How to use strtok() and strstr() with arduino?
You have to define a format for the header you will be parsing and stick to that format. Say this is a sample header terminated by null:

s=123 d=789 e=463


A common property of each assignment in the string is the '=' symbol. You can use that to locate each variable and the value assigned to it. strchr is the function to use to locate a single character. Once you locate the = character, you move back and then forward along the array to obtain the variable and its value.

I will make some assumptions here: that your variable names will be single character, that numbers assigned will be no bigger than ints, and a space character is used to separate assignments.

char header[] = "s=123 d=789 e=463";

int d, s, e;   //your variables to be assigned to
char * ptr = header;
char * eq = NULL; //locate assmts
int * num = NULL; //just for starters
while (1){
  eq = strchr(ptr, '=');
  ptr = eq; // update the pointer
  if (ptr == NULL) // found no = chars
    break;
  switch (*(ptr - 1)){ 
    case 'd':    //all the possible variables
      num = &amp;d; break;
    case 's': 
      num = &amp;s; break;
    case 'e': 
      num = &amp;e; break;
    default:   //unknown variable
      num = NULL;
  }
  ptr++;
  if (num == NULL) //unrecognized var
    continue;   // locate next = char
  *num = 0;
  while (*ptr &amp;&amp; (*ptr != ' ')){  // while space or end of string not yet reached
    *num *= 10;  // extract each int
    *num += *ptr - '0';
    ptr++;
  }
}

Serial.println(d);  //now contains the numbers in the header
Serial.println(s);
Serial.println(e);


Untested but it should work for the header sample I gave.