hook/table.c: Add IAT hooking mechanism

hook/meson.build

@@ -7,6 +7,8 @@ hook_lib = static_library(
         'pe.h',
         'peb.c',
         'peb.h',
+        'table.c',
+        'table.h',
     ],
 )
 

hook/table.c

@@ -0,0 +1,120 @@
+#include <windows.h>
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "hook/pe.h"
+#include "hook/peb.h"
+#include "hook/table.h"
+
+static void hook_table_apply_to_all(
+        const char *depname,
+        const struct hook_symbol *syms,
+        size_t nsyms);
+
+static void hook_table_apply_to_iid(
+        HMODULE target,
+        const pe_iid_t *iid,
+        const struct hook_symbol *syms,
+        size_t nsyms);
+
+static bool hook_table_match_proc(
+        const struct pe_iat_entry *iate,
+        const struct hook_symbol *sym);
+
+static void hook_table_apply_to_all(
+        const char *depname,
+        const struct hook_symbol *syms,
+        size_t nsyms)
+{
+    const peb_dll_t *dll;
+    HMODULE pe;
+
+    for (   dll = peb_dll_get_first() ;
+            dll != NULL ;
+            dll = peb_dll_get_next(dll)) {
+        pe = peb_dll_get_base(dll);
+
+        if (pe == NULL) {
+            continue; /* ?? Happens sometimes. */
+        }
+
+        hook_table_apply(pe, depname, syms, nsyms);
+    }
+}
+
+void hook_table_apply(
+        HMODULE target,
+        const char *depname,
+        const struct hook_symbol *syms,
+        size_t nsyms)
+{
+    const pe_iid_t *iid;
+    const char *iid_name;
+
+    assert(depname != NULL);
+    assert(syms != NULL || nsyms == 0);
+
+    if (target == NULL) {
+        /*  Call out, which will then call us back repeatedly. Awkward, but
+            viewed from the outside it's good for usability. */
+
+        hook_table_apply_to_all(depname, syms, nsyms);
+    } else {
+        for (   iid = pe_iid_get_first(target) ;
+                iid != NULL ;
+                iid = pe_iid_get_next(target, iid)) {
+            iid_name = pe_iid_get_name(target, iid);
+
+            if (_stricmp(iid_name, depname) == 0) {
+                hook_table_apply_to_iid(target, iid, syms, nsyms);
+            }
+        }
+    }
+}
+
+static void hook_table_apply_to_iid(
+        HMODULE target,
+        const pe_iid_t *iid,
+        const struct hook_symbol *syms,
+        size_t nsyms)
+{
+    struct pe_iat_entry iate;
+    size_t i;
+    size_t j;
+    const struct hook_symbol *sym;
+
+    i = 0;
+
+    while (pe_iid_get_iat_entry(target, iid, i++, &iate) == S_OK) {
+        for (j = 0 ; j < nsyms ; j++) {
+            sym = &syms[j];
+
+            if (hook_table_match_proc(&iate, sym)) {
+                if (sym->link != NULL) {
+                    *sym->link = *iate.ppointer;
+                }
+
+                pe_patch(iate.ppointer, &sym->patch, sizeof(sym->patch));
+            }
+        }
+    }
+}
+
+static bool hook_table_match_proc(
+        const struct pe_iat_entry *iate,
+        const struct hook_symbol *sym)
+{
+    if (    sym->name != NULL &&
+            iate->name != NULL &&
+            strcmp(sym->name, iate->name) == 0) {
+        return true;
+    }
+
+    if (sym->ordinal != 0 && sym->ordinal == iate->ordinal) {
+        return true;
+    }
+
+    return false;
+}

hook/table.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include <windows.h>
+
+#include <stddef.h>
+#include <stdint.h>
+
+struct hook_symbol {
+    const char *name;
+    uint16_t ordinal;
+    void *patch;
+    void **link;
+};
+
+void hook_table_apply(
+        HMODULE target,
+        const char *depname,
+        const struct hook_symbol *syms,
+        size_t nsyms);
+
+void hook_table_revert(
+        HMODULE target,
+        const char *depname,
+        const struct hook_symbol *syms,
+        size_t nsyms);