CONTRIB: hpack: add an hpack decoder

This decoder takes a series of hex codes on stdin using one line
per HEADERS frame and shows the decoded headers.

contrib/hpack/Makefile

@@ -1,5 +1,5 @@
-CFLAGS = -O2 -W -Wall -Wextra -g
-OBJS = gen-rht
+CFLAGS = -O2 -Wall -g -I../../include -I../../ebtree -fwrapv -fno-strict-aliasing
+OBJS = gen-rht decode
 
 all: $(OBJS)
 

contrib/hpack/decode.c

@@ -0,0 +1,210 @@
+/*
+ * HPACK stream decoder. Takes a series of hex codes on stdin using one line
+ * per HEADERS frame. Spaces, tabs, CR, '-' and ',' are silently skipped.
+ * e.g. :
+ *   echo 82864188f439ce75c875fa5784 | contrib/hpack/decode
+ *
+ * The DHT size may optionally be changed in argv[1].
+ *
+ * Build like this :
+ *    gcc -I../../include -I../../ebtree -O0 -g -fno-strict-aliasing -fwrapv \
+ *        -o decode decode.c
+ */
+#include <ctype.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <common/chunk.h>
+#include <common/hpack-dec.h>
+#include <common/mini-clist.h>
+#include <proto/h1.h>
+
+#define MAX_RQ_SIZE 65536
+#define MAX_HDR_NUM 1000
+
+char hex[MAX_RQ_SIZE*3+3]; // enough for "[ XX]* <CR> <LF> \0"
+uint8_t buf[MAX_RQ_SIZE];
+
+char trash_buf[MAX_RQ_SIZE];
+char tmp_buf[MAX_RQ_SIZE];
+
+struct chunk trash = { .str = trash_buf, .len = 0, .size = sizeof(trash_buf) };
+struct chunk tmp   = { .str = tmp_buf,   .len = 0, .size = sizeof(tmp_buf)   };
+
+/* displays a <len> long memory block at <buf>, assuming first byte of <buf>
+ * has address <baseaddr>. String <pfx> may be placed as a prefix in front of
+ * each line. It may be NULL if unused. The output is emitted to file <out>.
+ */
+void debug_hexdump(FILE *out, const char *pfx, const char *buf,
+                   unsigned int baseaddr, int len)
+{
+	unsigned int i;
+	int b, j;
+
+	for (i = 0; i < (len + (baseaddr & 15)); i += 16) {
+		b = i - (baseaddr & 15);
+		fprintf(out, "%s%08x: ", pfx ? pfx : "", i + (baseaddr & ~15));
+		for (j = 0; j < 8; j++) {
+			if (b + j >= 0 && b + j < len)
+				fprintf(out, "%02x ", (unsigned char)buf[b + j]);
+			else
+				fprintf(out, "   ");
+		}
+
+		if (b + j >= 0 && b + j < len)
+			fputc('-', out);
+		else
+			fputc(' ', out);
+
+		for (j = 8; j < 16; j++) {
+			if (b + j >= 0 && b + j < len)
+				fprintf(out, " %02x", (unsigned char)buf[b + j]);
+			else
+				fprintf(out, "   ");
+		}
+
+		fprintf(out, "   ");
+		for (j = 0; j < 16; j++) {
+			if (b + j >= 0 && b + j < len) {
+				if (isprint((unsigned char)buf[b + j]))
+					fputc((unsigned char)buf[b + j], out);
+				else
+					fputc('.', out);
+			}
+			else
+				fputc(' ', out);
+		}
+		fputc('\n', out);
+	}
+}
+
+/* enable DEBUG_HPACK to show each individual hpack code */
+#define DEBUG_HPACK
+#include "../src/hpack-huff.c"
+#include "../src/hpack-tbl.c"
+#include "../src/hpack-dec.c"
+
+/* display the message and exit with the code */
+__attribute__((noreturn)) void die(int code, const char *format, ...)
+{
+	va_list args;
+
+	if (format) {
+		va_start(args, format);
+		vfprintf(stderr, format, args);
+		va_end(args);
+	}
+	exit(code);
+}
+
+/* reads <hex> and stops at the first LF, '#' or \0. Converts from hex to
+ * binary, ignoring spaces, tabs, CR, "-" and ','. The output is sent into
+ * <bin> for no more than <size> bytes. The number of bytes placed there is
+ * returned, or a negative value in case of parsing error.
+ */
+int hex2bin(const char *hex, uint8_t *bin, int size)
+{
+	int a, b, c;
+	uint8_t code;
+	int len = 0;
+
+	a = b = -1;
+
+	for (; *hex; hex++) {
+		c = *hex;
+		if (c == ' ' || c == '\t' || c == '\r' ||
+		    c == '-' || c == ',')
+			continue;
+
+		if (c == '\n' || c == '#')
+			break;
+
+		if (c >= '0' && c <= '9')
+			c -= '0';
+		else if (c >= 'a' && c <= 'f')
+			c -= 'a' - 10;
+		else if (c >= 'A' && c <= 'F')
+			c -= 'A' - 10;
+		else
+			return -1;
+
+		if (a == -1)
+			a = c;
+		else
+			b = c;
+
+		if (b == -1)
+			continue;
+
+		code = (a << 4) | b;
+		a = b = -1;
+		if (len >= size)
+			return -2;
+
+		bin[len] = code;
+		len++;
+	}
+	if (a >= 0 || b >= 0)
+		return -3;
+	return len;
+}
+
+int main(int argc, char **argv)
+{
+	struct hpack_dht *dht;
+	struct http_hdr list[MAX_HDR_NUM];
+	int outlen;
+	int dht_size = 4096;
+	int len, idx;
+	int line;
+
+	/* first arg: dht size */
+	if (argc > 1) {
+		dht_size = atoi(argv[1]);
+		argv++;	argc--;
+	}
+
+	dht = hpack_dht_alloc(dht_size);
+	if (!dht) {
+		die(1, "cannot initialize dht\n");
+		return 1;
+	}
+
+	for (line = 1; fgets(hex, sizeof(hex), stdin); line++) {
+		len = hex2bin(hex, buf, sizeof(buf));
+		if (len <= 0)
+			continue;
+		printf("###### line %d : frame len=%d #######\n", line, len);
+		debug_hexdump(stdout, "   ", (const char *)buf, 0, len);
+
+		outlen = hpack_decode_frame(dht, buf, len, list,
+					    sizeof(list)/sizeof(list[0]), &tmp);
+		if (outlen <= 0) {
+			printf("   HPACK decoding failed: %d\n", outlen);
+			continue;
+		}
+
+		printf("<<< Found %d headers :\n", outlen);
+		for (idx = 0; idx < outlen - 1; idx++) {
+			//printf("      \e[1;34m%s\e[0m: ",
+			//       list[idx].n.ptr ? istpad(trash.str, list[idx].n).ptr : h2_phdr_to_str(list[idx].n.len));
+
+			//printf("\e[1;35m%s\e[0m\n", istpad(trash.str, list[idx].v).ptr);
+
+			printf("      %s: ", list[idx].n.ptr ?
+			       istpad(trash.str, list[idx].n).ptr :
+			       h2_phdr_to_str(list[idx].n.len));
+
+			printf("%s [n=(%p,%d) v=(%p,%d)]\n", istpad(trash.str, list[idx].v).ptr,
+			       list[idx].n.ptr, (int)list[idx].n.len, list[idx].v.ptr, (int)list[idx].v.len);
+		}
+		puts(">>>");
+#ifdef DEBUG_HPACK
+		printf("<<=== DHT dump [ptr=%p]:\n", dht);
+		hpack_dht_dump(stdout, dht);
+		puts("===>>");
+#endif
+	}
+	return 0;
+}