make it so

.gitignore

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+bin/

Makefile

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+TARGET=865
+BUILDDIR=bin/
+PREFIX=/usr/local/bin/
+MAIN=main.c
+override CFLAGS+=-Werror -Wall -g -fPIC -O2 -DNDEBUG -ftrapv -Wfloat-equal -Wundef -Wwrite-strings -Wuninitialized -pedantic -std=gnu11
+
+all: main.c
+	mkdir -p $(BUILDDIR)
+	$(CC) $(MAIN) -o $(BUILDDIR)$(TARGET) $(CFLAGS)
+
+install: all
+	install $(BUILDDIR)$(TARGET) $(PREFIX)$(TARGET)
+
+uninstall:
+	rm -rf $(PREFIX)$(TARGET)

README.md

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+# 865
+
+An implementation of [RFC 865](https://tools.ietf.org/html/rfc865), the “quote
+of the day” service, for the heck of it.
+
+## Limitations
+
+I don’t have many great quotes.

main.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+typedef struct {
+  char* said;
+  int len;
+} quote;
+
+quote** quotes = NULL;
+int n_quotes = 0;
+
+void die(const char *msg) {
+    perror(msg);
+    exit(1);
+}
+
+char* read_quotes_file() {
+  int size;
+  char* inp;
+  FILE* f = fopen("quotes.txt", "r");
+
+  if (!f) die("error reading quotes file");
+
+  fseek(f, 0, SEEK_END);
+  size = ftell(f);
+  fseek(f, 0, SEEK_SET);
+
+  inp = malloc(size+1);
+  fread(inp, size, 1, f);
+  fclose(f);
+
+  inp[size] = '\0';
+
+  return inp;
+}
+
+void make_quotes(char* contents) {
+  char* line;
+  quote* q;
+
+  while ((line = strsep(&contents, "\n"))) {
+    if (!strcmp(line, "")) continue;
+    q = malloc(sizeof(quote));
+    q->said = line;
+    q->len = strlen(line);
+    quotes = realloc(quotes, (++n_quotes)*sizeof(quote*));
+    quotes[n_quotes-1] = q;
+  }
+}
+
+void initialize_quotd() {
+  char* contents = read_quotes_file();
+
+  make_quotes(contents);
+}
+
+void cleanup_quotd() {
+  int i;
+
+  for (i = 0; i < n_quotes; i++) free(quotes[i]);
+  free(quotes);
+}
+
+int get_random_from_day() {
+  time_t t;
+  struct tm* tmp;
+  t = time(NULL);
+  tmp = localtime(&t);
+
+  srand(tmp->tm_yday); // hack to provide determinism per day.
+
+  return rand();
+}
+
+char* get_quotd(int* len) {
+  quote* q;
+  char* res;
+  int n;
+  n = get_random_from_day() % n_quotes;
+  q = quotes[n];
+  res = malloc(q->len+2);
+
+  snprintf(res, q->len+2, "%s\n", q->said);
+  *len = q->len+2;
+
+  return res;
+}
+
+int main(int argc, char *argv[]) {
+  int sockfd;
+  int newsockfd;
+  int port = 17;
+  socklen_t clilen;
+  struct sockaddr_in serv_addr, cli_addr;
+  int n;
+
+  initialize_quotd();
+
+  sockfd = socket(AF_INET, SOCK_STREAM, 0);
+  if (sockfd < 0) die("error opening socket.");
+
+  bzero((char *) &serv_addr, sizeof(serv_addr));
+  serv_addr.sin_family = AF_INET;
+  serv_addr.sin_addr.s_addr = INADDR_ANY;
+  serv_addr.sin_port = htons(port);
+  if (bind(sockfd, (struct sockaddr *) &serv_addr,
+     sizeof(serv_addr)) < 0) die("error binding socket.");
+
+  clilen = sizeof(cli_addr);
+
+  while (1) {
+    listen(sockfd, 5);
+
+    newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
+    if (newsockfd < 0) die("error accepting");
+
+    char* quotd = get_quotd(&n);
+    n = write(newsockfd, quotd, n);
+    free(quotd);
+    if (n < 0) die("error writing to socket");
+    close(newsockfd);
+  }
+
+  close(sockfd);
+  cleanup_quotd();
+  return 0;
+}

quotes.txt

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+"they're[timezones] a scourge upon the earth. the only thing worse than having timezones is not having timezones." -- Saul Pwanson
+"I know this will come as a shock to you, Mr. Goldwyn, but in all history, which has held billions and billions of human beings, not a single one ever had a happy ending." -- Dorothy Parker