#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <link.h>
#include <elf.h>

/*
 * this code resolves external library references etc.
 */

void resolve(void *l, char *what)
{
	struct link_map *lm = (struct link_map *)(l);
	
	Elf32_Dyn *dyn;
	Elf32_Sym *sym;
	char *strtab;
	
	for(;lm != NULL; lm = lm->l_next) {
		printf("load_addr: 0x%08x\n", lm->l_addr);
		printf("name: %s\n", lm->l_name);
		printf("dyn sect: 0x%08x\n", lm->l_ld);
		printf("lm->next: 0x%08x\n", lm->l_next);
		printf("--\n");

		dyn = (Elf32_Dyn *)(unsigned int)(lm->l_ld);
		sym = NULL;
		strtab = NULL;

		printf("dyn is @ 0x%08x\n", dyn); fflush(stdout);
		
		for(; dyn->d_tag != DT_NULL; dyn++) {
			if(dyn->d_tag == DT_STRTAB) strtab = (char *)(dyn->d_un.d_ptr);
			if(dyn->d_tag == DT_SYMTAB) sym = (Elf32_Sym *)(dyn->d_un.d_ptr);
		}
		
		while(sym) {
			if(sym->st_name > 0x10000) {
				printf("breaking cause sym->st_name is too large\n");
				break;
			}
			printf("%s\n", strtab + sym->st_name);
			printf("%d\n", sym->st_value);
			printf("%d\n", sym->st_info);
			printf("%d\n", sym->st_size);

			if(strcmp(strtab + sym->st_name, what)  == 0) {
				printf("--> we have found %s @ 0x%08x\n", strtab + sym->st_name, sym->st_value);
			}
			
			sym++;
		}
		
	}
}

int main(int argc, char **argv)
{
	Elf32_Ehdr *elf;
	Elf32_Phdr *phdr;
	Elf32_Dyn *dyn;
	int i, cnt;
	unsigned long *got;
	struct link_map *lm;

	elf = (Elf32_Ehdr *)((unsigned int)(main) & 0xfffff000);
	phdr = (Elf32_Phdr *)((unsigned char *)(elf) + elf->e_phoff);
	
	for(i = 0; i < elf->e_phnum; i++) {
		if(phdr[i].p_type == PT_DYNAMIC) break;
	}

	if(i == elf->e_phnum) {
		printf("Not a dynamic elf file?\n");
		exit(EXIT_FAILURE);
	}

	phdr += i;

	dyn = (Elf32_Dyn *)(phdr->p_vaddr);
	cnt = phdr->p_filesz / sizeof(Elf32_Dyn);

	got = NULL;
	for(i = 0; i < cnt; i++) {
		if(dyn[i].d_tag == DT_PLTGOT) got = (unsigned long *)(dyn[i].d_un.d_ptr);
	}

	if(got == NULL) {
		printf("Unable to find GOT\n");
		exit(EXIT_FAILURE);
	}

	lm = (struct link_map *)(got[1]);
	
	printf("link_map @ 0x%08x\n", lm);


	resolve(lm, "connect");
	resolve(lm, "read");
	
}