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RTMPDump（libRTMP）源代码分析 2：解析RTMP地址——RTMP_ParseURL()

2013-10-22 21:04 375 查看

“://”之前的是使用的协议类型，可以是rtmp，rtmpt，rtmps等

之后是服务器地址

再之后是端口号（可以没有，默认1935）

在之后是application的名字，在这里是“vod”

最后是流媒体文件路径。

关于URL就不多说了，可以查看相关文档，下面贴上注释后的代码（整个parseurl.c）：

/*
* 本文件主要包含了对输入URL的解析
*/
#include "stdafx.h"
#include <stdlib.h>
#include <string.h>

#include <assert.h>
#include <ctype.h>

#include "rtmp_sys.h"
#include "log.h"

/*解析URL，得到协议名称(protocol)，主机名称(host)，应用程序名称(app)
*
*/
int RTMP_ParseURL(const char *url, int *protocol, AVal *host, unsigned int *port,
AVal *playpath, AVal *app)
{
char *p, *end, *col, *ques, *slash;

RTMP_Log(RTMP_LOGDEBUG, "Parsing...");

*protocol = RTMP_PROTOCOL_RTMP;
*port = 0;
playpath->av_len = 0;
playpath->av_val = NULL;
app->av_len = 0;
app->av_val = NULL;

/* 字符串解析 */
/* 查找“://”  */
//函数原型：char *strstr(char *str1, char *str2);
//功能：找出str2字符串在str1字符串中第一次出现的位置（不包括str2的串结束符）。
//返回值：返回该位置的指针，如找不到，返回空指针。
p = strstr((char *)url, "://");
if(!p) {
RTMP_Log(RTMP_LOGERROR, "RTMP URL: No :// in url!");
return FALSE;
}
{
//指针相减，返回“://”之前字符串长度len
int len = (int)(p-url);
//获取使用的协议
//通过比较字符串的方法
if(len == 4 && strncasecmp(url, "rtmp", 4)==0)
*protocol = RTMP_PROTOCOL_RTMP;
else if(len == 5 && strncasecmp(url, "rtmpt", 5)==0)
*protocol = RTMP_PROTOCOL_RTMPT;
else if(len == 5 && strncasecmp(url, "rtmps", 5)==0)
*protocol = RTMP_PROTOCOL_RTMPS;
else if(len == 5 && strncasecmp(url, "rtmpe", 5)==0)
*protocol = RTMP_PROTOCOL_RTMPE;
else if(len == 5 && strncasecmp(url, "rtmfp", 5)==0)
*protocol = RTMP_PROTOCOL_RTMFP;
else if(len == 6 && strncasecmp(url, "rtmpte", 6)==0)
*protocol = RTMP_PROTOCOL_RTMPTE;
else if(len == 6 && strncasecmp(url, "rtmpts", 6)==0)
*protocol = RTMP_PROTOCOL_RTMPTS;
else {
RTMP_Log(RTMP_LOGWARNING, "Unknown protocol!\n");
goto parsehost;
}
}

RTMP_Log(RTMP_LOGDEBUG, "Parsed protocol: %d", *protocol);

parsehost:
//获取主机名称
//跳过“://”
p+=3;

/* 检查一下主机名 */
if(*p==0) {
RTMP_Log(RTMP_LOGWARNING, "No hostname in URL!");
return FALSE;
}
//原型：char *strchr(const char *s,char c);
//功能：查找字符串s中首次出现字符c的位置
//说明：返回首次出现c的位置的指针，如果s中不存在c则返回NULL。
end   = p + strlen(p);//指向结尾的指针
col   = strchr(p, ':');//指向冒号（第一个）的指针
ques  = strchr(p, '?');//指向问号（第一个）的指针
slash = strchr(p, '/');//指向斜杠（第一个）的指针

{
int hostlen;
if(slash)
hostlen = slash - p;
else
hostlen = end - p;
if(col && col -p < hostlen)
hostlen = col - p;

if(hostlen < 256) {
host->av_val = p;
host->av_len = hostlen;
RTMP_Log(RTMP_LOGDEBUG, "Parsed host    : %.*s", hostlen, host->av_val);
} else {
RTMP_Log(RTMP_LOGWARNING, "Hostname exceeds 255 characters!");
}

p+=hostlen;
}

/* 获取端口号 */
if(*p == ':') {
unsigned int p2;
p++;
p2 = atoi(p);
if(p2 > 65535) {
RTMP_Log(RTMP_LOGWARNING, "Invalid port number!");
} else {
*port = p2;
}
}

if(!slash) {
RTMP_Log(RTMP_LOGWARNING, "No application or playpath in URL!");
return TRUE;
}
p = slash+1;

{
/* 获取应用程序(application)
*
* rtmp://host[:port]/app[/appinstance][/...]
* application = app[/appinstance]
*/

char *slash2, *slash3 = NULL;//指向第二个斜杠，第三个斜杠的指针
int applen, appnamelen;

slash2 = strchr(p, '/');//指向第二个斜杠
if(slash2)
slash3 = strchr(slash2+1, '/');//指向第三个斜杠，注意slash2之所以+1是因为让其后移一位

applen = end-p; /* ondemand, pass all parameters as app */
appnamelen = applen; /* ondemand length */

if(ques && strstr(p, "slist=")) { /* whatever it is, the '?' and slist= means we need to use everything as app and parse plapath from slist= */
appnamelen = ques-p;
}
else if(strncmp(p, "ondemand/", 9)==0) {
/* app = ondemand/foobar, only pass app=ondemand */
applen = 8;
appnamelen = 8;
}
else { /* app!=ondemand, so app is app[/appinstance] */
if(slash3)
appnamelen = slash3-p;
else if(slash2)
appnamelen = slash2-p;

applen = appnamelen;
}

app->av_val = p;
app->av_len = applen;
RTMP_Log(RTMP_LOGDEBUG, "Parsed app     : %.*s", applen, p);

p += appnamelen;
}

if (*p == '/')
p++;

if (end-p) {
AVal av = {p, end-p};
RTMP_ParsePlaypath(&av, playpath);
}

return TRUE;
}

/*
* 从URL中获取播放路径（playpath）。播放路径是URL中“rtmp://host:port/app/”后面的部分
*
* 获取FMS能够识别的播放路径
* mp4 流: 前面添加 "mp4:", 删除扩展名
* mp3 流: 前面添加 "mp3:", 删除扩展名
* flv 流: 删除扩展名
*/
void RTMP_ParsePlaypath(AVal *in, AVal *out) {
int addMP4 = 0;
int addMP3 = 0;
int subExt = 0;
const char *playpath = in->av_val;
const char *temp, *q, *ext = NULL;
const char *ppstart = playpath;
char *streamname, *destptr, *p;

int pplen = in->av_len;

out->av_val = NULL;
out->av_len = 0;

if ((*ppstart == '?') &&
(temp=strstr(ppstart, "slist=")) != 0) {
ppstart = temp+6;
pplen = strlen(ppstart);

temp = strchr(ppstart, '&');
if (temp) {
pplen = temp-ppstart;
}
}

q = strchr(ppstart, '?');
if (pplen >= 4) {
if (q)
ext = q-4;
else
ext = &ppstart[pplen-4];
if ((strncmp(ext, ".f4v", 4) == 0) ||
(strncmp(ext, ".mp4", 4) == 0)) {
addMP4 = 1;
subExt = 1;
/* Only remove .flv from rtmp URL, not slist params */
} else if ((ppstart == playpath) &&
(strncmp(ext, ".flv", 4) == 0)) {
subExt = 1;
} else if (strncmp(ext, ".mp3", 4) == 0) {
addMP3 = 1;
subExt = 1;
}
}

streamname = (char *)malloc((pplen+4+1)*sizeof(char));
if (!streamname)
return;

destptr = streamname;
if (addMP4) {
if (strncmp(ppstart, "mp4:", 4)) {
strcpy(destptr, "mp4:");
destptr += 4;
} else {
subExt = 0;
}
} else if (addMP3) {
if (strncmp(ppstart, "mp3:", 4)) {
strcpy(destptr, "mp3:");
destptr += 4;
} else {
subExt = 0;
}
}

for (p=(char *)ppstart; pplen >0;) {
/* skip extension */
if (subExt && p == ext) {
p += 4;
pplen -= 4;
continue;
}
if (*p == '%') {
unsigned int c;
sscanf(p+1, "%02x", &c);
*destptr++ = c;
pplen -= 3;
p += 3;
} else {
*destptr++ = *p++;
pplen--;
}
}
*destptr = '\0';

out->av_val = streamname;
out->av_len = destptr - streamname;
}

rtmpdump源代码（Linux）：http://download.csdn.net/detail/leixiaohua1020/6376561

rtmpdump源代码（VC 2005 工程）：http://download.csdn.net/detail/leixiaohua1020/6563163

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