x%02x\n",(getLong(code.mne) ? getLong(code.mne) : code.opcode ), addr[0],addr[1],addr[2],addr[3]); | |
exit(0); | |
} |
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