133 lines
3.9 KiB
C
133 lines
3.9 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <ctype.h>
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#include <string.h>
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#include <assert.h>
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#include <arpa/inet.h>
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#include <netdb.h>
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#include <limits.h>
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// Mostly lifted from https://cs.nyu.edu/~mwalfish/classes/16sp/classnotes/handout01.pdf
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void panic(const char* s) {
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perror(s);
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exit(1);
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}
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struct Message {
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int priority;
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};
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int parse_message(struct Message* result, char* message) {
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/*
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parse a message like:
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<134>May 10 03:09:59 filterlog: 5,,,1000000103,cpsw0,match,block,in,4,0x20,,239,27547,0,none,6,tcp,40,185.216.140.37,24.4.129.164,57159,11111,0,S,3919167832,,1024,,
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Format:
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<priority>VERSION ISOTIMESTAMP HOSTNAME APPLICATION PID MESSAGEID STRUCTURED-DATA MSG
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Assumes null termed string
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*/
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printf("Got message: %s\n", message);
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// Must have >3 chars to form <x> priority
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if (strlen(message) < 3) return 1;
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// Must start with <
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if (message[0] != '<') return 1;
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printf("%lu\n", strlen(message));
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// const char delim = " "
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char digits[] = "\0\0\0";
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int num_digits = 0;
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int position = 1;
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//bool found_priority_end = false; // TODO
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while (position < 4) {
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printf("inspecting %c\n", message[position]);
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if(!isdigit(message[position])) return 1; // priority must be numeric
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digits[num_digits] = message[position];
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num_digits++;
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position++;
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if (message[position] == '>') {
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break;
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}
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// break;
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}
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if (num_digits == 0) return 1; // empty priority >< ?
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printf("found digits %d, aka %d\n", atoi(digits), atoi(digits)/2);
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// result = Message{atoi(digits)};
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result->priority = atoi(digits);
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// assert(0);
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// *strtok(char *str, const char *delim)
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}
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int main(int argc, char** argv) {
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int sock_fd;
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struct sockaddr_in my_addr, my_peer_addr;
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char* endptr;
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unsigned int portl;
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unsigned short port;
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int size_recvd;
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char msg[1024];
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socklen_t addrlen;
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if (argc != 2) {
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fprintf(stderr, "usage: %s <port>\n", argv[0]);
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exit(1);
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}
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/* convert from string to int */
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portl = strtol(argv[1], &endptr, 10);
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if (endptr == NULL || portl == 0)
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panic("strtol");
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assert(portl < USHRT_MAX);
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port = (unsigned short)portl;
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/*
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* Note! This code is not the same as what you need to do in lab1.
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*/
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if ((sock_fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
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panic("socket");
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int one = 1;
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setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(1));
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memset(&my_addr, 0, sizeof(my_addr));
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my_addr.sin_family = AF_INET;
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my_addr.sin_addr.s_addr = INADDR_ANY;
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my_addr.sin_port = htons(port);
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if (bind(sock_fd, (struct sockaddr*)&my_addr, sizeof(struct sockaddr_in)) < 0)
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panic("bind failed");
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while (1) {
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addrlen = sizeof(struct sockaddr_in);
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if ((size_recvd = recvfrom(sock_fd, /* socket */
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msg, /* buffer */
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sizeof(msg), /* size of buffer */
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0, /* flags = 0 */
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(struct sockaddr*)&my_peer_addr, /* who’s sending */
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&addrlen /* length of buffer to receive peer info */
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)) < 0)
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panic("recvfrom");
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assert(addrlen == sizeof(struct sockaddr_in));
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// TODO should we check that msg[size_recvd] == \0 ?
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// printf("From host %s src port %d got message %.*s\n",
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// inet_ntoa(my_peer_addr.sin_addr), ntohs(my_peer_addr.sin_port), size_recvd, msg);
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struct Message result;
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// printf("XXXsize: %lu", sizeof(result)); // curious how big the struct gets
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if(parse_message(&result, msg)) {
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printf("message is valid, priority %d\n", result.priority);
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}
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}
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exit(EXIT_SUCCESS);
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}
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