user: What is the c source code of the assembly code below?

```asm
<lookup>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %r14
  push   %r13
  push   %r12
  mov    %rdi,%r12
  push   %rbx
  sub    $0x10,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,-0x28(%rbp)
  xor    %eax,%eax
  call   <strlen@plt>
  mov    %rsp,%rdi
  lea    0x10(%rax),%rdx
  mov    %rax,%rcx
  mov    %rdx,%rsi
  and    $0xfffffffffffff000,%rdx
  sub    %rdx,%rdi
  and    $0xfffffffffffffff0,%rsi
  cmp    %rdi,%rsp
  je     L31
L137:
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  cmp    %rdi,%rsp
  jne    L137
L31:
  and    $0xfff,%esi
  sub    %rsi,%rsp
  test   %rsi,%rsi
  jne    L96
L86:
  mov    %rsp,%r13
  test   %eax,%eax
  jle    L89
  lea    -0x1(%rax),%r14d
  xor    %ebx,%ebx
  xchg   %ax,%ax
L67:
  movsbl (%r12,%rbx,1),%edi
  call   <tolower@plt>
  mov    %al,0x0(%r13,%rbx,1)
  mov    %rbx,%rax
  add    $0x1,%rbx
  cmp    %rax,%r14
  jne    L67
  mov    %r12,%rdi
  call   <strlen@plt>
  mov    %rax,%rcx
L89:
  lea    D76(%rip),%rsi
  mov    %r13,%rdi
  movb   $0x0,0x0(%r13,%rcx,1)
  call   <strcmp@plt>
  mov    %rax,%r8
  lea    D105(%rip),%rax
  test   %r8,%r8
  je     L46
  lea    D92(%rip),%rsi
  mov    %r13,%rdi
  call   <strcmp@plt>
  mov    %rax,%r8
  lea    D9(%rip),%rax
  test   %r8,%r8
  je     L46
  lea    D24(%rip),%rsi
  mov    %r13,%rdi
  call   <strcmp@plt>
  mov    %rax,%r8
  lea    D130(%rip),%rax
  test   %r8,%r8
  jne    L121
  cs nopw 0x0(%rax,%rax,1)
L46:
  mov    -0x28(%rbp),%rdx
  sub    %fs:0x28,%rdx
  jne    L5
  lea    -0x20(%rbp),%rsp
  pop    %rbx
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %rbp
  ret
L96:
  orq    $0x0,-0x8(%rsp,%rsi,1)
  jmp    L86
  nopl   0x0(%rax,%rax,1)
L121:
  lea    D111(%rip),%rsi
  mov    %r13,%rdi
  call   <strcmp@plt>
  mov    %rax,%r8
  lea    D124(%rip),%rax
  test   %r8,%r8
  je     L46
  lea    D36(%rip),%rsi
  mov    %r13,%rdi
  call   <strcmp@plt>
  mov    %rax,%r8
  lea    D46(%rip),%rax
  test   %r8,%r8
  je     L46
  lea    D107(%rip),%rsi
  mov    %r13,%rdi
  call   <strcmp@plt>
  mov    %rax,%r8
  lea    D62(%rip),%rax
  test   %r8,%r8
  je     L46
  lea    D127(%rip),%rsi
  mov    %r13,%rdi
  call   <strcmp@plt>
  mov    $0x0,%edx
  test   %rax,%rax
  lea    D90(%rip),%rax
  cmovne %rdx,%rax
  jmp    L46
L5:
  call   <__stack_chk_fail@plt>
```

tool_calls: name: extract_symbolic_data
arguments: tag: D76
type_infered: string
name: extract_symbolic_data
arguments: tag: D105
type_infered: string
name: extract_symbolic_data
arguments: tag: D92
type_infered: string
name: extract_symbolic_data
arguments: tag: D9
type_infered: string
name: extract_symbolic_data
arguments: tag: D24
type_infered: string
name: extract_symbolic_data
arguments: tag: D130
type_infered: string
name: extract_symbolic_data
arguments: tag: D111
type_infered: string
name: extract_symbolic_data
arguments: tag: D124
type_infered: string
name: extract_symbolic_data
arguments: tag: D36
type_infered: string
name: extract_symbolic_data
arguments: tag: D46
type_infered: string
name: extract_symbolic_data
arguments: tag: D107
type_infered: string
name: extract_symbolic_data
arguments: tag: D62
type_infered: string
name: extract_symbolic_data
arguments: tag: D127
type_infered: string
name: extract_symbolic_data
arguments: tag: D90
type_infered: string

tool: D76: css

tool: D105: text/css

tool: D92: html

tool: D9: text/html

tool: D24: js

tool: D130: text/javascript

tool: D111: gif

tool: D124: image/gif

tool: D36: ico

tool: D46: image/x-icon

tool: D107: jpg

tool: D62: image/jpg

tool: D127: png

tool: D90: image/png

assistant: ```c
const char *lookup(const char *extension) {
  char ext[strlen(extension) + 1];
  for (int i = 0, extlen = strlen(extension); i < extlen; i++)
    ext[i] = tolower(extension[i]);
  ext[strlen(extension)] = '\0';
  if (strcmp(ext, "css") == 0)
    return "text/css";
  else if (strcmp(ext, "html") == 0)
    return "text/html";
  else if (strcmp(ext, "js") == 0)
    return "text/javascript";
  else if (strcmp(ext, "gif") == 0)
    return "image/gif";
  else if (strcmp(ext, "ico") == 0)
    return "image/x-icon";
  else if (strcmp(ext, "jpg") == 0)
    return "image/jpg";
  else if (strcmp(ext, "png") == 0)
    return "image/png";
  else
    return NULL;
}
```