MINOR: peers: Replace hard-coded for peer protocol 64-bits value encoding by macros.
With this patch we define macros for the minimum values which are
encoded for 2 up to 10 bytes. This latter is big enough to encode
UINT64_MAX. We replaced at several places 240 value by PEER_ENC_2BYTES_MIN
which is the minimum value which is encoded with 2 bytes. The peer protocol
encoding consisting in encoding with only one byte a value which is
less than PEER_ENC_2BYTES_MIN and with at least 2 bytes a 64-bits value greater
than PEER_ENC_2BYTES_MIN.
diff --git a/src/peers.c b/src/peers.c
index d4fc812..039a625 100644
--- a/src/peers.c
+++ b/src/peers.c
@@ -172,6 +172,32 @@
/* The maximum length of an encoded data length. */
#define PEER_MSG_ENC_LENGTH_MAXLEN 5
+/* Minimum 64-bits value encoded with 2 bytes */
+#define PEER_ENC_2BYTES_MIN 0xf0 /* 0xf0 (or 240) */
+/* 3 bytes */
+#define PEER_ENC_3BYTES_MIN ((1ULL << 11) | PEER_ENC_2BYTES_MIN) /* 0x8f0 (or 2288) */
+/* 4 bytes */
+#define PEER_ENC_4BYTES_MIN ((1ULL << 18) | PEER_ENC_3BYTES_MIN) /* 0x408f0 (or 264432) */
+/* 5 bytes */
+#define PEER_ENC_5BYTES_MIN ((1ULL << 25) | PEER_ENC_4BYTES_MIN) /* 0x20408f0 (or 33818864) */
+/* 6 bytes */
+#define PEER_ENC_6BYTES_MIN ((1ULL << 32) | PEER_ENC_5BYTES_MIN) /* 0x1020408f0 (or 4328786160) */
+/* 7 bytes */
+#define PEER_ENC_7BYTES_MIN ((1ULL << 39) | PEER_ENC_6BYTES_MIN) /* 0x81020408f0 (or 554084600048) */
+/* 8 bytes */
+#define PEER_ENC_8BYTES_MIN ((1ULL << 46) | PEER_ENC_7BYTES_MIN) /* 0x4081020408f0 (or 70922828777712) */
+/* 9 bytes */
+#define PEER_ENC_9BYTES_MIN ((1ULL << 53) | PEER_ENC_8BYTES_MIN) /* 0x204081020408f0 (or 9078122083518704) */
+/* 10 bytes */
+#define PEER_ENC_10BYTES_MIN ((1ULL << 60) | PEER_ENC_9BYTES_MIN) /* 0x10204081020408f0 (or 1161999626690365680) */
+
+/* #7 bit used to detect the last byte to be encoded */
+#define PEER_ENC_STOP_BIT 7
+/* The byte minimum value with #7 bit set */
+#define PEER_ENC_STOP_BYTE (1 << PEER_ENC_STOP_BIT)
+/* The left most number of bits set for PEER_ENC_2BYTES_MIN */
+#define PEER_ENC_2BYTES_MIN_BITS 4
+
#define PEER_MSG_HEADER_LEN 2
#define PEER_STKT_CACHE_MAX_ENTRIES 128
@@ -260,17 +286,17 @@
unsigned char *msg;
msg = (unsigned char *)*str;
- if (i < 240) {
+ if (i < PEER_ENC_2BYTES_MIN) {
msg[0] = (unsigned char)i;
*str = (char *)&msg[idx+1];
return (idx+1);
}
- msg[idx] =(unsigned char)i | 240;
- i = (i - 240) >> 4;
- while (i >= 128) {
- msg[++idx] = (unsigned char)i | 128;
- i = (i - 128) >> 7;
+ msg[idx] =(unsigned char)i | PEER_ENC_2BYTES_MIN;
+ i = (i - PEER_ENC_2BYTES_MIN) >> PEER_ENC_2BYTES_MIN_BITS;
+ while (i >= PEER_ENC_STOP_BYTE) {
+ msg[++idx] = (unsigned char)i | PEER_ENC_STOP_BYTE;
+ i = (i - PEER_ENC_STOP_BYTE) >> PEER_ENC_STOP_BIT;
}
msg[++idx] = (unsigned char)i;
*str = (char *)&msg[idx+1];
@@ -297,14 +323,14 @@
goto fail;
i = *(msg++);
- if (i >= 240) {
- shift = 4;
+ if (i >= PEER_ENC_2BYTES_MIN) {
+ shift = PEER_ENC_2BYTES_MIN_BITS;
do {
if (msg >= (unsigned char *)end)
goto fail;
i += (uint64_t)*msg << shift;
- shift += 7;
- } while (*(msg++) >= 128);
+ shift += PEER_ENC_STOP_BIT;
+ } while (*(msg++) >= PEER_ENC_STOP_BYTE);
}
*str = (char *)msg;
return i;
@@ -1652,7 +1678,7 @@
*totl += reql;
- if ((unsigned int)msg_head[2] < 240) {
+ if ((unsigned int)msg_head[2] < PEER_ENC_2BYTES_MIN) {
*msg_len = msg_head[2];
}
else {