user: 请从给定的汇编指令推导出C源代码:

```asm
<handle_ccn_signature>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  mov    %rdi,%rbp
  push   %rbx
  mov    %rsi,%rbx
  sub    $0x48,%rsp
  mov    %rdx,0x10(%rsp)
  lea    0x28(%rsp),%r13
  lea    0x24(%rsp),%r12
  lea    0x2c(%rsp),%r15
  mov    %fs:0x28,%rax
  mov    %rax,0x38(%rsp)
  xor    %eax,%eax
  movq   $0x0,(%rsp)
  movq   $0x0,0x8(%rsp)
  nopl   (%rax)
L140:
  mov    %r13,%rcx
  mov    %r12,%rdx
  mov    %rbx,%rsi
  mov    %rbp,%rdi
  call   <ccnl_ccnb_dehead@plt>
  test   %rax,%rax
  jne    L154
  mov    0x24(%rsp),%esi
  mov    0x28(%rsp),%edi
  test   %esi,%esi
  jne    L70
  test   %edi,%edi
  je     L154
L59:
  mov    (%rbx),%r14d
L92:
  xor    %r9d,%r9d
  xor    %r8d,%r8d
  mov    %rbx,%rcx
  mov    %rbp,%rdx
  call   <ccnl_ccnb_consume@plt>
  test   %rax,%rax
  jns    L140
  nopw   0x0(%rax,%rax,1)
L108:
  xor    %eax,%eax
L1:
  mov    0x38(%rsp),%rdx
  sub    %fs:0x28,%rdx
  jne    L95
  add    $0x48,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   (%rax)
L70:
  cmp    $0x2,%edi
  jne    L59
  cmp    $0xe,%esi
  je     L101
  mov    (%rbx),%r14d
  cmp    $0x36,%esi
  jne    L92
  mov    %r15,%r9
  lea    0x30(%rsp),%r8
  mov    %rbx,%rcx
  mov    %rbp,%rdx
  mov    $0x36,%esi
  mov    $0x2,%edi
  call   <ccnl_ccnb_consume@plt>
  test   %rax,%rax
  js     L108
  mov    0x2c(%rsp),%eax
  lea    0x1(%rax),%edi
  call   <malloc@plt>
  test   %rax,%rax
  je     L108
  mov    0x2c(%rsp),%edx
  mov    0x30(%rsp),%rsi
  mov    %rax,%rdi
  mov    %rax,0x18(%rsp)
  call   <memcpy@plt>
  mov    0x18(%rsp),%rcx
  movslq 0x2c(%rsp),%rax
  mov    (%rsp),%rdi
  movb   $0x0,(%rcx,%rax,1)
  call   <free@plt>
  mov    0x18(%rsp),%rcx
  mov    %rcx,(%rsp)
  jmp    L140
  nopl   0x0(%rax,%rax,1)
L101:
  mov    %r15,%r9
  lea    0x30(%rsp),%r8
  mov    %rbx,%rcx
  mov    %rbp,%rdx
  call   <ccnl_ccnb_consume@plt>
  test   %rax,%rax
  js     L108
  mov    0x2c(%rsp),%eax
  lea    0x1(%rax),%edi
  call   <malloc@plt>
  test   %rax,%rax
  je     L108
  mov    0x2c(%rsp),%edx
  mov    0x30(%rsp),%rsi
  mov    %rax,%rdi
  mov    %rax,0x18(%rsp)
  call   <memcpy@plt>
  mov    0x18(%rsp),%rcx
  movslq 0x2c(%rsp),%rax
  mov    0x8(%rsp),%rdi
  movb   $0x0,(%rcx,%rax,1)
  call   <free@plt>
  mov    0x18(%rsp),%rcx
  mov    %rcx,0x8(%rsp)
  jmp    L140
  xchg   %ax,%ax
L154:
  mov    0x10(%rsp),%rdi
  mov    (%rbx),%eax
  mov    0x0(%rbp),%rsi
  test   %rdi,%rdi
  je     L108
  lea    0x4(%rax),%ecx
  lea    -0x1(%rax),%edx
  sub    %ecx,%r14d
  mov    (%rsp),%rcx
  mov    %r14d,%r8d
  call   <verify@plt>
  jmp    L1
L95:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int handle_ccn_signature(unsigned char **buf, int *buflen, char *relay_public_key) {
  int num, typ, verified = 0, siglen;
  unsigned char *sigtype = 0, *sig = 0;
  while (ccnl_ccnb_dehead(buf, buflen, &num, &typ) == 0) {
    if (num == 0 && typ == 0)
      break;
    if (typ == 2 && num == 14) {
      char *s;
      unsigned char *valptr;
      int vallen;
      if (ccnl_ccnb_consume(typ, num, buf, buflen, &valptr, &vallen) < 0)
        goto Bail;
      s = malloc(vallen + 1);
      if (!s)
        goto Bail;
      memcpy(s, valptr, vallen);
      s[vallen] = '\0';
      free(sigtype);
      sigtype = (unsigned char *)s;
      continue;
    }
    do {
    } while (0);
    siglen = *buflen;
    if (typ == 2 && num == 54) {
      char *s;
      unsigned char *valptr;
      int vallen;
      if (ccnl_ccnb_consume(typ, num, buf, buflen, &valptr, &vallen) < 0)
        goto Bail;
      s = malloc(vallen + 1);
      if (!s)
        goto Bail;
      memcpy(s, valptr, vallen);
      s[vallen] = '\0';
      free(sig);
      sig = (unsigned char *)s;
      continue;
    }
    do {
    } while (0);
    if (ccnl_ccnb_consume(typ, num, buf, buflen, 0, 0) < 0)
      goto Bail;
  }
  siglen = siglen - ((*buflen) + 4);
  unsigned char *buf2 = *buf;
  int buflen2 = *buflen - 1;
  if (relay_public_key) {
    verified = verify(relay_public_key, buf2, buflen2, (unsigned char *)sig, siglen);
  }
Bail:
  return verified;
}
```